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Grade XI

Biology Mock Test

Mock Test Biology

Questions

General Instructions:

(i) Question numbers 1 & 5 are one-mark questions. These are to be answered in one word or in one sentence.

(ii) Question numbers 6 to 12 are two-marks questions. These are to be answered in about 30 words each.

(iii) Question numbers 13 to 24 are three-marks questions. These are to be answered in about 50 words each.

(iv) Question numbers 25 to 27 are five-marks questions. These are to be answered in about 70 words each.

SECTION-A Q1. What is the floral formula for the members of the Family Solanaceae? 1

Q2. Which form of transport is Na+/K+ pump a part of? 1

Q3. Reproduction cannot be considered a defining characteristic of living organisms. Why? 1

Q4. The DNA content of a cell is 2C after the M phase. What would have been its DNA content during the M phase?

OR

What change does the cytoplasm undergo in an animal cell during the S phase? 1

Q5. Why are slime moulds not included in Kingdom Fungi?

OR

What is the role of heterocysts present in blue-green algae? 1

SECTION-B

Q6. Explain with the help of an illustration how two nucleotides are linked by a phosphodiester bond to form a nucleic acid. 2

Q7. Give a schematic representation of the steps involved in the conversion of atmospheric nitrogen into ammonia in nitrogen-fixing bacteria. 2

Q8. Why is the phenomenon of fertilisation considered to be unique in angiosperms?

OR

What are bulliform cells? What is the significance of these cells? 2

Q9. A patient has undergone angioplasty. What kind of disease is the person is suffering from? What are its causes? 2

Q10. (a) Which phytohormone can be used for the following? (i) Production of large size apples (ii) Thinning of fruits in cotton

(b) It has been observed by scientists that the winter varieties in wheat show flowering and fruiting only when they are sown during the autumn season. Explain the process behind this phenomenon.

OR Discuss the factors or properties of water on which the movement of water shown in the image given below depends?

2

Q11. Explain oxygen dissociation curve through a diagram. Name the factors that are favourable for dissociation of oxygen in tissue. 2

Q12. Mention the triggers required for the activation of following enzymes. (a) Salivary amylase (b) Pepsin (c) Trypsin (d) Bile juice 2

SECTION-C

Q13. How do chondrichthyes differ from osteichthyes?

OR Organisms of a particular phylum are known as ‘comb jellies’. Name the phyla and write any four of its characteristic features. 3

Q14. What is interkinesis? Describe the events following interkinesis with the help of a diagram. 3

Q15. The current availability of CO2 in the atmosphere is a limiting factor for C3 plants. Justify. 3

Q16. (a) Give two examples of leaves that have parallel venation. (b) Draw a well-labelled diagram to show the detailed anatomy of a monocot leaf.

OR

Briefly describe the activity of the cambial ring. 3

Q17. Explain in detail the structure that controls and coordinates all the activities of the cell. 3

Q18. Explain how the digested food is absorbed into the bloodstream and transported to the various parts of the body? 3

Q19. (a) Represent three stages involved in the Calvin cycle diagrammatically. (b) How many turns of the Calvin cycle are required to make one molecule of glucose? (c) How many ATP and NADPH are utilized in the Calvin cycle? 3

Q20. (a) State any three features of glandular epithelium. (b) Which is the most abundant tissue in the human body? Give any two examples of the same.

OR How can simple epithelium be classified on the basis of structural modifications. Give 3

diagrammatic representation and state one function of each type.

Q21. Q22. Q23. Q24.

What do you understand by competitive inhibition? Illustrate the phenomenon diagrammatically. State an example of the same. Plants do not require specialised respiratory organs. Why? What is the role of the succus entericus in the process of digestion? Write a note on the hypothalamus.

OR Classify neurons on the basis of number of axons and dendrites constituting them. 3

SECTION-D

Q25. How is the energy stored in NADH and FADH2 released during the process of respiration? Briefly explain the process involved.

OR (i) Which step of citric acid cycle is stimulated by citrate synthase? (ii) During which step of citric acid cycle, FADH2 is formed? (iii) Give the total number of ATP molecules produced during Kreb’s cycle. 5

Q26. Explain the mechanism of concentration of filtrate that occurs in kidney during the course of urine formation. Illustrate the process with suitable figures.

OR

(a) Draw a well-labelled structure of nephron. (b) Give an account on the permeability of ascending and descending limbs of loop of Henle in a nephron. 5

Q27. (a) Differentiate between cilia and flagella. (Give any 2 points) (b) How are plastids classified on the basis of the pigments present in them? What are their functions? (c) Differentiate between acrocentric and telocentric chromosomes. 5

OR Describe the ultrastructure of flagellum with the help of a well labelled diagram.

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Grade XI

Biology Mock Test Solutions

Mock Test Biology

Solutions

SECTION-A 1. The floral formula for the members of the Family Solanaceae can be represented as

2. Na+/K+ pump is a part of active transport.

3. Though non-living things are incapable of reproduction, reproduction cannot be considered an all-defining characteristic of living organisms. This is because some living organisms such as mules and worker bees are also incapable of reproduction. However, they cannot be deemed non-living because of this characteristic.

4. The M phase represents the phase of cell cycle during which mitosis occurs. If the DNA content of the cell is 2C after the M phase, then it would be 4C during the M phase.

OR During the S phase, the centrioles present in the cytoplasm of the animal cell duplicate.

5. Slime moulds are consumer decomposer protists. Formerly, they were included among fungi but now they are not because fungi are described as immotile, heterotrophic organisms with chitinous cell walls. Slime moulds move and lack chitin in their cell walls. So, they are now included in Kingdom Protista. Also, slime moulds are slimy masses during their vegetative phase and not moulds in true sense as in the case of fungi.

OR

Heterocysts are specialized thick-walled cells present in blue-green algae such as Nostoc and Anabaena. They help in fixing free atmospheric nitrogen.

SECTION-B

6.

7.

8. In angiosperms, the pollen grains contain two male gametes. One male gamete fuses with the egg cell to form the diploid zygote, while the other male gamete fuses with the diploid secondary nucleus to give rise to triploid primary endosperm nucleus. Since the event of fertilisation consists of two fusions, it is known as double fertilisation. This phenomenon is unique to angiosperms.

OR In monocots such as grasses, certain cells of adaxial epidermis near the veins get modified into large, empty and colourless cells called bulliform cells. When these cells absorb water, they become rigid and cause the leaf surface to be exposed to sunlight. When they lose water, they become flaccid and cause the leaves to curl inwards to minimise water loss.

9. Angioplasty is a surgery by which a thin tube is inserted into the arteries to open its blockage. The person is suffering from atherosclerosis. Atherosclerosis refers to the deposition of lipids (mainly cholesterol) on the walls lining the lumen of large and medium-sized arteries. Its formation starts with deposition of minute cholesterol in tunica intima and then these plaques increase in size resulting in reduction of lumen size and blockage of artery. Some common causes that lead to artery blockage are as follows: (a) Increased cholesterol (b) High blood pressure (c) Smoking (d) Stress

10. (a) (i) Gibberellins (ii) Ethylene (b) The winter varieties of wheat exhibit the phenomenon of vernalization, that is, the low

temperature promotion of flowering in plants. The winter varieties of wheat and barley are sown during autumn. They germinate and remain in seedling stage during the winters. On advent of springs, they resume their growth and show flowering and fruiting during summers.

OR The figure represents the transpiration driven ascent of xylem sap. This depends on the following physical properties of water: (a) Cohesion – It is the mutual attraction between the similar water molecules. (b) Adhesion – It is the attraction between the water molecules and the lignified walls of xylem. (c) Surface tension – Attraction between the water molecules will be higher in liquid phase than in gaseous phase thus increases surface tension between water molecules in liquid phase.

11. Oxygen dissociation curve is a sigmoid shaped curve, plotted between percentage saturation of oxyhaemoglobin and partial pressure of oxygen. It helps in understanding the effect of CO2 and proton concentration on the formation of oxyhaemoglobin.

The factors favourable for dissociation of oxygen in tissue are as follows: 1. High pCO2 2. High proton concentration 3. High temperature 4. Low pO2

12. (a) Salivary amylase It is secreted by salivary gland and is activated when carbohydrate-rich food enters the buccal cavity. It can work only when pH of buccal cavity is around 6.8. (b) Pepsin It is released in inactive form i.e. pepsinogen from the peptic cells of gastric gland. The pro-enzyme pepsinogen, when exposed to HCl, gets converted into active pepsin and carries out digestion of proteins. (c) Trypsin It is the active form of the zymogen, trypsinogen present in the pancreatic juice. Inactive trypsinogen is converted into trypsin by enterokinase enzyme secreted by intestinal mucosa. Trypsin carries out further digestion of partially digested proteins. (d) Bile juice When fat-rich food enters the duodenum, bile is released from gall bladder. The contraction of gall bladder for the release of bile is stimulated by cholecystokinin.

SECTION-C

13.

Chondrichthyes Osteichthyes

They are marine organisms. They are marine as well as freshwater organisms.

They have cartilaginous endoskeleton. They have bony endoskeleton.

They have gills without operculum. They have gills with operculum.

Their skin is covered with placoid scales. Their skin is covered with cycloid or ctenoid scale.

OR

Organisms of phylum Ctenophora are known as ‘comb jellies’. Their characteristic features include: (i) Exclusively marine habitat (ii) Radial symmetry

(iii) The property of bioluminescence (emitting light) (iv) Eight rows of ciliated comb plates located externally. They are used as locomotory organs.

14. The stage between two meiotic divisions is called interkinesis. It is usually short-lived. The events following interkinesis include (i) Prophase II: The nuclear membrane disappears and chromosomes become compact.

(ii) Metaphase II: Chromosomes align at equator and microtubules from opposite poles of the spindle get attached to kinetochores.

(iii) Anaphase II: Splitting of centromere and movement of chromosomes towards opposite poles take place.

(iv) Telophase II: Telophase II results in the enclosure of two groups of chromosomes by a nuclear membrane, followed by cytokinesis and formation of four haploid cells.

15. The current level of CO2 in the atmosphere is very low as compared to the concentration of other gases. In C3 plants, the rate of photosynthesis increases with increase in CO2 concentration, when other factors are not limiting. In C4 plants, same thing happens but C4 plants attain saturation at much lower CO2 concentration. On the other hand C3 plants need high CO2 concentration for saturation. Hence, it is believed that if CO2 concentration in the atmosphere could reach to higher levels, then C3 plants are likely to be benefitted. But present CO2 concentration is limiting factor for C3 plants.

16. (a) Wheat and banana are two examples of plants that have leaves with parallel venation. (b) Transverse section of monocot leaf

OR

Cambium refers to the meristematic tissue responsible for the formation of vascular tissue. The cells of cambium present between the xylem and the phloem in a dicot stem are known

as the intrafascicular cambium. It is present in the young stem as patches between the xylem and the phloem, which later forms a ring. The cambial ring cuts off cells both on the inner and the outer sides but is usually active on the inner side.The cells located towards the pith form secondary xylem, and those located towards the periphery form secondary phloem. Since the activity towards the inner side is greater, more xylem is produced than phloem. This may lead to the crushing of phloem at some places because of the continuous accumulation of the secondary xylem. At some places, cambium forms narrow bands of parenchyma known as medullary rays. These pass through the secondary xylem and phloem in a radial fashion. Hence, they are known as secondary medullary rays.

17.

The nucleus controls all the activities of the cell. Every cell has a nucleus except some cells such as the RBCs of mammals and the sieve tube cells in vascular plants. A cell usually has one nucleus except some variations. The structure of nucleus is described as follows:

● The nucleus is bound by a nuclear envelope which consists of two membranes with a perinuclear space (10−50 nm) between them.

● The perinuclear space acts as a barrier for the flow of materials between the inside of the nucleus and the cytoplast. Hence, to facilitate the transfer of RNA and proteins, nuclear pores are present.

● Nuclear pores are formed at those places where the two membranes fuse.

● Nuclear matrix or nucleoplasm consists of nucleolus and chromatin. ● Nucleolus (pl. nucleoli) is not bound by membrane and is the site of active rRNA

synthesis. The contents of nucleolus are continuous with the nucleoplasm. ● Chromatin: Loose, indistinct network of nucleoprotein fibres present in the

interphase. ● Chromosomes: Chromatin structures develop into distinct chromosomes during cell

division. ● Chromosomes contain DNA, histone proteins, non-histone proteins and also some

RNA. Chromosome has a primary constriction called centromere. Disc-shaped kinetochores are present on the sides of the centromere.

18. Absorption of food is a process through which the end products of digestion pass through the intestinal mucosa into the blood or lymph and becomes a part of circulation, to reach the various parts of the body. Various types of processes involved in the absorption of food are as follows:

1. Simple diffusion − Glucose, amino acids, electrolytes such as Cl− follow this method. It depends on the concentration gradient.

2. Facilitated transport − Fructose and some amino acids are absorbed by this method. Absorption occurs with the help of carrier ion such as Na+.

3. Active transport − Glucose, some amino acids, Na+ follow this method. Absorption is against the concentration gradient. Thus, it requires energy.

4. Fatty acids are insoluble in water. Hence, they are first broken down into small droplets called micelle, which further reform into small protein-coated fat globules called chylomicrons in the intestinal mucosa. These are then transported into lacteals in the villi, and are, finally, released into the blood stream along with the lymph.

19. (a) Three phases of Calvin cycle are: Carboxylation, Reduction and Regeneration

(b) Six turns of the Calvin cycle are required for producing one molecule of glucose. (c) 18 ATP and 12 NADPH are utilized in the Calvin cycle to produce 18 ADP and 12 NADP molecules.

20. (a) Three features of glandular epithelium are as follows: 1. The columnar/cuboidal cells become specialised for secretion. 2. Two types of glandular epithelium: Unicellular (as in goblet cells of the alimentary

canal) and multicellular (as in the salivary glands). 3. Glands are of two types: Exocrine (ductless) and endocrine (release products through

ducts). (b) Connective tissue is the most abundant tissue in the human body. They link or connect other tissues. Examples: Cartilage, bone, blood, etc.

OR On the basis of structural modifications, epithelium is divided into

1. Squamous: It consists of a single layer of thin-walled cells. It is present in the alveoli and blood capillaries and is helpful in diffusion across the membrane.

2. Cuboidal: It consists of cuboidal cells that may be ciliated or non-ciliated. It is involved in secretion and absorption.

3. Columnar: It consists of tall but slender layer of cells that are helpful in secretion and absorption. The cells lining the intestine are columnar epithelium.

21.

Competitive inhibition is the phenomenon where the inhibitor loosely resembles the substrate and binds with the active sites of enzymes. Hence, enzyme activity declines.

Example of competitive inhibition: Malonate resembles succinate structurally and blocks the activity of the enzyme succinic dehydrogenase.

22. Plants do not require specialised organs for respiration because: 1. Gaseous exchange occurs in each part of a plant. 2. Gaseous exchange is not a much-needed factor. The need for gaseous exchange is

met during photosynthesis. 3. Each living cell is located close to the surface of a plant. Hence, the distance that the

gases must diffuse through is not great.

23.

The secretions of brush border cells and the goblet cells of the intestinal mucosa constitute the succus entericus. It contains enzymes such as maltase, dipeptidase, lipase nucleosidase, etc. It also contains mucus, which in combination with bicarbonates released by pancreas, provides alkaline medium and prevents intestinal mucosa from the corrosive action of acids. The action of intestinal juice results in the following break down reactions:

The hypothalamus is located at the base of diencephalon, which is a part of the forebrain. It contains many neurosecretory cells that secrete hormones. These cells are also called nuclei. The hormones of the hypothalamus control the activity of the anterior pituitary gland. The posterior pituitary gland is in direct neural control of the hypothalamus.

24. Hormones originating from hypothalamic neurons pass through axons and are released from their nerve endings. They reach the pituitary gland through a portal circulatory system and regulate the functioning of the anterior pituitary gland. Two types of hormones are produced by the hypothalamus: Releasing hormones, which stimulate the secretion of pituitary hormones, and inhibiting hormones, which inhibit the secretion of pituitary hormones. Gonadotropin-releasing hormone (GnRH) is an example of releasing hormones; it stimulates the pituitary synthesis and release of gonadotropins.

Somatostatin is an example of inhibiting hormones; it inhibits the release of growth hormones from the pituitary gland.

OR The neurons are of three types based on the number of axons and dendrites.

1. Multipolar: They have one axon and two or more dendrites. These are found in the cerebral cortex.

2. Bipolar: They have one axon and one dendrite. These are found in the retina of eye. 3. Unipolar: They have a cell body with one axon only. These are found in the

embryonic stages of life.

SECTION-D

25. NADH and FADH2 are oxidised to release the energy stored in them through the electron transport scheme (ETS). In the ETS, the electrons are passed from one carrier to another, and finally to oxygen, thereby resulting in the formation of water.

● Electrons produced by NADH in the mitochondrial matrix are oxidised by complex

I (NADH dehydrogenase). ● Electrons are then transferred to ubiquinone, located in the inner mitochondrial

membrane. Ubiquinone receives reducing equivalents through complex II (FADH2). ● The reduced ubiquinone (ubiquinol) is then oxidised by the transfer of electrons

from complex III (cytochrome bc1 complex) to cytochrome c. ● Cytochrome c transfers the electrons between complex III and complex IV

(cytochrome c−oxidase complex consists of cyt a and a3, along with two copper centres).

● In the course of passing from one carrier to another, electrons couple with complex V (ATP synthase) and produce ATP.

● The oxidation of 1 NADH produces 3 ATPs, while the oxidation of 1 FADH2 produces 2 ATPs.

● Role of oxygen in the terminal stage of ETS: It acts as the final hydrogen acceptor; removes hydrogen from the process and drives the entire process.

OR

(i)

(ii) FADH2 is formed during the formation of malic acid from succinic acid.

(iii) 3NADH molecules are produced during one cycle 1 NADH yields 3 ATP so 3 NADH yields 9 ATP. 1 FADH2 formed yields 2 ATP molecules 1 ATP is directly formed Hence, 12 ATP molecules are produced per pyruvic acid molecule. Since, two molecules of pyruvic acid are produced from each molecule of glucose, 24 molecules of ATP are formed during the citric acid cycle.

26. Concentration of urine is achieved by the presence of a concentration gradient in medullary interstitium. Such a concentration gradient is maintained by a specialised mechanism called the counter-current mechanism. The flow of filtrate in two limbs of Henle's loop is in opposite directions. Flow of blood in vasa recta is also in opposite directions. Both these flows form a counter-current. Close proximity of Henle’s loop and vasa recta as well as the counter-current in them maintains an osmolarity that increases towards medullary interstitium. NaCl and urea also play a role in the maintenance of the gradient. (i) NaCl: Transported by the ascending limb of Henle’s loop and provided to the descending limb of vasa recta. (ii) Urea: Enters the thin segment of the ascending limb of Henle’s loop. NaCl is transported back to interstitium by the ascending portion of vasa recta and urea is transported back to interstitium by the collecting tubule. Thereby, concentration of filtrate is

achieved in kidney.

OR

The ascending limb of Henle’s loop is impermeable to water. However, it is permeable to many other electrolytes. On the other hand, the descending limb of Henle’s loop is

permeable to water, but impermeable to electrolytes.

27.

(a) Differences between cilia and flagella:

Cilia Flagella

They are short hair-like organelles. They are long whip-like organelles.

They exhibit sweeping or rowing motion. They exhibit undulatory motion.

(b) Plastids are classified into three types − chloroplasts, chromoplasts, and leucoplasts.

Plastid Pigment Function

Chloroplast It contains chlorophyll and carotenoid pigments.

It helps in photosynthesis. It traps solar energy through photosystems.

Chromoplast It contains carotenoid pigments such as carotene and xanthophylls.

It imparts various colours to the flowers in flowering plants.

Leucoplast It is colourless and lacks pigments. It helps in storage of food in the form of carbohydrates (starch), fats, and proteins.

(c) Difference between acrocentric chromosome and telocentric chromosome:

Acrocentric Chromosome Telocentric Chromosome

The centromere is situated close to the end of the chromosome, resulting in the formation oftwo unequal arms.

The centrosome lies at the terminal part of thechromosome.

OR

The flagella is a hair like outgrowth of a cell membrane. Flagella are long structures that help in movement of cell. When observed under electron microscope, it can be seen that flagella are covered by the plasma membrane. They consist of axoneme, which is the core of the internal portions of flagella. Axoneme contains microtubules. There are 9 pairs of peripheral doublet microtubules and one pair of central microtubules. This arrangement is called 9 + 2 array. Central tubules are connected by a bridge and enclosed within the central sheath, whereas

the radial spoke connects one of the tubules of each of the nine peripheral microtubules with the central sheath. Linkers interconnect the peripheral tubule, whereas the basal body is a centriole-like structure from where the flagella emerges.