Comprehensive Biology Test 8
351. Emulsification means - Breaking fats into small globules
Explanation: Bile salts break large fat droplets into smaller ones, increasing the surface area for enzyme action.
352. Double helix model of DNA was proposed by - Watson and Crick
Explanation: They described DNA as two helical strands joined by complementary base pairs, carrying genetic information.
353. Mendel is famous for - Genetic laws
Explanation: Gregor Mendel discovered inheritance patterns using pea plants, laying the foundation of modern genetics.
354. Exhaled air contains about - 4% carbon dioxide
Explanation: During respiration, cells release CO₂, which is exhaled through lungs, while oxygen is absorbed for metabolism.
355. Percentage of fat in ghee - 99%
Explanation: Ghee is almost pure fat, providing concentrated energy but no proteins or carbohydrates.
356. Sex chromosomes are called - Allosomes
Explanation: Allosomes determine an organism’s sex — XX for females and XY for males in humans.
357. Digestive bag of the cell is - Lysosome
Explanation: Lysosomes contain digestive enzymes that break down worn-out cell parts and foreign substances.
358. Master copy of genetic information - DNA
Explanation: DNA stores hereditary information and controls protein synthesis in all living organisms.
359. Term "Rhizosphere" was given by - Hiltner
Explanation: Rhizosphere refers to the soil region around roots influenced by microorganisms and nutrients.
360. Another name for kneecap - Patella
Explanation: The patella protects the knee joint and helps with leg extension during movement.
361. Main components of food - Fats, Proteins, Carbohydrates
Explanation: These macronutrients supply energy, build body tissues, and support vital biological functions.
362. Green pigment responsible for photosynthesis - Chlorophyll
Explanation: Chlorophyll absorbs sunlight (mainly red and blue light) and converts it into chemical energy for food production.
363. Which is the most sensitive indicator of the health of a community ?
Ans: Infant Mortality Rate
Explanation: Infant mortality rate shows how many infants die before one year. It reflects health care, nutrition, and hygiene standards of a community — hence the best indicator.
364. Which part of the elephant turns into tusks ?
Ans: Second incisor teeth
Explanation: The elephant’s tusks are elongated second incisors made of ivory, used for digging, defense, and lifting objects.
365. Which source is especially productive in nature ?
Ans: Marine source
Explanation: Oceans and seas are rich in minerals, planktons, and aquatic organisms, making marine sources highly productive biologically and economically.
366. Lichen is a symbiotic association between ?
Ans: Algae and Fungi
Explanation: Algae prepare food through photosynthesis, while fungi provide shelter and absorb moisture. Both live together mutually benefiting each other.
367. Many grass leaves can roll and unroll due to ?
Ans: Presence of special motor cells
Explanation: Grasses have bulliform (motor) cells that help roll leaves during water stress to reduce transpiration and unroll when hydrated.
368. What is used in the treatment of cancer ?
Ans: Chemotherapy
Explanation: Chemotherapy uses powerful chemicals to kill fast-growing cancer cells, slowing or stopping the spread of tumors in the body.
369. What is meant by the greenhouse effect ?
Ans: Trapping of solar energy by carbon dioxide and other gases
Explanation: Greenhouse gases like CO₂ trap heat in the atmosphere, increasing Earth's temperature and causing global warming.
370. Waste from toilets and urinals is called ?
Ans: Sanitary waste
Explanation: Human excreta and urine collected from toilets are termed sanitary waste, needing safe disposal to prevent pollution and diseases.
371. Red color of tomato is due to ?
Ans: Lycopene
Explanation: Lycopene is a red pigment and antioxidant in tomatoes that gives color and helps protect cells from damage.
372. Which organelle differentiates plant and animal cells ?
Ans: Chloroplast
Explanation: Chloroplasts are found only in plant cells for photosynthesis; animal cells lack them, making this a key difference.
373. Common spice “clove” is obtained from which part of the plant ?
Ans: Flower bud
Explanation: Clove is the dried unopened flower bud of the clove tree (Syzygium aromaticum), used as spice and medicine.
374. The final product of starch digestion in the alimentary canal is ?
Ans: Maltose
Explanation: Enzymes like amylase break starch into maltose, a simpler sugar that later converts into glucose for absorption.
375. Companion cells in phloem are found in ?
Ans: Angiosperms
Explanation: Companion cells are associated with sieve tubes in angiosperms, helping in translocation of food through the phloem.
376. The rearing of silkworms is called ?
Ans: Sericulture
Explanation: Sericulture is the practice of breeding silkworms to produce silk fibers from their cocoons.
376. Which part of the flower produces pollen grains ?
Ans: Anther
Explanation: The anther, part of the stamen, contains pollen sacs where male gametes (pollen grains) are formed.
377. Carrot is a rich source of which vitamin ?
Ans: Vitamin A
Explanation: Carrots contain beta-carotene, which converts to Vitamin A — essential for vision, growth, and immune function.
378. Toxicology is the study of ?
Ans: Poisons
Explanation: Toxicology deals with the effects, detection, and treatment of poisons in living organisms.
379. Alfalfa is a type of ?
Ans: Grass
Explanation: Alfalfa (Medicago sativa) is a leguminous forage crop rich in protein, often used as animal feed.
380. Which organelle is absent in bacterial cells ?
Ans: Nucleus
Explanation: Bacteria are prokaryotes; they lack a true membrane-bound nucleus, having only a nucleoid region containing DNA.
381. Which metal is a component of Vitamin B12 ?
Ans: Cobalt
Explanation: Vitamin B12 contains cobalt at its core (as cobalamin), vital for red blood cell formation and nerve function.
382. The two richest sources of dietary protein are ?
Ans: Soybean and Groundnut
Explanation: Both soybean and groundnut contain high-quality plant proteins, making them excellent alternatives to animal proteins.
383. How many ear bones are found in humans ?
Ans: Six (three in each ear)
Explanation: Each ear has three tiny bones — malleus, incus, and stapes — that transmit sound vibrations to the inner ear.
384. Animals of phylum Annelida are ?
Ans: Cylindrical worms
Explanation: Annelids are segmented, cylindrical worms like earthworms and leeches, having a true coelom and segmented body.
385. What type of tail is found in sharks ?
Ans: Heterocercal tail
Explanation: In sharks, the upper lobe of the tail is longer than the lower (heterocercal), aiding in upward thrust and balance.
386. 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.
387. 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.
388. Fruit whose seeds are outside - Strawberry.
Explanation: Strawberry’s seeds are embedded on its outer surface (achenes), not inside like other fruits.
389. Function of xylem in plants - Water conduction.
Explanation: Xylem transports water and minerals from roots to leaves through vessels and tracheids via transpiration pull.
390. Excretory pore in Paramecium is called - Cytopyge.
Explanation: Cytopyge is the site where waste materials are expelled from the body of Paramecium.
391. Test used to detect HIV - ELISA test.
Explanation: ELISA (Enzyme-Linked Immunosorbent Assay) identifies HIV antibodies in blood, confirming infection.
392. Number of chromosomes in humans - 46 (23 pairs).
Explanation: Humans have 23 pairs: 22 autosomes and 1 pair of sex chromosomes (XX/XY).
393. Claspers in male sharks are attached to - Pelvic fins.
Explanation: Claspers are reproductive organs used by male sharks to transfer sperm during mating.
394. Conglobate (leaf-like) gland found in - Male cockroach.
Explanation: This gland secretes substances aiding reproduction and is a characteristic of male cockroaches.
395. 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.
396. Orange color of carrot is due to - Carotene.
Explanation: Beta-carotene gives carrots their orange color and converts to Vitamin A in the body.
397. Reproductive organ of plants - Flower.
Explanation: The flower contains stamens and pistils, responsible for producing gametes and forming seeds after fertilization.
398. 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.
399. Offspring produced by vegetative propagation are called - Clones.
Explanation: Vegetative propagation gives genetically identical offspring (clones) to the parent plant.
400. After fermentation, molasses are mostly used to prepare - Ethanol.
Explanation: Molasses (sugarcane by-product) undergo fermentation by yeast to produce ethyl alcohol.