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Grade XIBiology

Mock Test

Mock Test Biology

Questions

Time allowed: 3 hrs. Maximum Marks: 70

General Instructions:

1. There are a total of 27 questions and five sections in the question paper. All questions are compulsory.

2. Section A contains question numbers 1 to 5, multiple choice questions of one mark each. Section B contains question numbers 6 to 12, short answer type I questions of two marks each. Section C contains question numbers 13 to 21, short answer type II questions of three marks each. Section D contains question numbers 22 to 24, case-based short answer type questions of three marks each. Section E contains question numbers 25 to 27, long answer type questions of five marks each.

3. There is no overall choice in the question paper. However, internal choices are provided in two questions of one mark, one question of two marks, two questions of three marks and all three questions of five marks. An examinee is to attempt any one of the questions out of the two given in the question paper with the same question number.

SECTION-A Q1. Which of the following statements regarding the rules for binomial nomenclature is

incorrect?

A. A binomial name is primarily written in latin and is generally italicised. B. The first word in a binomial nomenclature denotes the order whereas, the second

name denotes the species. C. In case when binomial names are handwritten, both the names should be

separately written and underlined. D. The first alphabet of the first word should be in capitals and the second word

should start with a small alphabet in binomial nomenclature. 1

Q2. In which of the following can one find heterocysts?

A. Anabaena 1

B. Nostoc C. Gonyaulax D. Both A and B

Q3. The characteristics such as presence of chlorophyll c, food stored as mannitol and presence of 2 flagella depict which of the following?

A. Rhodophyceae B. Chlorophyceae C. Phaeophyceae D. Both B and C

1

Q4. Which of the following Cniderians exhibit the property of metagenesis?

A. Obelia B. Aurelia C. Adamsia D. Hydra

OR

Which level of organisation is found in coelenterates?

A. Organ level B. Tissue level C. Cellular level D. Organ system level

1

Q5. Which of the following has been incorrectly matched?

A. Marginal placentation - pea B. Axile placentation - lemon C. Free central placentation - Argemone D. Basal placentation - sunflower

OR 1

Which of the following statements about fibrous root system is correct?

A. They usually don’t help in food storage B. Primary root developed from radicle is short lived. C. Root developed from radicle persists throughout the life. D. It is excellent for absorbing water from deeper layer of soil

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 double fertilisation considered to be unique in angiosperms?

OR

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

Q9. What are the functions of the root system? 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. Briefly outline the process behind this phenomenon. 2

Q11. Explain oxygen dissociation curve through a diagram. Name the factors that are favourable for dissociation of oxygen from haemoglobin. 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. 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 to produce 1 glucose molecule? 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 diagrammatic representation and state one function of each type. 3

Q21. Q22.

What do you understand by competitive inhibition? Illustrate the phenomenon diagrammatically. State an example of the same. Answer the given questions on the basis of your understanding of the following paragraph and the related studied concepts.

3

Q23. Q24.

The differences between a living and a non-living thing can be easily elucidated on the basis of certain characters. These characters include consciousness, reproduction, growth and metabolism. However, not every aspect of living things can precisely distinguish it from non-living things. a.) Provide an example of a character which can not precisely differentiate between a living and a non-living thing. b.) Give an example and definition of a character which is considered as a defining property of living things and explain the way in which it can be exhibited outside living systems. c.) Give reason for why reproduction can not be an all-inclusive property of all living things. Answer the given questions on the basis of your understanding of the following paragraph and the related studied concepts. Biological classification has taken different forms and many scientists have provided numerous contribution towards its development. The five kingdom system of classification is widely accepted method of biological classification. It is based on different characteristics and these characteristics are used to categorize organisms into their respective kingdoms. a.) In which kingdoms can one find saprophytic mode of nutrition? b.) What are the four common shapes found in bacteria? c.) Give one point of difference between archaebacteria and other bacteria. Answer the given questions on the basis of your understanding of the following paragraph and the related studied concepts. An important division of kingdom plantae is algae. These are photosynthetic organisms having simple body structure and autotrophic mode of nutrition. Their form and size is variable and they can be found as colonial forms and filamentous forms. The mode of reproduction in algae can be sexual, asexual or vegetative. Asexual reproduction generally involves the production of spores. a.) What are the characteristics of gametes produced by Ulothrix?

b.) Provide two examples of hydrocolloids produced by algae. c.) Enlist two algae which are used to obtain agar.

SECTION-D

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

OR (i) Which step of citric acid cycle is catalyzed by citrate synthase? (ii) During which step of citric acid cycle, FADH2 is formed? (iii) Calculate the total number of ATP molecules produced during Kreb’s cycle from one molecule of acetyl CoA. 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.

OR Describe the ultrastructure of flagellum with the help of a well labelled diagram. 5

Mock Test Biology

Solutions

SECTION-A 1. A binomial name is composed of two words. The first word represents the genus of the

organism and the second word denotes specific epithet. Hence, the correct answer is option B.

2. Heterocysts are specialized cellular structures which are produced by certain nitrogen-fixing eubacteria such as Nostoc and Anabaena. Hence, the correct answer is option D.

3. Chlorophyll c is present in the members of Phaeophyceae. Moreover, members of this division store food in the form of mannitol and laminarin, and have 2 flagella. Hence, the correct answer is option C.

4. Metagenesis is a property of Cnidarians by which some members show alteration of generation between medusa and polyp forms. It is exhibited by Obelia. Hence, the correct answer is option A.

OR

Coelenterates are not much advanced living forms and exhibit tissue level organization.

Hence, the correct answer is option B.

5. In the case of Argemone, parietal placentation is found. Hence, the correct answer is option C.

OR

In fibrous root system, the primary root developed from radicle is short lived.

Hence, the correct answer is Option B.

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 polar nuclei 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. The functions of the root system are as follows:

1. It helps in the absorption of water and minerals from soil. 2. It provides anchorage to plants. 3. It helps in the storage of reserve food material. 4. It helps in the synthesis of plant growth regulators.

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 the seedling stage during the winters. On advent of springs, they resume their growth and show flowering and fruiting during summers.

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 from haemoglobin 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 chief 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. 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 primary xylem and the primary 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 eukaryotic 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.

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, some amino acids and some electrolytes 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 proteins. 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 1 glucose molecule.

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 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. a.) Growth is a character which can not clearly distinguish between a living and a non-living thing. Even non-living things such as crystals have the ability to show growth. b.) One of the defining character of living things is metabolism which refers to all the biochemical reactions occurring within a cell. Although, metabolism is not found in non-living things, it can be demonstrated in lab conditions, outside the living cells. c.) Reproduction can not be considered as an all-inclusive property of all living things because certain living things such as mule are sterile and do not reproduce.

23. a.) Saprophytic mode of nutrition can be found in kingdoms monera, fungi and animalia. b.) Four common shapes found in bacteria are coccus, bacillus, coma-shaped and spiral. c.) The archaebacteria differ from other bacteria in terms of having different cell wall composition.

24. a.) In Ulothrix, the gametes are similar in size and flagellated. b.) Hydrocolloids produced by algae include carageen and algin. c.) Algae which are used to obtain agar include Gracilaria and Gelidium.

SECTION-D

25. NADH and FADH2 are oxidised to release the energy stored in them through the electron transport system (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 and drives the entire process.

OR

(i)

(ii) FADH2 is formed during the formation of fumarate from succinate. (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 acetyl CoA molecule.

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 structures. They are long whip-like structures.

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 one 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.