1. The mode of nutrition in which organisms prepare their own food from simple inorganic substances is called:
A. Heterotrophic nutrition
B. Autotrophic nutrition
C. Saprophytic nutrition
D. Parasitic nutrition
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Answer: B. Autotrophic nutrition
Explanation: Green plants and autotrophic bacteria synthesize organic food from inorganic raw materials like CO₂ and H₂O.
2. Which of the following raw materials are required for photosynthesis?
A. Carbon dioxide and Water
B. Chlorophyll and Sunlight
C. Both A and B
D. Oxygen and Glucose
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Answer: C. Both A and B
Explanation: Photosynthesis requires CO₂, H₂O, chlorophyll, and sunlight to synthesize carbohydrates.
3. What are the tiny pores present on the surface of leaves through which gaseous exchange takes place?
A. Chloroplasts
B. Stomata
C. Guard cells
D. Lenticels
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Answer: B. Stomata
Explanation: Stomata are microscopic openings present primarily on leaf epidermis that regulate transpiration and gas exchange.
4. Opening and closing of stomatal pores is regulated by:
A. Epidermal cells
B. Guard cells
C. Chloroplasts
D. Mesophyll cells
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Answer: B. Guard cells
Explanation: Guard cells swell when water flows into them causing stomatal pores to open, and shrink when water leaves causing pores to close.
5. Digestion of carbohydrates (starch) begins in which part of the human alimentary canal?
A. Stomach
B. Mouth (Mouth Cavity / Buccal Cavity)
C. Small Intestine
D. Oesophagus
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Answer: B. Mouth (Mouth Cavity / Buccal Cavity)
Explanation: Salivary amylase secreted by salivary glands in the mouth breaks down complex starch into simpler maltose sugar.
6. Hydrochloric acid (HCl) in the human stomach functions to:
A. Create an acidic medium to activate pepsin
B. Kill harmful bacteria present in food
C. Both A and B
D. Digest fats directly
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Answer: C. Both A and B
Explanation: HCl provides an acidic pH required for pepsin action and destroys pathogens entering with food.
7. Which enzyme is present in gastric juice to digest proteins in the stomach?
A. Trypsin
B. Pepsin
C. Lipase
D. Amylase
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Answer: B. Pepsin
Explanation: Gastric glands secrete pepsinogen, which gets converted to active pepsin in the presence of HCl to break down proteins.
8. Which internal organ secretes bile juice?
A. Pancreas
B. Stomach
C. Liver
D. Gall bladder
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Answer: C. Liver
Explanation: The liver produces bile juice (stored in gall bladder), which emulsifies large fat globules in the small intestine.
9. The complete digestion of carbohydrates, proteins, and fats takes place in the:
A. Stomach
B. Small Intestine
C. Large Intestine
D. Liver
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Answer: B. Small Intestine
Explanation: Small intestine receives intestinal, pancreatic, and biliary secretions, completing full food digestion.
10. Finger-like projections in the inner lining of the small intestine that increase surface area for absorption are called:
A. Cilia
B. Villi
C. Flagella
D. Alveoli
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Answer: B. Villi
Explanation: Villi are rich in blood vessels and significantly expand absorption surface area for digested food.
11. Breakdown of glucose (6-carbon molecule) into pyruvate (3-carbon molecule) takes place in the:
A. Mitochondria
B. Cytoplasm
C. Chloroplast
D. Nucleus
Show Answer
Answer: B. Cytoplasm
Explanation: Glycolysis occurs in cell cytoplasm, converting glucose into pyruvate without requiring oxygen.
12. Anaerobic respiration in yeast cells yields:
A. Lactic acid + Energy
B. Ethanol + Carbon dioxide + Energy
C. Carbon dioxide + Water + Energy
D. Pyruvate + Water
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Answer: B. Ethanol + Carbon dioxide + Energy
Explanation: Yeast undergoes fermentation (anaerobic respiration), converting pyruvate into ethanol and CO₂.
13. Cramps in human muscle cells during sudden heavy physical exercise are caused by accumulation of:
A. Ethanol
B. Pyruvate
C. Lactic acid
D. Carbon dioxide
Show Answer
Answer: C. Lactic acid
Explanation: Lack of oxygen during intense activity causes anaerobic conversion of pyruvate to lactic acid, producing muscle cramps.
14. Complete oxidation of pyruvate using oxygen to produce CO₂, water, and energy occurs in the:
A. Cytoplasm
B. Mitochondria
C. Ribosome
D. Endoplasmic Reticulum
Show Answer
Answer: B. Mitochondria
Explanation: Aerobic respiration takes place inside mitochondria, generating high amounts of ATP energy.
15. What energy currency of the cell is synthesized during cellular respiration?
A. ADP
B. ATP
C. DNA
D. RNA
Show Answer
Answer: B. ATP
Explanation: ATP (Adenosine Triphosphate) acts as the direct energy currency for endothermic cellular reactions.
16. Structural and functional unit of the human respiratory system where gas exchange occurs is:
A. Bronchioles
B. Alveoli
C. Trachea
D. Nephron
Show Answer
Answer: B. Alveoli
Explanation: Thin balloon-like alveoli surrounded by dense capillary networks facilitate gas exchange (O₂ and CO₂).
17. Respiratory pigment in human blood responsible for carrying oxygen is:
A. Plasma
B. Hemoglobin
C. Myoglobin
D. Chlorophyll
Show Answer
Answer: B. Hemoglobin
Explanation: Hemoglobin in Red Blood Corpuscles (RBCs) has high affinity for oxygen and transports it throughout the body.
18. Human heart consists of how many chambers?
A. Two
B. Three
C. Four
D. Five
Show Answer
Answer: C. Four
Explanation: Human heart has 4 chambers (2 upper atria, 2 lower ventricles) preventing mixing of oxygenated and deoxygenated blood.
19. Which blood vessel carries oxygenated blood from lungs to the left atrium of the heart?
A. Pulmonary Artery
B. Pulmonary Vein
C. Vena Cava
D. Aorta
Show Answer
Answer: B. Pulmonary Vein
Explanation: Pulmonary veins are exceptional veins carrying oxygen-rich blood from lungs back to heart.
20. Blood vessels that carry blood away from the heart to various body organs under high pressure are:
A. Veins
B. Capillaries
C. Arteries
D. Lymphatic vessels
Show Answer
Answer: C. Arteries
Explanation: Arteries have thick, elastic walls because blood emerges from heart under high pressure.
21. Component of blood responsible for clotting at the site of an injury to prevent blood loss is:
A. RBCs
B. WBCs
C. Platelets
D. Plasma
Show Answer
Answer: C. Platelets
Explanation: Blood platelets circulate in blood and seal leaks by forming clots at injured locations.
22. Plant vascular tissue responsible for transport of water and dissolved minerals from roots to leaves is:
A. Phloem
B. Xylem
C. Cambium
D. Cortex
Show Answer
Answer: B. Xylem
Explanation: Xylem tissue (vessels and tracheids) transports water and minerals unidirectionally upwards.
23. Transport of soluble products of photosynthesis (food) through phloem tissue is called:
A. Transpiration
B. Translocation
C. Evaporation
D. Osmosis
Show Answer
Answer: B. Translocation
Explanation: Translocation is the active transport of sucrose/amino acids via phloem using ATP energy.
24. Loss of water in the form of water vapor from aerial parts of plants is known as:
A. Translocation
B. Guttation
C. Transpiration
D. Excretion
Show Answer
Answer: C. Transpiration
Explanation: Transpiration pulls water upwards through xylem and regulates plant temperature.
25. Basic filtration units present in human kidneys are called:
A. Neurons
B. Nephrons
C. Alveoli
D. Villi
Show Answer
Answer: B. Nephrons
Explanation: Each kidney contains around a million structural filtration units called nephrons.
26. Cup-shaped structure present at the top of a nephron that collects filtrate is called:
A. Glomerulus
B. Bowman's Capsule
C. Loop of Henle
D. Ureter
Show Answer
Answer: B. Bowman's Capsule
Explanation: Bowman's capsule encloses the glomerulus tuft and catches the initial nitrogenous fluid filtrate.
27. What major nitrogenous waste product is removed from human blood by kidneys?
A. Ammonia
B. Urea and Uric Acid
C. Carbon dioxide
D. Lactic acid
Show Answer
Answer: B. Urea and Uric Acid
Explanation: Kidneys filter toxic nitrogenous breakdown products like urea and uric acid out into urine.
28. Which tube connects each kidney to the urinary bladder?
A. Urethra
B. Ureter
C. Nephron tube
D. Renal artery
Show Answer
Answer: B. Ureter
Explanation: Urine formed in kidneys travels through long muscular tubes called ureters into urinary bladder.
29. Artificial machine procedure used to clean blood in patients suffering from kidney failure is called:
A. Hemolysis
B. Hemodialysis
C. Plasmolysis
D. Hydrolysis
Show Answer
Answer: B. Hemodialysis
Explanation: Hemodialysis acts as an artificial kidney device to clear metabolic nitrogenous wastes from patient blood.
30. Gaseous waste product produced during photosynthesis in plants is:
A. Carbon dioxide
B. Nitrogen
C. Oxygen
D. Methane
Show Answer
Answer: C. Oxygen
Explanation: Oxygen is released as a byproduct during photolysis of water in photosynthesis.
