CBSE Sample Papers for Class 11 Biology Solved 2016 Set 3
Section A
1. What do you understand by hydrostatic skeleton?
2. Few organisms are known to have capacity to regenerate from their own body parts or cells. Which type of cell division do you think is responsible for it?
3. Name the most common respiratory substrate. Also suggest what would be its respiratory quotient when used in respiration.
4. Why there arises a need to classify organisms?
5. The cross section of a plant when observed under microscope shows a central core of xylem surrounded completely by phloem. Identify the type of vascular bundle, citing an example where it is found?
Section B
6. Though the opening of ureters into the urinary bladder is not guarded by valves, yet urine does not flow back into them on contraction of bladder. Explain.
7. Proteins have primary structure. If you are given a method to know which amino acid is at either of the two termini (ends) of a protein, can you connect this information to purity or homogeneity of a protein?
8. Name a chelating agent. In hydroponics, why iron is added along with chelating agent?
9. 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?
or
Both carrot and ginger grow underground, but are still different from each other. Give reasons in support of this statement.
Section C
10. Write a short note
(a) Synaptonemal complex
(b) Metaphase plate
11. Differentiate between metatheria and eutheria.
or
Justify the statement that ‘plant parts show symptoms of deficiency depending on the mobility of that element in the plant’.
12. Explain why pure water has the maximum water potential.
13. How do ears help us in maintaining equilibrium?
14. Name a gaseous plant hormone regulating its growth and other physiological functions. Describe some of its commercial uses in agriculture now-a-days.
15. Give a comparative account of ribosomes of prokaryotic and eukaryotic cells. Enumerate both the similarities and dissimilarities among them.
16. Palm is a monocotyledonous plant, yet it increases in girth. Why and how?
17. Enlist three factors that regulate glomerular filtration rate.
18. The heterosporous pteridophytes show certain characteristics. Which are precursor to the seed habit in gymnosperms? Explain.
19. State the differences between
(i) Chl-a and Chl-b (ii) Photosystem-I and II
20. Stratified epithelial cells have limited role in secretion. Justify their role in our skin.
21. While playing on a sunny afternoon, Payal felt dizzy, weak and fell on ground. Seeing this, one of her friend, Rahul took her in shade and called their class teacher. She gave her a glass of glucose water to drink, and within a few minutes, she regained her energy and stood up. To, this Rahul amazingly asked their teacher, how was this possible and how did the lunch she had did not give her energy?
(a) What could be the reason for glucose providing instant energy?
(b) Name the cellular energy currency and its components.
(c) What is the net gain of energy molecules from one molecule of glucose? .
(d) What values are reflected by Rahul?
Section D
22. ‘Hypothalamus and pituitary function as an integrated and coordinated system’. Justify the statement.
or
What are the assumptions made during the calculation of net gain of ATP during aerobic respiration ?
23. Structure and function are correctable in living organisms. Can you justify this by taking plasma membrane as an example?
or
Give an account of abdomen of female cockroach.
Answers
Section A
1. What do you understand by hydrostatic skeleton?
Ans. A hydrostatic skeleton or hydroskeleton is a structure found in many ectothermic organisms and soft bodied animals consisting of a fluid filled cavity called coelom, surrounded by muscles. The pressure of the fluid and action of muscles allow them to change shape and move.
2. Few organisms are known to have capacity to regenerate from their own body parts or cells. Which type of cell division do you think is responsible for it?
Ans. Since, the regeneration of an organism involves development from body cells or somatic cells, the mitotic or equational division is involved here.
3. Name the most common respiratory substrate. Also suggest what would be its respiratory quotient when used in respiration.
Ans. The most common respiratory substrate is glucose, that is catabolised in living cells to release energy. When glucose or any other carbohydrate is used as substrate, the RQ is always equal to 1 since, the amount of CO2 evolved is equal to amount of 02 consumed.
4. Why there arises a need to classify organisms?[1]
Ans. It becomes necessary to classify organisms for their easy identification and study. The classification of organisms into groups and bringing out similarities and dissimilarities helps in study and analyses of their relationship with other groups and organisms.
5. The cross section of a plant when observed under microscope shows a central core of xylem surrounded completely by phloem. Identify the type of vascular bundle, citing an example where it is found?[1]
Ans. The vascular bundle observed in a plant cross section in which xylem forms a central core and is surrounded by phloem is called concentric, amphicribal or hadrocentric bundle. It is found in dicots, e.g. Prunus and some ferns.
Section B
6. Though the opening of ureters into the urinary bladder is not guarded by valves, yet urine does not flow back into them on contraction of bladder. Explain. [2]
Ans. The ureters, i.e. terminal part of each ureter passes oblique through the bladder wall, therefore despite its opening into the urinary bladder, lacking valves, urine is prevented from flowing back into them.
7. Proteins have primary structure. If you are given a method to know which amino acid is at either of the two termini (ends) of a protein, can you connect this information to purity or homogeneity of a protein? [2]
Ans. The sequence of amino acids, i.e. the positional information in a protein, which is the first amino acid, which is second and so on is called the primary structure of a protein. The first amino acid is also called as N-terminal amino acid. The last amino acid is called the C-terminal amino acid. Yes, we can connect this information to purity or homogeneity of a protein. Based on number of amino and carboxyl groups, like there are acidic (e.g. glutamic acid), basic (lysine) and neutral (valine) amino acids, proteins may be acidic, basic and neutral.
8. Name a chelating agent. In hydroponics, why iron is added along with chelating agent?[2]
Ans. Na-EDTA is an example of chelating agent. This agent has a ability to chelate with most of the metals, but have high affinity particularly for Fe (iron). Therefore, it is added along with iron in hydroponics, so that it makes a complex there by making the solution stable and help the plant to uptake rest of the nutrients.
9. 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? [2]
or
Both carrot and ginger grow underground, but are still different from each other. Give reasons in support of this statement. [2]
Ans. Viruses are considered as living, when they are inside a host, but outside any host they are referred to as non-living due to their
(i) inert nature (ii) inability to reproduce
(iii) lack of cellular organisation (iv) inability for growth and cell division
These characters portrayed by viruses make them identical to non-living organisms. Viruses are considered a connecting link between living and non-living organisms.
or
Yes, carrot and ginger both grow underground, but the former is modification of root while latter is an underground modification of stem, i.e. rhizome.
The characteristics that differentiates modifications of underground stem from that of a roots includes the absence of root cap and root hairs, the presence of nodes and internodes, the presence of buds, scale leaves, exogenous branching, etc.
Section C
10. Write a short note o
(a) Synaptonemal complex
(b) Metaphase plate
Ans. (a) Synaptonemal complex It is formed, when corresponding chromosomes become intimately associated. The process of pairing is known as synapsis. It is so exact that pairing is not merely between corresponding chromosomes but between corresponding individual units.
(b) Metaphase plate The bivalent arrange themselves on the equator of the bipolar spindle. The centromeres slightly project towards the periphery. There are two centromeres in a bivalent and also the centromeres of all the bivalents produce a double metaphasic plate.
11. Differentiate between metatheria and eutheria.
or
Justify the statement that ‘plant parts show symptoms of deficiency depending on the mobility of that element in the plant’.
For elements that are actively mobilised within the plants and exported to young developing tissues, the deficiency symptoms tend to appear first in the older tissues.
For example, the deficiency symptoms of nitrogen, potassium and magnesium are visible first in the senescent leaves. In the older leaves, biomolecules containing these elements are broken down, making these elements available for mobilising to younger leaves.
The deficiency symptoms tend to appear first in the young tissues, whenever the’ elements are relatively immobile and are not transported out of the mature organs. For example, elements like sulphur and calcium are a part of the structural component of the cell hence, are not easily released.
13. How do ears help us in maintaining equilibrium?[3]
Ans. The innermost ear contains a complex system (above the cochlea) called the vestibular apparatus.
It comprises of three semi-circular canals, situated at right angle to each other, and otolith organ consisting of saccule and utricle. The semi-circular canals convey about movement of head, while the sensory hairs of utricule and saccule convey information when it is not moving.
The base of canals contains a projecting ridge called crista and utricule and saccule contains a projecting ridge called macula. Both crista and macula possess sensory hairs and act as specific receptors of vestibular apparatus, that helps to maintain equilibrium of body and posture.
14. Name a gaseous plant hormone regulating its growth and other physiological functions. Describe some of its commercial uses in agriculture now-a-days. [3]
Ans. Ethylene is a gaseous phytohormone that regulates a number of physiological processes in plants. Its commercial uses in agriculture are:
(a) Fruit ripening For stimulation of colour development and ripening of fruits, e.g. mango, apple, tomato, etc.
(b) Feminising effect It is applied externally to increase the number of female flowers in plants so as to increase fruits, e.g. cucumber.
(c) Early sprouting The storage organs such as rhizome, tubers, seeds can be made to sprout early by applying ethylene.
(d) Thinning Extra or excess’of flowers and young fruits are thinned by application of ethylene for the better growth of remaining fruits, e.g. cotton, walnut, cherry, etc.
15. Give a comparative account of ribosomes of prokaryotic and eukaryotic cells. Enumerate both the similarities and dissimilarities among them.
Ans. Ribosomes in the cytoplasm of prokaryotic and eukaryotic cells slightly differ. Prokaryotes have 70 S ribosomes, whereas, eukaryotes have 80 S ribosomes.
Differences between eukaryotic and prokaryotic ribosomes can be summarised as:
However, both prokaryotic and eukaryotic ribosomes are composed of ribosomal RNA and ribosomal proteins. Their basic functioning is protein synthesis.
16. Palm is a monocotyledonous plant, yet it increases in girth. Why and how?
Ans. Palm, despite being monocotyledonous plant show secondary growth, i.e. increase in girth. This is due to the division and enlargement of parenchymatous cells in the ground tissue. Thus, repeated divisions cause increase in girth of stem and this type of growth is referred to as diffused secondary growth.
17. Enlist three factors that regulate glomerular filtration rate.
Ans. The three factors or mechanisms that regulate glomerular filtration are:
(a) Myogenic mechanism The increase in blood pressure stretches the afferent arteriole which increases the flow of blood to glomerulus. With any contraction in the wall of arteriole, its diameter is reduced thereby increasing the flow.
(b) Juxtaglomerular mechanism The cells of juxtaglomerular apparatus secrete enzymes such as renin which modulate blood pressure and renal blood flow, that regulates the glomerular filtration rate.
(c) Neural control The nerve fibres innervating the blood vessels of kidney, when become activated they bring about constriction of renal arteries, thereby decreasing renal flow and glomerular filtration rate.
18. The heterosporous pteridophytes show certain characteristics. Which are precursor to the seed habit in gymnosperms? Explain. [3]
Ans. Heterospory, i.e. production of two types of spores smaller microspore and larger megaspore were first reported in Selaginella, a pteriodophyte. In Selaginella, the smaller mircospores are destined to produce male gametophytes and the larger megaspores in to female gametophyte. The male gametophyte produces male gametes, whereas the female gametophyte produces archegonia and also provides nourishment to the developing embryo.The phenomenon of heterospory, thus lead to the reduction of gametophyte.
In situ germination of spores, retention of megagametophyte in the megasporangia and finally to the seed development. Thus, the heterospory in Selaginella forms the base for seed habit development in gymnosperms.
19. State the differences between
(i) Chl-a and Chl-b (ii) Photosystem-I and II
20. Stratified epithelial cells have limited role in secretion. Justify their role in our skin. .
Ans. Stratified epithelium consists of epithelial cells in which the deepest layer is made up of columnar or cuboidal cells. It is a type of compound epithelium and in the outer few layers, a water proof protein called keratin is present.
These layers of dead cells are called horny layer which shed at intervals due to friction. Hence, has a limited role in secretion and absorption. The main function of stratified epithelium is to provide protection to the body against mechanical and chemical stresses.
21. While playing on a sunny afternoon, Payal felt dizzy, weak and fell on ground. Seeing this, one of her friend, Rahul took her in shade and called their class teacher. She gave her a glass of glucose water to drink, and within a few minutes, she regained her energy and stood up. To, this Rahul amazingly asked their teacher, how was this possible and how did the lunch she had did not give her energy?
(a) What could be the reason for glucose providing instant energy?
(b) Name the cellular energy currency and its components.
(c) What is the net gain of energy molecules from one molecule of glucose? .
(d) What values are reflected by Rahul?
Ans. (a) Glucose, being the simplest sugar enters the cell readily and gets easily oxidised, thus providing instant energy to the body. It does not need to undergo breakdown process to be converted into simpler forms.
(b) The cellular energy currency is ATR Its components include adenine, a ribose sugar and 3-phosphate groups attached to it.
(c)The net gain of ATP molecules from one molecule of glucose is 36.
(d) Rahul seems to be attentive, intelligent, helpful and curious to gain more insights about the subject and understanding of physiology.
Section D
22. ‘Hypothalamus and pituitary function as an integrated and coordinated system’. Justify the statement.[5]
or
What are the assumptions made during the calculation of net gain of ATP during aerobic respiration ?[5]
Ans. The hypothalamus and pituitary function as an integrated and coordinated system because both of them are connected at the base of the brain.
They interact with each other in two ways:
(i) By the hypophyseal portal system, which is a system of blood vessels that connects part of hypothalamus to the anterior lobe of pituitary gland. Hypothalamus secretes hormones into this portal system and the hormones act on the anterior pituitary, triggering the synthesis/secretion of pituitary hormone.
(ii) The other is that they have direct anatomical connection between the hypothalamus and the posterior lobe of pituitary (posterior pituitary is actually an extension of hypothalamus). Thus, it is said that hormones released through posterior pituitary are actually released from the hypothalamus.
or
The calculations of net gain of ATP can be made only on certain assumptions which are:
(i) There is a sequential, orderly pathway functioning, with one substrate forming the next and with glycolysis, TCA cycle and ETS pathway following one after another.
(ii) The NADH synthesised in glycolysis is transferred into the mitochondria and undergoes oxidative phosphorylation.
(iii) None of the intermediates in the pathway are utilised to synthesise any other compound.
(iv) Only glucose is being respired-no other alternative substrates are entering the pathway at any of the intermediary stages.
But these kind of assumptions are not really valid in a living system. All pathways work simultaneously and do not take place one after another. Substrates enter the pathways and are withdrawn from it as and when necessary; ATP is utilised as and when needed; enzymatic rates are controlled by multiple means. In over all steps, there is a net gain of 36 ATP molecules during aerobic respiration of one molecule of glucose.
23. Structure and function are correctable in living organisms. Can you justify this by taking plasma membrane as an example? [5]
or
Give an account of abdomen of female cockroach. [5]
Ans. In animals and plants, plasma membrane structure and functions are correlated. A cell membrane consists of protein, lipid and carbohydrates.
The protein component present in membrane acts as a solute channels allowing the flow of minerals, hormones and cellular information from one organelle to another or from one cell to another.
In case of plants where minerals are absorbed actively from the soil. The plasma membrane possesses proteinaceous carriers.
The oligosaccharides attached to membrane serve as recognition centres and help in recognising foreign entities before allowing their entry into the cell.
The lipid content of plasma membrane in plant and animal cells are arranged with their hydrophilic polar head directed outwards and non-polar hydrophobic tails directed inwards providing fluidity to the membrane. Glycocalyx present in cell membrane also helps in cellular attachment.
or
Abdomen of cockroach in both male and female comprises of 10 segments. It is the largest part of body that narrows posteriorly. The abdominal segments are enclosed by four sclerites. A typical thoracic segment consists of dorsal tergum, one ventral sternum and two lateral pleura. In females, 7th tergum covers the 8th and 9th terga, while the 10th one is large and notched in middle, projecting beyond the body. In females only 7 sterna are observed, the 7th one conceals the 8th and 9th sterna. It is boat-shaped and forms a genital pouch with the latter. The genital pouch is divisible into:
(i) Genital chamber, infront side, enclosing female genital pore, spermathecal pores and collateral glands
(ii) Vestibulum (oothecal chamber) behind.
The genital aperture is surrounded by sclerites known as gonapophyses. These arise from 8th and 9th abdominal segment and form an ovipositor to guide the fertilised eggs towards ootheca.
Besides these, the abdomen bears appendages such as Anal cerci, arising from 10th tergum which are sensitive to touch, sound and other vibrations.
The 5th and 6th abdominal terga consists of stink gland which produces a characteristic foul smell.
They also have eight abdominal spiracles, which are provided with fine bristles to prevent entry of dust particles in tracheae during respiration.
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