Table of Contents
CBSE Sample Papers for Class 11
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Biology 2016 Set 2
Section A
1. Name the reserve food material in the Phaeophyceae group of algae.
2. Inulin is a homopolysaccharide found in plants. What is the basic monomeric unit of this polymer?
3. We can observe different eye colours, i.e. green, brown, or black among ourselves. Name the pigment responsible for colour of eyes.
4. Name the epithelial tissues present on the inner surface of bronchioles and Fallopian tubes.
5. Think of a plant that lacks chlorophyll. From where will it obtain nutrition? Give an example of such a type of plant.
Section B
6. The cell cycle comprises long interphase and short dividing phase. What is the significance of the G0-phase in the cell cycle?
7. What conditions enable RuBisCO to function as an oxygenase? Explain the ensuring process.
8. Marine mammals are able to make long underwater dives. Justify the statement.
9. What is mesosome in a prokaryotic cell? Mention the function that it performs.
or
Name the types of joint present between(a) Atlas and axis (b) Phalanges
(c) Femur and acetabulum (d) Cranial bones
Section C
10. Write down the major characteristics of family-Solanaceae. Also, mention the floral formula and floral diagram of a flower belonging to this family.
11. What do you understand by ‘algal bloom’ and ‘ red tides’? How are they harmful for the environment?
12. (a) Differentiate between saturated and unsaturated fatty acids.
(b) What is cholesterol? Describe the two forms of cholesterol.
13. What are the main steps in aerobic respiration? Where does it take place?
14. How is cephalisation in animals considered as an asset in an adjustment with the environment?
15. Both lysosomes and vacuoles are a part of endomembrane structures, yet they differ in their functions. Comment.
16. When a freshly collected Spirogyrafilament is kept in a 10% potassium nitrate solution, it is observed that the protoplasm shrinks in size.
(a) What is this phenomenon called?
(b) What will happen if the filament is replaced in distilled water?
17. Differentiate between florigen and other growth hormones.
18. Describe the structure of a neuron with the help of a labeled diagram. Give an account of types of neurons based on structure.
19. Differentiate between
(a) Bract and bracteole (b) Spike and spadix
or
Name the structures forming the female reproductive part in flowering plants. Discuss the structures and state how placenta is related to this part. State the types of placentation found.
20. Name the hormones regulating the following.
(i) Control of skin colour (ii) Release of sugar from liver
(iii) Widening of pelvis at birth
Also mention from where these hormones are secreted.
21. Sneha’s mother while leaving in a hurry instructed her to keep the tomatoes and other fruits, e.g. apples and grapes inside the refrigerator. Sneha was busy preparing for her exams and forgot to keep them inside. When her mother came after two days, she observed them rotting in the kitchen and reminded Sneha of the instructions. She wondered how did they get spoilt in a day whereas we use them fresh for longer periods usually. To this, Sneha’s elder sister , a student of biology explained her the reason.
(a) How does the shelf life of fruits and vegetables increase in a refrigerator?
(b) Describe the influence of temperature on enzyme action through a graphical representation.
(c) Do you think, there might be some other factors that influence its action?
(d) What values are reflected by Sneha and her elder sister?
Section D
22. Terrestrial animals are generally either ureotelic or uricotelic not ammonotelic. Why?
or
Explain the mechanism of vision, i.e. image formation by human eye.
23. Plant hormones known for their various physiological functions may act synergistically or antagonistically. Give reasons in support of this statement.
or
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?
Answers
Section A
1. Name the reserve food material in the Phaeophyceae group of algae. [1]
Ans. The reserve food material in Phaeophyceae or brown algae is laminarin or mannitol.
2. Inulin is a homopolysaccharide found in plants. What is the basic monomeric unit of this polymer? [1]
Ans. Inulin is a homopolysaccharide, made up of polymers of fructose.
3. We can observe different eye colours, i.e. green, brown or black among ourselves. Name the pigment responsible for colour of eyes.[1]
Ans. Iris that forms a pigmented circle of muscular diaphragm gives the eye its varied colours in different individuals.
4. Name the epithelial tissues present on the inner surface of bronchioles and Fallopian tubes. [1]
Ans. The ciliated columnar epithelium is present on the inner surface of bronchioles, Fallopian tubes, respiratory tract, ventricles of the brain, etc.
5. Think of a plant which lacks chlorophyll. From where will it obtain nutrition? Give an example of such a type of plant.[1]
Ans. An angiosperm plant called Monotrapa does not contain chlorophyll. It grows on some other plant as a parasite and derives nutrition from the host plant. This plant is commonly known as ghost plant,
Section B
6. The cell cycle comprises of a long interphase and short dividing phase. What is the significance of G0-phase in cell cycle? [2]
Ans. G0-phase is the extension of Gr phase and is also known as the quiescent stage of the cell cycle. Cells in this stage remain metabolically active and function as reserve cells, but no longer proliferate unless called on to do so depending on the requirement of the organisms.
7. What conditions enable RuBisCO to function as an oxygenase? Explain the ensuring process. [2]
Ans. Carboxylation is the most crucial step of the Calvin cycle, where C02 is utilized for the carboxylation of RuBP. This reaction is catalysed by the enzyme RuBP carboxylase which results in the formation of two molecules of 3-PGA. Since, this enzyme also has an affinity for oxygen, it shows oxygenation activity when the CO2 concentration decreases. During high temperatures, the RuBP binds to 02 and acts as an oxygenase enzyme, which forces C02 to enter the C2 cycle thus leading to photorespiration and loss of C02.
8. Marine mammals are able to make long underwater dives. Justify the statement.[2]
Ans. Whales, seals, and other marine mammals can make long underwater dives because they have a huge spleen filled with blood and can store more oxygen in their blood and muscles. They can also reduce their oxygen consumption rate underwater, allowing them to stay underwater for longer periods of time.
9. What is mesosome in a prokaryotic cell? Mention the function that it performs.
or
Name the types of joint present between[1 +1]
(a) Atlas and axis (b) Phalanges
(c) Femur and acetabulum (d) Cranial bones
Ans. In a prokaryotic cell, the mesosome is an unique membrane structure created by the expansion of the plasma membrane into the cell. It aids in cell wall construction, DNA replication, and genetic material distribution to daughter cells. It also aids respiration and secretion activities by increasing plasma membrane surface area and enzymatic content.
or
The type of joints present between
(a) Atlas and axis is pivot joint.
(b) Phalanges is hinge joint.
(c) Femur and acetabulum is ball and socket joint.
(d) Cranial bones is suture (fibrous joint).
Section C
10. Write down the major characteristics of family-Solanaceae. Also, mention the floral formula and floral diagram of a flower belonging to this family.
11. What do you understand by ‘algal bloom’ and ‘ red tides’? How are they harmful for the environment?
Ans. Green algae such as Chlorella, Scenedesmus, and Spirogyra, for example, can overgrow in water bodies and turn the water green. Algal blooms are what they’re called. Crimson dinoflagellates (Gonyaulax) are abundant in the sea and give the water a red colour. This resembles red tides. Animal life suffers as a result of algae blooms and red tide, which produce poisons and oxygen deficit in the water.
12. (a) Differentiate between saturated and unsaturated fatty acids.
(b) What is cholesterol? Describe the two forms of cholesterol.
(b) Cholesterol is a common sterol found in animals and humans. Its molecular formula is C27H45 It occurs in both free and combined form when esterified with a fatty acid. It acts as a precursor of most steroid hormones.
Cholesterol exists in two forms:
(i) LDL (Low Density Lipoprotein) It can be small and dense or large and buoyant particles. It is known as bad cholesterol and is harmful since LDL can enter arterial walls and makes the blood sticky or clot.
(ii) HDL (High Density Lipoprotein) It is also known as good cholesterol. It is dense and removes scavenges LDL from the blood to liver, thus reducing the risk of heart disease.
13. What are the main steps in aerobic respiration? Where does it take place?[3]
Ans. The main steps in aerobic respiration are as follows:
(i) Glycolytic breakdown of glucose into pyruvic acid. It takes place in cytoplasm.
(ii) Oxidative decarboxylation of pyruvic acid to acetyl Co-A (acetyl coenzyme-A)
(iii) Krebs’ cycle. It occurs in mitochondrial matrix.
(iv) Terminal oxidation and phosphorylation in respiratory chain.
It occurs in the inner mitochondrial membrane.
14. How is cephalisation in animals considered as an asset in an adjustment with the environment? [3]
Ans. Bilaterally symmetric creatures travel forward with their front end front. Cephalisation, or the differentiation of a distinct head at the front end, has resulted as a result of this. The concentration of nerve tissue (brain) and sense organs in the head is known as cephalization. Because the front end of a moving animal is the first to face changes in the area it enters, this configuration is advantageous in adjusting to the environment.
15. Both lysosomes and vacuoles are a part of endomembrane structures, yet they differ in their functions. Comment.[3]
Ans. The endomembrane system is an intracellular membrane system that is connected by vesicles that allow membranes and chemicals to pass from one place to another. The endoplasmic reticulum, Golgi complex, lysosomes, and vacuoles are examples of membrane organelles that act in close conjunction with one another.
However, each component is designed to execute a certain role. Lysosomes, for example, are specialised for both intracellular and extracellular digestion. It also demonstrates autophagy and intracellular scavenging. Vacuoles, on the other hand, are used for substance storage, osmoregulation, and buoyancy maintenance.
16. When a freshly collected Spirogyrafilament is kept in a 10% potassium nitrate solution, it is observed that the protoplasm shrinks in size.
(a) What is this phenomenon called?
(b) What will happen if the filament is replaced in distilled water?
Ans. (a) Plasmolysis is the phenomenon occurring in Spirogyra filament when placed in 10% potassium nitrate solution(hypertonic solution). It occurs as water from the cell is drawn out to extracellular fluid causing the protoplast to shrink away from cell wall.
(b) When the above Spirogyra is placed in distilled water, it will again reabsorb water, protoplast will again come back in its original shape. This phenomenon is known as deplasmolysis.
17. Differentiate between florigen and other growth hormones.
18. Describe the structure of a neuron with the help of a labelled diagram. Give an account of types of neuron based on structure.
On the basis of structure, neurons can be classified as:
(a) Non-polar neurons possess several branched processes.
(b) Unipolar neurons possess single projection arising from cyton.
(c) Pseudounipolar neurons possess single process arising from cyton but divides into an axon and a dendrite.
(d) Bipolar neurons have two processes with axon at one end and dendrite at another end.
(e) Multipolar neurons possess several dendrites and an axon, and are the most common type of neurons.
19. Differentiate between
(a) Bract and bracteole (b) Spike and spadix
or
Name the structures forming the female reproductive part in flowering plants. Discuss the structures and state how placenta is related to this part. State the types of placentation found.
or
Gynoecium forms the female reproductive part of flower. It comprises of one or more carpels or pistils. The individual carpel consists of three parts:
Stigma is the tip of the carpel and acts as a receptive surface for pollen grain.
Style is tube like structure connecting ovary to stigma.
Ovary is the basal enlarged part. Each ovary bears one or more ovules attached to flattened cushion-like placenta.The arrangement of ovules inside a ovary is called placentation. It may be of following types:
20. Name the hormones regulating the following.
(i) Control of skin colour (ii) Release of sugar from liver
(iii) Widening of pelvis at birth
Also mention from where these hormones are secreted.[1 x 3]
Ans. The hormones controlling or regulating the
(i) Skin colour is MSH (Melanocyte Stimulating Hormone). It is secreted by the intermediate lobe of pituitary.
(ii) Release of sugar from liver is regulated by glucagon. It is secreted by a-cells of islets of Langerhans (pancreas).
(iii) Widening of pelvis at birth is regulated by oxytocin.lt induces contraction of smooth muscles of uterus during parturition. It is secreted originally by neurosecretory cells in hypothalamus but are stored and released from posterior lobe of pituitary gland.
21. Sneha’s mother while leaving in a hurry instructed her to keep the tomatoes and other fruits, e.g. apples and grapes inside the refrigerator. Sneha was busy preparing for her exams and forgot to keep them inside. When her mother came after two days, she observed them rotting in the kitchen and reminded Sneha of the instructions. She wondered how did they get spoilt in a day whereas we use them fresh for longer periods usually. To this, Sneha’s elder sister , a student of biology explained her the reason.
(a) How does the shelf life of fruits and vegetables increase in a refrigerator?
(b) Describe the influence of temperature on enzyme action through a graphical representation.
(c) Do you think, there might be some other factors that influence its action?
(d) What values are reflected by Sneha and her elder sister?
Ans.
(a) Food when kept inside a refrigerator is prevented from spoiling both by microorganisms and its own enzymes (present in living cells). Since refrigerator maintains low temperature, the enzymes remain inactive and don’t act upon complex substrates converting them into simpler forms, thus preventing degradation.
(b) The activity of enzymes decreases at both high and very low temperatures but is maximum at optimum temperatures.
(c) The other factors that affect the enzyme activity are pH, concentration of substrate and presence of inhibitors, if any.
(d) Sneha is curious with a quest to learn but a little careless. While Sneha’s sister being elder to her is more mature, attentive and had a better understanding of the subject along with its practical application. So, she seems intelligent as well.
Section D
22. Terrestrial animals are generally either ureotelic or uricotelic not ammonotelic. Why?[5]
or
Explain the mechanism of vision, i.e. image formation by human eye.[5]
Ans. For water conservation, terrestrial adaptation necessitates the creation of less toxic nitrogenous wastes such as urea and uric acid. Ureotelic animals are mammals, many terrestrial amphibians, and marine fish that mostly excrete urea. The liver of these animals converts ammonia produced by metabolism into urea, which is then released into the blood, where it is filtered and expelled by the kidneys.
To maintain a desired osmolarity, some of these animals’ kidney matrix may retain a little quantity of urea. Uricotelic animals are reptiles, birds, land snails, and insects that excrete nitrogenous wastes as uric acid in the form of a pellet or paste with minimal water loss.
or
The mechanism of image formation on the retina of human eye is as follows:
(i) Retina receives light rays (in visible wavelength) through the cornea and lens generate impulses in rods and cones.
(ii) The photosensitive compounds (photopigments) in the human eye are composed of opsin (a protein) and retinal (an aldehyde of vitamin-A).
(iii) The received light induces dissociation of the retinal from opsin resulting in changes in the structures of the opsin. This causes the changes in the permeability of membrane.
As a result, the potential difference is generated in the photoreceptor cells. This produces a signal that generates action potential in the ganglion cells through the bipolar cells.
(iv) These impulses (action potentials) are transmitted by the optic nerves to the visual cortex of the brain.
(v) In brain, neural impulses are analysed and the image formed on the retina is recognised (based on earlier memory and experience).
23. Plant hormones known for their various physiological functions may act synergistically or antagonistically. Give reasons in support of this statement. [5] or
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?[5]
Ans. The evidences that support phytohormones act synergistically or antagonistically are:
(i) Cell division is promoted by both auxins and cytokinins acting synergistically.
(ii) Auxin and cytokinins interact to control morphogenetic differentiation of shoot and root. When auxin is in excess, roots differentiate on the callus, while excess of cytokinins promote bud formation.
(iii) Auxins and cytokinins acts antagonistically in controlling apical dominance. Auxins causes apical dominance, while cytokinins overcome the same.
(iv) Senescence is prevented by auxins and cytokinins, while it is stimulated by abscisic acid.
(v) The activity of cambium and fruit growth seem to be promoted by auxins, gibberellins and cytokinins, the same is inhibited by abscisic acid.
(vi) The dormancy of seeds and buds is mostly due to abscisic acid, the same is broken by gibberellins.
(vii) Cytokinins cause opening of stomata, while abscisic results in their closure.
or
Abscission is the process by which deciduous plants shed their leaves during the hot summer or autumn. The cells of the abscission zone are thin-walled and lack lignin or suberin deposits anatomically. The middle lamella may dissolve between the cells of two middle layers during abscission, while the major wall remains intact. The main walls of the neighbouring cells, as well as the central lamella, are dissolved. Finally, all of the cells in the abscission layer’s middle layer dissolve completely. Wherever there is rainfall or wind, the plant organ, i.e. the leaf, is separated from the plant.
