Category: Class 11 Biology

NCERT Exemplar Class 11 Biology Chapter 8 Cell The Unit of Life are part of NCERT Exemplar Class 11 Biology. Here we have given NCERT Exemplar Class 11 Biology Chapter 8 Cell The Unit of Life. https://www.cbselabs.com/ncert-exemplar-problems-class-11-biology-chapter-8-cell-unit-life/

NCERT Exemplar Class 11 Biology Chapter 8 Cell The Unit of Life

Multiple Choice Questions

Q1. A common characteristic feature of plant sieve tube cells and most of mammalian erythrocytes is
(a) Absence of mitochondria (b) Presence of cell wall
(c) Presence of haemoglobin (d) Absence of nucleus
Ans: (d) A common characteristic feature of plant sieve tube cells and most of mammalian erythrocytes is absence of nucleus.

Q2. Select one which is not true for ribosomes.
(a) Made of two subunits (b) Form polysome
(c) May attach to mRNA (d) Have no role in protein synthesis
Ans: (d) Ribosomes is made of two subunits, form polysome and may attach to mRNA. Ribosomes are the site of protein synthesis.

Q3. Which one of these is not a eukaryote? .
(a) Euglena (b) Anabaena (c) Spirogyra (d) Agaricus
Ans: (b) Anabaena is a cynobacterium (prokaryote).

Q4. Which of the following dyes is not used for staining chromosomes?
(a) Basic Fuchsin (b) Salfanin
(c) Methylene green (d) Carmine
Ans: (b) Saffanin stain is not used for staining chromosomes while Basic Fuchsin, Methylene green and Carmine are used for staining chromosomes.

Q5. Different cells have different sizes. Arrange the following cells in an ascending order of their size. Choose the correct option among the following:
(i) Mycoplasma
(ii) Ostrich eggs
(iii) Human RBCs
(iv) Bacteria
(a) (i), (iv), (iii), (ii) (b) (i), (iii), (iv), (ii)
(c) (ii), (i), (iii), (iv) (d) (iii), (ii), (i), (iv)
Ans: (a) Ascending order of size:
Mycoplasma < Bacteria < Human RBCs < Ostrich eggs.

Q6. Which of the following features is common to prokaryotes and many eukaryotes?
(a) Chromatin material present
(b) Cell wall present
(c) Nuclear membrane present
(d) Membrane-bound subcellular organelles present
Ans: (b) Cell wall is present in all prokaryotes (except mycoplasma) and many eukaryotes (like plants and fungi).

Q7. Who proposed the fluid mosaic model of plasma membrane?
(a) Camillo Golgi (b) Schleiden and Schwann
(c) Singer and Nicolson (d) Robert Brown
Ans: (c) An improved model of the structure of cell membrane was proposed by
S.J. Singer and G.L. Nicolson (1972) widely accepted as fluid mosaic model.

Q8. Which of the following statements is true for a secretory cell?
(a) Golgi apparatus is absent.
(b) Rough Endoplasmic reticulum (RER) is easily observed in the cell.
(c) Only Smooth endoplasmic reticulum (SER) is present.
(d) Secretory granules are formed in nucleus.
Ans: (b) RER is frequently observed in the cells actively involved in protein synthesis and secretion. RER is well developed in cells engaged in synthesis of secretory products.

Q9. What is a tonoplast?
(a) Outer membrane of mitochondria
(b) Inner membrane of chloroplast
(c) Membrane boundary of the vacuole of plant cells
(d) Cell membrane of a plant cell.
Ans: (c) The vacuole is the membrane-bound space found in the cytoplasm. The vacuole is bound by a single membrane called tonoplast.

Q10. Which of the following is not true for an eukaryotic cell?
(a) Cell wall is made up of pepticjoglycans
(b) It has 80S type of ribosome present in the cytoplasm
(c) Mitochondria contain circular DNA
(d) Membrane bound organelles are present
Ans: (a) In bacteria (prokaryotes) cell wall is made up of peptidoglycan.

Q11. Which of the following statements is not true for plasma membrane?
(a) It is present in both plant and animal cell.
(b) Lipid is present as bilayer in it. .
(c) Proteins are present integrated as well as loosely associated with the lipid bilayer.
(d) Carbohydrates are never found in it.
Ans: (d) Chemical studies showed that the cell membrane is composed of lipids that are arranged in a bilayer. Later, biochemical investigation clearly revealed that the cell membranes also possess protein and carbohydrate.

Q12. Plastids differ from mitochondria on the basis of following features? Mark the right answer.
(a) Presence of two layers of membrane
(b) Presence of ribosome
(c) Presence of thylakoids
(d) Presence of DNA
Ans: (c) Thylakoids are present in plastids but not in mitochondria. Both plastids and mitochondria are similar in presence of two layers of membrane, presence of ribosome and presence of DNA.

Q13. Which of the following is not a function of cytoskeleton in a cell?
(a) Intracellular transport
(b) Maintenance of cell shape and structure
(c) Support of the organelle
(d) Cell motility
Ans: (a) The cytoskeleton in a cell are involved in many functions such as mechanical support, motility, maintenance of the shape of the cell.

Q14. The stain used to visualise mitochondria is
(a) Fast green (b) Saffanin (c) Aceto carmine(d) Janus green
Ans: (d) Janus green stain is used to visualise mitochondria.

Very Short Answer Type Questions
Q1. What is the significance of vacuole in a plant cell?
Ans: Vacuole in plant cells help in the storage, waste disposal and cell elongation and protection.

Q2. What does ‘S’ refer in a 70S and an 80S ribosome?
Ans: Svedberg’s Unit or sedimentation coefficient.

Q3. Mention a single membrane bound organelle which is rich in hydrolytic enzymes.
Ans: Lysosome

Q4. What are gas vacuoles? State their functions. ,
Ans: Gas vacuoles are aggregates of hollow cylindrical structures called gas vesicles. They are located inside some bacteria. The inflation and deflation of the vesicles provides buoyancy, allowing the bacterium to float at a desired depth in the water.

Q5. What is the function of a polysome? .
Ans: Several ribosomes may attach to a single mRNA and form a chain called polyribosome or polysome. The ribosomes of a polysome translate the mRNA into proteins.

Q6. What is the feature of a metacentric chromosome?
Ans: The metacentric chromosome has middle (medial) centromere forming two equal arms of the chromosome. Shape of metacentric chromosome is V-shaped.

Q7. What is referred to as satellite chromosome?
Ans: Sometimes a few chromosomes have non-staining secondary constrictions at a constant location. This gives the appearance of a small fragment called the satellite or trabant. These chromosomes are called sat (satellite) chromosome. Nucleolus is formed by sat chromosome.

Short Answer Type Questions
Q1. Discuss briefly the role of nucleolus in the cells actively involved in protein synthesis.
Ans: Nucleolus is a site for active ribosomal RNA synthesis. Larger and more numerous nucleoli are present in cells actively carrying out protein synthesis.

Q2. Explain the association of carbohydrate to the plasma membrane and its significance.
Ans: Carbohydrates forms glycoproteins and glycolipids by glycosylation. Glycoproteins and glycolipids are biochemicals that involved in cell recognition and adhesion.

Q3. Comment on the cartwheel structure of centriole.
Ans: Centrosome is an organelle usually containing two cylindrical structures called centrioles. Both the centrioles in a centrosome lie perpendicular to each other in which each has an organisation like the cartwheel. They are made up of nine evenly spaced peripheral fibrils of tubulin protein. Each of the peripheral fibril is a triplet. The adjacent triplets are also linked. The central part of the proximal region of the centriole is also proteinaceous and called the hub.

Q4. Briefly describe the cell theory.
Ans: Schleiden and Schwann together formulated the cell theory (1838-39). This theory, however, did not explain as to how new cells were formed. Rudolf Virchow (1855) first explained that cells divided and new cells are formed from pre-existing cells (Omnis cellula-e cellula). He modified the hypothesis of Schleiden and Schwann to give the cell theory a final shape. Cell theory as understood today is
(i) All living organisms are composed of cells and products of cells.
(ii) All cells arise from pre-existing cells.

Q5. Differentiate between Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER).
Ans: The ER often shows ribosomes attached to their outer surface. The endoplasmic reticulum bearing ribosomes on their surface is called rough endoplasmic reticulum (RER). In the absence of ribosomes they appear smooth and are called smooth endoplasmic reticulum (SER). RER is frequently observed in the cells actively involved in protein synthesis and secretion. They are extensive and continuous with the outer membrane of the nucleus. The smooth endoplasmic reticulum is the major site for synthesis of lipid. In animal cells lipid-like steroidal hormones are synthesised in SER.

Q6. Give the biochemical composition of plasma membrane. How are lipid molecules arranged in the membrane?
Ans: The detailed structure of the membrane was studied only after the advent of the electron microscope in the 1950s. Meanwhile, chemical studies on the cell membrane, especially in human red blood cells (RBCs), enabled the scientists to deduce the possible structure of plasma membrane. These studies showed that the cell membrane is composed of lipids that are arranged in a bilayer. Also, the lipids are arranged within the membrane with the polar head towards the outer sides and the hydrophobic tails towards the inner part. This ensures that the nonpolar tail of saturated hydrocarbons is protected from the aqueous environment. The lipid component of the membrane mainly consists of phosphoglycerides. Later, biochemical investigation clearly revealed that the cell membranes also possess protein and carbohydrate. The ratio of protein and lipid varies considerably in different cell types. In human beings, the membrane of the erythrocyte has approximately 52 per cent protein and 40 per cent lipids.

Q7. What are plasmids? Describe their role in bacteria?
Ans: In addition to the genomic DNA (the single chromosome/circular DNA), many bacteria have small circular DNA outside the genomic DNA. These smaller DNA are called plasmids. The plasmid DNA confers certain unique phenotypic characters to such bacteria. One such character is resistance to antibiotics. This plasmid DNA is used to monitor bacterial transformation with foreign DNA.

Q8. What are histones? What are their functions?
Ans: In eukaryotes there is a set of positively charged, basic proteins called histones. Histones are rich in the basic amino acid residues lysines and arginines. Both the amino acid residues carry positive charges in their side chains. Histones are organised to form a unit of eight molecules called as histone octamer. The negatively charged DNA is wrapped around the positively charged histone octamer to form a structure called nucleosome. A typical nucleosome contains 200 bp of DNA helix.

Long Answer Type Questions
Q1. What structural and functional attributes must a cell have to be called a living cell?
Ans: All cells have an outer membrane called the cell membrane. Inside each cell is a dense membrane bound structure called nucleus. This nucleus contains the chromosomes which in turn contain the genetic material, DNA. Cells that have membrane bound nuclei are called eukaryotic whereas cells that lack a membrane bound nucleus are prokaryotic. In both prokaryotic and eukaryotic cells, a semi-fluid matrix called cytoplasm occupies the volume of the cell. The cytoplasm is the main arena of cellular activities in both the plant and animal cells. Various chemical reactions occur in it to keep the cell in the ‘living state’.
Besides the nucleus, the eukaryotic cells have other membrane bound distinct structures called organelles like the endoplasmic reticulum (ER), the golgi complex, lysosomes, mitochondria, raicrobodies and vacuoles. The prokaryotic cells lack such membrane bound organelles. Ribosomes are non-membrane bound organelles found in all cells—both eukaryotic as well as prokaryotic.

Q2. Briefly give the contributions of the following scientists in formulating the cell theory
a. Rudolf Virchow
b. Schielden and Schwann
Ans: In 1838, Matthias Schleiden, a German botanist, examined a large number of plants and observed that all plants are composed of different kinds of cells which form the tissues of the plant. At about the same time, Theodore Schwann (1839), a British Zoologist, studied different types of animal cells and reported that cells had a thin outer layer which is today known as the ‘plasma membrane’. He also concluded, based on his studies on plant tissues, that the presence of cell wall is a unique character of the plant cells. On the basis of this, Schwann proposed the hypothesis that the bodies of animals and plants are composed of cells and products of cells. Schleiden and Schwann together formulated the cell theory. This theory however, did not explain as to how new cells were formed. Rudolf Virchow (1855) first explained that cells divided and new cells are formed from pre-existing cells (Omnis cellula-e c’ellula). He modified the hypothesis of Schleiden and Schwann to give the cell theory a final shape. Cell theory as understood today is :
(i) all living organisms are composed of cells and products of cells.
(ii) all cells arise from pre-existing cells.

Q3. Is extra genomic DN A present in prokaryotes and eukaryotes? If yes, indicate their location in both the types of organisms.
Ans: Yes, extra genomic DNA present in prokaryotes and eukaryotes. In addition to the genomic DNA (the single chromosome/circular DNA), many bacteria (prokaryotes) have small circular DNA outside the genomic DNA. These smaller extra genomic DNA are called plasmids. The plasmid DNA confers certain unique phenotypic characters to such bacteria. One such character is resistance to antibiotics. This plasmid DNA is used to monitor bacterial transformation with foreign DNA. In eukaryotes, extra genomic DNA is present in two organelles- mitochondria and plastids. ’

Q4. Structure and function are correlatable in living organisms. Can you justify this by taking plasma membrane as an example?
Ans: The shape of the cell may vary with the function they perform. For example, RBCs are round and biconcave to pass through capillaries and carry more Oz. WBCs are amoeboid to do phagocytosis and diapedesis.
The quasi-fluid nature of lipid enables lateral movement of proteins within the overall bilayer. This ability to move within the membrane is measured as its fluidity. The fluid nature of the membrane is also important from the point of view of functions like cell growth, formation of intercellular junctions, secretion, endocytosis, cell division etc.

Q5. Eukaryotic cells have organelles which may
a. not be bound by a membrane
b. bound by a single membrane
c. bound by a double membrane
Group the various sub-cellular organelles into these three categories.
Ans: a. Non-membrane bound cell organelles—Ribosome, Centrosome (Centriole), Nucleolus, Cytoskeletal structures.
b. Single membrane bound cell organelles—ER, GB, Lysosome, Vacuoles, Microbodies (Glyoxysomes and Peroxisomes), Thylakoid.
c. Double membrane bound cell organelles—Plastid, Mitochondria and Nucleus.

Q6. The genomic content of the nucleus is constant for a given species whereas the extra chromosomal DNA is found to be variable among the members of a population. Explain.
Ans: The genomic content of the nucleus is constant for a given species whereas the extra chromosomal DNA is found to be variable among the members of a population. For humans (Homo sapiens) the genomic content of the nucleus is constant, i.e. 46 chromosomes. But extra chromosomal DNA is found to be variable among the members of the population like different humans have different amount of extra chromosomal DNA in their mitochondria.

Q7. Justify the statement, “Mitochondria are power houses of the cell”.
Ans: Each mitochondrion is a double membrane-bound structure with the outer membrane and the inner membrane dividing its lumen distinctly into two aqueous compartments, i.e. the outer compartment and the inner compartment. The inner compartment is called the matrix. The outer membrane forms the continuous limiting boundary of the organelle. The inner membrane forms a number of infoldings called the cristae (sing.: crista) towards the matrix. The cristae increase the surface area. The two membranes have their own specific enzymes associated with the mitochondrial function. Mitochondria are the sites of aerobic respiration. They produce cellular energy in the form of ATP, hence they are called ‘power houses’ of the cell.

Q8. Is there a species specific or region specific type of plastids? How does one distinguish one from the other?
Ans: Yes, plastids are species specific or region specific. Plastids are found in all plant cells and in euglenoids. These are easily observed under the microscope as they are large. They bear some specific pigments, thus imparting specific colours to the plants. Based on the type of pigments plastids can be classified into chloroplasts, chromoplasts and leucoplasts. The chloroplasts contain chlorophyll and carotenoid pigments which are responsible for trapping light energy essential for photosynthesis. In the chromoplasts fat soluble carotenoid pigments like carotene, xanthophylls and others are present. This
gives the part of the plant a yellow, orange or red colour. The leucoplasts are the colourless plastids of varied shapes and sizes with stored nutrients: Amyloplasts store carbohydrates (starch), e.g., potato; elaioplasts store oils and fats whereas the aleuroplasts store proteins.

Q9. Write the functions of the following:
a. Centromere
b. Cell wall
c. Smooth ER
d. Golgi Apparatus
e. Centrioles
Ans: a. Centromere: Every chromosome essentially has a primary constriction or the centromere. Two sister chromatids are joined together at the centromere.
b. Cell wall: Cell wall not only gives shape to the cell and protects the cell from mechanical damage and infection, it also helps in cell-to-cell interaction and provides barrier to undesirable macromolecules.
c. Smooth ER: The smooth endoplasmic reticulum is the major site for synthesis of lipid. In animal cells lipid-like steroidal hormones are synthesised in SER.
d. Golgi Apparatus: Golgi apparatus is the important site of formation of glycoproteins and glycolipids.
e. Centrioles: The centrioles form the basal body of cilia or flagella, and spindle fibres that give rise to spindle apparatus during cell division in animal cells.

Q10. Are the different types of plastids interchangeable? If yes, give examples where they are getting converted from one type to another.
Ans: Yes, different types of plastids are interchangeable.
Conversion of green tomatoes (or chilli) into red form is due to formation of chromoplasts from chloroplasts. Chromoplasts also formed from leucoplasts by development of some pigments (like carotenes in carrot).

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NCERT Exemplar Class 11 Biology Chapter 6 Anatomy of Flowering Plants are part of NCERT Exemplar Class 11 Biology. Here we have given NCERT Exemplar Class 11 Biology Chapter 6 Anatomy of Flowering Plants. https://www.cbselabs.com/ncert-exemplar-problems-class-11-biology-chapter-6-anatomy-flowering-plants/

NCERT Exemplar Class 11 Biology Chapter 6 Anatomy of Flowering Plants

Multiple Choice Questions

Q1. A transverse section of stem is stained first with safranin and then with fast green following the usual schedule of double staining for the preparation of a permanent slide. What would be the colour of the stained xylem and phloem?
(a) Red and green (b) Green and red
(c) Orange and yellow (d) Purple and orange
Ans: (a) A transverse section of stem is stained first with safranin and then with fast green following the usual schedule of double staining for the preparation of a permanent slide. Red and green colour of the stained xylem and phloem appear.

Q2. Match the following and choose the correct option from below.

A.	Meristem	(i)	Photosynthesis, storage
B.	Parenchyma	(ii)	Mechanical support
C.	Collenchyma	(iii)	Actively dividing cells
D.	Sclerenchyma	(iv)	Stomata
E.	Epidermal tissue	(v)	Sclereids

Options:
(a) A—(i), B—(iii), C—(v), D—(ii), E—(iv)
(b) A—(iii), B—(i), C—(ii), D—(v), E—(iv)
(c) A—(ii), B—(iv), C—(v), D—(i), E—(iii)
(d) A—(v), B—(iv), C—(iii), D—(ii), E—(i)

Ans:

A.	Meristem	(iii)	Actively dividing cells                    •
B.	Parenchyma	(i)	Photosynthesis, storage
C.	Collenchyma	(ii)	Mechanical support
D.	Sclerenchyma	(v)	Sclereids
E.	Epidermal tissue	(iv)	Stomata

Q3. Match the following and choose the correct option from below.

A.	Cuticle	(i)	Guard cells
B.	Bulliform cells	(ii)	Single layer
C.	Stomata	(iii)	Waxy layer
D.	Epidermis	(iv)	Empty colourless cell

Options:
(a) A—(iii), B—(iv), C—(i), D—(ii)
(b) A—(i), B—(ii), C—(iii), D—(iv)
(c) A—(iii), B—(ii), C—(iv), D—(i)
(d) A—(iii), B—(ii), C—(i), D—(iv)

Ans. (a)

A.	Cuticle	(iii)	Waxy layer
B.	Bulliform cells	(iv)	Empty colourless cell
C.	Stomata	(i)	Guard cells
D.	Epidermis	(ii)	Single layer

Q4. Identify the simple tissue from among the following.
(a) Parenchyma (b) Xylem (c) Epidermis (d) Phloem
Ans: (a) A simple tissue is made of only one type of cells so the origin of simple tissue is homogenous. Parenchyma, collenchyma and sclerenchyma comes under simple tissue.

Q5. Cells of this tissue are living and show angular wall thickening. They also provide mechanical support. The tissue is
(a) Xylem (b) Sclerenchyma fc) Collenchyma (d) Epidermis
Ans: (c) Collenchyma occurs only in dicots. Collenchyma is living mechanical tissue having cellulosic cell wall. Collenchyma is found in climbing stems like Cucurbita. In Cucurbita lacunate or angular collenchyma is present.

Q6. Epiblema of roots is equivalent to
(a) Pericycle (b) Endodermis (c) Epidermis (d) Stele
Ans: (c) The outermost (piliferous) layer is epidermis (epiblema) or rhizodermis.

Q7. A conjoint and open vascular bundle will be observed in the transverse section of
(a) Monocot root (b) Monocot stem (c) Dicot root (d) Dicot stem
Ans: (d) Each vascular bundle is conjoint, collateral, open, and with endarch in protoxylem dicot stem.

Q8. Interfascicular cambium and cork cambium are formed due to
(a) Cell division (b) Cell differentiation
(c) Cell dedifferentiation (d) Redifferentiation
Ans: (c) Interfascicular cambium and cork cambium are formed due to cell dedifferentiation. .

Q9. Phellogen and phellem respectively denote
(a) Cork and cork cambium (b) Cork cambium and cork
(c) Secondary cortex and cork (d) Cork and secondary cortex
Ans: (b) Phellogen and phellem respectively denote cork cambium and cork.

Q10. In which of the following pairs of parts of a flowering plants is epidermis absent?
(a) Root tip and shoot tip (b) Shoot bud and floral bud
(c) Ovule and seed (d) Petiole and pedicel
Ans. (a) In root tip and shoot tip, epidermis is absent. .

Q11. How many shoot apical meristems are likely to be present in a twig of a plant possessing, 4 branches and 26 leaves?
(a) 26 (b) L (c) 5 (d) 30 (e) 4
Ans: (c) Five shoot apical meristems are likely to be present in a twig of a plant possessing 4 branches and 26 leaves.

Q12. A piece of wood having no vessels (trachea) must be belonging to
(a) Teak (b) Mango (c) Pine (d) Palm
Ans: (c) The presence of vessels is a characteristic feature of angiosperms.

Q13. A plant tissue, when stained, showed the presence of hemicellulose and pectin in cell wall of its cells. The tissue represents
(a) Collenchyma (b) Sclerenchyma (c) Xylem (d) Meristem
Ans: (a) A plant tissue, when stained, showed the presence of hemicellulose and pectin in cell wall of its cells. The tissue represents collenchyma.

Q14. In conifers fibres are likely to be absent in
(a) Secondary phloem (b) Secondary xylem
(c) Primary phloem (d) Leaves
Ans: (b) In conifers fibres are likely to be absent in secondary xylem.

Q15. When we peel the skin of a potato tuber, we remove
(a) Periderm (b) Epidermis (c) Cuticle (d) Sapwood
Ans: (a) When we peel the skin of a potato tuber, we remove periderm.

Q16. A vesselless piece of stem possessing prominent sieve tubes would belong to
(a) Pinus (b) Eucalyptus
(c) Grass (d) Trochodendron
Ans: (d) A vesselless piece of stem possessing prominent sieve tubes would belong to Trochodendron.

Q17. Which one of the following cell types always divides by anticlinal cell division?
(a) Fusiform initial cells (b) Root cap
(c) Protoderm (d) Phellogen
Ans: (c) Protoderm cell always divides by anticlinal cell division.

Q18. What is the fate of primary xylem in a dicot root showing extensive secondary growth?
(a) It is retained in the centre of the axis.
(b) It gets crushed.
(c) May or may not get crushed.
(d) It gets surrounded by primary phloem.
Ans: (a) The fate of primary xylem in a dicot root showing extensive secondary growth because it is retained in the centre of the axis.

Very Short Answer Type Questions

Q1. Product of photosynthesis is transported from the leaves to various parts of the plants and stored in some cell before being utilised. What are the cells/ tissues that store them?
Ans: Parenchyma –

Q2. Protoxylem is the first formed xylem. If the protoxylem lies next to phloem what kind of arrangement of xylem would you call it?
Ans: Exarch

Q3. What is the function of phloem parenchyma?
Ans: The phloem parenchyma stores food material and other substances like resins, latex and mucilage.

Q4. What is present on the surface of the leaves which helps the plant prevent loss of water but is absent in roots?
Ans: Cuticle is present on the surface of the leaves which helps the plant prevent loss of water but is absent in roots.

Q5. What is the epidermal cell modification in plants which prevents water loss?
Ans: In grasses, certain adaxial epidermal cells along the veins modify themselves into large, empty, colourless cells. These are called bulliform cells or motor cells. Bulliform cells help in folding and unfolding of grass leaves.
When the bulliform cells in the leaves have absorbed water and are turgid, the leaf surface is exposed. When they are flaccid due to water stress, they make the leaves curl inwards (inrolling) to minimise water loss (transpiration).

Q6. What part of the plant would show the following?
a. Radial vascular bundle
b. Polyarch xylem
c. Well developed pith
Ans: a. Radial vascular bundle: Root
b. Polyarch xylem: Monocot root
c. Well developed pith: Dicot stem and monocot root

Q7. What are the cells that make the leaves curl in plants during water stress?
Ans: Bulliform/motor cells

Q8. What constitutes the cambial ring?
Ans: Interfascicular cambium + intrafascicular cambium .

Q9. Give one basic functional difference between phellogen and phelloderm.
Ans. Phellogen is a couple of layers thick. It is made of narrow, thin-walled and nearly rectangular cells. Phellogen cuts off cells on both sides. The outer cells differentiate into cork or phellem while the inner cells differentiate into secondary cortex or phelloderm.

Q10. Arrange the following in the sequence you would find them in a plant starting from the periphery—phellem, phellogen, phelloderm.
Ans: Phellem -» phellogen -» phelloderm.

Q11. If one debarks a tree, what parts of the plant is being removed?
Ans: On debarking a tree, all tissue exterior to vascular cambium gets removed (i.e., periderm and 2° phloem).

Q12. The cross-section of a plant material showed the following features when viewed under the microscope.
a. The vascular bundles were radially arranged.
b. Four xylem strands with exarch condition of protoxylem.
To which organ should it be assigned?
Ans: Dicot root

Q13. What do hard wood and soft wood stand for?
Ans: Gymnosperm wood is called softwood due to absence of vessels (therefore it is called non-porous wood). Dicot angiospermic wood is called hardwood because it possess abundant vessels.

Short Answer Type Questions

Q1. While eating peach or pear it is usually seen that some stone like structures get entangled in the teeth, what are these stone like structures called?
Ans: The structures that get entangled in the teeth while eating fruits like peach and pear are actually the stone cells or brachysclereids which are unbranched, short and isodiametric type of sclereids. These stone cells usually occur in groups and provide grit or stone like hardness that get entangled in the spaces between teeth.

Q2. What is the commercial source of cork? How is it formed in the plant?
Ans: Commercial source of cork is oak (Quercus suber). As the stem continues to
increase in girth due to the activity of vascular cambium, the outer cortical and epidermis layers get broken and need to be replaced to provide new protective cell layers. Hence, sooner or later, another meristematic tissue called cork cambium or phellogen develops, usually in the cortex region. Phellogen is a couple of layers thick. It is made of narrow, thin-walled and
nearly rectangular cells. Phellogen cuts off cells on both sides. The outer cells differentiate into cork or phellem.

Q3. Below is a list of plant fibres. From which part of the plant these are obtained
a. Coir b. Hemp
c. Cotton d. Jute
Ans: a. Coir—Mesocarp of coconut fruit (drupe)
b. Hemp—Phloem or bast fibre
c. Cotton—Epidermal hair of seed
d. Jute—Phloem or bast fibre

Q4. What are the characteristic differences found in the vascular tissue of gymnosperms and angiosperms?
Ans.
• Xylem functions as a conducting tissue for water and minerals from roots to the stem and leaves. It also provides mechanical strength to the plant parts. It is composed of four different kinds of elements, namely, tracheids, vessels, xylem fibres and xylem parenchyrtia. Gymnosperms lack vessels in their xylem.
• Phloem transports food materials, usually from leaves to other parts of the plant. Phloem in angiosperms is composed of sieve tube elements, companion cells, phloem parenchyma and phloem fibres. Gymnosperms have albuminous cells and sieve cells. They lack sieve tubes and companion cells.

Q5. Epidermal cells are often modified to perform specialized functions in plants. Name some of them and function they perform.
Ans:
• Root hairs: The root hairs are unicellular elongations of the epidermal cells and help absorb water and minerals from the soil.
• Stem hairs or trichomes: On the stem the epidermal hairs are called trichomes. The trichomes in the shoot system are usually multicellular.
They may be branched or unbranched and soft or stiff. They may even be secretory. The trichomes help in preventing water loss due to transpiration.
• Bulliform cells: In grasses, certain adaxial epidermal cells along the veins modify themselves into large, empty, colourless cells. These are called
bulliform cells. When the bulliform cells in the leaves have absorbed water and are turgid, the leaf surface is exposed. When they are flaccid due to water stress, they make the leaves curl inwards to minimise water loss.

Q6. The lawn grass (Cyandon dactylon) needs to be mowed frequently to prevent its overgrowth. Which tissue is responsible for its rapid growth?
Ans: Intercalary meristem: The meristem which occurs between mature tissues is known as intercalary meristem. They occur in grasses and regenerate parts removed by the grazing herbivores.

Q7. Plants require water for their survival. But when watered excessively, plants die. Discuss.
Ans: Irrigation without proper drainage of water leads to waterlogging in the soil. Besides affecting the crops, waterlogging draws salt to the surface of the soil. The salt then is deposited as a thin crust on the land surface or starts collecting at the roots of the plants. This increased salt content is inimical to the growth of crops and is extremely damaging to agriculture and plants may die.

Q8. A transverse section of the trunk of a tree shows concentric rings which are known as growth rings. How are these rings formed? What is the significance of these rings?
Ans: The activity of cambium is under the control of many physiological and environmental factors. In temperate regions, the climatic conditions are not uniform through the year. In the spring season, cambium is very active and produces a large number of xylary elements having vessels with wider cavities. The wood formed during this season is called spring wood or early wood. In winter, the cambium is less active and forms fewer xylary elements that have narrow vessels, and this wood is called autumn wood or late wood.
The spring wood is lighter in colour and has a lower density whereas the autumn wood is darker and has a higher density. The two kinds of woods that appear as alternate concentric rings, constitute an annual ring. Annual rings seen in a cut stem give an estimate of the age of the tree.

Q9. Trunks of some of the aged tree species appear to be composed of several fused trunks. Is it a physiological or anatomical abnormality? Explain in detail.
Ans: Trunks of some of the aged tree species appear to be composed of several fused trunks. It is an anatomical abnormality. It is due to the abnormal secondary growth.

Q10. What is the difference between lenticels and stomata?
Ans: At certain regions, the phellogen cuts off closely arranged parenchymatous cells on the outer side instead of cork cells. These parenchymatous cells soon rupture the epidermis, forming a lensshaped openings called lenticels.
• Lenticels permit the exchange of gases between the outer atmosphere and the internal tissue of the stem. These occur in most woody trees. Lenticels remains open permanently.
• Stomata are structures present in the epidermis of leaves. Stomata regulate the process of transpiration and gaseous exchange. Each stoma is composed of two beanshaped cells known as guard cells which enclose stomatal pore. In grasses, the guard cells are dumb-bell shaped. The outer walls of guard cells (away from the stomatal pore) are thin and the inner walls (towards the stomatal pore) are highly thickened. The guard cells possess chloroplasts and regulate the opening and closing of stomata.

Q11. Write the precise function of:
a. Sieve tube
b. Interfasicular cambium
c. Collenchyma
d. Aerenchyma
Ans: a. Sieve tube—Conduction of food
b. Interfasicular cambium—Formation of vascular cambium
c. Collenchyma—Mechanical support
d. Aerenchyma—Provides buoyancy

Q12. The stomatal pore is guarded by two kidney shaped guard cells. Name the epidermal cells surrounding the guard cells. How does a guard cell differ from an epidermal cell? Use a diagram to illustrate your answer.
Ans: Stomata are structures present in the epidermis of leaves. Stomata regulate the process of transpiration and gaseous exchange. Each stoma is composed of two beanshaped cells known as guard cells which enclose stomatal pore. The guard cells possess chloroplasts which are absent in other epidermal cells. Sometimes, a few epidermal cells, in the vicinity of the guard cells become specialised in their shape and size and are known as subsidiary ceils.

 Q13. Point out the differences in the anatomy of, leaf of peepal (Ficus religiosa) and maize {Zea mays). Draw the diagrams and label the differences.
Ans: Leaf of peepal (Ficus religiosa) is an example of dorsiventral leaf (dicot) and maize (Zea mays) is an example of isobilateral leaf (monocot).

Dicot leaves                      ‘		Monocot leaves
1.	Dorsiventral	1.	Isobilateral
2.	Stomata usually present in lower surface.	2.	Surface equally present on both surfaces.
3.	Stomata have bean shaped guard cells.	3,	Stomata have dumb bell shaped guard cells.
4.	Mesophyll is differentiated in palisade and spongy parenchyma.	4.	Mesophyll is undifferentiated.
5.	Bulliform cells are absent.	5.	Bulliform cells are present.

Q14. Palm is a monocotyledonous plant, yet it increases in girth. Why and how?
Ans: A palm tree is a monocotyledonous plant and like all other monocots the stems do not have primary cambium in the vascular bundles. However, with age, the tree grows in diameter, though slowly, as a result of the growth of the ground tissue. A secondary cambium may be formed in the hypodermal region of the stem. The later forms the conjunctive tissue and patches of meristematic cell. The activity of the meristematic cells result in the formation of secondary vascular bundles.

Long Answer Type Questions

Q1. The arrangement of ovules within the ovary is known as placentation. What does the term placenta refer to? Draw various types of placentations in the flower as seen in T.S. and V.S.
Ans: Placentation: The arrangement of ovules within the ovary is known as placentation. The placentation are of different types namely, marginal, axile, parietal, basal, central and free central. In marginal placentation, the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows, as in pea. When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentation is said to be axile, as in china rose, tomato and lemon. In parietal placentation, the ovules develop on the inner wall of the ovary or on peripheral part. Ovary is one- chambered but it becomes two-chambered due to the formation of the false septum, e.g., mustard and Argemone. When the ovules are borne on central axis and septa are absent, as in Dianthus and Primrose the placentation is called free central. In basal placentation, the placenta develops at the base of ovary and a single ovule is attached to it, as in sunflower, marigold.

Q2. Deciduous plants shed their leaves during hot summer or in autumn. This process of shedding of leaves is called abscission. Apart from physiological changes what anatomical mechanism is involved in the abscission of leaves.
Ans: Anatomical mechanism involved in the abscission of leaves:
(1) Structural: In deciduous trees, an abscission zone, also called a separation zone, is formed at the base of the petiole. It is composed of a top layer that has cells with weak walls, and a bottom layer that expands in the autumn, breaking the weak walls of the cells in the top layer. This allows the leaf to be shed.
(2) The loss of chlorophyll may also contribute to the abscission process.
(3) Hormonal: Abscisic acid to be the hormone that stimulates abscission (for which the hormone was named).

Q3. Is Pinus an evergreen tree? Comment.
Ans: Yes, Pinus trees are evergreen, coniferous resinous trees. The leaves in gymnosperms are well-adapted to withstand extremes of temperature, humidity and wind. In conifers, the needle-like leaves reduce the surface area. Their thick cuticle and sunken stomata also help to reduce water loss. Unlike deciduous plants, Pinus do not shed their leaves so it is an evergreen tree.

Q4. Assume that a pencil box held in your hand, represents a plant cell. In how many possible planes can it be cut? Indicate these cuts with the help of line drawings.
Ans: When any plane passing through the central axis of the plant cell divides the cell into two identical halves, it is called radial symmetry. If the plant cell
can be divided into identical left and right halves in only one vertical plane, exhibit bilateral symmetry.

Q5. Each of the following terms has some anatomical significance. What do these terms mean? Explain with the help of line diagrams.
a. Plasmadesmoses/Plasmodesmata
b. Middle lamella
c. Secondary wall
Ans: a. Plasmodesmata are the protoplasmic strands between adjacent plant cells. Plasmodesmata connections help in movement of substances between cells.
b. The middle lamella is a layer mainly of calcium pectate which holds or glues the different neighbouring cells together. Middle lamella is made up of calcium pectate (mainly) and magnesium pectate.During ripening a fruit becomes soft and pulpy due to dissolution of middle lamella.
c. The cell wall of a young plant cell, the primary wall is capable of growth, which gradually diminishes as the cell matures and the secondary wall is formed on the inner (towards membrane) side of the cell. Secondary wall may have the deposition of lignin. Secondary wall help in the differentiation of the cell.

Q6. Distinguish between the following:
(a) Exarch and endarch condition of protoxylem
(b) Stele and vascular bundle
(c) Protoxylem and metaxylem
(d) Interfasicular cambium and intrafasicular cambium
(e) Open and closed vascular bundles
(f) Stem hair and root hair. .
Ans: (a) Exarch and endarch condition of protoxylem: In stems, the protoxylem lies towards the centre (pith) and the metaxylem lies towards the periphery of the organ. This type of primary xylem is called endarch. In roots, the protoxylem lies towards periphery and metaxylem lies towards the centre. Such arrangement of primary xylem is called exarch.
(b) Stele and vascular bundle: All tissues on the innerside of the endodermis such as pericycle, vascular bundles and pith constitute the stele. The vascular system consists of complex tissues, the phloem and the xylem. The xylem and phloem together constitute vascular bundles.
(c) Protoxylem and metaxylem: Primary xylem is of two types— protoxylem and metaxylem. The first formed primary xylem elements are called protoxylem and the later formed primary xylem is called
metaxylem.
(d) Interfasicular cambium and intrafasicular cambium; In dicot stems, the cells of cambium present between primary xylem and primary phloem is the intrafascicular cambium. The cells of medullary rays, adjoining these intrafascicular cambium become meristematic and form
the interfascicular cambium.
(e) Open and closed vascular bundles: In dicotyledonous stems, cambium is present between phloem and xylem. Such vascular bundles because of the presence of cambium possess the ability to form secondary xylem and phloem tissues, and hence are called open vascular bundles. In the monocotyledons, the vascular bundles have no cambium present in them. Hence, since they do not form secondary tissues they are referred to as closed.
(f) Stem hair and root hair: The root hairs are unicellular elongations of the epidermal cells and help absorb water and minerals from the soil. On the stem the epidermal hairs are called trichomes or stem hairs. The trichomes in the shoot system are usually multicellular. They may be branched or unbranched and soft or stiff. They may even be secretory. The trichomes help in preventing water loss due to transpiration.

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NCERT Exemplar Class 11 Biology Chapter 2 Biological Classification

Multiple Choice Questions
Single Correct Answer Type

Q1. All eukaryotic unicellular organisms belong to
(a) Monera (b) Protista (c) Fungi (d) Bacteria
Ans: (b) Monera—Kingdom of prokaryotes
• All eukaryotic unicellular organisms belong to protista.
Q2. The five kingdom classification was proposed by
(a) R.H. Whittaker . (b) C. Linnaeus
(c) A. Roxberg (d) Virchow
Ans: (a) This phylogenetic classification was proposed by R.H. Whittaker (1969). He created new kingdom ‘Fungi’. The five kingdom classification are as follows: 1. Plantae, 2. Animalia, 3. Protista. 4. Monera and 5. Fungi.
Whittaker has used 5 criteria for the 5 kingdom classification and are as follows:
1. Reproduction,
2. Cell structure,
3. Phylogenetic relationships,
4. Mode of nutrition,
5. Thallus organisation

Q3. Organisms living in salty areas are called as
(a) Methanogens (b) Halophiles
(c) Heliophytes (d) Thermoacidophiles
Ans: (b)
• Halophiles: Bacteria living in extremely salty areas.
• Thermoacidophiles: Bacteria living in hot springs/deep sea water.
E.g.: Thermococcus
• Methanogens: Bacteria living in marshy areas and produce methane gas.
• Heliophytes: Sun loving plants

Q4. Naked cytoplasm, multinucleated and saprophytic are the characteristics of
(a) Monerans (b) Protists (c) Fungi (d) Slime moulds
Ans: (d) Slime moulds are saprophytic protists, without cell walls. The spores
of slime moulds possess true walls. Thalloid multinucleate body of a slime mould is called plasmodium. Spores are dispersed by air currents.
E.g.: Acellular slime mould—Physarum, Cellular slime mould—Dictyostelium.

Q5. An association between roots of higher plants and fungi is called .
(a) Lichen (b) Fern (c) Mycorrhiza (d) BGA
Ans: (c) Lichens are symbiotic associations, i.e. mutually useful associations, between algae and fungi. This relationship is best known as helotism.

Q6. A dikaryon is formed when
(a) Meiosis is arrested
(b) The two haploid cells do not fuse immediately
(c) Cytoplasm does not fuse
(d) None of the above
Ans: (b) In some fungi the fusion of two haploid cells immediately results in diploid cells (2n). However, in other fungi (ascomycetes and basidiomycetes), an intervening dikaryotic stage (n + n, i.e. two nuclei per cell) occurs. Such a condition is called a dikaryon and the phase is called dikaryophase of fungus. A dikaryotic cell has two dissimilar haploid nuclei.

Q7. Contagium vivum fluidum was proposed by
(a) D. J. Ivanowsky (b) M. W. Beijerinck
(c) Stanley (d) Robert Hooke
Ans: (b) D.J. Ivanowsky (1892) discovered the virus and has recognised certain microbes as causal organism of the mosaic disease of tobacco. M.W. Beijerinck (1898) demonstrated that the extract of the infected plants of tobacco could cause infection in healthy plants and called the fluid as Contagium vivum fluidum (infectious living fluid). W. M. Stanley (1935) first time showed that viruses could be crystallised and crystals consist largely of proteins.

Q8. Association between mycobiont and phycobiont are found in
(a) Mycorrhiza (b) Root (c) Lichens (d) BGA
Ans. (c) Association between mycobiont and phycobiont are found in lichens.

Q9. Difference between virus and viroid is
(a) Absence of protein coat in viroid but present in virus
(b) Presence of low molecular weight RNA in virus but absent in viroid
(c) Both (a) and (b)
(d) None of the above
Ans: (a) Viroids are smaller than viruses and the cause of potato spindle tuber disease, chrysanthemum stunt disease. It was found to be a free RNA and lacked the protein coat that is found in viruses, hence the name viroid.

Q10. With respect to the fungal sexual cycle, choose the correct sequence of events.
(a) Karyogamy, plasmogamy and meiosis
(b) Meiosis, plasmogamy and karyogamy
(c) Plasmogamy, karyogamy and meiosis
(d) Meiosis, karyogamy and plasmogamy
Ans: (c) The sexual cycle involves the following three steps:
1. Fusion of protoplasms between two motile or non-motile gametes called
plasmogamy.
• Plasmogamy is fusion of two haploid cells without nuclear fusion.
2. Fusion of two nuclei is called karyogamy.
3. Meiosis in zygote resulting in haploid spores.

Q11. Viruses are non-cellular organisms but replicate themselves once they infect the host cell. To which of the following kingdom do viruses belong to?
(a) Monera (b) Protista (c) Fungi (d) None of these
Ans: (d) Viruses did not find a place in classification since they are not truly ‘living’ if we understand living as those organisms that have a cell structure. Viruses are neither prokaryotes nor eukaryotes. They are inert outside their specific host cell and cannot multiply of their own because they lack cellular machinery to use its genetic material. Viruses can only multiply in host or living cell.

Q12. Members of Phycomycetes are found in
(1) Aquatic habitats
(ii) On decaying wood
(iii) Moist and damp places
(iv) As obligate parasites on plants Choose from the following options.
(a) None of the above (b) (i) and (iv)
(c) (ii) and (iii) (d) All of the above
Ans: (d) Members of Phycomycetes are found in aquatic habitats, on decaying wood, moist and damp places and as obligate parasites on plants.

Very Short Answer Type Questions
Q1. What is the principle underlying the use of cyanobacteria in agricultural fields for crop improvement?
Ans: Cyanobacteria (BGA) are autotrophic microbes. Cyanobacteria are widely distributed in aquatic and terrestrial environments. Nostoc, Ariabaena and Oscillatoria are BGA that can fix atmospheric nitrogen. These organisms can fix atmospheric nitrogen in specialised cells called heterocysts, e.g., Nostoc and Anabaena. In paddy fields cyanobacteria serve as an important biofertiliser. BGA also add organic matter to the soil and increase its fertility.

Q2. Suppose you accidentally find an old preserved permanent slide without a label. In your effort to identify it, you place the slide under microscope and observe the following features:
a. Unicellular ‘
b. Well defined nucleus
c. Biflagellate—one flagellum lying longitudinally and the other transversely.
What would you identify it as? Can you iiame the kingdom it belongs to?
Ans: Dinoflagellates are unicellular eukaryotes. Most of them have two flagella; one lies longitudinally and the other transversely in a furrow between the wall plates. Dinoflagellates belongs to kingdom protista.

Q3. How is the five-kingdom classification advantageous over the two kingdom classification?
Ans: Two Kingdom system of classification with Plantae and Animalia kingdoms.
1. Two kingdom classification did not distinguish between the prokaryotes and eukaryotes. E.g.: It brought together the prokaryotic bacteria and blue green algae with other groups (like plant, fungi and animals) which were eukaryotic.
2. Two kingdom classification did not distinguish between the unicellular and multicellular organisms. E.g:: Chlamydomonas (unicellular) and Spirogyra (multicellular) were placed together under algae.
3. This system did not distinguish between autotrophic/photosynthetic (green algae and plants) and the heterotrophic/non-photosynthetic organisms (fungi).
Five Kingdom Classification:
1. Fungi were placed in a separate kingdom—kingdom fungi.
2. It has put together organisms which were placed in different kingdoms in earlier classifications.
Kingdom Protista brought together Chlamydomonas, Chlorella (earlier placed in algae within plants and both having cell walls) with Amoeba and Paramoecium (earlier plaeed in the animal kingdom and both lacking cell walls).
3. Animal and plant kingdoms become more homogenous than they are in the two kingdom classification. So, it is the advantageous over the two kingdom classification.

Q4. Polluted water bodies have usually very high abundance of plants like Nostoc and Oscillitoria. Give reasons.
Ans: Polluted water bodies (Ponds, ditches and rivers etc.) have usually nutrient contents (such as nitrate, phosphates) domestic sewage primarily contains biodegradable organic matter. Presence of large amount of nutrients in waters also causes excessive growth of Planktonic (free floating algae) called an algal bloom, which imparts a distinct colour to water bodies.
Algal bloom causes deterioration of the water quality and fish mortality. Some bloom forming algae mainly Nostoc and Oscillitoria are extremely toxic to human beings and animals.

Q5. Are chemosynthetic bacteria—autotrophic or heterotrophic?
Ans: Chemosynthetic bacteria oxidise various inorganic substances such as nitrates, nitrites and ammonia and use the released energy for their ATP production. So chemosynthetic bacteria are autotrophic in nature.

Q6. The common name of pea is simpler than its botanical (scientific) name Pisum sativum. Why then is the simpler common name not used instead of the complex scientific/botanical name in biology?
Ans: As we know that pea (vernacular name or local name) is simpler than its botanical (scientific) name Pisum sativum. These local names would vary from place to place, even within a country. Probably one would recognise the confusion that would be created if we did not find ways and means to talk to each other, to refer to organisms we are talking about.
Hence, there is a need to standardise the naming of living organisms such that a particular organism is known by the same name all over the world.

Q7. A virus is considered as a living organism and an obligate parasite when inside a host cell. But virus is not classified along with bacteria or fungi. What are the characters of virus that are similar to non-living objects?
Ans: Virus are living organisms inside a host cell. But virus is not classified along with bacteria or fungi because they having an inert crystalline structure outside the living cell. They are inert outside their specific host cell and cannot multiply of their own because they lack cellular machinery to use its genetic material.

Q8. In the five kingdom system of Whittaker, how many kingdoms are eukaryotes?
Ans: In the five kingdom system of Whittaker, four kingdoms (Protista, fungi,
plantae and animalia) belong to eukaryotes.

Short Answer Type Questions

Q1. Diatoms are also called as ‘pearls of ocean’, why? What is diatomaceous earth?
Ans: The diatoms are the unique organisms, because of their distinctive cell walls. The walls are embedded with silica and thus the walls are indestructible. It show sculpturing and ornamentation that why Diatoms are also called as ‘Pearls of Ocean’.
Diatoms have left behind large amount of cell wall deposits in their habitat; this accumulation over billions of years is referred to as ‘diatomaceous earth’. Being gritty this soil is used in polishing, filtration of oils and syrups. Diatoms are the chief ‘producers’ in the oceans.

Q2. There is a myth that immediately after heavy rains in forest, mushrooms appear in large number and make a very large ring or circle, which may be several metres in diameter. These are called as ‘Fairy rings’. Can you explain this myth of fairy rings in biological terms?
Ans: After heavy rains in forest, moisture and nutrients pass down in soil and activates the growth of mushroom mycelium. The basidiocarps of Agaricus (mushroom) arise from the mycelium present in the soil. They appear in a circle like a ring. As these basidiocarps resemble buttons and grow in rings, they are known as fairy rings.

Q3. Neurospora—an ascomycetes fungus has been used as a biological tool to understand the mechanism of plant genetics much in the same way as Drosophila has been used to study animal genetics. What makes Neurospora so important as a genetic tool?
Ans: Neurospora is used as a genetic tool because it is easy to grow and has a haploid life cycle that makes genetic analysis simple since recessive traits will show up in the offspring. Beadle and Tatum exposed Neurospora crassa to X-rays, causing mutations. This led them to propose the “one gene, one en2yme” hypothesis that specific genes code for specific proteins.

Q4. Cyanobacteria and heterotrophic bacteria have been clubbed together in Eubacteria of kingdom Monera as per the “Five Kingdom Classification” even though the two are vastly different from each other. Is this grouping of the two types of taxa in the same kingdom justified? If so, why?
Ans: Cyanobacteria and heterotrophic bacteria have been clubbed together in Eubacteria of Kingdom Monera as per the “Five Kingdom Classification” because they do not have nuclear envelope and membrane bound organelles. Their genetic material is naked. They have 70S type of ribosomes. So, cyanobacteria and heterotrophic bacteria are prokaryotes and belong, to Kingdom Monera.

Q5. At a stage of their cycle, ascomycetes fungi produce the fruiting bodies like apothecium, perithecium or cleistothecium. How are these three types of fruiting bodies different from each other?
Ans: An apothecium is a wide, open, saucer-shaped or cup-shaped fruit body. It is sessile and fleshy. A cleistothecium is a globose, completely closed fruit body with no special opening to the outside. Perithecium are flask shaped structures opening by a pore or ostiole (short papilla opening by a circular pore).

Q6. What observable features in Trypanosoma would make you classify it under Kingdom Protista?
Ans: Trypanosoma is classified under the Kingdom Protista because it is unicellular eukaryotes. It has well defined nucleus with nuclear envelope, membrane bound organelles, 80S ribosomes and flagella with 9 + 2 organisation.

Q7. Fungi are cosmopolitan, write the role of fungi in your daily life.
Ans: Dough which is used for making bread, is fermented by fungi Saccharomyces cerevisiae (Baker’s yeast).
Roquefort cheese are ripened by growing a specific fungi on them, which gives them a particular flavour.
Microbes mainly yeasts used for the production of beverages like wine, beer, whisky, brandy or rum. For this purpose the yeast (Saccharomyces cerevisiae) used for fermenting malted cereals and juices to produce ethanol and commonly called Brewer’s yeast

Antibiotics produced by Fungi:

1.	Penicillin	Penicillium notatum and Penicillium chrysogenum
2.	Griseofulvin	Penicillium griseofulvum
3.	Cephalosporin	Cephalosporium acremonium
4.	Gentomycin	Micromonospora purpurea

• Cyclosporin A is produced by Trichoderma polysporum (Fungus). Cyclosporin A is used as an immunosuppressive agent in organ transplant patients.
• Statins produced by Monascus purpureus(Yeast). Statins used as blood- cholesterol lowering agent.
• Mushrooms, morels (Morchella) and truffles are edible fungi.
• Fungi causes several diseases in plants and animals including human beings.

Long Answer Type Questions
Q1. Algae are known to reproduce asexually by variety of spores under different environmental conditions. Name these spores and the conditions under which they are produced.
Ans: Asexual reproduction is by the production of different types of spores, the most common being the zoospores. They are flagellated (motile) and on germination gives rise to new plants.
Types of asexual reproduction:
1. Zoospores: Motile and formed in favourable condition.
2. Aplanospores: Thin walled, non-motile and formed in unfavourable condition.
3. Hypnospore: Thick walled, non-motile and formed in unfavourable condition.
4. Akinete: Under unfavourable condition, entire cell becomes thick.
5. Palmella stage: In condition of drought, protoplast is surrounded by gelatinous covering.

Q2. Apart from chlorophyll, algae have several other pigments in their chloroplast. What pigments are found in blue-green, red and brown algae that are responsible for their characteristic colours?
Ans: Apart from chlorophyll, algae have several other pigments in their chloroplast like carotenoids, xanthophylis (fucoxanthin) and r-phycoerythrin. In blue- green algae phycocyanin and r-phycoerythrin pigments are present beside chlorophyll a.
• Brown algae possess chlorophyll a, c, carotenoids and xanthophylls. They vary in colour from olive green to various shades of brown depending upon the amount of the xanthophyll pigment, fucoxanthin present in them.
• Red algae possess chlorophyll a, d and phycoerythrin in their body. The members of rhodophyceae are commonly called red algae because of the predominance of the red pigment, r-phycoerythrin in their body.

Q3. Make a list of algae and fungi that have commercial value as source of food,
chemicals, medicines and fodder.
Ans:
A. Economic importance of Algae:
1. Many species of Porphyra, Laminaria and Sargassum are among the 70 species of marine, algae used as food. Chlorella and Spirullina are unicellular algae, rich in proteins and are used as food supplements even by space travellers.
2. Certain marine brown and red algae produce large amounts of hydrocolloids (water holding substances) or phycocolloids, e.g.: algin (brown algae) and carrageen (red algae) are used commercially. Agar, one of the commercial products obtained from Gelidium and Gracilaria are used to grow microbes and in preparations of ice-creams and jellies.
3. Bromine is obtained from red algae Polysiphonia. Macrocystis is the source of Potash. Laminaria and Fucus are the source of Iodine.
B. Economic importance of Fungi:
1. Mushrooms, morels (Morchella) and truffles are edible fungi.
2. Microbes mainly yeasts used for the production of beverages like wine, beer, whisky, brandy or rum. For this purpose the yeast {Saccharomyces cerevisiae) used for fermenting malted cereals and juices to produce ethanol and commonly called Brewer’s yeast.
• Cyclosporin A is produced by Trichoderma polysporum (Fungus). Cyclosporin A is used as an immunosuppressive agent in organ transplant patients.
• Statins produced by Monascus purpureus (Yeast). Statins used as the blood-cholesterol lowering agent.

Penicillin	Penicillium notatum and Penicillium chrysogenum
Griseofulvin	Penicillium griseofulvum
Cephalosporin	Cephalosporium acremonium
Gentomycin	Micromonospora purpurea

Q4. ‘Peat’ is an important source of domestic fuel in several countries. How is ‘peat’ formed in nature?
Ans: Species of Sphagnum, a moss, provide peat that have long been used as fuel and because of their capacity to hold water as packing material for trans-shipment of living material. Peat forms when plant material decaying fully by acidic and anaerobic conditions. Peat is soft and easily compressed. Under pressure, water in the peat is forced out. Upon drying, peat can be used as fuel.

Q5. Biological classification is a dynamic and ever evolving phenomenon which keeps changing with our understanding of life forms. Justify the statement taking any two examples.
Ans: Kingdom Protista brought together Chlamydomonas, Chlorella (earlier placed in algae within plants and both having cell walls) with Amoeba and Paramoecium (earlier placed in the animal kingdom and both lacking cell walls). Five kingdom classification has put together organism (like Chlamydomonas and Amoeba) which were placed in different kingdoms in earlier classifications. This change happened because the criteria for classification changed. This kind of changes will take place in future too depending on the improvement in our understanding of characteristics and evolutionary relationships. So, biological classification is a dynamic and ever evolving phenomenon which keeps changing with our understanding of life forms.

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NCERT Exemplar Class 11 Biology Chapter 5 Morphology of Flowering Plants are part of NCERT Exemplar Class 11 Biology. Here we have given NCERT Exemplar Class 11 Biology Chapter 5 Morphology of Flowering Plants. https://www.cbselabs.com/ncert-exemplar-problems-class-11-biology-chapter-5-morphology-flowering-plants/

NCERT Exemplar Class 11 Biology Chapter 5 Morphology of Flowering Plants

Multiple Choice Questions

Q1. Rearrange the following zones choose the correct option as seen in the root in vertical section and choose the correct option
(A) Root hair zone
(B) Zone of meristems
(C) Root cap zone
(D) Zone of Maturation
(E) Zone of elongation

(a) C, B, E, A, D
(b) A,B,C,D,E
(c) D , E , A , C , B
(d) E , D ,C ,B ,A

Ans: (a) (C) Root cap zone, (B) Zone of meristems, (E) Zone of elongation, (A) Root hair zone, (D) Zone of maturation

Q2. In an inflorescence where flowers are borne laterally in an acropetal succession, the position of the youngest floral bud shall be
(a) Proximal (b) Distal (d) Intercalary (d) Anywhere
Ans: (b) In racemose type of inflorescences the main axis continues to grow, the flowers are borne laterally in an acropetal succession, i.e. youngest flower is present at apex and oldest flower is present at the base. In racemose, inflorescence the growth of floral axis is unlimited or indefinite.
In cymose type of inflorescence the main axis terminates in a flower, hence is limited in growth. The flowers are borne in a basipetal. order, i.e. youngest flower is present at the base and oldest flower is present at the apex. In cymose inflorescence oldest flower remains in center and youngest towards the periphery. This type of arrangement is called centrifugal.

Q3. The mature seeds of plants such as gram and peas, possess no endosperm, because
(a) These plants are not angiosperms
(b) There is no double fertilization in them
(c) Endosperm is not formed in them
(d) Endosperm gets used up by the developing embryo during seed development.
Ans: (d) The mature seeds of plants such as gram and peas, possess no endosperm, because endosperm gets used up by the developing embryo during seed development.

Q4. Roots developed from parts of the plant other than radicle are called
(a) Tap roots (b) Fibrous roots
(c) Adventitious roots (d) Nodular roots
Ans: (c) Roots developed from parts of the plant other than radicle are called adventitious roots.

Q5. Venation is a term used to describe the pattern of arrangement of
(a) Floral organs (b) Flowers in inflorescence
(c) Veins and veinlets in a lamina (d) All of them
Ans: (c) Venation is a term used to describe the pattern of arrangement of veins and veinlets in a lamina.
Q6. Endosperm, a product of double fertilization in angiosperms is absent in the seeds of
(a) Coconut (b) Orchids (c) Maize (d) Castor
Ans: (b) Endosperm, a product of double fertilization in angiosperms is absent in the seeds of orchids. .

Q7. Many pulses of daily use belong to one of the families below (tick the correct
answer). –
(a) Solanaceae (b) Fabaceae (c) Liliaceae (d) Poaceae
Ans: (b) Many pulses of daily use belong to one of the family fabaceae. Solanaceae (potato family)
Liliaceae (lily family)
Poaceae (cereal or grass family). „

Q8. The placenta is attached to the developing seed near the
(a) Testa (b) Hilum (c) Micropyle (d) Chalaza
Ans: (b) The placenta is attached to the developing seed near the hilum.

Q9. Which of the following plants is used to extract the blue dye?
(a) Trifolium (b) Indigofera (c) Lupin (d) Cassia
Ans: (b) Blue dye is obtained from Indigofera tinctoria which belongs to family fabaceae.

Q10. Match the followings and choose the correct option.

Group A		Group B
A.	Aleurone layer	(i)	Without fertilization
B.	Parthenocarpic fruit	(ii)	Nutrition
C.	Ovule	(iii)	Double fertilization
D.	Endosperm	(iv)	Seed

Options:

• A—(i), B—(ii), C—(iii), D—(iv)
• A—(ii), B—(i), C—(iv), D—(iii)
• A—(iv), B—(ii), C—(i), D—(iii)
• A—(ii), B—(iv), C—(i), D—(iii)

Ans. (b)

A.	Aleurone layer	(ii)	Nutrition
B.	Parthenocarpic fruit	(i)	Without fertilization
C.	Ovule	(iv)	Seed
D.	Endosperm	(iii)	Double fertilization

Very Short Answer Type Questions

Q1. Roots obtain oxygen from air in the soil for respiration. In the absence or deficiency of 02, root growth is restricted or completely stopped. How do the plants growing in marshlands or swamps obtain their 02 required for root respiration?
Ans: In some plants such as Rhizophora and Sonneratia (mangrove plant) growing in swampy areas near river mouths (saline marshy soil or halophytes), many roots come out of the ground and grow vertically upwards (negatively geotropic: against gravitational force). Such roots, called pneumatophores or breathing roots or respiratory roots, help to get oxygen for respiration.

Q2. Write floral formula for a flower which, is bisexual; actinoiflorphic; sepals five, twisted aestivation, petals five; valvate aestivation; stamens six; ovary tricarpellary, syncarpous, superior, trilocular with axile placentation.

Q3. In Opuntia the stem is modified into a flattened green structure to perform the function of leaves (i.e., photosynthesis). Cite some other examples of modifications of plant parts for the purpose of photosynthesis.
Ans: Some plants of arid regions modify their stems into flattened {Opuntia), or fleshy cylindrical {Euphorbia) structures. These modified stems of indefinite growth are called phylloclades. They contain chlorophyll and carry out photosynthesis.

Q4. In swampy areas like the Sunderbans in West Bengal, plants bear special kind
of roots called __________ .
Ans: Pneumatophores

Q5. In aquatic plants like Pistia and Eichhomia, leaves and roots are found near
Ans: Node

Q6. Reticulate and parallel venation are characteristic of ________ and ______ respectively.
Ans: Dicotyledons and monocotyledons

Q7. Which parts in ginger and onion are edible?
Ans: Ginger: rhizome and onion: fleshy leaves

Q8. In epigynous flower, ovary is situated below the _________.
Ans: Calyx, corolla and androecium.

Q9. Add the missing floral organs of the given floral formula of Fabaceae.

Short Answer Type Questions

Q1. Give two examples of roots that develop from different parts of the angiospermic plant other than the radicle.
Ans: The root that arise from parts of plant other than radicle are called adventitious roots.
Pneumatophores—for respiration Stilt roots—for support Prop roots—for support

Q2. The essential functions of roots are anchorage and absorption of water and minerals in the terrestrial plant. What functions are associated with the roots of aquatic plants? How are roots of aquatic plants and terrestrial plants different?
Ans: The roots of aquatic plants help in balancing and anchorage. In terrestrial plants, functions of roots are anchorage and absorption of water and minerals.

Q3. Draw diagrams of a typical monocot and dicot leaves.to show their venation pattern.

Q4. A typical angiosperm flower consists of four floral parts. Give the names of the floral parts and their arrangements sequentially.
Ans: A typical flower has four different kinds of whorls arranged successively on the swollen end of the stalk or pedicel, called thalamus or receptacle. These are calyx, corolla, androecium and gynoecium. The calyx is the outermost whorl of the flower and the members are called sepals. Corolla is the second outermost whorl composed of petals. Androecium is the second innermost whorl composed of stamens. Gynoecium is the innermost whorl which is female reproductive part of the flower and is made up of one or more carpels.

Q5. Given below are a few floral formulae of some well known plants. Draw floral diagrams from these formulae.

Q6. Reticulate venation is found in dicot leaves while in monocot leaves venation is of parallel type. Biology being a ‘Science of exceptions’, find out any exception to this generalization.
Ans: Smilax and Dioscorea are monocots having reticulate venation. Calophyllum and Eryngium are dicots having parallel venation.

Q7. You have heard about several insectivorous plants that feed on insects. Nepenthes or the pitcher plant is one such example, which usually grows in shallow water or in marsh lands. What part of the plant is modified into a ‘pitcher’? How does this modification help the plant for food even though it can photosynthesize like any other green plant?
Ans: In Nepenthes, picher is modified lamina. Insectivorous plants capable of growing in nitrogen or nitrate deficient soil. Pitcher help in providing the nitrogen to the plant. Leaves also photosynthesize their food.

Q8. Mango and coconut are ‘drupe’ type of fruits. In mango fleshy mesocarp is edible. What is the edible part of coconut? What does milk of tender coconut represent?
Ans: Edible part of coconut is endosperm or seed. Milk of tender coconut represent free nuclear liquid endosperm.

Q9. How can you differentiate between free central and axile placentation?
Ans: When the ovules are borne on central axis and septa are absent, as in Dianthus
and Primrose the placentation is called free central.
When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentation is said to be axile, as in China rose, tomato and lemon.

Q10. Tendrils are found in the following plants. Identify whether they are stem tendrils or leaf tendrils,
a.Cucumber
b. Peas
c. Pumpkins 
. Grapevine
e. Watermelons
Ans. a. Cucumber—stem tendrils
b. Peas Leaf Tendrils
c. Pumpkins—stem tendrils
d. Grapevine – stem tendrils
e. Watermelons—stem tendrils

Q11. Why is maize grain usually called as a fruit and not a seed?
Ans: Maize is an example of caryopsis fruit which is a simple, one seeded dry, indehiscent fruit in which pericarp and testa are fused. Pericarp is also called fruit wall which is present in maize grain, hence maize grain is actually a fruit and not a seed.

Q12. Tendrils of grapevines are homologous to the tendril of pumpkins but are analogous to that of pea. Justify the above statement.
Ans: Tendrils of grapevines are homologous to the tendril of pumpkins because both are the modification of stem (i.e., stem tendrils). Homologous structure have same origin.
Analogous structure have different origin but similar function. Tendrils of grapevines are analogous to that of pea because tendrils of grapevines are modification of stem while tendrils of pea are modification of leaves. Both have different origin but performing same function, i.e., support.

Q13. Rhizome of ginger is like the roots of other plants that grows underground. Despite this fact ginger is a stem and not a root. Justify. .
Ans:Rhizome is a underground stem growing parallel to soil surface. Ginger is a stem which can be differentiated from root as it has nodes and intemodes.

Q14. Differerifiate between.
a. Bract and Bracteole
b. Pulvinus and petiole
c. Pedicel and peduncle
d. Spike and spadix
e. Stamen and staminoide
f. Pollen and pollenium
Ans: a. Reduced leaf found at the base of the pedicel is called bract while leaf like structure present between bract and flower is called bracteole.
b. In some leguminous plants the leafbase may become swollen is called pulvinus. The petiole (mesopodium) connect the leafbase with lamina and help hold the blade to light.
c. Pedicie is the stalk of flower while peduncle is the stalk of inflorescence.
d. In spike sessile flowers are attached on elongated peduncle. E.g.: Achyranthes. Spadix is a special type of spike having a fleshy peduncle and a large brightly coloured bract called spathe. E.g.: Palm, Colocasia.
e. Androecium is composed of stamens. Each stamen represents the male reproductive organ. A sterile stamen is called staminode.
f. Male gametophyte of angiosperms is called pollen or microspore. A group of pollens forms the pollinium (present in Calotropis).

Long Answer Type Questions
1. Distinguish between families Fabaceae, Solanaceae, Liliaceae on the basis of gynoecium characteristics (with figures), Also write economic importance of any one of the above family.
Ans: a. Gynoecium
i. Fabaceae— Monocarpellary, ovary unilocular, marginal placentation

ii. Solgnaceae—Bicarpellary,* syncarpous, carpels placed obliquely, bilocular, axile placentation

iii. Liliaceae—Tricarpellary, syncarpous, ovary superior, axile placentation

b. Economic importance of fabacae:
i. Source of pulses (gram, arhar)
ii. Edible oil (soyabean, groundnut)
iii. Dye (Indigofera)
iv. Fibres (sunhemp)
v. Fodder (Sesbania, Trifolium)
vi. Ornamental {Lupin)
vii. Medicine (mulaithi)

Q2. Describe various stem modifications associated with food storage, climbing and protection.
Ans: The stem may not always be typically like what they are expected to be. They are modified to perform different functions. Underground stems of potato, ginger, turmeric, zaminkand, Colocasia are modified to store food in them. They also act as organs of perennation to tide over conditions unfavourable for growth. Stem tendrils which develop from axillary buds, are slender and spirally coiled and help plants to climb such as in gourds (cucumber, pumpkins, watermelon) and grapevines. Axillary buds of stems may also get modified into woody, straight and pointed thorns. Thoms are found in many plants such as Citrus, Bougainvillea. They protect plants from browsing animals. Some plants of arid regions modify their stems into flattened {Opuntia), or fleshy cylindrical {Euphorbia) structures. They contain chlorophyll and carry out photosynthesis.

Q3. Stolon, offset and rhizome are different forms of stem modifications. How can these modified forms of stem be distinguished from each other?
Ans: Underground stems called stolon of some plants spread to new niches and when older parts die new plants are formed.
OfFest: A lateral branch with short intemodes and each node bearing a rosette of leaves and a tuft of roots is found in aquatic plants like Pistia and Eichhornia.
Rhizome is underground stem growing parallel to soil surface. In ginger, turmeric, Gloriosa and lotus stem is called rhizome which is differentiated from roots in having scale leaves and axillary buds and helps in vegetative propagation.

Q4. The mode of arrangements of sepals or petals in a floral bud is known as aestivation. Draw the various types of aestivation possible for a typical pentamerous flower.
Ans: The mode of arrangement of sepals or petals in floral bud with respect to the other members of the same whorl is known as aestivation. The main types of aestivation are valvate, twisted, imbricate and vexillary. When sepals or petals in a whorl just touch one another at the margin, without overlapping, as in Calotropis, it is said to be valvate. If one margin of the appendage overlaps that of the next one and so on as in china rose, lady’s finger and cotton, it is called twisted. If the margins of sepals or petals overlap one another but not in any particular direction as in Cassia and gulmohur, the aestivation is called imbricate. –
In pea, bean and Crotolaria flowers, there are five petals, the largest (standard) overlaps the two lateral petals (wings) which in turn overlap the two smallest anterior petals (keel); this type of aestivation is known as vexillary or papilionaceous (or descending imbricate).

Q5. The arrangements of ovules within the ovary is known as placentation. What does the term placenta refer to? Name and draw various types of placentations in the flower as seen in T.S. or V.S.
Ans: The ovules are female reproductive structures and borne in the ovary of the flower. The number, structure, their position in the ovary varies in different plants. They also differ in mode of attachment with the ovary wall. At the point of attachment there is a cellular ridge or cushion of cells called placenta. The mode of attachment of ovule to the placenta is known as placentation which is of the following types: (a) Parietal (b) Marginal (c) Axile (d) Free central (e) Basal.

 

Q6. Sunflower is not a flower. Explain.
Ans: Sunflower is actually an inflorescence (capitulum), it is not a flower.
Capitulum (Head): Here the peduncle is flattened which is called receptacle. Inflorescence is surrounded by whorl of bracts collectively called involucre. On receptacle two kinds of florets are present: .
1. Ray florets: Zygomorphic, unisexual female, corolla ligulate or strap shaped.
ii. Disc florets: Actinomorphc, bisexual, corolla tubular, present in centre. Ray florets present towards periphery and disc florets present in the centre, e.g.: Compositae (Asteraceae) family—Sunflower (Helianthus), Tagetus (Marigold) and Dahlia.

Q7. How do you distinguish between hypogeal germination and epigeal germination? What is the role of cotyledon (s) and the endosperm in the germination of seeds?
Ans: 1. Hypogeal Germination: When the epicotyl grows first, only the plumule is pushed out of the soil. While cotyledons and all other parts remain under the soil, the germination is called hypogeal. E.g.: Most of the monocots (Maize^’ Rice and Coconut) and some of the dicots (Pea, Gram, Broad bean = Vicia faba, Mango).
2. Epigeal Germination: When hypocotyl grows first, it pushes the cotyledons and other parts of the seed out of the soil. This germination is called epigeal. E.g.: Helianthus (sunflower), mustard, cucurbits, castor, Onion, Tamarindus, French bean, Alisma.

Q8. Seeds of some plants germinate immediately after shedding from the plants while in other plants they require a period of rest before germination. The later phenomena is called as dormancy. Give the reasons for seed dormancy and some methods to break it.
Ans: There are certain seeds which fall to germinate even when external conditions are favourable. Such seeds are understood to be undergoing a period of dormancy which is controlled not by external environment but are under endogenous control or conditions within the seeds itself.
Reasons for seed dormancy:
• Impermeable and hard seed coat; presence of chemical inhibitors such as abscisic acid (ABA), phenolic acid; para-ascrobic acid; and immature embryos are some of the reasons which causes seed dormancy.
Methods of breaking seed dormancy:
• Seed dormancy allows the plants to overcome unfavourable climatic conditions. This dormancy however can be overcome through natural means and various other man-made measures. For example, the seed coat barrier in some seeds cane be broken by mechanical abrasions are caused by microbial action, and passage through digestive tract of animals. Weakening of hard seed coat with sharp edge or knives is called scarification. Prechilling treatment to break seed dormancy is called stratification. Effect of inhibitory substances can be removed by subjecting the seeds to chilling conditions or by application of certain chemical like gibberellic acid and nitrates. Seed domancy is also breaked by auxin and cytokinin. Changing the environment conditions, such as light and temperature and other methods to overcome seed dormancy.

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NCERT Exemplar Class 11 Biology Chapter 3 Plant Kingdom are part of NCERT Exemplar Class 11 Biology. Here we have given NCERT Exemplar Class 11 Biology Chapter 3 Plant Kingdom. https://www.cbselabs.com/ncert-exemplar-problems-class-11-biology-chapter-3-plant-kingdom/

NCERT Exemplar Class 11 Biology Chapter 3 Plant Kingdom

Multiple Choice Questions

Q1. Cyanobacteria are classified under
(a) Protista (b) Plantae (c) Monera (d) Algae
Ans: (c) Cyanobacteria are classified under Kingdom Monera.
• Protista— unicellular eukaryotes
• Plantae, all members of Kingdom Plantae are eukaryotic chloroplast ‘chlorophyll containing organisms commonly called plants. These are autotrophic/holophytic.

Q2. Fusion of two motile gametes which are dissimilar in size is termed as
(a) Oogamy (b) Isogamy (c) Anisogamy (d) Zoogamy
Ans: (c) Fusion of two motile gametes which are dissimilar in size is termed as anisogamy.

Q3. Holdfast, stipe and frond constitute the plant body in case of
(a) Rhodophyceae (b) Chlorophyceae
(c) Phaeophyceae (d) All of the above
Ans: (c) The plant body of phaeophyceae is usually attached to the substratum by a holdfast, and has a stalk, the stipe and leaf like photosynthetic organ—the frond.

Q4. A plant shows thallus level of organization. It shows rhizoids and is haploid. It needs water to complete its life cycle because the male gametes are motile. It may belong to
(a) Pteridophytes (b) Gymnosperms
(c) Monocots (d) Bryophytes
Ans: (d) A plant shows thallus level of organization. It shows rhizoids and is haploid. It needs water to complete its life cycle because the male gametes are motile. It may belong to bryophytes.

Q5. A prothallus is ‘ ‘
(a) A structure in pteridophytes formed before the thallus develops
(b) A sporophytic free living structure formed in pteridophytes
(c) A gametophyte free living structure formed in pteridophytes
(d) A primitive structure formed after fertilization in pteridophytes
Ans. (c) In pteridophytes, meiosis or R/D occurs at the time of spore formation. The spores germinate to give rise to inconspicuous, small but multicellular, free-living, mostly photosynthetic thalloid gametophytes called prothallus. Prothallus tepresents the gametophytic phase in pteridophytes.

Q6. Plants of this group are diploid and well adapted to extreme conditions. They grow bearing sporophylls in compact structures called cones. The group in reference is
(a) Monocots (b) Dicots
(c) Pteridophytes (d) Gymnosperms
Ans: (d) Plants of this group are diploid and well adapted to extreme conditions. They grow bearing sporophylls in compact structures called cones. The group in reference is gymnosperms.

Q7. The embryo sac of an Angiosperm is made up of
(a) 8 cells .(b) 7 cells and 8 nuclei
(c) 8 nuclei (d) 7 cells and 7 nuclei
Ans: (b) The embryo sac of an Angiosperm is made up of 7 cells and 8 nuclei.

Q8. If the diploid number of a flowering plant is 36, what would be the chromosome number in its endosperm?
(a) 36 (b) 18 (c) 54 ‘ (d) 72
Ans: (c) Diploid number (2«) of a flowering plant is 36.
The chromosome number in its endosperm 3n = 54.

Q9. Protonema is
(a) Haploid and is found in mosses
(b) Diploid and is found in liverworts
(c) Diploid and is found in pteridophytes
(d) Haploid and is found in pteridophytes
Ans: (a) The predominant stage of the life cycle of a moss is the gametophyte which consists of two stages. The first stage is the protonema stage (juvenile stage) and the second stage is the leafy stage. Moss protonema resembles to multicellular green algae in structure. Moss plant develops from protonema.

Q10. The giant Redwood tree (Sequoia sempervirens) is a/an .
(a) Angiosperm (b) Free fern
(c) Pterdophyte (d) Gymnosperm
Ans: (d) One of the gymnosperms, the giant redwood tree Sequoia is one of the tallest tree species.

Very Short Answer Type Questions

Q1. Food is stored as Floridean starch in Rhodophyceae. Mannitol is the reserve food material of which group of algae?
Ans: Mannitol is the reserve food material of brown algae or phaeophyceae.

Q2. Give an example of plants with
a. Haplontic life cycle
b. Diplontic life cycle
c. Haplo-diplontic life cycle
Ans: a. Haplontic life cycle—Volvox, Spirogyra and some species of Chlamydomonas
b. Diplontic life cycle—AH seed-bearing plants, i.e. (gymnosperms and angiosperms)
c. Haplo-diplontic life cycle—Bryophyfes and Pteridophytes

Q3. The plant body in higher plants is well differentiated and well developed. Roots are the organs used for the purpose of absorption. What is the equivalent of roots in the less developed lower plants?
Ans: In lower plants like algae, holdfast is present and in bryophytes, rhizoids are present instead of roots.

Q4. Most algal genera show haplontic life style. Name an alga which is
a. Haplo-diplontic
b. Diplontic
Ans: a. Haplo-diplontic—Ectocarpus, Polysiphonia and Kelps b. Diplontic—Fucus

Q5. In Bryophytes male and female sex organs are called _______ and __________
Ans: In Bryophytes male sex organ is called antheridium and female sex organ is called archegonium.

Short Answer Type Questions

Q1. Why are bryophytes called the amphibians of the plant kingdom?
Ans: Bryophytes are also called amphibians of the plant kingdom because these . plants can live in soil but are dependent on water for sexual reproduction.

Q2. The male and female reproductive organs of several pteridophytes and gymnosperms are comparable to floral structures of angiosperms. Make an attempt to compare the various reproductive parts of pteridophytes and gymnosperms with reproductive structures of angiosperms

Ans.

	Reproductive parts of pteridophytes and gymnosperms	Reproductive structures of angiosperms
(0	Strobili/cone	Flower
(ii)	Microsporophyll	Stamen
(iii)	Megasporophyll	Pistil/Carpel
(iv)	Microsporangium	Anther
(v)	Megasporangium	Ovule

 

Q3. Heterospory, i.e. formation of two types of spores—microspores and megaspores is a characteristic feature in the life cycle of a few members of pteridophytes and all spermatophytes. Do you think heterospory has some evolutionary significance in plant kingdom?
Ans: In majority of the pteridophytes all the spores are of similar kinds, such plants are called hom’osporous. Genera like Selaginella, Salvirtia, Marsilea and Azolla which produce two kinds of spores, macro (large) and micro (small) spores are known as heterosporous. The megaspores and microspores germinate and give rise to female and male gametophytes, respectively.
The female gametophytes in these plants are retained on the parent sporophytes for variable periods. The development of the zygotes into young embryos take place within the female gametophytes. This event is a precursor to the seed habit considered an important step in evolution.

Q4. How far does Selaginella one of the few living members of lycopodiales (pteridophytes) fall short of seed habit?
Ans: Selaginella produce two kinds of spores, macro (large) and micro (small) spores. The megaspores and microspores germinate and give rise to female and male gametophytes, respectively. But Selaginella falls short of seed habit due to lack of integument around the megasporangium.

Q5. Each plant or group of plants has some phylogenetic significance in relation to evolution: Cycas, one of the few living members of gymnosperms is called as the ‘relic of past’. Can you establish a phylogenetic relationship of Cycas with any other group of plants that justifies the above statement?
Ans: Cycas, one of the few living members of gymnosperms is called as the ‘relic of past’ because it shows many characteristics which are similar to pteridophytes, like, flagellated antherozoids, circinate ptyxis, megasporophyll is leaf like, presence of archegonia, etc.

Q6. The heterosporous pteridophytes show certain characteristics, which are precursor to the seed habit in gymnosperms. Explain.
Ans: In majority of the pteridophytes all the spores are of similar kinds, such plants are called homosporous. Genera like Selaginella, Salvinia, Marsilea and Azolla which produce two kinds of spores, macro (large) and micro (small) spores, are known as heterosporous. The megaspores and microspores germinate and give rise to female and male gametophytes, respectively.
The female gametophytes in these plants are retained on the parent sporophytes for variable periods. The development of the zygotes into young embryos take place within the female gametophytes. This event is a precursor to the seed habit considered an important step in evolution.

Q7. Comment on the life cycle and nature of a fern prothallus.
Ans: The diploid sporophyte is represented by a dominant, independent, photosynthetic, vascular plant body. It alternates with multicellular, saprophytic/autotrophic, independent but short-lived haploid gametophyte . called prothallus. Such a pattern is known as haplo-diplontic life cycle. All
pteridophytes exhibit this pattern.
These gametophytes require cool, damp, shady places to grow. Because of this specific restricted requirement and the need of water for fertilisation, the spread of living pteridophytes is limited and restricted to narrow geographical regions. The gametophytes (prothallus) bear male and female sex organs ‘ called antheridia and archegonia, respectively.
Water is required for transfer of antherozoids—the male gametes released from the antheridia, to the mouth of archegonium. Fusion of male gamete … with the egg present in the archegonium result in the fonnation of zygote.
• Zygote thereafter produces a multicellular well-differentiated sporophyte which is the dominant phase of the pteridophytes.

Q8. How arc the male and female gametophytes of pteridophytes and gymnosperms different from each other?
Ans: Male and female gametophytes of pteridophytes are free living while in gymnosperms male and female gametophyte do not have free-living * existence. They remain within the sporangia retained on sporophytes

Pteridophytes		Gymnosperms
(0	Flagellated male gamete	(a)	Non-flagellated male gamete
(ii)	Water is essential for fertilisation	(b)	Water is not essential
(iii)	Pollen tubes are not formed	(c)	Pollen tubes are formed
(iv)	Archegonia with neck canal cells	(d)	Neck canal cells are absent

Q9. In which plant will you look for mycorrhiza and corolloid roots? Also explain w’hat these terms mean.
Ans: Roots in some genera have fungal association in the form of mycorrhiza (Finns), while in some others (Cvms) small specialised roots called coralloid roots are associated with N2-fixing cyanobacteria

Long Answer Type Questions

Q1. Gametophyte is a dominant phase in the life cycle of a bryophyte. Explain.
Ans: The main plant body of the biyophyte is haploid. It produces gametes, hence is called a gametophyte. The sex organs in bryophytes are multicellular.
The male sex organ is called antheridium. They produce biflagellate antherozoids or biciliated sperms. The female sex organ called archegonium is flask-shaped and produces a single egg. The antherozoids are released into water where they come in contact with archegonium. An antherozoid fuses with the egg to produce the zygote. Zygote do not undergo reduction division immediately. They produce a multicellular body called a sporophyte.

Q2. With the help of a schematic diagram, describe the haplo–diptontic life cycle pattern of a plant group.
Ans: In a sexually reproducing plant there is an alternation of generation between a haploid and a diploid phase of plant bodies. The haploid plant body is termed gametophyte while the diploid plant body is called sporophyte. The gametophyte produces gametes by mitosis while the haploid spores are produced by sporophyte following meiosis (reduction division). Two gamete fuse together to produce a zygote which develops into the diploid sporophyte.

In a haplodiplontic life cycle pattern, such as in bryophyta or pteridophyta both the phases of life are multicellular. However, in bryophytes, the gametophytes are small, photosynthetic, independent and represent dominant phase. The partly or totally dependent sporophyte is physically attached to the gametophyte. The (n) spores dispersed by sporophyte germinate into individual gametophytic plants. However, in pteridophytes the 2n (diploid) phase is dominant, well organized, independent while the n phase though also free-living and independent is short lived and photosynthetic. In both of these groups of plants the mobile male gametes, antherozoid produced by sex organ antheridium, travel to archegonium (bearing an egg cell) via the medium of water. Egg cell is non-motile hence the reproduction is oogamous.

Q3. Lichen is usually cited as an example of‘symbiosis’ in plants where an algal and a fungal species live together for their mutual benefit. Which of the following will happen if algal and fungal partners are separated from each other?
a. Both will survive and grow normally and independent from each other.
b. Both will die.
c. Algal component will survive while the fungal component will die.
d. Fungal component will survive while algal partner will die.
Based on your answer how do you justify this association as symbiosis.
Ans: Lichen is usually cited as an example of symbiosis in biology where in a fungal and an algal species live together for mutual benefit. The algal component synthesizes the food through photosynthesis which is utilized by the fungal species for its survival. The fungal component in return provides shelter and waste products that are consumed by algal species.
Experiments though have shown that algal component can grow independently when separated from fungal species. But same is not true with the fungal component which dies when separated from algal component. This association is, therefore, a typical case of master-slave relationship where fungus (master) has trapped the algal components (slave) for its own survival while giving nothing in return to it. Some authors consider this association as controlled parasitism or helotism due to the fact that sometimes the fungus sends its haustoria into the algal cells to derive nourishment.

Q4. Explain why sexual reproduction in angiosperms is said to take place through double fertilization and triple fusion. Also draw a labelled diagram of embryo sac to explain the phenomena.
Ans: After entering one of the synergids, the pollen tube release the two male gametes into the cytoplasm of the synergid.

Q5. Draw labelled diagrams of
a. Female and male thallus of a liverwort.
b. Gametophyte and sporophyte of Funaria.
c. Alternation of generation in Angiosperm.

Ans:  a. Female and male thallus of a liverwort.

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