Comprehensive Biology Test 10
451. Thrombin involved in – Blood clotting
Explanation: Thrombin converts fibrinogen to fibrin, forming a clot to stop bleeding and protect the body from blood loss.
452. Weight of kidney – 150 grams
Explanation: A normal human kidney weighs about 150 g, helping filter blood, remove waste, and balance body fluids.
453. Main protein in milk – Casein
Explanation: Casein forms about 80% of milk protein; it provides amino acids and calcium, essential for growth and bone strength.
454. Part with most bones – Fingers
Explanation: Fingers contain 14 phalanges in each hand; thus, they have the highest number of small bones in the body.
455. Vitamin role – Synthesis of Prothrombin
Explanation: Vitamin K helps synthesize prothrombin, a protein essential for blood clotting and preventing excessive bleeding.
456. Tadpole breathes through – External gills
Explanation: Newly hatched tadpoles have external gills for respiration, which later change into lungs as they mature into frogs.
457. Biodiesel mostly produced by – Euphorbiaceae
Explanation: Euphorbia plants (like Jatropha) in the Euphorbiaceae family yield oil-rich seeds used for making biodiesel fuel.
458. Food transport in plants – By Phloem
Explanation: Phloem carries prepared food (mainly sucrose) from leaves to other plant parts through translocation.
459. Lactose found in – Milk
Explanation: Lactose is a natural sugar in milk, composed of glucose and galactose, providing energy for infants.
460. Bile secreted by – Liver
Explanation: The liver produces bile, stored in the gallbladder, which helps digest fats in the small intestine.
461. Curcumin extracted from – Turmeric
Explanation: Curcumin is the yellow pigment in turmeric with strong antioxidant and anti-inflammatory properties.
462. Controller of heartbeat – Pacemaker
Explanation: The sinoatrial node acts as the heart’s natural pacemaker, generating impulses that regulate heartbeat rhythm.
463. Platelets die in – Spleen
Explanation: The spleen destroys old or damaged platelets and red blood cells, maintaining healthy blood cell balance.
464. Pollution monitor organism – Lichen
Explanation: Lichens are sensitive to air pollutants like sulfur dioxide, making them natural indicators of air quality.
465. Air pollution increases when ventilation coefficient – >6000 m²/s
Explanation: Higher ventilation coefficient (>6000 m²/s) disperses pollutants quickly, while lower values cause accumulation and poor air quality.
466. Meningitis affects – Brain
Explanation: Meningitis is inflammation of the brain and spinal cord membranes, caused by bacteria or viruses.
467. Bile is – Yellow-green alkaline fluid
Explanation: Bile is an alkaline digestive fluid that emulsifies fats, aiding lipid digestion and absorption.
468. Lac used for sealing produced by – Insect
Explanation: Lac is a resin secreted by Laccifer lacca insects, used in polish and sealing wax.
469. Hashish obtained from – Stem and male inflorescence exudate
Explanation: Hashish is a resinous exudate from stems and flowers of the Cannabis plant, containing psychoactive compounds.
470. Smallest cell – Mycoplasma
Explanation: Mycoplasma are the smallest living cells (0.1 µm), lacking a cell wall but capable of independent growth.
471. Disease with high blood sugar – Diabetes Mellitus
Explanation: In diabetes, insufficient insulin causes elevated blood glucose, leading to fatigue and other health issues.
472. Thrombin involved in – Blood clotting
Explanation: Thrombin converts fibrinogen to fibrin, forming a clot to stop bleeding and protect the body from blood loss.
473. Cockroach cannot survive in water because its respiratory organ is - Trachea.
Explanation: Cockroaches breathe through tracheal tubes (air-filled). Water blocks air entry, preventing oxygen intake and leading to suffocation.
474. Octopus belongs to - Mollusca.
Explanation: Octopus is a soft-bodied marine mollusk with tentacles and suction cups; it breathes through gills and has a well-developed nervous system.
475. Fruit whose seeds are outside - Strawberry.
Explanation: Strawberry’s seeds are embedded on its outer surface (achenes), not inside like other fruits.
476. Function of xylem in plants - Water conduction.
Explanation: Xylem transports water and minerals from roots to leaves through vessels and tracheids via transpiration pull.
477. Excretory pore in Paramecium is called - Cytopyge.
Explanation: Cytopyge is the site where waste materials are expelled from the body of Paramecium.
478. Test used to detect HIV - ELISA test.
Explanation: ELISA (Enzyme-Linked Immunosorbent Assay) identifies HIV antibodies in blood, confirming infection.
479. Number of chromosomes in humans - 46 (23 pairs).
Explanation: Humans have 23 pairs: 22 autosomes and 1 pair of sex chromosomes (XX/XY).
480. Claspers in male sharks are attached to - Pelvic fins.
Explanation: Claspers are reproductive organs used by male sharks to transfer sperm during mating.
481. Conglobate (leaf-like) gland found in - Male cockroach.
Explanation: This gland secretes substances aiding reproduction and is a characteristic of male cockroaches.
482. Normal blood sugar level in humans - Around 80–90 mg/dl.
Explanation: This is the fasting glucose level essential for body energy balance; higher or lower causes disorders.
483. Orange color of carrot is due to - Carotene.
Explanation: Beta-carotene gives carrots their orange color and converts to Vitamin A in the body.
484. Reproductive organ of plants - Flower.
Explanation: The flower contains stamens and pistils, responsible for producing gametes and forming seeds after fertilization.
485. Edible part of guava, grape, custard apple, and tomato - Pericarp.
Explanation: The pericarp is the ripened ovary wall that becomes fleshy and edible in these fruits.
486. Offspring produced by vegetative propagation are called - Clones.
Explanation: Vegetative propagation gives genetically identical offspring (clones) to the parent plant.
487. After fermentation, molasses are mostly used to prepare - Ethanol.
Explanation: Molasses (sugarcane by-product) undergo fermentation by yeast to produce ethyl alcohol.
488. Largest bird in the world - Ostrich.
Explanation: Ostriches are flightless African birds, the tallest and heaviest, known for running fast.
489. Kidney stone in humans is made of - Calcium oxalate.
Explanation: Crystallized calcium oxalate forms hard deposits (stones) in kidneys, causing pain and urinary problems.
490. Discoverer of cholera bacteria - Robert Koch.
Explanation: German scientist Koch identified Vibrio cholerae as the causative organism of cholera.
491. Sterilization in males is called - Vasectomy.
Explanation: Vasectomy involves cutting or sealing vas deferens to prevent sperm release during ejaculation.
492. Hormone that stimulates heartbeat - Thyroxine.
Explanation: Thyroxine (from thyroid gland) increases metabolism and heart rate by regulating oxygen use in cells.
493. Number of cartilages in human larynx - Nine.
Explanation: The larynx (voice box) has nine cartilages including thyroid, cricoid, and epiglottis for voice and airway protection.
494. Genetically resistant organisms are called - Recalcitrant.
Explanation: Recalcitrant species naturally resist microbial attack or genetic modification due to strong defense mechanisms.
495. Most endangered top predator of Asia - Dhole.
Explanation: The Asiatic wild dog (Cuon alpinus) is critically endangered due to habitat loss and disease.
496. Scavengers of the Earth - Bacteria and fungi.
Explanation: These decomposers recycle nutrients by breaking down dead plants and animals into simpler substances.
497. Alzheimer’s disease affects - Brain.
Explanation: Alzheimer’s causes degeneration of neurons in the brain, leading to memory loss and confusion.
498. Harmful substances produced by pathogens - Toxins.
Explanation: Pathogenic microbes secrete toxins that damage host tissues and cause diseases.
499. Number of chambers in frog’s heart - Three.
Explanation: Frogs have two atria and one ventricle, allowing partial mixing of oxygenated and deoxygenated blood.
500. Leaving land uncultivated for some years - Fallowing.
Explanation: Fallowing restores soil fertility by allowing natural processes to replenish nutrients.