Life Processes Part 3: MCQs (Q51–Q75)
📘 Life Processes – MCQs (Class 10 Science)
🔹 Part 3: Questions 51–75
Q51. What is the mode of nutrition in fungi?
A) Autotrophic
B) Saprotrophic
C) Parasitic only
D) Holozoic
Correct Answer: B) Saprotrophic
Explanation:
- A) Autotrophic → Plants, not fungi.
- ✅ B) Saprotrophic → Fungi absorb nutrients from dead and decaying matter.
- C) Parasitic only → Some fungi are parasitic, but not all.
- D) Holozoic → Animals.
Q52. In human respiration, oxygen is transported by:
A) Plasma
B) Platelets
C) Hemoglobin
D) White blood cells
Correct Answer: C) Hemoglobin
Explanation:
- A) Plasma → Transports nutrients and CO₂.
- B) Platelets → Clotting.
- ✅ C) Hemoglobin in RBCs → Binds and carries oxygen.
- D) WBC → Defense.
Q53. Which of the following organisms uses diffusion for exchange of gases?
A) Earthworm
B) Amoeba
C) Fish
D) Human
Correct Answer: B) Amoeba
Explanation:
- A) Earthworm → Uses moist skin.
- ✅ B) Amoeba → Single-celled, diffusion across surface.
- C) Fish → Uses gills.
- D) Humans → Lungs.
Q54. Which organ in humans stores glycogen?
A) Stomach
B) Liver
C) Kidney
D) Pancreas
Correct Answer: B) Liver
Explanation:
- A) Stomach → Digestion only.
- ✅ B) Liver → Stores glycogen as reserve energy.
- C) Kidney → Excretion.
- D) Pancreas → Secretes enzymes & hormones.
Q55. Which blood vessel supplies blood to the kidneys?
A) Renal vein
B) Renal artery
C) Hepatic artery
D) Vena cava
Correct Answer: B) Renal artery
Explanation:
- ✅ B) Renal artery → Brings blood to kidneys for filtration.
- A) Renal vein → Carries filtered blood away.
- C) Hepatic artery → Supplies liver.
- D) Vena cava → Returns blood to heart.
Q56. What is the end product of anaerobic respiration in human muscles?
A) Ethanol
B) Lactic acid
C) Carbon dioxide
D) Pyruvate
Correct Answer: B) Lactic acid
Explanation:
- A) Ethanol → Produced in yeast.
- ✅ B) Lactic acid → Causes muscle fatigue and cramps.
- C) CO₂ → Produced but not the main end product.
- D) Pyruvate → Intermediate, not final product.
Q57. Which part of the nephron is responsible for ultrafiltration?
A) Loop of Henle
B) Bowman’s capsule
C) Collecting duct
D) Proximal tubule
Correct Answer: B) Bowman’s capsule
Explanation:
- A) Loop of Henle → Reabsorbs water.
- ✅ B) Bowman’s capsule → Filters blood under pressure.
- C) Collecting duct → Collects urine.
- D) PCT → Absorbs useful substances.
Q58. Which structure in plants controls the rate of transpiration?
A) Cuticle
B) Xylem
C) Stomata
D) Phloem
Correct Answer: C) Stomata
Explanation:
- A) Cuticle → Waxy layer, reduces transpiration.
- B) Xylem → Water transport, not control.
- ✅ C) Stomata → Open and close to regulate water loss.
- D) Phloem → Food transport.
Q59. Which gas is produced during photosynthesis?
A) Carbon dioxide
B) Oxygen
C) Nitrogen
D) Methane
Correct Answer: B) Oxygen
Explanation:
- A) CO₂ → Consumed, not produced.
- ✅ B) O₂ → Released as byproduct of splitting water.
- C, D → Not related.
Q60. The breakdown of food in mitochondria is called:
A) Glycolysis
B) Krebs cycle
C) Respiration
D) Oxidative phosphorylation
Correct Answer: B) Krebs cycle
Explanation:
- A) Glycolysis → Occurs in cytoplasm.
- ✅ B) Krebs cycle → Takes place in mitochondria matrix.
- C) Respiration → General term, not specific.
- D) Oxidative phosphorylation → Occurs in mitochondrial membrane.
Q61. In humans, digestion of fats begins in:
A) Mouth
B) Stomach
C) Small intestine
D) Large intestine
Correct Answer: C) Small intestine
Explanation:
- A) Mouth → Only carbohydrate digestion begins.
- B) Stomach → Proteins digested.
- ✅ C) Small intestine → Bile emulsifies fats, lipase digests them.
- D) Large intestine → Water absorption.
Q62. The site of photosynthesis in plants is:
A) Mitochondria
B) Chloroplast
C) Vacuole
D) Cytoplasm
Correct Answer: B) Chloroplast
Explanation:
- A) Mitochondria → Respiration.
- ✅ B) Chloroplast → Contains chlorophyll, site of photosynthesis.
- C) Vacuole → Storage.
- D) Cytoplasm → No photosynthesis.
Q63. Which of the following is not an excretory organ in humans?
A) Lungs
B) Kidney
C) Skin
D) Heart
Correct Answer: D) Heart
Explanation:
- A) Lungs → Excrete CO₂.
- B) Kidney → Excrete urea.
- C) Skin → Excretes sweat.
- ✅ D) Heart → Circulates blood, not excretory organ.
Q64. Which type of circulatory system is present in humans?
A) Open
B) Closed
C) Single
D) None
Correct Answer: B) Closed
Explanation:
- A) Open → Arthropods.
- ✅ B) Closed → Blood flows in vessels in humans.
- C) Single → Found in fishes.
- D) None → Incorrect.
Q65. Which of the following maintains the water balance in the body?
A) Lungs
B) Liver
C) Kidneys
D) Heart
Correct Answer: C) Kidneys
Explanation:
- A) Lungs → Gas exchange.
- B) Liver → Metabolism.
- ✅ C) Kidneys → Regulate water by urine formation.
- D) Heart → Pumps blood.
Q66. Which vein brings blood from the lower body to the heart?
A) Pulmonary vein
B) Hepatic vein
C) Superior vena cava
D) Inferior vena cava
Correct Answer: D) Inferior vena cava
Explanation:
- A) Pulmonary vein → From lungs.
- B) Hepatic vein → From liver.
- C) Superior vena cava → From upper body.
- ✅ D) Inferior vena cava → From lower body to right atrium.
Q67. Which is the first enzyme to act on food in the human digestive system?
A) Pepsin
B) Salivary amylase
C) Lipase
D) Trypsin
Correct Answer: B) Salivary amylase
Explanation:
- A) Pepsin → Protein digestion in stomach.
- ✅ B) Amylase → In saliva, acts on starch in mouth.
- C) Lipase → Fats in intestine.
- D) Trypsin → Proteins in intestine.
Q68. The transport of food in phloem is called:
A) Transpiration
B) Translocation
C) Respiration
D) Conduction
Correct Answer: B) Translocation
Explanation:
- A) Transpiration → Water loss.
- ✅ B) Translocation → Movement of sucrose through phloem.
- C) Respiration → Energy release.
- D) Conduction → General transport, not specific.
Q69. In photosynthesis, the light reaction occurs in:
A) Stroma
B) Thylakoid membrane
C) Cytoplasm
D) Mitochondria
Correct Answer: B) Thylakoid membrane
Explanation:
- A) Stroma → Dark reaction (Calvin cycle).
- ✅ B) Thylakoid membrane → Light reaction takes place.
- C, D → Not related.
Q70. In which part of the digestive system is hydrochloric acid secreted?
A) Mouth
B) Small intestine
C) Stomach
D) Pancreas
Correct Answer: C) Stomach
Explanation:
- A) Mouth → No acid secretion.
- B) Small intestine → Alkaline medium.
- ✅ C) Stomach → HCl kills germs and activates pepsin.
- D) Pancreas → Produces enzymes, no HCl.
Q71. What is the function of platelets in blood?
A) Carry oxygen
B) Transport food
C) Help in clotting
D) Defend against infection
Correct Answer: C) Help in clotting
Explanation:
- A) Oxygen → RBCs.
- B) Food → Plasma.
- ✅ C) Platelets → Release clotting factors.
- D) Defense → WBCs.
Q72. Which type of transport in plants requires energy?
A) Diffusion
B) Osmosis
C) Active transport
D) Transpiration
Correct Answer: C) Active transport
Explanation:
- A) Diffusion → Passive.
- B) Osmosis → Passive.
- ✅ C) Active transport → Against gradient, requires ATP.
- D) Transpiration → Passive.
Q73. Which of the following is the main nitrogenous waste in humans?
A) Ammonia
B) Uric acid
C) Urea
D) Creatinine
Correct Answer: C) Urea
Explanation:
- A) Ammonia → Excreted in fish.
- B) Uric acid → Birds and reptiles.
- ✅ C) Urea → Humans are ureotelic.
- D) Creatinine → Minor waste.
Q74. In which organ of the human body are nephrons found?
A) Heart
B) Brain
C) Kidney
D) Lungs
Correct Answer: C) Kidney
Explanation:
- A) Heart → No nephrons.
- B) Brain → Neurons.
- ✅ C) Kidney → Nephrons are functional units of kidney.
- D) Lungs → Alveoli, not nephrons.
Q75. Which organelle is called the powerhouse of the cell?
A) Ribosome
B) Chloroplast
C) Mitochondria
D) Endoplasmic reticulum
Correct Answer: C) Mitochondria
Explanation:
- A) Ribosome → Protein synthesis.
- B) Chloroplast → Photosynthesis.
- ✅ C) Mitochondria → Produce ATP, energy currency.
- D) ER → Transport of substances.
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