NIOS Class 12 BIOLOGY Oct 2024 ESS Set C Solved

NIOS Biology Question Paper 2024 Class 12 Set C

1 MARK QUESTIONS

SECTION–A

1. Which one of the following is not produced due to undersecretion of thyroxine?

(A) Goitre 

(B) Cretinism

(C) Myxoedema 

(D) Rickets

2. In the following flow chart A, B, C, and D represent

(A) A-AA+ZW, B-A+W, C-AA+ZW, D-AA+ZW

(B) A-AA+ZZ, B-A+W, C-AA+ZW, D-AA+ZW

(C) A-AA+ZW, B-A+Z, C-AA+ZW, D-AA+ZW

(D) A-AA+ZW, B-A+W, C-AA+ZW, D-AA+ZZ

3. Name the cells that are seen in the lymph nodes and attack bacteria

(A) Lymphocytes 

(B) Monocytes

(C) Granulocytes 

(D) Erythrocytes

4. The bacteria that help in the fixation of atmospheric nitrogen:

(A) Rhizobium 

(B) Streptomyces

(C) Salmonella 

(D) Lactobacillus

5. Which one of the following represent the gametophyte of fern?

(A) Indusium 

(B) Sorus

(C) Prothallus 

(D) Frond

6. In the given food chain identify the trophic level of frog.

(A) First trophic level 

(B) Second trophic level

(C) Third trophic level 

(D) Tertiary trophic level

7. The biological community in an area or ecosystem is a complex network of interactions.

Interactions may be of various types. In commensalism type

(A) One species gets benefitted, and the other species is neither harmed nor benefitted.

(B) One species is inhibited and the other is unaffected.

(C) One species is benefitted and the other is harmed and inhibited.

(D) Both the species are benefitted.

8. The formation of RNA from DNA is known as

(A) Translation 

(B) Transcription

(C) Transformation 

(D) Transduction

9. Identify “A” in the given diagram

(A) Cerebellum 

(B) Cerebrum

(C) Medulla oblongata 

(D) Pons

10. The blood protein that provides factors for clotting is

(A) Albumin 

(B) Fibrinogen

(C) Globulin

(D) Thrombin

11. Identify the immunoglobulin found in highest concentration in our body

(A) IgD 

(B) IgA 

(C) IgG 

(D) IgM

12. Which one of the following adaptations is seen in plants to promote self-pollination?

(A) Cleistogamy 

(B) Dichogamy 

(C) Unisexuality 

(D) Self-sterility

13. Corpus luteum produces

(A) Oestrogen 

(B) Androgens 

(C) Progesterone 

(D) Prolactin

14. The biological community in an area or ecosystem is a complex network of interactions. Interactions may be of various types. In commensalism type

(A) One species gets benefitted, and the other species is neither harmed nor benefitted.

(B) One species is inhibited and the other is unaffected.

(C) One species is benefitted and the other is harmed and inhibited.

(D) Both the species are benefitted.

15. Biotechnology helps in synthesizing enzymes from cloned genes. Your friend wants to manufacture meat tenderisers. Which enzyme would you recommend to him?

(A) Lipases 

(B) Proteases 

(C) Amylases 

(D) Glucoisomerases

16. Which one of the following is not the step in Recombinant DNA technology? 

(A) Selection of specific restriction enzymes.

(B) Cell culture with required gene in the cell is obtained.

(C) Use of restriction enzymes to obtain a restriction fragment.

(D) Amplification of DNA fragments by using Primers.

SECTION B

Question No 17 – 28 objective-type questions carry 2 marks each (with 2 sub-parts of 1 mark each). Attempt these questions as per the instructions given for each of the questions.

17. Name the following: 

(i) An example of fresh water animal of phylum Cnidaria – __________.

(ii) The organelle in Euglena that regulates osmoregulation – ___________.

Ans: 

(i) Hydra

(ii) Contractile Vacuole

18. Match the statement given in Column I with the right option in Column II 

Column-I	Column-II
(i) Copper-T	(a) Interfere with the ovulation process and prevent fertilization
(ii) Condoms	(b) Prevent sperm from meeting the ovulated egg
	(c) Implantation is not possible
	(d) Permanently prevent fertilization

Ans: 

(i) Copper-T – (a) Interfere with the ovulation process and prevent fertilization

(ii) Condoms – (b) Prevent sperm from meeting the ovulated egg

19. Study the flow chart and complete it by substituting A-D with suitable words. (Attempt any two parts from A-D).

Ans: 

• A – Glycolysis
• B – Ethanol + CO2
• C – Anaerobic respiration in Muscle cells
• D – Krebs’ Cycle

20. Fill in the spaces A and B in the sentences given below: 

(a) Cell-mediated immune response is mediated by  A .

(b) Humoral immune responses is mediated by  B .

Ans: 

1. T-cells
2. Antibodies

21. Aquatic ecosystems are classified on the basis of salinity into two types: freshwater and Marine. The common flora and fauna found in freshwater bodies like rivers, lakes include phytoplanktons, water hyacinth, water lily and zooplankton, crab, and fish, respectively. Wetlands are between aquatic and terrestrial ecosystems. They show an edge effect and form an ecotone.

(a) What is the study of freshwater ecosystems known as?

(b) Define ecotone.

Ans: 

1. Limnology
2. Ecotone is a transitional zone between two ecosystems.

22. Given below is the list of vitamins with their functions. Choose the incorrect pairs of vitamins with reference to their function.

(a) Vitamin A: Maintenance of vision

(b) Vitamin C: Formation of blood

(c) Vitamin D: Healthy bones and teeth

(d) Vitamin K: antioxidant: ageing vitamin

Ans: Incorrect pairs are, 

• (b) Vitamin C: Formation of blood
• (d) Vitamin K: antioxidant: ageing vitamin

23. Photosynthesis occurs in green parts of the plants mostly the leaves which have chloroplasts. The thylakoids of chloroplast contain pigments which absorb light of different wavelengths and carry out the photochemical reactions. These pigments are packed into functional clusters called photosystems-PS-I and PS-II.

(a) Name the pigments that constitute the photosystems.

(b) What is the function of Photosystems?

Ans: 

• (i) Chlorophyll a, P₇₀₀, P₆₈₀.
• (ii) To trap the solar energy and convert it into chemical energy

24. Match Column I with the functions given in Column II.

Column-I	Column-II
(i) Pneumatophores	(a) Roots with chlorophyll and manufacture food
(ii) Haustoria	(b) Roots developing from nodes and provide anchorage
	(c) Roots which grow vertically up in the air and help in respiration
	(d) Roots which penetrate the host plant and suck food from host

Ans: 

• (i) Pneumatophores- (c) Roots which grow vertically up in the air and help in respiration
• (ii) Haustoria- (d) Roots which penetrate the host plant and suck food from the host

25. Supply the technical term for the following:

(a) Low temperature treatment which stimulates early flower formation in some plants – __________.

(b) The biological response in growth and flowering to the duration of light and dark period received by a plant in a specific sequence – __________.

Ans: 

1. Vernalisation
2. Photoperiodism

26. Observe the diagrams given below and assign the correct name from the list supplied.

(Attempt any two parts from A-D)

(Rhizome, Tuber, Corm, Bulb)

Ans: 

• Rhizome – A
• Tuber – D
• Corm – B
• Bulb – C

27. Read the following passage and fill in the blanks with appropriate words: 

(Attempt any two parts A-D)

In 1984, Alec Jeffreys invented a technique which could distinguish the DNA of a person from that of another and called this technique as _________A__________ . This technique is now used for __________ B __________ of crime, for example identifying correctly the ______C __________ in murder or to solve __________ D _________ disputes.

Ans: 

1. Genetic fingerprinting
2. Scientific investigation
3. Accused
4. Paternity disputes

28. Study the diagram given below carefully and answer the questions that follow. Identify the processes “A” and “B”.

Ans: 

• A – Photosynthesis
• B – Respiration

SECTION C 

29. Observe the given diagram and answer the questions that follow.

(a) In which direction does the enzyme DNA polymerase catalyze DNA replication – 5′ to 3′ or 3′ to 5′?

(b) Which enzymes join the Okazaki fragments to form a complete DNA strand?

Ans: 

1. In 5’-3’ direction
2. Enzyme ligase

30. (a) Following is the representation of how a plasmid isolated from bacterium that causes galls in several plants is used to produce transgenic plants.

(i) Name the bacterium that causes galls in plants.

(ii) Name the plasmid used to transmit the desired genes.

Ans: 

(i) Agrobacterium tumefaciens causes galls (tumours) in plants.

(ii) T_i plasmid

OR

(b) Given below is the picture of a normal mouse (A) and a transgenic mouse (B).

Why is there an increase in the size of mouse (B).

Ans: A Gene for growth hormone from rats was microinjected into mouse eggs. These mice grew larger than their littermates. This was because the rat gene got integrated into the mouse DNA and was being expressed.

31. How do methanogenic bacteria differ from halophilic bacteria?

Ans: Methanogenic bacteria live in sewage and the intestinal tracts of animals. They are used in sewage treatment plants to clean water. Halophilic bacteria live in salty conditions where the hot sun concentrates seawater.

32. (a) Why is the process of fertilization in flowering plants said to be double fertilization?

Ans: In flowering plants, one sperm fuses with the egg (syngamy) and forms a diploid zygote. The other sperm fuses with the secondary nucleus to form the primary endosperm nucleus, which is triploid in nature. Since two types of fusion, syngamy and triple fusion, take place in an embryo sac, the process is termed double fertilization.

OR

(b) What is the function of Endosperm in the flowering plants? Write the names of any

types of endosperms.

Ans: Endosperm provides food to the developing embryo. Types of endosperm are nuclear type, cellular type, and helobial type of endosperm. 

33. A group of food items is given in the table. Categorize them into energy-providing foods and bodybuilding foods.

Cereals, legumes, meat, sugar, oil, fish, egg, jaggery

Ans: 

• Energy-providing foods: Cereals, Sugar, oil, and jaggery
• Body Building Foods: Legumes, meat, fish, and eggs. 

34. Analyse the differences between striated muscles and unstriated muscles with reference to their shape.

Ans: 

Striated muscles	Unstriated muscles
Elongated, cylindrical, and unbranched fibres	Spindle-shaped and tapering.
Myofibrils are so arranged in the cytoplasm that striations are seen.	No such striations are seen here as myofibrils are not uniformly arranged.

35. Identify A in the diagram given below and state its function

Ans: 

• A- Sinu auricular node.
• It initiates and regularises the heartbeat. Therefore, it is also called the pacemaker. 

36. (a) Name the two biochemical reactions for biosynthesis of amino acids in plants.

Ans: 

(i) Reductive amination reaction

(ii) Transamination reaction

OR

(b) Name the two proteins found in root nodules and helps in nitrogen fixation.

Ans: 

(i) Leghaemoglobin

(ii) Nodulins

37. Identify the type of neuron given in the diagram and state the function of axon.

Ans: 

• It is a neuron that conducts nerve impulses. 
• Axon: An axon carries the impulse from the cell body towards its terminal branches, which may either pass on the impulse to another neuron, or into a muscle or gland to bring about the required action.

38. Name the protein present in the following: 

(a) Nails and Hair

(b) Connective tissue

(c) Muscles

Ans: 

(a) Nails and Hair: Keratin

(b) Connective tissue: Elastin and collagen

(c) Muscles: Actin and Myosin, Troponin and Tropomyosin

39. (I) Observe the Lac operon diagram given below and answer the questions that follow.

(a) Which substance acts as inducer in this operon?

(b) Where does RNA polymerase bind to initiate transcription?

(c) What are the genes z, y, a called as?

Ans: 

1. Lactose is the inducer in this operon. 
2. RNA polymerase binds to the promoter gene p. 
3. Genes z, y, and a are structural genes, where gene a codes for the enzymes galactosidase, permease, and transacetylase. 

OR

(II) Study the karyotype given below and answer the questions that follow.

(a) What is this disorder known as?

(b) How many chromosomes are present in the individuals with this disorder?

(c) State one typical feature of this syndrome.

Ans: 

1. Klinefelter’s syndrome
2. This individual male has 47 chromosomes with an extra X chromosome. 
3. A typical feature of this syndrome is being tall and mentally retarded. 

40. (I) Illustrate the 3 major phases in glycolysis.

Ans: The three major phases of glycolysis are activation, splitting of glucose, and oxidation. 

OR

(II) Distinguish between C3 and C4 plants with reference to the following characteristics.

Features C3 Plants C4 Plants

(a) Carbon dioxide acceptor

(b) Carbon dioxide fixing enzymes

(c) First product of photosynthesis

Ans: 

	C3 Plants	C4 Plants
(a) Carbon dioxide acceptor	5-Carbon sugar- ribulose biphosphate or RuBP	Phosphoenol pyruvic acid or PEP,
(b) Carbon dioxide fixing enzymes	Ribulose bisphosphate carboxylase/oxygenase or Rubisco.	Phosphoenol pyruvate carboxylase (PEP carboxylase)
(c) First product of photosynthesis	3-Phosphoglyceric acid (PGA).	Oxaloacetic acid (OAA).

41. (a) Define obesity.

(b) List any two causes of obesity.

(c) State two Harmful effects of obesity.

Ans: 

1. The overweight and bulkiness of a person’s body due to the accumulation of carbohydrates and fats is called obesity.
2. Two causes of obesity are overeating and insufficient exercise
3. Hypertension and atherosclerosis are two harmful effects of obesity.

SECTION E

42. (a) Explain C4 cycle with a schematic diagram. 

Ans: 

• In C4 plants, the initial acceptor of CO2 is phosphoenol pyruvic acid or PEP, a 3-carbon compound. 
• It combines with CO2 in the presence of an enzyme, Phosphoenol pyruvate carboxylase (PEP carboxylase), and forms a C4 acid, oxaloacetic acid (OAA). 
• This fixation of CO2 occurs in the cytosol of the mesophyll cells of the leaf. 
• OAA is the first stable product of this cycle, which is a 4-carbon compound, and hence the name C4 pathway is given.
• OAA then travels from mesophyll cells to the chloroplasts of bundle sheath cells, where it releases the fixed CO2. 
• Thus, in the C4 pathway of dark reaction, there are two carboxylase enzymes that take part. PEP carboxylase (PEPCo) in the mesophyll cells and RUBP carboxylase (Rubisco) in the bundle sheath cells.

OR

(b) Explain the role of the following parts :

(i) Retina

(ii) Aqueous chamber

(iii) Lens

(iv) Pinna

(v) Auditory nerves

Ans: 

43. (a) A snapdragon plant with red flowers (RR) is crossed with a plant with white flowers

(rr). Work out the cross upto F2 generation. Find out the phenotypic and genotypic ratio.

Ans: 

Parents	RR x rr
Gametes	R, R x r, r
F1	Rr (Pink)
F2	1 red: 2 Pink: 1 White
	1RR: 2Rr: 1rr

OR

(b) A tall pea plant with red flowers (TTRR) is crossed with white dwarf plants (ttrr). Work out the phenotypic ratio in F2 for this cross.

Ans: 

Cross between TTRR (tall red) x ttrr (Dwarf white)

Gametes formed by TTRR are TR, TR

Gametes formed by ttrr are tr and tr

Gametes	TR	TR
tr	TtRr – Tall red	TtRr – Tall red
tr	TtRr – Tall red	TtRr – Tall red

F1 generation is all Tall red with a genotype of TtRr. 

F2 is crossed between TtRr x TtRr

The gametes procured are TR, Tr, tR, tr

Gametes	TR	Tr	tR	tr
TR	TTRRTall red	TTRrTall red	TtRRTall red	TtRrTall red
Tr	TTRrTall red	TTrrTall white	TtRrTall red	TtrrTall white
tR	TtRRTall red	TtRrTall red	ttRRDwarf red	ttRrDwarf red
tr	TtRrTall red	TtrrTall white	ttRrDwarf red	TtrrDwarf white

The phenotypic ratio in F2 is 9 tall red: 3Dwarf red: 3 Tall white: 1 Dwarf white

Additional Study Materials

• NIOS Class 12 Biology PYQ Oct 2024 Set A
• NIOS Class 12 Biology PYQ Oct 2024 Set B