biology MCQs – Page 18

Practise multiple-choice questions from biology for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

biology Mcqs

341. Which statement is incorrect about Lock and Key Model________________?
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A. It explains the mechanism of every chemical reaction

B. Active site of an enzyme is a non flexible structure

C. Active site does not change before during or even after the reaction

D. Specific enzyme can transform only a specific substrate

342. Purines and pyrimidines are in equal ration in DNA. It was indicated by_______________?
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A. Watson & Crick

B. F.Miescher

C. Harshay & Chase

D. Chargaff

343. Genes will not be found in gene pairs in the_____________?
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A. Uterine cells of dog

B. Guard cells of leaf

C. Muscle cell of worm

D. Sperm cells of frog

344. The one which is present in all living things is ___________?
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A. DNA or RNA

B. Vacuole

C. Cell nucleus

D. Cell membrane

345. Far-red light promotes flowering in_______________?
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A. None of these

B. Day neutral plant

C. Long day plant

D. Short day plant

346. Which step causes activation of catalytic site of an enzyme__________________?
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A. Change in temperature

B. Formation of Enzyme Susstrate complex.

C. Change in the charge of the active site.

D. Change in pH of the surroundings.

347. Which of the following polysaccharide is called animal starch_________________?
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A. None of these

B. Starch

C. Glycogen

D. Cellulose

348. Which statement is true about an aqueous medium________________?
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A. Enzymes can not perform catalysis reaction in this medium

B. Ionic as well as non ionic substance in aqueous media retains their identity

C. Ions and molecules move randomly thus are in more favorable state to react with other molecules and ions

D. It is less favorable media for chemical reactions

349. _____________ is a nervous disorder characterized by involuntary tremors, diminished motor power and rigidity?
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A. Parkinsons disease

B. Alzheimers disease

C. Epilepsy

D. Meningitis

350. Protein coasts of viruses are synthesized in____________?
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A. Lytic cycle

B. Lysogenic cycle

C. Both a & b

D. All of these

351. On which of the following component of chloroplast chlorophyll is arranged?
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A. Matrix

B. Stroma

C. Cell membrane

D. Thylakoids?

352. Animals obtain carbohydrates mainly from___________?
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A. Sucrose

B. Starch

C. Glucose

D. Glycogen

353. The type of plastids which help in pollination is_________?
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A. All of these

B. Chloroplasts

C. Leucoplasts

D. Chromoplasts

354. lubb sound is produced due to___________________?
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A. Closure of outlet valve

B. Closure of inlet valve

C. Opening of inlet valve

D. Opening of outlet valve

355. Which one of the following is most likely to occur in an animal during winter?
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A. Activation of sweat glands

B. Dilation of skin blood vessels

C. Thermogenesis

D. Panting

356. Antibodies play important role against microorganisms and other pathogens to which type of proteins do they belong________?
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A. Globular proteins

B. Fibrous Proteins

C. Both a and b

D. None of these

357. Which of the following is an autosomal disorder______________?
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A. Klinifelters syndrome

B. Turners syndrome

C. Downs syndrome

D. Jacobs syndrome

358. If more substrate to already occurring enzymatic reaction is added and there is no effect on the rate of the reaction what is the form given to this situation___________?
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A. Saturation

B. Composition

C. Denaturation

D. Inhibition

359. Which one are most complex sugar_____________?
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A. Polysaccharides

B. Monosaccharides

C. Oligosaccharides

D. None of these

360. The active site of an enzyme______________?
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A. Forms no chemical bond with substrate

B. Never changes

C. They are non specific in their action

D. Determined by structure and the specificity of the enzyme

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