Lakhmir Singh Science Class 8 Solutions Chapter 8 Cell Structure and Functions

S Chand Science Class 8 Solutions Chapter 8 Cell Structure and Functions

Lakhmir Singh Science Class 8 Chapter 8 Very Short Answer Type Questions

Question 1.
Which instrument was essential for the study of cells ?
Answer:
Microscope was essential for the study of cells.

Question 2.
What is the basic similarity among all the living organism (plants and animals) ?
Answer:
The basic similarity among all the living organisms is that they all are made up of cells.

Question 3.
Name the scientist who observed a thin slice of cork through a microscope and coined the team ‘cell’.
Answer:
Robert Hooke in 1665 observed a thin slice of cork through a microscope and coined the term ‘cell’

Question 4.
Name the outermost layer of an animal cell.
Answer:
Plasma membrane is the outermost layer of an animal cell.

Question 5.
Which part of the cell contains organelles?
Answer:
Cell organelles are present in the cytoplasm.

Question 6.
Name any two organelles present in a cell.
Answer:
Mitochondria and Endoplasmic reticulum.

Question 7.
Which part of a cell carries out respiration?
Answer:
Mitochondria is the site of respiration.

Question 8.
What are the units of inheritance in living organisms?
Answer:
Gene is a unit of inheritance in living organisms.

Question 9.
Which is the largest floating body generally in the center of a cell?
Answer:
Nucleus is the largest floating body generally in the center of a cell.

Question 10.
What is the function of nucleus in a cell?
Answer:
Nucleus controls all activities of the cell, hence it is also called Master or Director of the cell.

Question 11.
What do the chloroplasts contain?
Answer:
They possess photosynthetic pigment called chlorophyll.

Question 12.
What kind of cells are surrounded by a cell wall?
Answer:
Plant cells are surrounded by a cell wall.

Question 13.
What sort of cells do not have a cell wall around them ?
Answer:
Animal cells do not have a cell wall around them.

Question 14.
Name the layer which is outside the cell membrance of a plant cell.
Answer:
Cell wall

Question 15.
How is the outside of a plant cell different from that of an animal cell ?
Answer:
Plant cells differ from animal cells in having an additional layer around the cell membrane termed cell wall.

Question 16.
Name the organelle of a plant cell where photosynthesis takes place.
Answer:
Chloroplast is the organelle of a plant cell where photosynthesis takes place.

Question 17.
Which part of a plant cell protects outside of the cell ?
Answer:
Cell wall protects outside to the plant cell.

Question 18.
Which part of plant cell releases energy from food?
Answer:
Mitochondria releases energy from food in the plant cell.

Question 19.
What causes the red colour in tomatoes?
Answer:
Coloured plastid (Chromoplasts) gives the red colour in tomatoes.

Question 20.
Which part of the two has a large vacuole: a plant cell or an animal cell ?
Answer:
A plant cell has a large vacuole.

Question 21.
Name any two parts which are present in a plant cell but not in an animal cell.
Answer:
Cell wall and plastids are present only in a plant cell.

Question 22.
Which cells transmit message between the brain and other parts of the body?
Answer:
Nerve cell transmit message between the brain and other parts of the body.

Question 23.
Which cells in the human body can contract (and relax) ?
Answer:
Muscle cells in the human body can contract and relax.

Question 24.
Name the spindle-shaped cells present in the human body.
Answer:
The spindle-shaped cells present in the human body are muscle cells.

Question 25.
State an important characteristic of muscles cells.
Answer:
A muscle cell is pointed at both ends and has a spindle shape.

Question 26.
Name a single cell (other than Amoba cell) which can change its shape.
Answer:
White blood cells present in human blood is a single cell (other than Ameoba cell) which can change its shape.

Question 27.
Name one ‘single cell’ which behaves like a complete organism.
Answer:
Amoeba is a single cell which behaves like a complete organism.

Question 28.
Name one cell which can be seen easily with naked eye and one cell which can be seen only through a microscape.
Answer:
The bird’s egg are very large cell which can be seen easily with naked eye while bacterial cells are extremely small which can be seen only through a microscope.

Question 29.
State whether the following statements are true or false :
(a) Unicellular organism have one- celled body.
(b) Muscle cells are branched.
(c) Amoeba has irregular shape.
(d) All the cells in our body are alike.
(e) A hen’s egg is a group of cells.
(f) The basic living unit of an organism is organ.
Answer:
(a) True, unicellular organisms (single celled organisms) are made up of only one cell.
(b) False, muscle cell are not branched.

Question 30.
Name the smallest unit of life.
Answer:
Cell is the smallest unit of life.

Question 31.
What is a ‘cell’ in biology ?
Answer:
Cell is structural and functional unit of all living beings.

Question 32 A.
What are the basic parts of all the cells ?
Answer:
The basic parts of all the cells are – cell membrane, cytoplasm and nucleus.

Question 32 B.
What parts are present only in plant cells ?
Answer:
The parts which are present only in plant cells are – Cell wall, chloroplasts and large vacuole.

Question 33.
What controls the flow of substance in and out of a cell ?
Answer:
Plasma membrane controls the flow of substance in and out of a cell.

Question 34.
Which part of a cell controls all the activities of the cell ?
Answer:
Nucleus controls all the activities of the cell.

Question 35.
Name the animal cell which is long and has thread-like branches.
Answer:
Nerve cell is a long and has thread like branches.

Question 36.
What is the function of chloroplasts in a plant cell ?
Answer:
Chloroplasts help in the synthesis of food by the process of photosynthesis.

Question 37.
Name an organism which has no definite shape, and it keeps on changing its shape.
Answer:
Amoeba has no definite shape, and it keeps on changing its shape.

Question 38.
Name one cell in human body which is spherical in shape.
Answer:
Red blood cell is spherical in shape.

Question 39.
Which organism has the smallest cell?
Answer:
Bacteria mycoplasma is the smallest cell measuring 0.1 micrometer.

Question 40.
Name the biggest cell ?
Answer:
The largest cell measuring 170 mm × 130 mm, is the egg of an ostrich.

Question 41.
Name two animal organs and two plant organs.
Answer:
There are different animal organs. Some of the names are Heart, Stomach, brain and lungs. Stem, Leaf, Roots etc are plant organs.

Question 42.
Name two plant organ which is responsible for :
(a) making of food.
(b) absorption if water and minerals.
Answer:
(a) Leaves are responsible for synthesis of food.
(b) Plant roots help in the absorption water and minerals.

Question 43.
Which of the two does not have a true nucleus: prokaryotic cell or eukaryotic cell?
Answer:
Prokaryotic cell does not have a true nucleus.

Question 44.
Name one prokaryotic cell and one eukaryotic cell.
Answer:
Prokaryotic cell – Blue green algae
Eukaryotic cell – Onion peel cell

Question 45.
Fill in the blanks with suitable words :
(a) Cells were first observed in cork by ………………… in 1665.
(b) What is brick to a house is …………. To an organism.
(c) The cytoplasm and nucleus make up the ……………………………….
(d) The shape and size of a cell is related to its ………………………….
(e) The bacteria cells are ……….. to ………………micrometer in length.
(f) The smallest unit of life is a ………
(g) Tissues make up ………………..
(h) Organ systems make up an …………
(i) Cells make up …………………………………
(j) Organs make up …………………………..
Answer:
(a) Robert Hooke
(b) Cell
(c) protoplasm
(d) function
(e) 0.1; 0.5
(f) cell
(g) organs
(h) organism
(i) tissue
(j) organ system

Lakhmir Singh Science Class 8 Chapter 8 Short Answer Type Questions

Question 46.
Why are plant and animal specimens usually stained with dyes before observing them through a microscape ? Name one stain (or dye) used for this purpose.
Answer:
The various parts of the cell are colorless and hence, difficult to distinguish. So, various stains are used to colour the parts of the cell to study the detailed structure through a microscope.

The dyes (stains ) which are used in the study of cell structure are methylene blue, dilute iodine solution, etc.

Question 47.
What is a tissue? Give two examples of tissues.
Answer:
A tissue is a group of similar cells performing a specific function.
Examples – Epithelial tissue, muscle tissue.

Question 48.
What is an organ? Give two examples of organs.
Answer:
A organ is a group of different tissues which work together to perform a specific function in the body of an organism.
Examples – Organs in the animal body – Brain and kidney
Organs in the plant body – Root and leaves.

Question 49.
What is an organ system ?
(a) Give two examples of organ systems in animals.
(b) Name the two main organ systems in plants .
Answer:
Organ system – A group of closely related organs that work together to perform a specific function for the organism is called organ system.
(a) Muscular system and digestive system are examples of organ systems in animals.
(b) Root system and shoot system are main organ systems in plants .

Question 50.
Which of the following are plant organs and which are animal organs ?
Brain, Leaf, Lungs, Roots, Stem, Kidneys, Flower, Heart
Answer:

Plant organs	Animal organs
Leaf	Brain
Roots	Lungs
Stem	Kidneys
Flower	Heart

Question 51.
What are the functions of the following organs ?
(a) Heart
(b) Brain
(c) Roots
(d) Leaves
Answer:
(a) Heart – It pumps blood throughout the body.
(b) Brain – It controls the activities of other parts of the body.
(c) Roots – These help in absorption of water and minerals.
(d) Leaves – These are responsible for synthesis of food.

Question 52.
What is the shape of red blood cells in human blood? What function do red blood cells perform ?
Answer:
Red blood cells (RBCs) are usually spherical in shape. The main function of red blood cells is to carry oxygen from the lungs to the tissues around the body.

Question 53 A.
State the difference between prokaryotes and eukaryotes.
Answer:
Prokaryotes have nuclear material without nuclear membrane whereas eukaryotes have well organized nucleus with a nuclear membrane.

Question 53 B.
Name two prokaryotes and two eukaryotes.
Answer:
Prokaryotes – Blue green algae and bacteria
Eukaryotes – Onion cells and cheek cells

Question 54 A.
Why are nerve cells long and have branches ?
Answer:
Nerve cells (neurons) are long, branched and have thread-like projections so that they can connect other nerves cells and transmit messages over long distance

Question 54 B.
What is the other name of a nerve cell ?
Answer:
The other name of a nerve cell is neuron.

Question 55 A.
Why could cells not be observed and studied for thousands of years ?
Answer:
Most of cells are extremely small and cannot seen with naked eye, hence cells could not be observed and studied for thousands of years.

Question 55 B.
State the cell theory of organisms.
Answer:
Two biologists, Schleiden (1839) and Schwann (1839) presented the cell theory. This stated that all the plants and animals are composed of cells and the cell is the basic unit of life.

Question 56.
Explain the function of mitocheondria in a cell.
Answer:
Mitochondria is the site of cellular respiration or oxidation of food in a cell. It uses glucose and oxygen to produce energy. Hence, it is knowns as “Powerhouse of the cell”.

Question 57.
Make a sketch of human nerve cell. What function do nerve cells perform ?
Answer:

The function of nerve cell: The nerve cell receives and transfers messages, thereby helping to control and coordinate the working of different parts of the body.

Question 58.
Make a sketch of the human muscle cell. What are the functions do muscles cell perform ?
Answer:

The muscle cells are responsible for movement in our body by contracting and relaxing.

Question 59.
What are pseudopodia in Ameoba? What are the functions of pseudopodia?
Answer:
The finger-like projection of varying lengths protruding out of the body of Amoeba, is called pseudopodia. These projections appear and disappear as Amoeba moves or feeds.

Thus, the function of pseudopodia is to facilitates movement and help in capturing food.

Question 60.
Where are chromosomes found in a cell ? State their function.
Answer:
Chromosomes are thread-like structures usually present in the nucleus that become visible only during cell divisions.
The function of chromosomes is to transfer the characters from parents to the offsprings through the genes located on them.

Question 61.
What are genes ? Where are genes located ?
Answer:
Gene is a unit of inheritance in living organisms. It controls the transfer of a hereditary characteristic from parents to offspring. Genes are located on chromosomes.

Question 62.
What is a plastid ? What is the name of green plastids present in plant cells ?
Answer:
Plastids are major organelles found only in plant cells. The green coloured plastids present in plant cells, are called chloroplast. It contains photosynthetic pigment called chlorophyll which helps in the synthesis of food.

Question 63.
What is the size of an ostrich egg ? Is it a single cell or a group of cells ?
Answer:
The size of an ostrich egg is 170 mm × 130 mm. It is the largest cell. It is a single cell called “fertilized egg cell” or “zygote”.

Question 64.
What is the function of cell wall in a plant cell ?
Answer:
Cell wall provides shape and rigidity to the plant cell. It also provides protection the cell.

Question 65.
Name two cells which are found in animals and two which are found in plants.
Answer:
The cells which are found in animals are – Red blood cells (RBCs) and Muscle cells
The cells which are found in plants are – Xylem cells and phloem cells

Lakhmir Singh Science Class 8 Chapter 8 Long Answer Type Questions

Question 66 A.
What is cytoplasm? What is its function?
Answer:
Cytoplasm is a jelly-like substance present between the cell membrane and the nucleus. Cytoplasm contains many specialised cell organelles. Each of these organelles performs a specific function for the cell. Cytoplasm contains a number of minute living structure known as cell organelles. Each of these organelles performs a specific function for the cell.

Most of the chemical reactions which are necessary to keep cell alive take place in the cytoplasm.

Question 66 B.
What is protoplasm ? Name the elements which make up major part of protoplasm.
Answer:
Cell without its cell membrane is called Protoplasm. The Cytoplasm and Nucleus taken together make up the protoplasm.

Question 67 A.
What are unicellular organisms ? Name two unicellular organisms.
Answer:
The organisms made up of single cell are called unicellular organisms. Examples- Amoeba, Paramecium.

Question 67 B.
What are multicellular organisms ? Name two multicellular organisms.
Answer:
The organisms made up of many cells are called multicellular organisms. Examples- Animal and plant.

Question 68 A.
Draw the general diagram of an animal cell and label it.
Answer:

Question 68 B.
Draw the general diagram of a plant cell and label it.
Answer:

Question 68 C.
Explain why, chloroplasts are found only in plant cells.
Answer:
Chloroplasts are the green coloured plastids present in the cytoplasm of plant cells. They possess photosynthetic pigment called chlorophyll. Chlorophyll absorbs energy from the sunlight during the process of photosynthesis. In the process of photosynthesis, green plants make their own food in the presence of sunlight and chlorophyll with the help of inorganic substances like carbon dioxide and water. Thus, chloroplast help in the synthesis of food by green plants.

Question 69 A.
An Ameoba cell can change its shape and a white blood cell in human blood can also changing its shapes. What is the difference between an Amoeba cell and a white blood cell?
Answer:
An Ameoba cell can change its shape and a white blood cell in human blood can also changing its shapes. The difference between an Amoeba cell and a white blood cell is that the Amoeba cell is a full-fledged organism which is capable of independent existence. While white blood cell is only a cell of human blood which is not a full-fledged organism and hence cannot exist independently. White blood cells can exist only inside the blood.

Question 69 B.
Out of Amoeba cell and white blood cell, which one is

eukaryotic cell, and
prokaryotic cell ?

Answer:
Amoeba cell and White Blood Cell both are eukaryotic cell because they have well defined nucleus with a nuclear membrane.

Question 70 A.
State three difference between a plant cell and animal cell ?
Answer:
Differences between a plant cell and animal cell:

Plant cell	Animal cell
A plant cell has a cell wall around its cell membrane. Blue-green algae cell	An animal cell does not have a cell wall around it.
Plastids are present.	Plastids are absent.
A single large vacuole is present.	Vacuoles either are absent or if present, they are smaller in size.

Question 70 B.
Which of the following are prokaryotic cells and which are eukaryotic cells ?
Amoeba cell, Bacterium cell, Human cheek cell, Blue-green algae cell, onion peel cell.
Answer:

Prokaryotic cells

Eukaryotic cells

Bacterium cell

Amoeba cell

Blue-green algae cell

Human cheek cell

onion peel cell

Lakhmir Singh Science Class 8 Chapter 8 Multiple Choice Questions (MCQs)

Question 71.
The organelles which provide energy for all activities of a cell are :
A. chloroplasts
B. mitrochondria
C. golgi bodies
D. ribosomes
Answer:
B. mitrochondria
Mitochondria is the site of cellular respiration or oxidation of food in a cell. It uses glucose and oxygen to produce energy. Hence, it is knowns as “Powerhouse of the cell”.

Question 72
In a living cell, chromatin is present in :
A. cytoplasm
B. chloroplasts
C. nucleus
D. vacuole
Answer:
A. cytoplasm
Chromatin material is a tangled fibrous mass. The chromatin material condenses to form chromosomes during cell division.

Question 73.
The cell wall in onion peel cell is made of :
A. starch
B. gelatin
C. cellulose
D. cell sap
Answer:
C. cellulose
The cell wall in onion peel cell is made of cellulose.

Question 74.
The group of similar cell which work together to perform a particular functions is called :
A. organ
B. organelle
C. organisms
D. tissue
Answer:
D. tissue
The group of similar cells which work together to perform a particular function is called tissue.

Question 75.
A long and branched animal cell is :
A. muscle cell
B. epithelial cell
C. nerve cell
D. cartilage cell
Answer:
C. nerve cell
Nerve cells (neurons) are long, branched and have thread-like projections so that they can connect other nerves cells and transmit messages over long distance

Question 76.
Which of the following is not a unicellular organism ?
A. Amoeba
B. Yak
C. Yeast
D. Rhizobium
Answer:
A. Amoeba
Amoeba, yeast and rhizobium are examples of unicellular organisms while Yak is an example of multicellular organisms.

Question 77.
Which of the following organelle is not found in the root cells of a plant ?
A. nucleus
B. vacuole
C. mitochondria
D. chloroplasts
Answer:
D. chloroplasts
Chloroplasts are found only in those plant cells which carry out photosynthesis like the cells in green leaves. So, chloroplasts are not found in the root cells of a plant.

Question 78.
The part of a cell which plays a role in inheritance is :
A. nucleus
B. cytoplasm
C. plasma membrane
D. mitochondria
Answer:
A. nucleus
The correct Answer: is option (b) Nucleus.
Explanation: Nucleus contains thread-like structures called chromosomes. These carry genes and help in inheritance or transfer of characters from the parents to the offspring.

Question 79.
The basic similarity among all the living organisms is that they are made up of :
A. tissue
B. organs
C. cells
D. organ systems
Answer:
C. cells
The basic similarity among all the living organisms is that they are made up of cells. Cell is the structural and functional unit of life.

Question 80.
The structural and functional unit of life called cell was discovered by :
A. Robert Boyle
B. Charles Darwin
C. Robert Koch
D. Robert Hooke
Answer:
D. Robert Hooke
The structural and functional unit of life called cell was discovered by Robert Hooke.

Question 81.
Which of the following cell does not have a nucleus ?
A. white blood cell
B. red blood cell
C. nerve cell
D. muscle cell
Answer:
B. red blood cell
Red blood cell does not have a nucleus.

Question 82.
The parts which are not present in an animal cell are :
A) Cell membrane
B) Chloroplast
C) Cell wall
D) Mitochondria
A. A and B
B. B and C
C. A and D
D. B and D
Answer:
B. B and C
The correct option is B.

Question 83.
All the living matter in a cell is called :
A. endoplasm
B. protoplasm
C. cytoplasm
D. cell sap
Answer:
B. protoplasm
The entire content of a living cell is known as protoplasm. It includes the cytoplasm and the nucleus. Protoplasm is called the living substance of the cell.

Question 84.
Which of the following is a plant cell ?
A. cartilage cell
B. neuron
C. epidermal cell
D. epithelial cell
Answer:
C. epidermal cell
Epidermal cell is a plant cell while cartilage cell, neuron and epithelial cell are animal cells.

Question 85.
The egg cell measuring about 17 cm × 13 cm is most likely that of :
A. hummingbird
B. hen
C. elephant
D. ostrich
Answer:
D. ostrich
The largest cell measuring 170 mm ×130 mm, is the egg of an ostrich.

Question 86.
Which of the following have cell walls ?
A) Epidermal cell
B) Epithelial cell
C) Mesophyll cell
D) Liver cell
A. A and B
B. B and C
C. A and C
D. B and D
Answer:
C. A and C
Cell wall is a characteristics of plant cell only and absent in animal cell. It is an outer, rigid, protective and supportive covering of plant cells. The cell wall lies outside of the plasma membrane. Epidermal cell and mesophyll cell are examples of plant cells. Thus, they have cell wall.

Question 87.
Which of the following are prokaryotes ?
A. Protozoa
B. Blue – green algae
C. Fungi
D. Bacteria
Answer:
D. Bacteria
Organisms which do not have true nucleus are called prokaryotes. Bacteria and blue green algae are examples of prokaryotes.

Question 88.
Which of the following human system includes oesophagus ?
A. respiratory system
B. circulatory system
C. digestive system
D. reproductive system
Answer:
C. digestive system
Oesophagus is a part of human digestive system. It is a muscular tube which connects the pharynx to the stomach. It is also known as food pipe.

Question 89.
Which of the following cells can change their shape ?
A) White blood cell
B) Amoeba cell
C) Red blood cell
D) Euglena cell
A. A and B
B. B and C
C. A and D
D. B and D
Answer:
A. A and B
An amoeba cell and white blood cell present in human blood can change their shape.

Question 90.
The non-living part of a tomato cell is its :
A. cell membrane
B. nucleus
C. chloroplasts
D. cell wall
Answer:
D. cell wall
The non-living part of a tomato cell is its cell wall. Cell wall is the outer most covering of a plant cell. It is a non-living and rigid.

Lakhmir Singh Science Class 8 Chapter 8 Questions Based on High Order Thinking Skills (HOTS)

Question 91.
The part of P and Q are present only in plant cells, and they are not present in animal cells. The part P contains a green pigment called R whereas part Q is made of a tough material S. The part P takes part in the food making process whereas part Q gives shape and support to the plant cell.
(a) What is (i) P, and (ii) Q?
(b) What is (i) R, and (ii) S?
Answer:
(a) (i) The part P is Chloroplasts
Chloroplasts are the food producers in plant cells and they are not present in animal cells because animal cells do not make their own food.
(ii) The part Q is Cell wall
The cell wall is absent in the animal cells because they don’t need cell walls. The main purpose of a cell wall is to provide stability and stiffness to the cell. And it is made up of cellulose.

(b) (i) The part R is Chlorophyll
Chlorophyll is the green pigment present in the leaves.
(ii) The part S is Cellulose
Cellulose is a fiber and wood, cotton, etc. all contain cellulose.

Question 92.
A, B, C and D are the basic part of all the cells. The part A contains thread- like structures called E which transfer the characteristic from parents to their offsprings. The part B uses glucose and oxygen to produce energy whereas part C controls the movement of substance into the cell. The part D is a transparent, jelly-like material. What could A, B, C, D and E be ?
Answer:
A is nucleus ; B is mitochondria; C is cell membrane ; D is cytoplasm; and E is chromosomes.

Question 93.
X and Y are the two types of cells. The cells X have a well organized nucleus which is separated from the cytoplasm by the nuclear membrane On the other hand, cells Y do not have a real nucleus, their nuclear material is in direct contact with the cytoplasm.
(a) what type of cells are
(i) X, and (ii) Y ?
(b) Give one example each of cells like
(i) X, and (ii) Y ?
Answer:
(a) (i) Eukaryotic cell (ii) Prokaryotic cell
(b) (i) Amoeba cell (ii) Bacterium cell

Question 94.
The cytoplasm of the cells of a tomato plant contains organelles X having different pigments which impart different colours to the leaves of tomato plants and its fruits.
(a) What is the general name of the organelles X ?
(b) What is the (i) name (ii) colour, and (iii) function, of organelles X present in the leaves of Tomato plant?
(c) What is the colour of organells X which are present in the ripe fruits of tomato plant ?
Answer:
(a) The general name of the organelles X is plastids.
(b) (i) Chloroplasts (ii) green (iii) Chloroplasts (X) help in the synthesis of food by the process of photosynthesis.
(c) The colour of organells X which are present in the ripe fruits of tomato plant is red.

Question 95.
Cell make up A; A make up B; B make up C, and finally C make up an organism. What are A, B, and C ?
Answer:
A is tissue; B is organ; and C is organ system.