Practice Set 001 WBSSC 2025

Practice Set 001 WBSSC 2025

1. In an experiment, a plant was kept in the dark and supplied with water containing radioactive oxygen (H₂¹⁸O). During photosynthesis, the radioactive oxygen will be released in –

a) Glucose       

b) CO₂

c) O₂

d) ATP

 

2. If a person’s pancreas is surgically removed, which of the following will be most affected?

a) Digestion of proteins only

b) Regulation of blood sugar level only

c) Both digestion of food and regulation of blood sugar

d) Absorption of food in intestine

 

3. A homozygous tall pea plant (TT) is crossed with a dwarf plant (tt). In F₂ generation, what will be the ratio of tall to dwarf?

a) 3:1

b) 1:1

c) 2:1

d) 4:0

 

4. If the mitochondria of a cell are destroyed, the cell will not be able to –

a) Synthesize proteins

b) Produce ATP

c) Carry out transcription

d) Store genetic information

 

5. The oxygen carrying capacity of blood decreases at high altitudes because –

a) Oxygen is absent

b) RBC count decreases

c) Partial pressure of oxygen decreases

d) Hemoglobin is destroyed

 

6. If the thyroid gland becomes overactive, which of the following symptoms may appear?

a) Slower heartbeat, weight gain

b) Faster heartbeat, weight loss

c) Low body temperature

d) Thickening of bones

 

7. A patient is advised to take more citrus fruits and guava. This indicates deficiency of –

a) Vitamin A, leading to night blindness

b) Vitamin B₁, leading to beriberi

c) Vitamin C, leading to scurvy

d) Vitamin D, leading to rickets

 

8. If meiosis does not occur during gamete formation in humans, what will be the consequence?

a) Gametes will have half the chromosome number

b) Gametes will have the same chromosome number as somatic cells

c) Zygote will have half the chromosome number

d) No fertilization will take place

 

9. The energy flow in an ecosystem is always –

a) Cyclic, because energy is recycled like nutrients

b) Linear, because it moves from producers to consumers and finally lost as heat

c) Random, depending on food habits of organisms

d) Controlled only by decomposers

 

10. BCG vaccine is given for protection against –

a) Tetanus

b) Tuberculosis

c) Polio

d) Cholera

 

11. Which of the following is not a greenhouse gas?

a) CO₂

b) Methane

c) Nitrous oxide

d) Oxygen

 

12. The first antibiotic discovered was –

a) Streptomycin

b) Penicillin

c) Tetracycline

d) Chloramphenicol

 

13. Which technique is used for DNA fingerprinting?

a) PCR

b) ELISA

c) RIA

d) Electrophoresis

14. Which part of brain controls respiration?

a) Cerebrum

b) Cerebellum

c) Medulla oblongata

d) Pons

 

15. The biggest biosphere reserve in India is –

a) Nanda Devi

b) Sunderbans

c) Nilgiri

d) Simlipal

 

16. Silent Valley is situated in –

a) Kerala

b) Assam

c) West Bengal

d) Jharkhand

 

17. Down syndrome is caused by –

a) Monosomy

b) Trisomy of chromosome 21

c) Deletion mutation

d) Translocation

 

18. The Barr body is associated with –

a) X-chromosome inactivation

b) Y-chromosome activity

c) Autosomes

d) Mitochondrial DNA

 

16. Which type of joint is present in the knee?

a) Ball and socket

b) Hinge joint

c) Pivot joint

d) Saddle joint

 

17. The functional unit of heredity is –

a) Chromosome

b) Gene

c) DNA

d) Nucleus

 

18. The xylem in plants transports –

a) Water and minerals

b) Food

c) Hormones

d) Enzymes

19. The reserve food material in fungi is –

a) Starch

b) Cellulose

c) Glycogen

d) Inulin

20. The term "double fertilization" was coined by –

a) Strasburger

b) Guignard

c) Nawaschin

d) Mendel

 

21. The cork cambium is also known as –

a) Phellogen

b) Xylem

c) Phloem

d) Periderm

 

22. Which plant hormone is responsible for apical dominance?

a) Cytokinin

b) Gibberellin

c) Auxin

d) Abscisic acid

 

23. C4 pathway was first discovered in –

a) Rice

b) Wheat

c) Maize

d) Mango

 

24. Red drop effect in photosynthesis was first observed by –

a) Emerson

b) Calvin

c) Blackman

d) Engelmann

 

25. If a flower has both androecium and gynoecium but they mature at different times, the condition is called –

a) Cleistogamy

b) Dichogamy

c) Heterostyly

d) Polygamy

 

26. A maize grain is called a caryopsis because –

a) Pericarp and seed coat remain fused

b) Pericarp and seed coat are free

c) Fruit is dry indehiscent

d) It develops from inferior ovary

 

27. If a flower is epigynous, then the ovary is –

a) Superior

b) Half-inferior

c) Inferior

d) Any position

 

28. Which of the following is a modification of stem for photosynthesis?

a) Tuber

b) Phylloclade

c) Thorn

d) Rhizome

 

29. In sweet potato, the edible part is a –

a) Root tuber

b) Stem tuber

c) Tap root

d) Storage root

 

30. The presence of a pseudocoelom is a characteristic feature of –

a) Platyhelminthes

b) Nematoda

c) Annelida

d) Mollusca

 

31. In sponges, water current is generated by –

a) Amoebocytes

b) Choanocytes

c) Pinacocytes

d) Spicules

 

32. Which of the following is a connecting link between annelids and arthropods?

a) Balanoglossus

b) Peripatus

c) Amphioxus

d) Limulus

33. A distinguishing feature of mammals compared to all other vertebrates is –

a) Pulmonary respiration

b) Warm-blooded nature

c) Presence of mammary glands

d) Internal fertilization

 

34. If a transverse section of a dicot stem shows large well-developed vessels arranged in a ring, this arrangement helps in –

a) Providing flexibility to stem

b) Efficient conduction and mechanical support

c) Only food transport

d) Preventing transpiration

 

35. If the stomata remain open even in the dark, it indicates –

a) The plant is C₃ type

b) The plant is C₄ type

c) The plant is CAM type

d) Abnormal guard cell function

 

36. A dicot root cut in transverse section shows xylem in the form of a star. The main advantage of this arrangement is –

a) Efficient absorption of water

b) Provides more surface area for lateral roots

c) Better anchorage in soil

d) Symbiotic association with mycorrhiza

 

37. Secondary growth in dicot stem increases –

a) Girth of the stem

b) Length of the stem

c) Number of leaves

d) Size of the epidermis

 

38. The presence of annual rings in trees is due to –

a) Activity of apical meristem

b) Activity of vascular cambium

c) Deposition of cutin

d) Secondary phloem formation only

 

39. If a plant shows collenchyma with thickened corners, it indicates –

a) Tissue specialized for conduction

b) Tissue providing tensile strength and flexibility

c) Tissue for food storage

d) Dead supportive tissue

 

40. When a person moves from sea level to high altitude, the oxygen level in blood decreases initially because –

a) RBCs are destroyed

b) Hemoglobin loses affinity for oxygen

c) Partial pressure of oxygen is low

d) Lungs fail to expand

 

41. If platelets are absent from blood, the consequence is –

a) Oxygen transport stops

b) Blood fails to clot

c) Antibody formation fails

d) Infection increases

 

42. If bile secretion is blocked, which nutrient’s digestion is most affected?

a) Carbohydrates

b) Proteins

c) Lipids

d) Nucleic acids

 

43. When a person moves from sea level to high altitude, the oxygen level in blood decreases initially because –

a) RBCs are destroyed

b) Hemoglobin loses affinity for oxygen

c) Partial pressure of oxygen is low

d) Lungs fail to expand

 

44. If DNA replication were dispersive instead of semi-conservative, after one generation in N¹⁵ medium and transfer to N¹⁴ medium, Meselson & Stahl would have observed –

a) Only light band

b) Only heavy band

c) One intermediate band

d) Both light and heavy bands

 

45. The reason DNA polymerase needs a primer is because –

a) It cannot recognize DNA template

b) It requires free 3′-OH group to initiate synthesis

c) It can synthesize DNA only in 5′ → 5′ direction

d) It needs ATP to start

 

46. If a bacterial cell lacks LacI gene, it will –

a) Not metabolize lactose at all

b) Continuously produce β-galactosidase

c) Produce β-galactosidase only in presence of glucose

d) Die in absence of lactose

 

47. In rDNA technology, plasmids are used as vectors because –

a) They can integrate with host chromosome

b) They replicate independently and carry foreign genes

c) They always code for antibiotic resistance

d) They are larger than host DNA

 

48. During PCR, Taq polymerase is used because –

a) It is cheap

b) It can synthesize RNA primers

c) It is thermostable and resists denaturation

d) It prevents mutation

 

49. In gel electrophoresis, smaller DNA fragments move faster than larger ones because –

a) They are lighter and pass easily through gel pores

b) They carry fewer negative charges

c) They are attracted more strongly to positive electrode

d) They bind more dye

50. In the Human Genome Project, one major finding was that –

a) Humans have 1,00,000 genes

b) Humans have fewer than expected (~20,000–25,000 genes)

c) Most DNA is coding

d) All genes are on autosomes

 

51. If a DNA sample shows 40% G + C, then the percentage of adenine will be –

a) 10%

b) 20%

c) 30%

d) 40%

 

52. Golden Rice was developed by introducing genes for –

a) Vitamin C biosynthesis

b) β-carotene biosynthesis

c) Iron storage proteins

d) Nitrogen fixation

 

53. Which ecosystem has the highest net primary productivity?

a) Desert

b) Grassland

c) Tropical rainforest

d) Ocean

 

54. If two species occupy the same niche, eventually –

a) Both will coexist stably

b) One will outcompete the other

c) Both will become extinct

d) Both will shift to another ecosystem

 

55. Which of the following Pteridophytes shows a dormant embryo stage, resembling seed habit?

a) Psilotum

b) Lycopodium

c) Selaginella

d) Equisetum

 

56. Water is essential in Pteridophyte reproduction because –

a) Archegonia require water

b) Antherozoids are motile and need water to reach the egg

c) Spore germination needs water

d) Sporophyte growth requires water

 

57. Coralloid roots are found in Cycas. They harbor –

a) Azolla

b) Anabaena and Nostoc

c) Mycorrhiza

d) Frankia

 

58. Glossopteris is an important fossil plant because –

a) It provided evidence for continental drift

b) It was the ancestor of gymnosperms

c) It shows alternation of generations

d) It was the earliest algae fossil

 

59. Which of the following fungi lack a sexual stage and are called Fungi Imperfecti?

a) Basidiomycota

b) Ascomycota

c) Deuteromycota

d) Zygomycota

 

 

60. If the genetic code were overlapping, mutation in one base would –

a) Change only one codon

b) Change multiple codons

c) Have no effect

d) Only stop protein synthesis

 

 

ANSWER:

1. Radioactive oxygen from H₂¹⁸O is released in – c) O₂

👉 During photosynthesis, O₂ comes from water splitting, not CO₂. Radioactive oxygen labels O₂.

 

2. Removal of pancreas affects – c) Both digestion of food and regulation of blood sugar

👉 Pancreas has digestive enzymes (exocrine) + insulin/glucagon (endocrine).

 

3. TT × tt → F₂ ratio = a) 3:1

👉 F₁: all tall (Tt). F₂: TT, Tt, Tt, tt → 3 tall : 1 dwarf.

 

4. Without mitochondria, cell cannot – b) Produce ATP

👉 Mitochondria = site of oxidative phosphorylation → main ATP source.

 

5. At high altitude, oxygen carrying capacity ↓ due to – c) Partial pressure of oxygen decreases

👉 Less oxygen dissolves in blood at low pO₂.

 

6. Hyperthyroidism symptoms – b) Faster heartbeat, weight loss

👉 Due to excess thyroxine, metabolic rate ↑.

 

7. Citrus/guava deficiency → c) Vitamin C → Scurvy

👉 Required for collagen formation.

 

8. No meiosis → gametes have somatic number → b) Gametes will have the same chromosome number as somatic cells

👉 Fertilization would produce polyploid zygote.

 

9. Energy flow → b) Linear

👉 Energy flows one-way; unlike nutrients, it’s not recycled.

 

10. BCG vaccine → b) Tuberculosis

 

11. Not a greenhouse gas → d) Oxygen

 

12. First antibiotic → b) Penicillin (discovered by Fleming, 1928).

 

13. DNA fingerprinting → d) Electrophoresis (separates DNA fragments).

 

14. Respiration control → c) Medulla oblongata

 

15. Biggest biosphere reserve → c) Nilgiri

 

16. Silent Valley → a) Kerala

 

17. Down syndrome → b) Trisomy of chromosome 21

 

18. Barr body → a) X-chromosome inactivation

 

EXTRA 16. Knee joint → b) Hinge joint

 

EXTRA 17 Functional unit of heredity → b) Gene

 

EXTRA 18 Xylem transports → a) Water and minerals

 

19. Reserve food of fungi → c) Glycogen

 

20. Double fertilization term by – c) Nawaschin

 

21. Cork cambium = a) Phellogen

 

22. Apical dominance hormone → c) Auxin

 

23. C4 pathway discovered in – c) Maize

 

24. Red drop effect → a) Emerson

 

25. Different maturation time (androecium vs gynoecium) → b) Dichogamy

 

26. Maize grain = caryopsis → a) Pericarp and seed coat fused

 

27. Epigynous flower → c) Inferior ovary

 

28. Stem modification for photosynthesis → b) Phylloclade

 

29. Sweet potato edible part → d) Storage root

 

30. Pseudocoelom present in – b) Nematoda

 

31. Water current in sponges by – b) Choanocytes

 

32. Connecting link annelids–arthropods → b) Peripatus

 

33. Mammal unique feature → c) Mammary glands

 

34. Dicot stem vessels in ring → b) Efficient conduction + support

 

35. Stomata open in dark → d) Abnormal guard cell function (CAM plants open at night, not in dark continuously).

 

36. Dicot root star-shaped xylem → c) Better anchorage in soil

 

37. Secondary growth in dicot stem → a) Girth of stem

 

38. Annual rings → b) Vascular cambium activity

 

39. Collenchyma → b) Tensile strength + flexibility

 

40. High altitude O₂ ↓ due to – c) Partial pressure low (repeat Q, same as #5).

 

41. If platelets are absent from blood, blood fails to clot because platelets play a vital role in initiating and forming the platelet plug and releasing clotting factors at the site of injury; while red blood cells transport oxygen, white blood cells form antibodies and fight infection, the absence of platelets specifically impairs clotting, leading to uncontrolled bleeding even from minor wounds. →(b) Blood fails to clot.

 

42. Bile, secreted by the liver and stored in the gallbladder, contains bile salts that emulsify fats into tiny droplets, increasing the surface area for lipase action; if bile secretion is blocked, lipid digestion and absorption are severely affected, while carbohydrates, proteins, and nucleic acids remain largely unaffected as their digestion does not require bile.  → (c) Lipids.

 

43. At high altitudes, the atmospheric pressure drops, which lowers the partial pressure of oxygen in the air; as a result, less oxygen diffuses into the blood across the alveoli, initially reducing blood oxygen levels, while red blood cells are not destroyed, hemoglobin retains its affinity, and the lungs can still expand normally. →(c) Partial pressure of oxygen is low

 

 

44. If dispersive replication → c) One intermediate band

 

45. DNA polymerase needs primer because – b) Needs free 3′-OH

 

46. No LacI → b) Continuous β-galactosidase production

 

47. Plasmids as vectors → b) Replicate independently + carry genes

 

48. Taq polymerase used in PCR → c) Thermostable

 

49. Smaller DNA moves faster → a) Easier through gel pores

 

50. HGP finding → b) ~20,000–25,000 genes

 

51. If G+C = 40% → A+T = 60%, so A = b) 20%

 

52. Golden Rice → b) β-carotene biosynthesis

 

53. Highest NPP → c) Tropical rainforest

 

54. Same niche species → b) One outcompetes other (Competitive exclusion principle).

 

55. Pteridophyte with dormant embryo → c) Selaginella

 

56. Water in pteridophytes → b) Antherozoids need water to reach egg

 

57. Coralloid roots in Cycas → b) Anabaena + Nostoc

 

58. Glossopteris importance → a) Evidence for continental drift

 

59. Fungi Imperfecti → c) Deuteromycota

 

60. Overlapping code → b) Change multiple codons