NIOS Class 12 BIOLOGY April 2023 SET  C  (65/ASS/3)

NIOS Biology Question Paper 2023 Class 12 Set C

1 MARK QUESTIONS

1. Cholera is caused by: 

(A) Salmonella typhi 

(B) Vibrio cholerae 

(C) Mycobacterium 

(D) Azotobacter 

2. Desert plants conserve water by 

(A) developing waxy coating on leaves. 

(B) having more stomata. 

(C) having broad leaves. 

(D) having more hydathodes. 

3. The phyto-hormone used as weedicide is – 

(A) Auxin 

(B) Gibberellins 

(C) 2, 4-D 

(D) Ethylene 

4. Niche is understood as: 

(A) Space between two habitats 

(B) Functional role of species in a habitat 

( C ) Space available on a tree 

(D) Space shared by two or more species 

5. In the alcohol manufacturing industry the organisms used is: 

(A) Saccharomyces 

(C) Chlamydomonas 

(B) Streptomyces 

(D) Leuconostoc 

6. The type of placentation found in cucumber is: 

(A) Parietal 

(C) Free central 

(B) Axile 

(D) Superficial 

7. The association between maternal and foetal tissue is called: 

(A) endometrium 

(B) placenta 

(C) umbilical chord 

(D) wall of uterus 

8. During asexual reproduction Rhizopus produces a large number of: 

(A) Spores 

(C) Buds 

(B) Gametes 

(D) Fission-forms 

2 MARKS QUESTIONS

9. What are non-specific immune responses? Write any two examples of it. 

Ans: Non-specific immune responses are those that non-selectively protect against foreign substances or cells without having to recognise their specific identities. Phagocytosis (engulfing of particulate matter) by macrophages and extracellular killing by proteins known as ‘complement’.

10. (a) What is central dogma in molecular biology? 

(b) What is reverse transcription? 

Ans: 

1. The transfer of information from genes to the site of protein synthesis constitutes the Central Dogma.
2. In retroviruses, the synthesis of DNA from RNA in the presence of the enzyme reverse transcriptase is called reverse transcription.

11 Write any two important characters of insect-pollinated flowers. Write one example of it. 

Ans: 

• Flowers are usually large, coloured, and showy to attract insects.
• Some of these flowers secrete nectar to attract insects. Salvia flowers show special adaptations for pollination by bees.

12. Write the three types of RNAs present in our cells. Write the function of RNA polymerase. 

Ans: The three types of RNAs present in our cells are mRNA (messenger RNA, rRNA (ribosomal RNA), and tRNA (transfer RNA). RNA polymerase catalyses the synthesis of mRNA, signalled by a protein, sigma factor. 

13. ( a ) Name two microbes which help plants in getting nutrients. Explain how? 

(b) Write any one example. 

Ans: 

1. Rhizobium and Azotobacter are two microbes that help plants get nutrients. Rhizobium lives in the roots of legumes where it fixes atmospheric nitrogen into ammonia, which is later converted into amino acids. Azotobacter makes the soil fertile by fixing atmospheric nitrogen.
2. Rhizobium lives in the roots of Pea plants.

14. What is the source of O₂ released during photosynthesis? What is the process called? Also write its equation. 

Ans: Water molecule, H₂O, is the source of O₂, which is released during photosynthesis. The process that splits the water molecule that release O₂ is called photolysis. 

15. The plant Nepenthes lives in nitrogen-deficient soils. How does it get Nitrogen, necessary for its living? 

Ans: Nepenthes feed on insects and rely on them as the source of nitrogen. Their shiny surface 

and nectar attract the insects. Their digestive enzymes digest these insects into amino acids, which are absorbed by the inner surface of their leaves. 

16. Explain the process of Sex determination in honey bees. 

Ans: In honey bees, fertilised eggs emerge as females and unfertilised eggs develop into males. Since fertilised eggs and females are diploid, and unfertilised eggs and malesare  haploid. 

17. Write the functions of following organs of male reproductive system of man: 

(a) Seminal vesicles 

(b) Prostate glands 

Ans: 

1. Seminal vesicles are small white sacs at the anterior end of the ejaculatory duct that store sperm.
2. Prostate glands secrete an alkaline fluid that keeps the sperm alive and helps them to swim vigorously.

18. Label the parts a, b, and c of the following curve. Name the curve. What does it depict? 

Ans: 

1. Slow growth
2. Rapid growth
3. No growth

The curve is called the Sigmoid curve. It depicts the increase in cell number (growth rate) against time. 

19. What is cellular respiration? Write its products. Write the name of organelle involved in this process. 

Ans: The biochemical process, which occurs within cells and oxidises food to obtain energy, is known as cellular respiration.

It occurs in the mitochondria. 

20. Draw a lined diagram of stomatal apparatus found in Dicots and label its any four parts. 

Ans: 

4 MARKS QUESTIONS

21. Name the type of animal tissue which are responsible for the following functions: 

(a) Storage of fats 

(b) Production of RBC 

(c) Lining of salivary gland 

(d) Eating up of foreign bodies 

Ans: 

1. Adipose tissue
2. Bone marrow
3. Glandular tissue
4. White Blood Cells

22. (a) Name any four types of immunoglobulins produced in human body. 

(b) What is triple vaccine? At what stage is it administered in human beings? Name the diseases it prevents. 

Ans: 

1. Types of immunoglobulin found in the human body are IgD, IgA, IgE, IgG, and IgM.
2. A triple vaccine carries antigens for three diseases. DPT has diphtheria and tetanus toxoids, and for pertussis, Bordetella pertussis, the whooping cough organism. The vaccine is given in the infant age.

23. Write any three differences between aerobic and anaerobic respiration. Write one example for each type. 

Ans: Any three. 

Takes place in the complete absence of oxygen.	Anaerobic respiration
Takes place in the presence of oxygen.	Takes place in the complete absenceof oxygen.
Leads to the complete oxidation of the organic substrate.	Incomplete oxidation of the organic substrate takes place.
It is most common in higher organisms (both plants and animals).	Takes place in lower organisms, such as bacteria, fungi, and in higher animals under limiting conditions of oxygen (e.g., in muscles when oxygen present is insufficient).
C6H12O6 → 6CO2 + 6H2O + 6O2 +38 ATP	C6H12O6 → 2Ethyl alcohol + 2CO2 +2 ATP(as in yeast) C6H12O6 → 2 Lactic acid + 2 ATP (muscles)
Takes place in the cytoplasm and mitochondria in eukaryotes and the plasma membrane in prokaryotes.	Takes place in the cytoplasm.

24. (a) Define ecotone. 

(b) Why grasslands and wetlands are considered as ecotone? Explain with the help of one example of each. 

Ans: Ecotone is a transitional zone between two ecosystems.

• Grasslands represent an ecotone (a zone in between two ecosystems) and are found between forests on one side and deserts on the other.
• Wetlands are between aquatic and terrestrial ecosystems. They show an edge effect and form an ecotone.

25. (a) Draw a neat and labelled diagram of a DNA molecule showing formation of new DNA strands. 

(b) In which direction does a new strand of DNA is formed during replication? 

(c) What are Okazaki fragments? 

Ans: 

1. Formation of new DNA strands.

2. New strands are formed from the 5’ end to the 3’ end.
3. The DNA synthesis on the lagging strand is discontinuous by forming small pieces. These fragments are called Okazaki fragments.

26. (a) How does our skin help in maintaining body temperature during summers and winters. 

(b ) What are poikilotherms and homotherms? Explain with example. 

Ans: 

1. In summer, we sweat a lot, and when this sweat evaporates, we feel cool. IN winter, sweat glands under the skin will not perspire much and preserve the body heat.
2. Poikilotherms are animals that acquire their body temperature from their surroundings. Homoiotherms are animals that maintain a constant temperature without any fluctuations.

6 MARKS QUESTIONS

27. (a) Name any two food items that could prevent Vitamin D deficiency in our body. 

(b) Name the disease caused due to deficiency of Vitamin A and also write any one symptom of it. 

(c) Write any three methods for conservation of soil. 

Ans: 

1. Milk, egg, and cod liver oil.
2. Night blindness- Cannot see in dim light.
3. Soil conservation:

1. Planting of trees and vegetation reduces soil erosion.
2. Dividing a slope into several flat fields to control the rapid run of water, especially in hilly areas.
3. Grazing should be allowed only in specified areas.

28. (a) Define Mendel’s law of independent assortment. 

(b) Explain it with the help of Punnett square. 

(c) Write the phenotypic ratio of F2 generation. 

Ans: 

1. The law of independent assortment states that the inheritance of factors controlling one character does not depend on the inheritance of any other factor controlling any other character.
2. In a cross between a red tall and a white dwarf plant. (TTRR x ttrr) with gametes: TR, tr

F1: TtRr

When the F1 is selfed, the F2 is obtained as below. 

Gametes	TR	Tr	tR	tr
TR	TTRR (Tall red)	TTRr (Tall red)	TtRR (Tall red)	TtRr (Tall red)
Tr	TTRr (Tall red)	TTrr (Tall white)	TtRr (Tall red)	Ttrr (Dwarf White)
tR	TtRR (Tall red)	TtRr (Tall red)	ttRR (Dwarf red)	ttRr (Dwarf red)
tr	TtRr (Tall red)	Ttrr (Dwarf white)	ttRr (Dwarf red)	Ttrr (Dwarf white)

The F2 showed independent assortment of two pairs of genes. R for red flower, r for white flower, T for tallness, and t for dwarfness. 

3. The phenotypic ratio in F2 is 9 Tall Red: 3 Tall White: 3 Dwarf Red: 1 Dwarf white

29. (a) Write one character of following plant tissues. Also mention their location. 

(i) Parenchyma (ii) Xylem (iii) Meristematic tissue 

(b) Write name of one organism having following structures/characters: 

(i) Canal system 

(ii) Tentacles 

(iii) Absence of digestive system 

(iv) Suckers 

(v) Jointed legs 

(vi) Tube feet 

Ans: 

1. Characters and location

• Parenchyma: These are living cells with thin walls. They are found in the pith and cortex of roots and stems.
• Xylem: Xylem is a conducting tissue that conducts water and salts upward from roots to leaves. It is found in vascular bundles.
• Meristematic tissue: Composed of immature or undifferentiated cells without intercellular spaces. It is found at the root and shoot tips.

b) Organisms having these characteristics:

• Canal system: Sponges.
• Tentacles: Hydra
• Absence of digestive system: Planaria
• Suckers: Fasciola
• Joined legs: Crab
• Tube feet: Starfish

30. (a) Draw a lined diagram to show the microscopic structure of human  kidney and label its: 

Cortex, Medulla, Nephron, Pyramids, Pelvis, renal artery and ureter. 

(b ) What are malpighian tubules? Which organism contains it? 

Ans: 

1. Microscopic structure of human kidney

2. The malpighian tubules are long, blind ended tubules attached to the alimentary canal at the junction of mid and hindgut. They are found in cockroaches.

Additional Study Materials

• NIOS Class 12 Biology PYQ April 2023 Set A
• NIOS Class 12 Biology PYQ April 2023 Set B