Biology

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

NIOS Biology Question Paper 2023 Class 12 Set B ASS

1 MARK QUESTIONS

1. Dendrites are present in:

(A) Cardiac muscles.

(B) Neurons

(D) Bone marrow

2. Niche is understood as:

(A) Space between two habitats

(B) Functional role of species in a habitat

(D) Space shared by two or more species

3. Desert plants conserve water by

(A) developing waxy coating on leaves.

(B) having more stomata.

(D) having more hydathodes.

4. The phyto-hormone used as weedicide is

(A) Auxin

(B) Gibberellins

(C) 2, 4-D

(D) Ethylene

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

(A) endometrium

(B) placenta

(D) wall of uterus

6. A perfect flower has ______ whorls.

(A) one

(B) two

(D) four

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

(A) Saccharomyces

(B) Streptomyces

(D) Leuconostoc

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

(A) Spores

(B) Gametes

(D) Fission-forms

2 MARK QUESTIONS

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

Ans:

Slow growth
Rapid growth
No growth

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

10. Write any four differences between DNA and RNA.

Ans:

DNA	RNA
Double-stranded	Single-stranded
Contains deoxyribose sugar	Contains ribose sugar
Pyrimidine base complementary to Adenine is Thymine	Pyrimidine base complementary to adenine is Uracil; No thymine in RNA
Only function is to bear hereditary information	Different types of RNAs exist, and each has different functions.

11. 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’.

12. Write names of the purines and pyrimidines bases found in a DNA molecule.

Ans:

Purines: Adenine and Guanine
Pyrimidines: Thymine and Cytosine

13. 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.

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

(b) Write any one example.

Ans:

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.
Rhizobium lives in the roots of Pea plants.

15. 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.

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:

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

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

Ans:

19. 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.

20. 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.

4 MARK QUESTIONS

21. (a) Name the group of plants that need both land and water for their survival.

(b) Name the male and female sex organs found in moss plants.

(c) In which group of plantae are naked seeds developed?

Ans:

Bryophytes
Antheridia and archegonia
Gymnosperms

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

Ans: Any three.

Aerobic respiration	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.

23. (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:

Types of immunoglobulin found in the human body are IgD, IgA, IgE, IgG, and IgM.
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.

24. (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:

Formation of new DNA strands.

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

25. (a) Define ecotone.

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

Ans: An Ecotone is a transitional zone between two ecosystems.

Grasslands represent an ecotone (a zone 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.

26 (a) Write the major parts of human central nervous system.

(b) Write any two functions of each of the following structures:

(i) Cerebellum

(ii) Medulla oblongatus

(iii) Hypothalamus

Ans:

Brain and spinal cord.
Functions
1. Cerebellum: Maintains balance of the body and coordinates muscular activities.
2. Medulla oblongata: It is the centre for breathing and controlsthe heartbeat.
3. Hypothalamus: It controls motivated behaviour such as eating and controls the secretions of the pituitary glands.

6 MARK QUESTIONS

27. (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:

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

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

28. (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:

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

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

29. (a) In photosynthesis, there are two reactions: light and dark reactions. Why are they called so? Explain.

(b) What are the products obtained in each reaction?

(c) What are P₆₈₀ and P₇₀₀?

Ans:

Light reactions are reactions of photosynthesis that are light-dependent and cannot happen without the presence of light. E.g.. Electron Transport Chain. The reactions of photosynthesis that are independent of light, i.e., light is not necessary but can continue in light as well if products of the light reaction are available, are called dark reactions. E.g. reduction of CO₂.
Products
1. Light reaction: ATPs and O₂.
2. Dark reaction: Glucose, NADP⁺, and ADP
P₆₈₀ is the reaction centre of chlorophyll a in PS II, with the maximum absorption at 680 nm wavelength. P₇₀₀ is the reaction centre of chlorophyll a in PS I with a maximum absorption at 700 nm wavelength.

30. (a) How is lymph different from blood? Write any 4 differences.

(b) Write any two lymphocytes found in our immune system.

(c) What is atherosclerosis and arteriosclerosis? Explain.

Ans:

Lymph Vs Blood
1. Blood is red and lymph is colorless.
2. Blood flows rapidly, while lymph flow is very slow.
3. Blood contains RBCs, WBCs, platelets, and plasma. Lymph contains plasma and WBC.
4. Blood flows from heart → arteries → capillaries → veins → heart.

Lymph flows from Tissue spaces → lymph capillaries → lymph vessels → subclavian vein → heart.

Lymphocytes: T-cells and B-cells.
Atherosclerosis is the condition of having fat deposition on the inner walls of the arteries, which narrows its lumen and affects the functioning of the heart. Arteriosclerosis is the condition of hardening of artery walls and loss of their flexibility, which also affects the functioning of the heart.