Biology

NIOS Class 12 Biology Oct 2022 Set B

NIOS Biology Question Paper 2022 October Set B

1 MARK QUESTIONS

1. Guttation is performed by:

(A) Stomata

(B) Parenchyma

(D) Xylem

2. Endonucleases are:

(A) Molecular scissors

(B) Plasmids

(D) DNA fragments

3. Plasmodium belongs to phylum:

(A) Cnidaria

(B) Protozoa

(D) Arthropoda

4. Rhizome of ginger is a modified:

(A) Stem

(B) Leaf

(D) Adventitious root

5. In an aquatic ecosystem, the producers are:

(A) Zooplanktons

(B) Phytoplanktons

(D) Fishes

6. Seed coat develops from this part of the ovule:

(A) Integuments

(B) Nucellus

(D) Carpel

7. Isogamy type of sexual reproduction is found in:

(A) Flowering plants

(B) Gymnosperms

(C) Chlamydomonas

(D) Amoeba

8. Bacteria is included in kingdom monera because its body has:

(A) Single cell

(B) Multicellular structure

(D) Cellulose cell wall

2 MARK QUESTIONS

9. Name any two disorders caused by single gene. How can it be rectified?

Ans: Haemophilia and Sickle cell anaemia. Somatic cell gene therapy is one way to rectify such diseases, where a gene for the production of certain proteins is inserted into the genome.

10. Explain Hydrotropism and Phototropism giving one example for each.

Ans:

Hydrotropism is a type of tropic movement in plants in response to the external stimulus, water. E.g.. Roots grow towards water.
Phototropism is the tropic movement in plants in response to the external stimulus of light. E.g.. Stem grows towards the light.

11. Explain the tissue culture technique. Mention the 2 (two) advantages of it.

Ans: In tissue culture, a cell from a plant can be grown in a nutrient medium to grow into a plant in the presence of nutrients and specific growth hormones. Its advantages are,

It allows for mass production quickly
Produce genetically identical plants.

12. (a) Define placentation with respect to ovary of a plant. 2

(b) After fertilisation, what is the fate of ovary in plants?

Ans: a) Placenta is the point of attachment of ovules (or future seeds) in the ovary.

b) After fertilisation, the ovary forms the fruit in plants.

13. Why is Ca++ considered as macronutrient for plants? What is its role in plant structure?

Ans: Ca++ is an essential nutrient for the plant and is required in larger quantities.

Ca++ is part of the middle lamella of cell walls
Activates enzymes needed for the growth of the root and shoot tips.
Needed for normal cell wall development.
Required for cell division, cell enlargement.

14. Explain the role of the enzymes RUBISCO and PEPco in C4 cycle.

Ans: In C4 plants, PEPCo or the PEP carboxylase is the primary carbon acceptor, which catalyses the carboxylation of phosphoenol pyruvic acid or PEP, to form oxaloacetic acid. This process happens in the mesophyll cells. This, when transported to the bundle sheath cell, releases a carbon dioxide molecule. In the bundle sheath, RUBISCO helps fix this CO₂ molecule through the Calvin cycle, preventing photorespiration.

15. What is “Central Dogma”? How does information flow from nucleus to cytoplasm? Write in an equation form.

Ans: The transfer of information from genes to the site of protein synthesis constitutes the Central Dogma. The central dogma operates from the DNA in the nucleus to messenger RNA (transcription). mRNA moves out of the nucleus to the cytoplasm, where it is translated to form a protein.

DNA (Transcription) → RNA (Translation) → Protein

16. What are the two PEM disorders seen in our country? Write at least one symptom for each one.

Ans:

Marasmus and Kwashiorkor are two PEM disorders. Symptoms of Marasmus are,

Wasting of muscles reduces the child to skin and bones.
Folded skin.
Sunken eyes, thin face, thinning of limbs and abdominal walls.
Retarded physical and mental growth.
Ribs become prominent (Pigeon chest).
Oedema and skin pigmentation are absent.

17. Differentiate between biological and abiological N₂ fixation in the soil.

Ans:

Biological nitrogen fixation is the reduction of molecular nitrogen to ammonia by a living cell in the presence of enzymes called nitrogenases.
In abiological nitrogen fixation, the nitrogen is reduced to ammonia without involving any living cell.

18. What is saprophytic mode of nutrition? Explain with any one example.

Ans: Plants that grow on live or dead organic matter of animals and plant remains secrete extracellular enzymes that break down the complex organic compounds into simpler forms and absorb them for their nutrition. This is the saprophytic mode of nutrition. Eg. The Indian pipe plant, Monotropa found in Khasi Hills.

20. Which phytohormone is called growth inhibitor? Name the part of the plant that produces it.

Ans: Abscisic acid is called the growth inhibitor. It is synthesised in leaves.

4 MARK QUESTIONS

21. Explain the following briefly with one example for each:

(a) Passive immunity

(b) Active immunity

Ans:

Passive immunity is an acquired immunity brought about by the transfer of an actively immunised individual through blood, serum components, etc. E.g.. Transfer of antibodies (e.g. IgG) from mother into foetus across the placenta.
Active immunity is an acquired immunity brought about by injection so that antibodies are produced against the infective agent and by deliberate artificial immunisation. E.g.. Immunity against chicken pox after an infection.

22. (a) Draw and label sigmoid growth curve.

(b) Explain the three important phases of growth. Which phase is the longest one?

Ans: (a)

(b) The three phases of growth are,

(i) Lag Phase – This is the initial phase of growth when the rate of growth is very slow.
(ii) Log Phase – It shows rapid growth and is maximum during the entire life span.
(iii) Stationary Phase – Here, the rate of growth starts decreasing, and finally it stops.

The log phase is the longest one.

23. What are C3 and C4 plants? Write any three differences. Give one example for each type.

Ans: Plants that produce a 3-carbon compound, such as 3-phosphoglyceric acid (PGA), as their first stable product of photosynthesis are called C3 plants. Plants that produce the 4-carbon compound, oxaloacetic acid (OAA), as the first stable product during photosynthesis are known as C4 plants. The difference between C3 and C4 plants is as follows. (any three).

C3 Plants	C4 Plants
Carbon dioxide fixation occurs once	Carbon dioxide fixation occurs twice, first in the mesophyll and then in bundle sheaths.
RuBP is the only one-carbon dioxide acceptor.	There are two carbon dioxide acceptors- the 3-carbon compound PEP (phosphoenol pyruvate) in the mesophyll and RuBP in the bundle sheath
RuBP carboxylase, which is not efficient when the CO₂ concentration is low	PEP carboxylase, which is very efficient, even if the CO₂ conc. It has low RuBP carboxylase, works efficiently because the carbon dioxide concentration is high.
The first stable product is 3-C compound phosphoglyceric acid	The first product is the 4-C compound is oxaloacetic acid
Higher CO₂ concentration promotes photosynthesis	Photosynthetic efficiency is high even if the CO₂ concentration is low.
Only one type of chloroplast	Two types of chloroplasts (dimorphic) are present.
Photorespiration occurs.	Photorespiration is absent.
Less efficient photosynthesis than C4 plants. Yields are usually much lower.	More efficient photosynthesis as compared to that of the C3 plants. Yields are usually much higher.

C3 plants: Rice
C4 plants: Maize.

24. Give one-word answers to the statements given below. 4

(a) Plant cells, that continue dividing.

(b) Xylem and Phloem called together.

(c) Plant cells having similar cells.

(d) Dead tissue that gives support to soft tissues in stem.

Ans:

25. (a) What are the two hormones involved in osmoregulation in human beings?

(b) What is the condition of the body called when

(i) Glucose is present in urine.

(ii) Uric acid crystals are present in urine.

Ans:

Osmoregulation in humans is controlled by ADH (Anti-Diuretic Hormone) and aldosterone.
1. Hyperglycemia or Diabetes mellitus
2. Gout

26. (a) What is biodiversity? What is its advantage to mankind?

(b) Write any four human activities which are destroying it.

Ans: a) Biodiversity can be defined as the flora and fauna, i.e. variety of all plants, animals, and microbes of a region.

b) Human activities that destroy biodiversity are,

Destruction of habitat by cutting down trees, filling up the wetland, ploughing of grassland or burning a forest.
Indiscriminate killing of animals for different purposes has resulted in their reduction.
Industrialisation and urbanisation has changed and destroyed the natural habitat of plants and animals.
Pollution of soil, air and water changes the habitat quality and may reduce or eliminate sensitive species.

6 MARK QUESTIONS

27. (a) Why do we consider a habitat as address of an organism and niche as its profession? Write definition of both the terms.

(b) What is the role of

(i) Vit.A

(ii) Ca++ and

(iii) Glucose in our body?

Ans:

Habitat is the physical environment in which an organism lives and is thus considered its address. Niche is the sum of all the activities and relationships of a species by which it uses the resources in its habitat for its survival and reproduction. In other words, a niche is the functional characteristics of the species, thus considered its profession.
1. Vitamin A is essential for the synthesis of visual pigment and helps maintain vision.
2. Calcium helps with the formation of bones and teeth. It is also essential for nerves and muscles.
3. Glucose is the main source of energy for our body and is also the only source of energy for the central nervous system.

28. (a) Draw a neat diagram of transverse section (T.S) of human ovary and label its following parts:

(i) Primary follicle

(ii) Graffian follicle

(iii) Corpus luteum

(iv) Released ovum

(b) Write location, and function of each of the following:

(i) Fallopian tube

(ii) Endometrium

(iii) Fimbriae

Ans:

1. Fallopian tubes are oviducts through which the egg passes to the uterus
2. Endometrium is the innermost layer of the uterus that is rich in blood vessels.
3. Fimbriae are finger-like projections that help the egg pass through to the oviduct.

29. (a) Write one function of each of the following:

(i) RBC

(ii) Platelets

(iii) Plasma

(b) Why a person with blood group AB can’t donate blood to the persons with other blood groups, i.e, A, B, and O, explain.

Ans:

1. RBC- transports oxygen and carbon dioxide
2. Platelets help in blood clotting
3. Plasma transport of products of digestion from the small intestine to various tissues.
A person with the AB blood group contains both antigen A and antigen B in the blood. Blood group A contains antibody b, the blood group B contains antibody a and those with the O group contain both antibody a and antibody b. If their blood is mixed with blood group AB, it will cause a life-threatening transfusion reaction as the respective antibodies react with the antigens in the AB blood group.

30. Write answers to following briefly: 6

(a) Write any two differences between angiosperms and gymnosperms.

(b) Write any two important characters of arthropods. Give one example.

(c) Name the family the Pea plant belongs to. Write any two characters of it, which support your answer.

Ans: a) Any two.

Gymnosperms	Angiosperms
Seeds are naked and not enclosed in an ovary.	Seeds are enclosed in fruit (a mature, fertilised ovary).
Independent plants are sporophytes that bear cones	Independent plants are sporophytes that bear flowers
Xylem has mainly tracheids usually absent	Xylem has both vessels as well as tracheids.

b) Segmented body differentiated into head, thorax and abdomen. Jointed legs for locomotion, one pair each on some or all body segments

c) Fabaceae. Plants of this family are herbs and shrubs, and rarely trees. They also have bisexual flowers.