WBCS Prelims Biology Questions 2024
1. Which of the following animals is the natural reservoir of Nipah virus?
(A) Bats
(B) Turtles
(C) Migratory birds
(D) Horses
Answer & Explanation
Answer: (A) Bats
Explanation
Nipah virus is a zoonotic virus whose natural reservoir is fruit bats of the genus Pteropus (flying foxes). The virus can spread from bats to animals such as pigs and then to humans, or directly from bats to humans through contaminated food or close contact. Human-to-human transmission has also been reported during outbreaks.
Exam Facts
- Natural reservoir: Fruit bats (Pteropus spp.).
- Nipah virus is a zoonotic disease (transmitted from animals to humans).
- It mainly affects the brain (encephalitis) and respiratory system.
- First outbreak: Malaysia, 1998–99.
- Human-to-human transmission has also been reported.
- WHO has listed Nipah virus as a priority disease due to its epidemic potential.
2. Ginger is a stem because
(A) it grows horizontally in the soil.
(B) it stores food materials.
(C) absence of chlorophyll.
(D) it has nodes and inter-nodes.
Answer & Explanation
Answer: (D) it has nodes and inter-nodes.
Explanation
Ginger is an underground modified stem (rhizome). It is identified as a stem because it possesses nodes, internodes, scale leaves, and buds, which are characteristic features of stems. Merely growing underground or storing food does not distinguish a stem from a root.
Exam Facts
- Ginger (Zingiber officinale) is an underground modified stem (rhizome).
- Rhizome examples: Ginger, turmeric (Curcuma longa), and canna.
- Tuber (modified stem): Potato – has ‘eyes’, which are buds.
- Corm (modified stem): Colocasia (taro), gladiolus.
- Bulb (modified stem): Onion and garlic; food is mainly stored in fleshy scale leaves.
- Stem characters: Presence of nodes, internodes, buds, and leaves.
- Root characters: Root cap and root hairs are present; nodes and internodes are absent.
- Function of underground modified stems: Storage of food, perennation, and vegetative propagation.
3. Agar-agar is derived from a/an
(A) Bryophytes
(B) Algae
(C) Fungi
(D) Pteridophytes
Answer & Explanation
Answer: (B) Algae
Explanation
Agar-agar is obtained from red algae (Rhodophyceae), mainly from the genera Gelidium and Gracilaria. It is widely used as a solidifying agent in microbiological culture media, as well as in the food and pharmaceutical industries.
Exam Facts
- Source of agar: Red algae (Rhodophyceae).
- Major genera: Gelidium and Gracilaria.
- Primary use: Solidifying agent in microbiological culture media.
- Other uses: Food industry (jellies, desserts), pharmaceuticals, cosmetics, and biotechnology.
- Algal pigments: Red algae contain phycoerythrin, which gives them their red colour.
- Commercial products from algae: Agar, algin (brown algae), and carrageenan (red algae).
- Study of algae: Phycology.
- Algae are photosynthetic organisms and contribute significantly to global oxygen production and aquatic food chains.
4. How does a non-green (coloured) leaf synthesize food?
(A) The red and purple pigments directly absorb heat from the sunlight, thus replacing the need for photosynthesis.
(B) The leaf contains green chlorophyll but it remains hidden under other pigments.
(C) Coloured leaves steal glucose from neighbouring green plants through air using microscopic spores.
(D) None of the above.
Answer & Explanation
Answer: (B) The leaf contains green chlorophyll but it remains hidden under other pigments.
Explanation
Non-green leaves also contain chlorophyll, but it is masked by pigments like anthocyanin or carotenoids. Chlorophyll performs photosynthesis, allowing these leaves to prepare food like green leaves.
Exam Facts
- Chlorophyll is the main pigment responsible for photosynthesis.
- Anthocyanin gives red, purple, and blue colours to leaves, flowers, and fruits.
- Carotenoids produce yellow and orange colours and act as accessory pigments.
- Photosynthesis takes place in chloroplasts.
- Chlorophyll ‘a’ is the primary photosynthetic pigment.
- Examples of coloured-leaf plants: Croton and Coleus.
5. Why are antibiotics not prescribed to kill viral infections?
(A) Viruses take refuge in a cell organelle where antibiotics cannot reach.
(B) Viruses neither have cell walls nor their own metabolic machinery that can be targeted by antibiotics.
(C) Viruses mutate rapidly.
(D) None of the above.
Answer & Explanation
Answer: (B) Viruses neither have cell walls nor their own metabolic machinery that can be targeted by antibiotics.
Explanation
Antibiotics act by targeting bacterial structures such as cell walls, ribosomes, or metabolic pathways. Viruses lack these structures and depend entirely on the host cell for reproduction. Therefore, antibiotics are ineffective against viral infections.
Exam Facts
- Antibiotics are effective against bacteria, not viruses.
- Viral diseases include COVID-19, dengue, measles, chickenpox, polio, and influenza.
- Bacterial diseases include tuberculosis, typhoid, cholera, and tetanus.
- Antiviral drugs are used to treat viral infections, not antibiotics.
- Unnecessary use of antibiotics can lead to antimicrobial resistance (AMR).
- Alexander Fleming discovered penicillin in 1928, the first antibiotic.
6. Pneumatophores are modified roots and negatively geotropic. These are—
(A) Respiratory roots
(B) Photosynthetic roots
(C) Food storing roots
(D) Water storing roots
Answer & Explanation
Answer: (A) Respiratory roots
Explanation
Pneumatophores are specialized respiratory roots found in mangrove plants growing in waterlogged, oxygen-deficient soils. They grow upward (negative geotropism) above the soil surface and contain lenticels that help in gaseous exchange.
Exam Facts
- Pneumatophores are also called breathing roots or respiratory roots.
- They exhibit negative geotropism (grow upward against gravity).
- Commonly found in mangrove plants.
- Examples: Avicennia and Sonneratia.
- Lenticels present on pneumatophores facilitate the exchange of gases.
- Sundarbans in West Bengal is the largest mangrove forest in the world and a common habitat of plants with pneumatophores.
7. The most abundant enzyme in the living world is ________.
(A) Lipase
(B) DNase
(C) Zymase
(D) Rubisco
Answer & Explanation
Answer: (D) Rubisco
Explanation
Rubisco (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is the most abundant enzyme on Earth. It plays a key role in photosynthesis by fixing atmospheric carbon dioxide during the Calvin cycle to produce carbohydrates.
Exam Facts
- Rubisco is the most abundant enzyme in the living world.
- It is present in the chloroplasts of green plants.
- It catalyzes the first step of carbon fixation in the Calvin cycle.
- Calvin cycle is also known as the dark reaction or light-independent reaction of photosynthesis.
- Melvin Calvin received the 1961 Nobel Prize in Chemistry for discovering the Calvin cycle.
- Rubisco acts as both a carboxylase and an oxygenase enzyme.
8. Synapsis occurs during
(A) Leptotene
(B) Diplotene
(C) Zygotene
(D) Pachytene
Answer & Explanation
Answer: (C) Zygotene
Explanation
Synapsis is the pairing of homologous chromosomes during Zygotene, a stage of Prophase I of meiosis. This pairing forms bivalents, which are essential for the exchange of genetic material in the next stage.
Exam Facts
- Synapsis occurs during the Zygotene stage of Prophase I.
- Crossing over takes place during the Pachytene stage.
- Chiasmata become visible during the Diplotene stage.
- Leptotene is the stage where chromosomes first become visible.
- Meiosis produces four haploid daughter cells from one diploid cell.
- Crossing over increases genetic variation in offspring.
9. Which of the following carries oxygenated blood?
(A) Hepatic portal veins
(B) Pulmonary veins
(C) Renal veins
(D) Pulmonary artery
Answer & Explanation
Answer: (B) Pulmonary veins
Explanation
Pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart. They are the only veins in the human body that normally carry oxygen-rich blood. In contrast, the pulmonary artery carries deoxygenated blood from the heart to the lungs.
Exam Facts
- Pulmonary veins carry oxygenated blood to the left atrium.
- Pulmonary artery carries deoxygenated blood from the right ventricle to the lungs.
- Hepatic portal vein carries nutrient-rich blood from the digestive organs to the liver.
- Renal veins carry deoxygenated blood from the kidneys to the inferior vena cava.
- Exception: Pulmonary veins and the umbilical vein carry oxygenated blood, unlike most veins.
- Exception: Pulmonary artery and the umbilical arteries carry deoxygenated blood, unlike most arteries.
10. Growth inhibiting hormone of plant is
(A) Auxin
(B) Gibberellin
(C) Cytokinin
(D) Abscisic acid
Answer & Explanation
Answer: (D) Abscisic acid
Explanation
Abscisic acid (ABA) is known as the growth-inhibiting or stress hormone of plants. It inhibits plant growth, induces seed and bud dormancy, and causes the closure of stomata during water stress to reduce water loss.
Exam Facts
- Abscisic acid (ABA) is called the stress hormone of plants.
- It inhibits plant growth and promotes seed and bud dormancy.
- ABA causes stomatal closure during drought conditions.
- Auxin promotes cell elongation and apical dominance.
- Gibberellin promotes stem elongation and seed germination.
- Cytokinin promotes cell division and delays leaf senescence.
11. Water available for plants within the soil is
(A) Hygroscopic water
(B) Capillary water
(C) Mineral water
(D) Chemically bound water
Answer & Explanation
Answer: (B) Capillary water
Explanation
Capillary water is held in the small pores between soil particles and is the main source of water absorbed by plant roots. Hygroscopic water and chemically bound water are held too tightly by soil particles to be available to plants.
Exam Facts
- Capillary water is the plant-available water in the soil.
- Hygroscopic water is tightly bound to soil particles and cannot be absorbed by plants.
- Gravitational water drains downward due to gravity and is generally unavailable after drainage.
- Chemically bound water is part of soil minerals and is unavailable to plants.
- Root hairs absorb water mainly through osmosis.
- Loamy soil is considered the best for plant growth because it retains adequate capillary water while allowing proper aeration.
12. Which of the following ape(s) is/are genetically closest to the modern humans (Homo sapiens)?
(A) Chimpanzee and Bonobo
(B) Gorilla
(C) Orangutan
(D) Gibbon
Answer & Explanation
Answer: (A) Chimpanzee and Bonobo
Explanation
Chimpanzees and bonobos are the closest living relatives of modern humans. Humans share about 98–99% of their DNA with these apes, indicating a common ancestor that lived millions of years ago.
Exam Facts
- Chimpanzee and Bonobo are the closest living relatives of Homo sapiens.
- Humans share approximately 98–99% DNA with chimpanzees and bonobos.
- Bonobo is also known as the pygmy chimpanzee.
- Scientific name of modern humans: Homo sapiens.
- Order: Primates; Family: Hominidae (Great Apes).
- Evolutionary sequence often asked in exams: Gibbon → Orangutan → Gorilla → Chimpanzee/Bonobo → Human (in increasing genetic closeness to humans).
WBCS Prelims Biology Questions 2023
13. Which of the following pairs comprises of the smallest and the largest endocrine glands of human respectively?
(A) Pituitary – Thyroid
(B) Thyroid – Pituitary
(C) Pineal body – Ovary
(D) Pineal body – Thyroid
Answer & Explanation
Answer: (D) Pineal body – Thyroid
Explanation
The pineal gland is the smallest endocrine gland in the human body, while the thyroid gland is the largest purely endocrine gland. The pineal gland secretes melatonin, whereas the thyroid gland secretes thyroxine (T₄) and triiodothyronine (T₃), which regulate metabolism.
Exam Facts
- Smallest endocrine gland: Pineal gland (Pineal body).
- Largest purely endocrine gland: Thyroid gland.
- Largest endocrine organ (not purely endocrine): Pancreas (mixed gland).
- Pineal gland secretes melatonin, which regulates the sleep–wake cycle.
- Thyroid gland secretes T₃ (Triiodothyronine) and T₄ (Thyroxine).
- Pituitary gland is known as the ‘Master gland’ because it controls the activity of many other endocrine glands.
14. Cause of myopia is
(A) Contraction of eyeball
(B) Expansion of eyeball
(C) Dryness of optic nerve
(D) All are true
Answer & Explanation
Answer: (B) Expansion of eyeball
Explanation
Myopia (short-sightedness) occurs when the eyeball becomes elongated (expanded) or the eye lens has excessive curvature. As a result, light rays are focused in front of the retina, making distant objects appear blurred. It is corrected using a concave (diverging) lens.
Exam Facts
- Myopia is also called short-sightedness.
- In myopia, the image is formed in front of the retina.
- It is corrected with a concave (diverging) lens.
- Hypermetropia (long-sightedness) is corrected with a convex lens.
- Presbyopia occurs due to age-related loss of elasticity of the eye lens.
- Astigmatism is caused by irregular curvature of the cornea or lens and is corrected using a cylindrical lens.
15. Which hormone is responsible for breaking the dormancy of a seed?
(A) Auxin
(B) Dormin
(C) Cytokinin
(D) Gibberellin
Answer & Explanation
Answer: (D) Gibberellin
Explanation
Gibberellins break seed dormancy and promote seed germination by stimulating the production of enzymes needed for the mobilization of stored food. They also promote stem elongation and flowering in some plants.
Exam Facts
- Gibberellin breaks seed dormancy and promotes germination.
- Abscisic acid (ABA) induces seed dormancy and inhibits plant growth.
- Auxin promotes cell elongation and apical dominance.
- Cytokinin promotes cell division and delays leaf senescence.
- Ethylene is a gaseous plant hormone that promotes fruit ripening.
- Remember: Gibberellin = Germination, ABA = Dormancy (frequently asked in competitive exams).
16. Which of the following reproduction is found in plants alone?
(A) Vegetative reproduction
(B) Asexual reproduction
(C) Sexual reproduction
(D) Parthenogenesis
Answer & Explanation
Answer: (A) Vegetative reproduction
Explanation
Vegetative reproduction is a type of asexual reproduction in which new plants arise from vegetative parts such as roots, stems, or leaves. It is characteristic of plants and does not occur naturally in animals.
Exam Facts
- Vegetative reproduction occurs through root, stem, or leaf.
- Examples: Potato (tuber), Ginger (rhizome), Onion (bulb), Bryophyllum (leaf).
- It is a form of asexual reproduction.
- Plants produced by vegetative reproduction are genetically identical (clones) to the parent plant.
- Parthenogenesis is the development of an individual from an unfertilized egg and is seen in organisms like honey bees, aphids, and some reptiles.
- Sexual reproduction occurs in both plants and animals.
17. One of the following terms includes the rest of the lot. Identify that single term:
Glucocorticoids, Adrenaline, Mineralocorticoids, Suprarenal gland.
(A) Mineralocorticoids
(B) Adrenaline
(C) Suprarenal gland
(D) Glucocorticoids
Answer & Explanation
Answer: (C) Suprarenal gland
Explanation
The suprarenal (adrenal) gland includes the rest because it secretes adrenaline, glucocorticoids, and mineralocorticoids. Thus, it is the broader term that encompasses the other three.
Exam Facts
- Suprarenal gland is another name for the adrenal gland.
- It is located above each kidney.
- Adrenal medulla secretes adrenaline (epinephrine).
- Adrenal cortex secretes glucocorticoids (e.g., cortisol).
- Adrenal cortex also secretes mineralocorticoids (e.g., aldosterone).
- Adrenaline is known as the “emergency” or “fight-or-flight” hormone.
18. In which substage of interphase is DNA doubled?
(A) G₁
(B) S
(C) G₂
(D) G₀
Answer & Explanation
Answer: (B) S
Explanation
DNA replication takes place during the S (Synthesis) phase of interphase. During this stage, the amount of DNA in the cell doubles, preparing the cell for division, while the chromosome number remains unchanged.
Exam Facts
- S phase is the stage of DNA replication.
- G₁ phase: Cell growth and synthesis of proteins and RNA.
- G₂ phase: Preparation for cell division.
- G₀ phase: Resting or inactive phase; the cell does not divide.
- Interphase consists of G₁, S, and G₂ phases.
- M phase is the phase of cell division (mitosis or meiosis).
19. Which of the following diseases is autosomal?
(A) Haemophilia
(B) Thalassemia
(C) Colourblindness
(D) All of the above
Answer & Explanation
Answer: (B) Thalassemia
Explanation
Thalassemia is an autosomal recessive genetic disorder, meaning the defective gene is located on an autosome (non-sex chromosome). In contrast, haemophilia and colour blindness are X-linked recessive disorders, occurring due to mutations on the X chromosome.
Exam Facts
- Thalassemia is an autosomal recessive disorder.
- Haemophilia is an X-linked recessive disorder affecting blood clotting.
- Colour blindness is also an X-linked recessive disorder.
- Sickle cell anaemia is another autosomal recessive genetic disease.
- Males are more commonly affected by X-linked recessive disorders because they have only one X chromosome.
- Carrier screening is important in the prevention of thalassemia in high-risk populations.
WBCS Prelims Biology Questions 2022
20. Phytophthora palmivora is a
(A) Bio-pesticide
(B) Bio-insecticide
(C) Mycoherbicide
(D) First bio-herbicide
Answer & Explanation
Answer: (D) First bio-herbicide
Explanation
Phytophthora palmivora was developed as DeVine, the world’s first commercially registered bio-herbicide. It is used to control milkweed vine in citrus plantations and is therefore recognized as the first bio-herbicide.
Exam Facts
- DeVine is the first commercially registered bio-herbicide.
- It is based on Phytophthora palmivora.
- It is used to control milkweed vine in citrus orchards.
- A mycoherbicide is a herbicide derived from fungi or fungus-like organisms.
- Phytophthora belongs to the group Oomycetes (water moulds).
- Another well-known mycoherbicide is Collego, developed from Colletotrichum gloeosporioides.
21. ‘ELISA’ test is employed to diagnose
(A) Polio Virus
(B) AIDS antibodies
(C) Tuberculosis
(D) Cancer
Answer & Explanation
Answer: (B) AIDS antibodies
Explanation
ELISA (Enzyme-Linked Immunosorbent Assay) is commonly used to detect antibodies against HIV, the virus that causes AIDS. It is a screening test, and positive results are usually confirmed by more specific tests.
Exam Facts
- ELISA stands for Enzyme-Linked Immunosorbent Assay.
- It is widely used for screening HIV (AIDS) infection.
- ELISA detects antigens or antibodies in blood samples.
- HIV stands for Human Immunodeficiency Virus.
- AIDS stands for Acquired Immunodeficiency Syndrome.
- ELISA is also used to diagnose several other infectious and autoimmune diseases.
22. Which of the following is an aquatic fern?
(A) Adiantum
(B) Dryopteris
(C) Salvinia
(D) Equisetum
Answer & Explanation
Answer: (C) Salvinia
Explanation
Salvinia is a free-floating aquatic fern commonly found in ponds, lakes, and other freshwater bodies. The other options are terrestrial plants, while Equisetum is a horsetail and not a true fern.
Exam Facts
- Salvinia is a floating aquatic fern.
- Azolla is another important aquatic fern, often used as green manure in paddy fields.
- Adiantum is commonly known as the Maidenhair fern.
- Dryopteris is a terrestrial fern (wood fern).
- Equisetum is commonly called horsetail and belongs to the Pteridophytes.
- Pteridophytes are the first vascular plants and reproduce by spores.
23. Which one of the following animals is known as a ‘living fossil’?
(A) Peripatus
(B) Amoeba
(C) Prawn
(D) Apple snail
Answer & Explanation
Answer: (A) Peripatus
Explanation
Peripatus is called a living fossil because it has retained many primitive characteristics over millions of years. It is also regarded as a connecting link between Annelida (segmented worms) and Arthropoda (joint-legged animals).
Exam Facts
- Peripatus is known as a living fossil.
- It is a connecting link between Annelida and Arthropoda.
- Limulus (King crab) and Sphenodon (Tuatara) are other famous examples of living fossils.
- Living fossils are organisms that have remained largely unchanged for millions of years.
- Amoeba is a unicellular protozoan.
- Prawn is a crustacean, while Apple snail is a mollusc.
24. The vitamin which helps in clotting of blood is
(A) A
(B) D
(C) B
(D) K
Answer & Explanation
Answer: (D) K
Explanation
Vitamin K is essential for the synthesis of prothrombin and other clotting factors in the liver. A deficiency of Vitamin K can lead to excessive bleeding due to impaired blood clotting.
Exam Facts
- Vitamin K is essential for blood clotting.
- It helps in the synthesis of prothrombin (Factor II).
- Deficiency of Vitamin K causes delayed blood clotting and bleeding.
- Vitamin A is important for vision and healthy skin.
- Vitamin D helps in the absorption of calcium and phosphorus for healthy bones.
- Vitamin B-complex is mainly involved in energy metabolism and nervous system functions.
25. What is the chromosome number in human ovum?
(A) 36
(B) 46
(C) 48
(D) None of the above
Answer & Explanation
Answer: (D) None of the above (Human ovum contains 23 chromosomes.)
Explanation
A human ovum is a haploid (n) cell formed by meiosis and therefore contains 23 chromosomes. After fertilization, the ovum (23) fuses with the sperm (23) to form a diploid zygote (46 chromosomes).
Exam Facts
- Human ovum: 23 chromosomes (n).
- Human sperm: 23 chromosomes (n).
- Human somatic (body) cells: 46 chromosomes (2n).
- Zygote: 46 chromosomes (2n) after fertilization.
- Meiosis produces haploid gametes.
- Mitosis maintains the chromosome number in body cells.
26. ‘Seahorse’ is a
(A) Mammal
(B) Plant
(C) Fish
(D) None of the above
Answer & Explanation
Answer: (C) Fish
Explanation
The seahorse is a marine fish belonging to the genus Hippocampus. It breathes through gills, has fins, and belongs to the family Syngnathidae. Unlike most fishes, the male seahorse carries and incubates the eggs in a brood pouch.
Exam Facts
- Seahorse is a marine fish.
- Scientific genus: Hippocampus.
- Family: Syngnathidae.
- Male seahorse carries the fertilized eggs in a brood pouch.
- Seahorses breathe through gills and swim using fins.
- The male gives birth to the young, a unique feature among fishes.
27. The ‘powerhouse’ of the cell is
(A) Nucleus
(B) Lysosome
(C) Mitochondria
(D) DNA
Answer & Explanation
Answer: (C) Mitochondria
Explanation
Mitochondria are called the powerhouse of the cell because they produce ATP (Adenosine Triphosphate) through cellular respiration. ATP serves as the primary source of energy for various cellular activities.
Exam Facts
- Mitochondria are known as the powerhouse of the cell.
- They produce ATP, the energy currency of the cell.
- Mitochondria contain their own DNA and ribosomes.
- They are double membrane-bound organelles.
- Nucleus is the control centre of the cell.
- Lysosomes are called the ‘suicidal bags’ of the cell due to their digestive enzymes.
28. Which metal is present in haemoglobin?
(A) Iron
(B) Zinc
(C) Magnesium
(D) Copper
Answer & Explanation
Answer: (A) Iron
Explanation
Haemoglobin contains iron (Fe) in its haem group. Iron binds with oxygen in the lungs and transports it to different parts of the body through the blood.
Exam Facts
- Iron (Fe) is the metal present in haemoglobin.
- Haemoglobin is found in red blood cells (RBCs).
- The main function of haemoglobin is transport of oxygen.
- Iron deficiency can cause anaemia.
- Magnesium (Mg) is the central metal ion in chlorophyll.
- Copper (Cu) is present in the respiratory pigment haemocyanin of some molluscs and arthropods.
29. Which part of the human eye has the maximum refractive index?
(A) Aqueous humour
(B) Vitreous humour
(C) Lens
(D) Cornea
Answer & Explanation
Answer: (C) Lens
Explanation
The crystalline lens has the highest refractive index among the transparent parts of the human eye. It helps focus light precisely on the retina by changing its curvature during accommodation.
Exam Facts
- Lens has the maximum refractive index in the human eye.
- Cornea provides the maximum refraction (bending of light) in the eye.
- Lens is responsible for accommodation (adjusting focus for near and distant objects).
- Aqueous humour is present between the cornea and lens.
- Vitreous humour is present between the lens and retina.
- Retina is the light-sensitive layer where the image is formed.
30. ‘Ornithology’ is the science of
(A) Birds
(B) Reptiles
(C) Amphibians
(D) Mammals
Answer & Explanation
Answer: (A) Birds
Explanation
Ornithology is the branch of zoology that deals with the study of birds. It includes their classification, behaviour, anatomy, ecology, and evolution.
Exam Facts
- Ornithology – Study of birds.
- Herpetology – Study of reptiles and amphibians.
- Ichthyology – Study of fishes.
- Entomology – Study of insects.
- Mammalogy – Study of mammals.
- Ophiology – Study of snakes.
31. Which one of the following animals is not ‘warm-blooded’?
(A) Hen
(B) Tiger
(C) Bat
(D) Toad
Answer & Explanation
Answer: (D) Toad
Explanation
Toad is an amphibian and is cold-blooded (ectothermic), meaning its body temperature varies with the surrounding environment. Birds and mammals, such as hen, tiger, and bat, are warm-blooded (endothermic) and maintain a nearly constant body temperature.
Exam Facts
- Birds and mammals are warm-blooded (endothermic) animals.
- Amphibians, reptiles, and fishes are cold-blooded (ectothermic).
- Toad belongs to Class Amphibia.
- Bat is the only true flying mammal.
- Hen belongs to Class Aves.
- Tiger belongs to Class Mammalia.
32. The first transgenic crop was
(A) Tobacco
(B) Cotton
(C) Pea
(D) Rice
Answer & Explanation
Answer: (A) Tobacco
Explanation
Tobacco was the first transgenic crop developed using genetic engineering. A foreign gene was introduced into the tobacco plant to demonstrate that desirable traits could be transferred into plants through recombinant DNA technology.
Exam Facts
- Tobacco was the first transgenic crop.
- The first commercial transgenic crop was the Flavr Savr tomato (1994).
- Bt cotton is the first GM crop commercially cultivated in India.
- Bt cotton contains the Cry gene from the bacterium Bacillus thuringiensis (Bt).
- Golden Rice is a genetically modified crop enriched with Vitamin A (β-carotene).
- Genetic engineering involves the transfer of desirable genes using recombinant DNA (rDNA) technology.
33. Fermentation ability of Yeast is due to
(A) Amylase
(B) Zymase
(C) Invertase
(D) Galactase
Answer & Explanation
Answer: (B) Zymase
Explanation
Zymase is an enzyme complex present in yeast that converts sugars into ethyl alcohol and carbon dioxide during fermentation. This process is widely used in the baking and brewing industries.
Exam Facts
- Zymase is the enzyme complex responsible for alcoholic fermentation in yeast.
- Yeast is a unicellular fungus (Saccharomyces cerevisiae).
- Fermentation produces ethyl alcohol and carbon dioxide (CO₂).
- CO₂ released during fermentation helps bread dough rise.
- Invertase converts sucrose into glucose and fructose.
- Yeast reproduces mainly by budding.
WBCS Prelims Biology Questions 2020
34. Plants receive nutrients from
(A) Atmosphere
(B) Chlorophyll
(C) Soil
(D) Light
Answer & Explanation
Answer: (C) Soil
Explanation
Plants absorb mineral nutrients such as nitrogen, phosphorus, potassium, calcium, and magnesium from the soil through their roots. While carbon dioxide comes from the atmosphere and light provides energy for photosynthesis, mineral nutrients are obtained mainly from the soil.
Exam Facts
- Plants absorb water and minerals from the soil through their roots.
- Root hairs increase the surface area for absorption.
- Nitrogen (N), Phosphorus (P), and Potassium (K) are the primary macronutrients (NPK).
- Chlorophyll helps in photosynthesis; it is not a source of nutrients.
- Sunlight provides energy for photosynthesis but is not a nutrient.
- Carbon dioxide is taken from the atmosphere for photosynthesis, while mineral nutrients come from the soil.
35. Which can bind O₂ molecules?
(A) Red blood cells
(B) White blood cells
(C) Vitamin B₁₂
(D) Vitamin E
Answer & Explanation
Answer: (A) Red blood cells
Explanation
Red blood cells (RBCs) contain haemoglobin, which binds with oxygen in the lungs and transports it to different tissues of the body. White blood cells are involved in immunity, while Vitamins B₁₂ and E do not transport oxygen.
Exam Facts
- Haemoglobin in RBCs binds and transports oxygen.
- Red blood cells (RBCs) are also called erythrocytes.
- White blood cells (WBCs) provide defence against infections.
- Vitamin B₁₂ is essential for RBC formation and nervous system function.
- Vitamin E acts as an antioxidant.
- RBCs are produced in the red bone marrow and have an average lifespan of about 120 days.
36. Excess fluoride in drinking water causes
(A) Lung disease
(B) Intestinal infection
(C) Fluorosis
(D) Rickets
Answer & Explanation
Answer: (C) Fluorosis
Explanation
Excess intake of fluoride through drinking water causes fluorosis, which affects the teeth and bones. Long-term exposure can lead to dental fluorosis (discoloured teeth) and skeletal fluorosis (joint pain and bone deformities).
Exam Facts
- Excess fluoride in drinking water causes fluorosis.
- Dental fluorosis causes mottling and discoloration of teeth.
- Skeletal fluorosis affects bones and joints.
- Rickets is caused by Vitamin D deficiency, not fluoride.
- Deficiency of fluoride may increase the risk of dental caries (tooth decay).
- Fluorosis is a common public health problem in some parts of Rajasthan, Andhra Pradesh, Telangana, Gujarat, and Karnataka.
WBCS Prelims Biology Questions 2019
37. The number of spinal nerves in the human body is
(A) 12 pairs
(B) 31 pairs
(C) 31
(D) 12
Answer: (B) 31 pairs
38. The food that gives more calories per unit mass is
(A) Protein
(B) Carbohydrates
(C) Fat
(D) Water
Answer: (C) Fat
39. ECG records
(A) Rate of heart beats
(B) Potential difference
(C) Ventricular contraction
(D) Volume of blood pumped
Answer: (B) Potential difference
40. In persons addicted to alcohol, the liver gets damaged because it
(A) Has to detoxify the alcohol
(B) Stores excess glycogen
(C) Is overstimulated to secrete more bile
(D) Accumulates excess fats
Answer: (D) Accumulates excess fats
WBCS Prelims Biology Questions 2018
41. Deficiency of Vitamin D results in
(A) Night blindness
(B) Rickets
(C) Scurvy
(D) Hairfall
Answer: (B) Rickets
42. Life span of red blood cells is
(A) 60 days
(B) 120 days
(C) 180 days
(D) 240 days
Answer: (B) 120 days
43. The number of milk teeth in humans is
(A) 28
(B) 29
(C) 20
(D) 12
Answer: (C) 20
44. Muscle fatigue is due to the accumulation of
(A) Carbon dioxide
(B) Creatinine
(C) Lactic acid
(D) Ethyl alcohol
Answer: (C) Lactic acid
45. The amount of O₂ normally carried by 100 ml of human blood is
(A) 40 ml
(B) 10 ml
(C) 20 ml
(D) 30 ml
Answer: (C) 20 ml
46. Which one of the following organs is the main respiratory organ of the whale?
(A) Integuments
(B) Gills
(C) Lungs
(D) Trachea
Answer: (C) Lungs
WBCS Prelims Biology Questions 2017
47. Necton are
(A) Floating organisms in water.
(B) Swimming organisms in water.
(C) Animals associated with aquatic plants.
(D) Submerged plants in water.
Answer: (B) Swimming organisms in water.
48. Barr body is absent in the somatic cell of
(A) Klinefelter syndrome individual
(B) Triple X syndrome individual
(C) Turner syndrome individual
(D) Sub-human mammalian female individual
Answer: (C) Turner syndrome individual
49. A mammal that lays eggs is
(A) Talpa
(B) Echidna
(C) Pteropus
(D) Lemur
Answer: (B) Echidna
50. Which one of the following animal phyla was discovered most recently?
(A) Pogonophora
(B) Kinorhyncha
(C) Loricifera
(D) Ctenophora
Answer: (C) Loricifera
51. An example of a modified underground stem is
(A) Carrot
(B) Potato
(C) Groundnut
(D) Turnip
Answer: (B) Potato
52. Crossing over occurs during meiosis at
(A) Leptotene
(B) Anaphase I
(C) Pachytene
(D) Diakinesis
Answer: (C) Pachytene
53. “Particulate theory of inheritance” was proposed by
(A) Charles Darwin
(B) Gregor Johann Mendel
(C) Herman Muller
(D) T. H. Morgan
Answer: (B) Gregor Johann Mendel
54. What is a bacteriophage?
(A) A virus
(B) A bacterium growing in artificial nutrient medium
(C) A fungus causing disease
(D) A phagocytic protozoan
Answer: (A) A virus
55. The nature of stele in primitive vascular plants was
(A) Protostele
(B) Siphonostele
(C) Dictyostele
(D) Atactostele
Answer: (A) Protostele
56. Which of the following processes makes direct use of oxygen?
(A) Glycolysis
(B) Fermentation
(C) Citric acid cycle
(D) Electron transport
Answer: (D) Electron transport
57. The well-known antibiotic penicillin is obtained from which plant group?
(A) Algae
(B) Fungi
(C) Lichen
(D) Angiosperm
Answer: (B) Fungi
WBCS Prelims Biology Questions 2016
58. An ophthalmologist deals with
(A) Kidney
(B) Liver
(C) Eyes
(D) Heart
Answer: (C) Eyes
59. Which metal is present in chlorophyll?
(A) Iron
(B) Zinc
(C) Aluminium
(D) Magnesium
Answer: (D) Magnesium
60. A pure red-flowered plant is crossed with a pure white-flowered plant and the F₁ plants bear pink flowers. This is an example of
(A) Pseudo-dominance
(B) Dominance
(C) Epistasis
(D) Co-dominance
Answer: (D) Co-dominance
61. A short-day plant has a critical day length of 14 hours. It will flower when the day length is
(A) 15 hours
(B) 18 hours
(C) 12 hours
(D) 16 hours
Answer: (C) 12 hours
62. An endobiotic fungus is
(A) Agaricus
(B) Morchella
(C) Synchytrium
(D) Polyporus
Answer: (C) Synchytrium
63. Gynobasic style is present in which family?
(A) Malvaceae
(B) Solanaceae
(C) Labiatae
(D) Orchidaceae
Answer: (C) Labiatae
64. ‘Globule’ and ‘Nucule’ are found in
(A) Oedogonium
(B) Rhizopus
(C) Calamites
(D) Chara
Answer: (D) Chara
65. Spindle fibres are made up of
(A) Flagellin
(B) Tubulin
(C) Cellulose
(D) Chitin
Answer: (B) Tubulin
66. A carcinoma is a cancer originating from
(A) Epithelial tissue
(B) Connective tissue
(C) Muscular tissue
(D) Nerve tissue
Answer: (A) Epithelial tissue
67. A muscle that is consciously controlled is
(A) Striated voluntary
(B) Striated involuntary
(C) Non-striated voluntary
(D) Non-striated involuntary
Answer: (A) Striated voluntary
68. Grub is the larva of
(A) Insects
(B) Crustacea
(C) Beetle
(D) Sponges
Answer: (C) Beetle
69. According to the competitive exclusion principle, two species cannot continue to occupy the same
(A) Biome
(B) Habitat
(C) Territory
(D) Niche
Answer: (D) Niche
70. Darwin and Wallace were both strongly influenced by the book An Essay on the Principle of Population written by
(A) Erasmus
(B) Malthus
(C) Volthus
(D) Lamarck
Answer: (B) Malthus
WBCS Prelims Biology Questions 2015
71. Cerebral malaria is caused by
(A) Plasmodium vivax
(B) Plasmodium malariae
(C) Plasmodium falciparum
(D) None of the above
Answer: (C) Plasmodium falciparum
72. ‘Natural Selection’ is the theory of
(A) G. J. Mendel
(B) Charles Darwin
(C) T. H. Morgan
(D) None of the above
Answer: (B) Charles Darwin
73. One turn of the DNA helix measures
(A) 34 Å
(B) 3.4 Å
(C) 24 Å
(D) 44 Å
Answer: (A) 34 Å
74. Cranial nerves in mammals are
(A) 10 pairs
(B) 10
(C) 12 pairs
(D) 12
Answer: (C) 12 pairs
75. ‘Tasar’ silk fibre is produced by
(A) Antheraea mylitta
(B) Bombyx mori
(C) Philosamia ricini
(D) Antheraea assamensis
Answer: (A) Antheraea mylitta
76. The phenotypic ratio of a Mendelian dihybrid cross is
(A) 9 : 3 : 3 : 1
(B) 1 : 1 : 1 : 1
(C) 3 : 4 : 3 : 1
(D) 1 : 2 : 1 : 1
Answer: (A) 9 : 3 : 3 : 1
77. Coal, petroleum and natural gas are examples of
(A) Fossil fuels
(B) Cryogenic fuels
(C) Indigenous fuels
(D) Radioactive fuels
Answer: (A) Fossil fuels
78. Which one of the following is the natural auxin?
(A) NAA
(B) IAA
(C) 2,4-D
(D) IBA
Answer: (B) IAA
79. During cell division, DNA synthesis takes place in
(A) Interphase
(B) Anaphase
(C) Prophase
(D) Telophase
Answer: (A) Interphase
80. Which of the following gets its name from a river in the Democratic Republic of the Congo?
(A) Chikungunya virus
(B) Lassa fever
(C) Salmonella bacteria
(D) Ebola virus
Answer: (D) Ebola virus
81. Transfer of pollen from the anther to the stigma of the same flower is referred to as
(A) Allogamy
(B) Geitonogamy
(C) Xenogamy
(D) Autogamy
Answer: (D) Autogamy
82. The pyrimidine bases in DNA are
(A) Adenine and Guanine
(B) Thymine and Adenine
(C) Cytosine and Guanine
(D) Thymine and Cytosine
Answer: (D) Thymine and Cytosine
83. In Mendel’s monohybrid cross, when a pure tall plant was crossed with a dwarf plant, all the F₁ progeny were tall because of
(A) Co-dominance
(B) Dominance
(C) Incomplete dominance
(D) Epistasis
Answer: (B) Dominance
84. One of the characteristics of the atmosphere of prebiotic primitive Earth was
(A) Absence of hydrogen
(B) Absence of water vapour
(C) Absence of nitrogen
(D) Absence of oxygen
Answer: (D) Absence of oxygen
WBCS Prelims Biology Questions 2014
85. Clove is obtained from
(A) Root
(B) Stem
(C) Leaf
(D) Flower bud
Answer: (D) Flower bud
86. Which one of the following is not a true fruit?
(A) Date
(B) Plum
(C) Apple
(D) Grape
Answer: (C) Apple
87. Which one of the following is a protein deficiency disease?
(A) Pellagra
(B) Rickets
(C) Kwashiorkor
(D) Retinoblastoma
Answer: (C) Kwashiorkor
88. Which disease is caused by a fungus?
(A) Polio
(B) Malaria
(C) Dermatitis
(D) Cholera
Answer: (C) Dermatitis
89. AIDS is caused by
(A) Bacteria
(B) Virus
(C) Protozoa
(D) Helminth
Answer: (B) Virus
90. Monocotyledonous plants show which of the following features?
(A) Leaf shows reticulate venation
(B) Tap root system
(C) Flowers are trimerous
(D) Perennial growth
Answer: (C) Flowers are trimerous
91. A compound microscope has
(A) Two lenses
(B) Requires a UV light source
(C) Is used to view only dead organisms
(D) Requires a large room space
Answer: (A) Two lenses
92. During which stage of mitosis do chromosomes become V-, J-, L- or I-shaped?
(A) Prophase
(B) Metaphase
(C) Anaphase
(D) Telophase
Answer: (C) Anaphase
93. The longest cell in animals is
(A) Nerve cell
(B) Hepatocyte (Liver cell)
(C) Blood cell
(D) Muscle cell
Answer: (A) Nerve cell
94. Digested food is absorbed in the
(A) Stomach
(B) Small intestine
(C) Large intestine
(D) Colon
Answer: (B) Small intestine
95. The identifying feature of carrot roots is
(A) Conical with small roots
(B) Conical without small roots
(C) Round with small roots
(D) Irregular with no small roots
Answer: (A) Conical with small roots
96. Rhizome is a modified stem because
(A) It grows vertically upward in the soil and has fleshy leaves.
(B) It has nodes and eyes which bear germinating buds.
(C) Its stem is highly condensed and disc-like.
(D) It has nodes, internodes and brown scaly leaves.
Answer: (D) It has nodes, internodes and brown scaly leaves.
WBCS Prelims Biology Questions 2013
97. Which metal ion is associated with haemoglobin?
(A) Mg²⁺
(B) Fe²⁺
(C) Al³⁺
(D) Mn²⁺
Answer: (B) Fe²⁺
98. In angiosperms, triple fusion is required for the formation of
(A) Embryo
(B) Endosperm
(C) Suspensor
(D) Pericarp
Answer: (B) Endosperm
99. Oil is obtained from the endosperm of
(A) Groundnut
(B) Coconut
(C) Mustard
(D) Sesame
Answer: (B) Coconut
100. The number of cervical vertebrae in mammals is
(A) Seven
(B) Seventeen
(C) Seventy-seven
(D) Eleven
Answer: (A) Seven
101. Limbless amphibians belong to the order
(A) Urodela
(B) Anura
(C) Gymnophiona
(D) None of the above
Answer: (C) Gymnophiona
102. Which one of the following is a rich source of amylase?
(A) Brain
(B) Blood
(C) Thyroid
(D) Pancreas
Answer: (D) Pancreas
103. Birds differ from bats in the absence of
(A) Warm blood
(B) Four-chambered heart
(C) Trachea
(D) Diaphragm
Answer: (D) Diaphragm
104. The portion of the carapace which covers the gills of a prawn is known as
(A) Bronchus
(B) Branchiostegal membrane
(C) Branchiostegite
(D) Branchiostegal spine
Answer: (C) Branchiostegite
WBCS Prelims Biology Questions 2012
105. Proteins are detected by
(A) Molisch’s test
(B) Biuret test
(C) DNP test
(D) Benedict’s test
Answer: (B) Biuret test
106. The enzyme DNA gyrase is associated with
(A) Protein synthesis
(B) DNA replication
(C) Lipid biosynthesis
(D) DNA damage
Answer: (B) DNA replication
107. The presence of pneumatophores (breathing roots) is found in
(A) Mangrove plants
(B) Epiphytic plants
(C) Hydrophytic plants
(D) Insectivorous plants
Answer: (A) Mangrove plants
108. The ‘Theory of Natural Selection’ was proposed by
(A) J. B. S. Haldane
(B) G. J. Mendel
(C) A. I. Oparin
(D) C. R. Darwin
Answer: (D) C. R. Darwin
109. Xylem tissue is mainly concerned with the
(A) Photosynthesis of plants
(B) Transport of water and mineral nutrients in plants
(C) Storage of prepared food in plants
(D) Transport of enzymes in plants
Answer: (B) Transport of water and mineral nutrients in plants
110. The plant body is not differentiated into root, stem and leaves in
(A) Pteridophytes
(B) Angiosperms
(C) Gymnosperms
(D) Algae
Answer: (D) Algae
111. Adult Filaria worms live in human
(A) Blood
(B) Lymphatics
(C) Liver
(D) Intestine
Answer: (B) Lymphatics
112. The disease caused due to lack of ADH is
(A) Diabetes insipidus
(B) Diabetes mellitus
(C) Graves’ disease
(D) Cushing’s disease
Answer: (A) Diabetes insipidus
113. Which one of the following is a viral disease?
(A) Trypanosomiasis
(B) Giardiasis
(C) Encephalitis
(D) Oriental sore
Answer: (C) Encephalitis
114. The non-poisonous snake is
(A) Viper
(B) Krait
(C) Python
(D) Coral snake
Answer: (C) Python
115. Normal human blood is
(A) Acidic
(B) Alkaline
(C) Neutral
(D) Variable
Answer: (B) Alkaline
116. The animal group that is not found in marine water is
(A) Mammals
(B) Amphibia
(C) Reptiles
(D) Aves
Answer: (B) Amphibia
WBCS Prelims Biology Questions 2011
117. Name one rootless plant.
(A) Ceratophyllum
(B) Eichhornia
(C) Monochoria
(D) Pistia
Answer: (A) Ceratophyllum
118. Watson and Crick are famous for their discovery of
(A) Life history of Plasmodium vivax
(B) Vaccinia
(C) Structure of DNA
(D) Antibodies
Answer: (C) Structure of DNA
119. Nerve cells originate from the embryonic
(A) Ectoderm
(B) Endoderm
(C) Mesoderm
(D) Both endoderm and mesoderm
Answer: (A) Ectoderm
120. The number of amino acids occurring in nature is
(A) 10
(B) 20
(C) 30
(D) 40
Answer: (B) 20
121. Which of the following is an unmatching group?
(A) Crayfish, cuttlefish and hagfish
(B) Starfish, sea urchin and sea cucumber
(C) Cockroach, crab and spider
(D) Whale, lizard and frog
Answer: (A) Crayfish, cuttlefish and hagfish
122. The smallest size of a cell which can be seen with the unaided eye is
(A) One micron
(B) 10 microns
(C) 100 microns
(D) 1000 microns
Answer: (C) 100 microns
123. The gastric glands in the stomach produce the enzyme
(A) Insulin
(B) Ptyalin
(C) Pepsin
(D) Trypsin
Answer: (C) Pepsin
124. Which of the following is a terrestrial alga?
(A) Chlorella
(B) Trentepohlia
(C) Spirulina
(D) Sargassum
Answer: (B) Trentepohlia
125. The lowest rate of photosynthesis takes place in
(A) Blue light
(B) Orange light
(C) Green light
(D) Red light
Answer: (C) Green light
126. Kranz anatomy indicates that the plant has
(A) C₃ cycle
(B) C₄ cycle
(C) C₂ cycle
(D) Both C₃ and C₄ cycle
Answer: (B) C₄ cycle
127. The essential carbohydrate constituent of the plant cell is
(A) Cellulose
(B) Sucrose
(C) Starch
(D) Lignin
Answer: (A) Cellulose
WBCS Prelims Biology Questions 2010
128. The gene for haemophilia is
(A) X-linked recessive
(B) X-linked dominant
(C) Y-linked
(D) Located in autosomes
Answer: (A) X-linked recessive
129. The narrow portion between the uterus and vagina of higher mammals is known as
(A) Clitoris
(B) Urethra
(C) Oviduct
(D) Cervix
Answer: (D) Cervix
130. The vegetative body of a bryophyte (moss) represents the
(A) Sporophyte
(B) Gametophyte
(C) Sporophyte or gametophyte
(D) Sporophyte and gametophyte
Answer: (B) Gametophyte
131. Enzymes speed up biochemical reactions by
(A) Increasing the activation energy of the reaction
(B) Lowering the temperature of the reaction
(C) Increasing the temperature of the reaction
(D) Lowering the activation energy of the reaction
Answer: (D) Lowering the activation energy of the reaction
132. Cardiac muscles do not undergo fatigue because of
(A) Interconnection of cells by intercalated discs
(B) Having numerous mitochondria
(C) Having more actin
(D) Having more myosin
Answer: (B) Having numerous mitochondria
133. In photosynthesis, the light reaction takes place in the
(A) Cytosol
(B) Grana of chloroplast
(C) Stroma of chloroplast
(D) Ribosome
Answer: (B) Grana of chloroplast
134. Haversian system is a part of
(A) Kidney
(B) Bone
(C) Heart
(D) Brain
Answer: (B) Bone
135. Polytene chromosomes are found in the cells of
(A) Salivary glands of fly larvae
(B) Liver of man
(C) Neurons of insects
(D) None of the above
Answer: (A) Salivary glands of fly larvae
136. Presence of sunken stomata in leaves indicates the character of
(A) Hydrophytes
(B) Xerophytes
(C) Halophytes
(D) Mesophytes
Answer: (B) Xerophytes
137. Which metal ion is responsible for electron transport in photosynthesis?
(A) Sodium
(B) Potassium
(C) Cobalt
(D) Iron
Answer: (D) Iron
138. The technique of DNA sequencing was discovered by
(A) H. G. Khorana
(B) Watson and Crick
(C) Frederick Sanger
(D) E. M. Southern
Answer: (C) Frederick Sanger
139. A cladogram depicts the hypothesis of
(A) Evolutionary relationship
(B) Phenetic relationship
(C) Genetic relationship
(D) Taxonomic relationship
Answer: (A) Evolutionary relationship
140. AIDS/HIV virus is a type of
(A) DNA virus
(B) RNA virus
(C) Either DNA or RNA virus
(D) Both DNA and RNA virus
Answer: (B) RNA virus
141. In respiration, the cytosol plays a significant role in
(A) Oxidative phosphorylation
(B) Oxidative decarboxylation of pyruvic acid
(C) Krebs cycle
(D) Glycolysis
Answer: (D) Glycolysis
WBCS Prelims Biology Questions 2009
142. How much per cent of the human body is water by weight?
(A) 66
(B) 50
(C) 33
(D) 10
Answer: (A) 66
143. Iodine is administered to patients suffering from
(A) Goitre
(B) Night blindness
(C) Rickets
(D) Rheumatism
Answer: (A) Goitre
144. Vitamin C is
(A) Tocopherol
(B) Cyanocobalamin
(C) Ascorbic acid
(D) Thiamine
Answer: (C) Ascorbic acid
145. The edible portion of coconut is the
(A) Fruit wall
(B) Endosperm
(C) Cotyledon
(D) Embryo
Answer: (B) Endosperm
146. From which part of the Cinchona plant is quinine obtained?
(A) Seed
(B) Leaf
(C) Flower
(D) Bark
Answer: (D) Bark
147. Malaria parasite can best be obtained from the blood of a patient
(A) One hour before the rise of temperature
(B) Five hours after temperature rises
(C) When temperature rises with rigor
(D) At any time
Answer: (C) When temperature rises with rigor
148. Which of the following vitamins forms the prosthetic group of acyl-CoA dehydrogenase?
(A) Nicotinic acid
(B) Pyridoxine
(C) Pantothenic acid
(D) Riboflavin
Answer: (D) Riboflavin
149. Name the excretory organ of prawn
(A) Salivary gland
(B) Green gland
(C) Ink gland
(D) Malpighian tubule
Answer: (B) Green gland
150. Ruminant stomach is possessed by
(A) Cow
(B) Dog
(C) Pigeon
(D) Chameleon
Answer: (A) Cow
151. From Antheraea assamensis, the type of silk obtained is
(A) Tasar
(B) Muga
(C) Eri
(D) Mulberry silk
Answer: (B) Muga
WBCS Prelims Biology Questions 2008
152. Amount of blood pumped by an adult heart per hour is about
(A) 150 litres
(B) 200 litres
(C) 300 litres
(D) 340 litres
Answer: (C) 300 litres
153. A bacterium differs from a virus with respect to
(A) DNA
(B) RNA
(C) Both RNA and DNA
(D) None of the above
Answer: (C) Both RNA and DNA
154. The instrument used for measuring blood pressure is called
(A) Barometer
(B) Sphygmomanometer
(C) Tonometer
(D) None of the above
Answer: (B) Sphygmomanometer
155. Pneumatophores are
(A) Pneumonia victims of Sundarbans
(B) Marshy areas of Sundarbans
(C) Stems of Sundari trees
(D) Breathing roots of mangroves
Answer: (D) Breathing roots of mangroves
156. The ingredient that assists clotting of blood is
(A) Vitamin A
(B) Folic acid
(C) Vitamin D
(D) Vitamin K
Answer: (D) Vitamin K
157. The causative organism of malignant malaria in humans is
(A) Plasmodium vivax
(B) Plasmodium falciparum
(C) Plasmodium malariae
(D) Plasmodium ovale
Answer: (B) Plasmodium falciparum
158. The nitrogen base absent in DNA is
(A) Uracil
(B) Adenine
(C) Thymine
(D) Cytosine
Answer: (A) Uracil
159. Succinic acid dehydrogenase produces
(A) Malic acid
(B) Formic acid
(C) Isocitric acid
(D) Fumaric acid
Answer: (D) Fumaric acid
160. Ribosomes play a significant role in
(A) Photosynthesis
(B) Protein synthesis
(C) Lipid synthesis
(D) Respiration
Answer: (B) Protein synthesis
161. Name an insectivorous plant
(A) Gulancha
(B) Nayantara
(C) Basak
(D) Pitcher plant
Answer: (D) Pitcher plant
162. Cancer is caused by activation of genes called
(A) Regulatory genes
(B) Oncogenes
(C) Structural genes
(D) Jumping genes
Answer: (B) Oncogenes
163. Parkinson’s disease is characterised by the loss of nerve cells in the
(A) Cingulate cortex
(B) Substantia nigra
(C) Reticular formation
(D) Cerebral cortex
Answer: (B) Substantia nigra
164. Flowers without petals are pollinated by
(A) Bees
(B) Birds
(C) Butterflies
(D) Wind
Answer: (D) Wind
165. Predisposing causes of a disease are referred to as
(A) Ethnology
(B) Ecology
(C) Etiology
(D) Environmental factors
Answer: (C) Etiology
166. The biochemical processes taking place in the body are known as
(A) Anabolism
(B) Catabolism
(C) Metabolism
(D) None of the above
Answer: (C) Metabolism
167. RNA of a retrovirus can produce DNA by
(A) DNA polymerase
(B) RNA polymerase
(C) Endonuclease
(D) Reverse transcriptase
Answer: (D) Reverse transcriptase
168. The intermediate host of Leishmania donovani is
(A) Sand fly
(B) Tse-tse fly
(C) Dragonfly
(D) Anopheles mosquito
Answer: (A) Sand fly
WBCS Prelims Biology Questions 2007
169. The phytohormone responsible for senescence is
(A) Cytokinin
(B) Auxin
(C) Gibberellin
(D) Ethylene
Answer: (D) Ethylene
170. Which one of the following is not a hereditary disease in humans?
(A) Hemophilia
(B) Colour blindness
(C) Alzheimer’s disease
(D) Down’s syndrome
Answer: (C) Alzheimer’s disease
171. A virion is
(A) Infective particle of a virus
(B) Infective particle of a bacteriophage
(C) Infective stage of a virus
(D) None of the above
Answer: (A) Infective particle of a virus
172. A peduncle is the
(A) Stalk of a flower
(B) Stalk of a leaf
(C) Stalk of a fruit
(D) None of the above
Answer: (A) Stalk of a flower
173. Kala-azar in humans is spread by the bite of a
(A) Culex mosquito
(B) Phlebotomus sandfly
(C) Cimex bed-bug
(D) Sarcoptes mite
Answer: (B) Phlebotomus sandfly
174. The genetic make-up of a normal human male consists of
(A) XY chromosomes
(B) XO chromosomes
(C) XX chromosomes
(D) XXO chromosomes
Answer: (A) XY chromosomes
175. Which one of the following is a polymorphic species?
(A) Garden lizard
(B) Spider
(C) Gorilla
(D) Ant
Answer: (D) Ant
176. A plant virus causing disease in vegetables is
(A) Tobacco Mosaic Virus
(B) Cauliflower Mosaic Virus
(C) Adenovirus
(D) None of the above
Answer: (B) Cauliflower Mosaic Virus
177. Chemically, sporopollenin is a
(A) Co-polymer of carotenoids and fatty acids
(B) Carbohydrate
(C) Protein
(D) Lactic acid
Answer: (A) Co-polymer of carotenoids and fatty acids
WBCS Prelims Biology Questions 2006
178. The connecting link between reptiles and birds is
(A) Archaeopteryx
(B) Platypus
(C) Java Ape-man
(D) Whale
Answer: (A) Archaeopteryx
179. Which one of the following is not a protozoan?
(A) Hydra
(B) Euglena
(C) Amoeba
(D) Paramecium
Answer: (A) Hydra
180. Which of the following is not a function of the kidney?
(A) Ultrafiltration
(B) Tubular reabsorption
(C) Tubular secretion
(D) Phagocytosis
Answer: (D) Phagocytosis
181. Loop of Henle lies in the
(A) Cortex
(B) Medulla
(C) Renal pelvis
(D) Ureter
Answer: (B) Medulla
182. A viral disease is
(A) Cancer
(B) Leukaemia
(C) Typhoid
(D) Yellow fever
Answer: (D) Yellow fever
183. Fruit fall can be prevented by spraying
(A) Indole-3-acetic acid (IAA)
(B) Abscisic acid
(C) Cytokinins
(D) Naphthalene acetic acid (NAA)
Answer: (D) Naphthalene acetic acid (NAA)
184. Coconut inflorescence is
(A) Racemose
(B) Hypanthodium
(C) Cyathium
(D) Spadix
Answer: (D) Spadix
185. Urea is produced in the human body in the
(A) Liver
(B) Urinary bladder
(C) Kidney
(D) Haemoglobin
Answer: (A) Liver
186. Restriction endonucleases are synthesized by
(A) All eukaryotic cells
(B) Yeast and bacteria only
(C) Bacteria only
(D) All cells
Answer: (C) Bacteria only
187. In plants, the receptor for detecting photoperiod is
(A) Sensory cell
(B) Sensory organelles
(C) Protein molecule
(D) Gradient of K⁺
Answer: (C) Protein molecule
188. Primary and secondary growth are inhibited by
(A) Auxin
(B) Gibberellins
(C) Abscisic acid
(D) Cytokinins
Answer: (C) Abscisic acid
189. From a cross between a pure strain of plants with yellow peas and a pure strain of plants with green peas, how many different types of gametes are produced by the F₁ offspring?
(A) 1
(B) 2
(C) 4
(D) 8
Answer: (B) 2
WBCS Prelims Biology Questions 2005
190. Cholesterol is a/an
(A) Saturated fat
(B) Unsaturated fat
(C) Steroid
(D) Diglyceride
Answer: (C) Steroid
191. Which one of the following animals possesses the least number of body segments?
(A) Flatworm
(B) Earthworm
(C) Prawn
(D) Cockroach
Answer: (A) Flatworm
192. According to Darwin, the unit of natural selection is
(A) Individual
(B) Family
(C) Genus
(D) Species
Answer: (A) Individual
193. The amount of blood in the circulatory system of an adult human is
(A) One litre
(B) Two litres
(C) Five litres
(D) Ten litres
Answer: (C) Five litres
194. Sweat, saliva and tears contain an enzyme called lysozyme. It kills
(A) Virus-infected cells
(B) Protozoa
(C) Bacteria
(D) Viruses
Answer: (C) Bacteria
195. The main function of norepinephrine is to
(A) Increase blood pressure
(B) Increase urine formation
(C) Increase cellular respiration
(D) Release epinephrine
Answer: (A) Increase blood pressure
196. Plants store glucose in the form of
(A) Monosaccharide
(B) Cellulose
(C) Starch
(D) Glycogen
Answer: (C) Starch
197. According to cellular structure, which one of the following is the most complex?
(A) Bacteria
(B) Protozoa
(C) Algae
(D) Fungi
Answer: (D) Fungi
198. The scientific name of Vitamin C is
(A) Acetic acid
(B) Muriatic acid
(C) Ascorbic acid
(D) Lactic acid
Answer: (C) Ascorbic acid
199. Which one of the following plant tissues is composed of dead cells?
(A) Xylem
(B) Phloem
(C) Parenchyma
(D) Hypodermis
Answer: (A) Xylem
200. Which one of the following blood groups is called the universal donor?
(A) A
(B) B
(C) AB
(D) O
Answer: (D) O
201. Antibodies are synthesized by
(A) Bone marrow
(B) Plasma cells and lymphocytes
(C) Liver
(D) Kidney
Answer: (B) Plasma cells and lymphocytes
202. Which one of the following plants keeps its stomata open during the night and closed during the day?
(A) Water lily
(B) Cactus
(C) Sunflower
(D) Fern
Answer: (B) Cactus
203. The first hormone produced by genetic engineering is
(A) Estrogen
(B) Testosterone
(C) Thyroxine
(D) Insulin
Answer: (D) Insulin
204. Out Of the twenty amino acids, how many are considered essential?
(A) Six
(B) Eight
(C) Twelve
(D) Fourteen
Answer: (B) Eight
WBCS Prelims Biology Questions 2003
205. Pitcher plant is
(A) Autotrophic
(B) Heterotrophic
(C) Insectivorous
(D) Actinomorphic
Answer: (C) Insectivorous
206. AIDS is a
(A) Viral disease
(B) Fungal disease
(C) Bacterial disease
(D) Genetic disease
Answer: (A) Viral disease
207. Universal donor in blood transfusion refers to
(A) Blood group A
(B) Blood group B
(C) Blood group AB
(D) Blood group O
Answer: (D) Blood group O
208. Scurvy is caused by the deficiency of
(A) Vitamin A
(B) Vitamin B
(C) Vitamin C
(D) Vitamin D
Answer: (C) Vitamin C
209. Which of the following becomes zero in a fully turgid cell?
(A) Water potential
(B) Wall pressure
(C) Osmotic pressure
(D) All of the above
Answer: (A) Water potential
210. Colles’ fracture is associated with the
(A) Humerus
(B) Radius
(C) Ulna
(D) Femur
Answer: (B) Radius
211. Septicemia is
(A) Food poisoning
(B) Blood poisoning
(C) Mental disorder
(D) None of the above
Answer: (B) Blood poisoning
212. Malaria is caused by
(A) Plasmodium
(B) Anopheles mosquito
(C) Culex mosquito
(D) Bad air
Answer: (A) Plasmodium
213. The following animal has vision most similar to humans
(A) Crow
(B) Owl
(C) Horse
(D) Pigeon
Answer: (A) Crow
214. Genetic information is carried by
(A) Protein
(B) Fatty acids
(C) Nucleic acids
(D) Carbohydrate
Answer: (C) Nucleic acids
215. Which of the following is the hardest substance in the human body?
(A) Bone
(B) Enamel
(C) Dentine
(D) Nail
Answer: (B) Enamel
216. Which of the following animals is called the friend of the farmer?
(A) Cow
(B) Earthworm
(C) Rhizobium
(D) Honey-bee
Answer: (B) Earthworm
WBCS Prelims Biology Questions 2002
217. During photosynthesis
(A) Presence of oxygen is essential
(B) Catabolic reaction takes place
(C) Light energy is stored as potential chemical energy in food (glucose)
(D) Stored potential chemical energy of food is released as heat and other forms of energy
Answer: (C) Light energy is stored as potential chemical energy in food (glucose)
218. Which one is the connecting link between reptiles and mammals?
(A) Peripatus
(B) Lungfish
(C) Duck-billed platypus
(D) Archaeopteryx (Extinct)
Answer: (C) Duck-billed platypus
219. A plant cell shrinks when placed in
(A) Water
(B) A solution isotonic with the cell sap
(C) A hypertonic solution
(D) A hypotonic solution
Answer: (C) A hypertonic solution
220. Nitrogen fixation means
(A) Liquefaction of nitrogen
(B) Conversion of atmospheric nitrogen into useful compounds
(C) Manufacture of nitrogen from air
(D) Conversion of nitrogen into nitric acid
Answer: (B) Conversion of atmospheric nitrogen into useful compounds
221. Which one of the following is not an endocrine gland?
(A) Adrenal gland (cortex)
(B) Pituitary gland
(C) Salivary gland
(D) Thyroid gland
Answer: (C) Salivary gland
222. Which is the largest animal ever to live on Earth?
(A) Dinosaur
(B) Whale
(C) Elephant
(D) Anaconda
Answer: (B) Whale
223. The simple microscope was first invented by
(A) Robert Hooke
(B) Antonie van Leeuwenhoek
(C) Purkinje
(D) Robert Brown
Answer: (B) Antonie van Leeuwenhoek
224. Normal leaves are called
(A) Seed leaves
(B) Floral leaves
(C) Foliage leaves
(D) Scale leaves
Answer: (C) Foliage leaves
225. Roots of a tree are
(A) Negatively geotropic
(B) Positively geotropic
(C) Positively phototropic
(D) Negatively hydrotropic
Answer: (B) Positively geotropic
226. Majority of animal viruses contain
(A) DNA
(B) RNA
(C) Both RNA and DNA
(D) Neither DNA nor RNA
Answer: (B) RNA
227. In which part of the human body is urea produced?
(A) Kidneys
(B) Liver
(C) Pancreas
(D) Urinary bladder
Answer: (B) Liver
228. Which of the following vitamins is most easily destroyed by heat and air?
(A) Vitamin A
(B) Vitamin B
(C) Vitamin C
(D) Vitamin D
Answer: (C) Vitamin C
229. Refrigeration helps in food preservation by
(A) Killing bacteria and germs
(B) Greatly retarding the rates of biochemical reactions
(C) Providing a cover of ice over food
(D) Stopping enzyme action
Answer: (B) Greatly retarding the rates of biochemical reactions
230. Which of the following is an infectious bacterial disease?
(A) Conjunctivitis
(B) Diphtheria
(C) Influenza
(D) Measles
Answer: (B) Diphtheria
WBCS Prelims Biology Questions 2001
231. Ichthyology is related to
(A) Fish
(B) Bird
(C) Insect
(D) Mammal
Answer: (A) Fish
232. Lysine is an essential amino acid because
(A) It is very rare
(B) It is an important constituent of all proteins
(C) It has a high nutritive value
(D) It is not formed in the body and has to be provided through food
Answer: (D) It is not formed in the body and has to be provided through food
233. ______ is an antivitamin.
(A) Beta-carotene
(B) Methylcobalamin
(C) Pyrithiamine
(D) Folic acid
Answer: (C) Pyrithiamine
234. Which part of the ear maintains the balance of our body?
(A) Otolith
(B) Malleus
(C) Tympanic membrane
(D) Cochlea
Answer: (A) Otolith
235. Which one of the following is a protozoan?
(A) Pea mosaic virus
(B) Entamoeba histolytica
(C) Yeast
(D) Variola virus
Answer: (B) Entamoeba histolytica
236. The disease caused by the deficiency of Vitamin B₁₂ is
(A) Aplastic anaemia
(B) Sickle cell anaemia
(C) Normocytic anaemia
(D) Pernicious anaemia
Answer: (D) Pernicious anaemia
WBCS Prelims Biology Questions 2000
237. Which one of the following is not an autotroph?
(A) Grass
(B) Green algae
(C) Fungus
(D) Fern
Answer: (C) Fungus
238. Photosynthetic plants store glucose as
(A) Sucrose
(B) Starch
(C) Cellulose
(D) Glycogen
Answer: (B) Starch
239. In the present concept of evolution, the unit of evolution is
(A) Individual
(B) Families
(C) Population
(D) Species
Answer: (C) Population
240. Which one of the following is a reptile?
(A) Salamander
(B) Turtle
(C) Newt
(D) Shark
Answer: (B) Turtle
241. Yellowing of plant leaves is called chlorosis. Insufficiency of which causes it?
(A) Sodium
(B) Phosphorus
(C) Calcium
(D) Magnesium
Answer: (D) Magnesium
242. A red blood cell lives for about
(A) One week
(B) One month
(C) Three months
(D) One year
Answer: (C) Three months
243. The percentage of solar energy absorbed by the leaves of green plants in photosynthesis is
(A) 1
(B) 10
(C) 30
(D) 50
Answer: (A) 1
244. Which one of the following is used in ripening fruits?
(A) Ethylene
(B) Acetylene
(C) Methane
(D) Polyvinyl chloride
Answer: (A) Ethylene
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