Biology MCQs

Science

Biology MCQs

Practice complete Biology MCQs covering Introduction to Biology, Cell Biology, Cell Structure, Cell Division, Biomolecules, Plant Physiology, Human Physiology, Genetics, Evolution, Biotechnology, Ecology, Classification of Living Organisms, Plant Kingdom, Animal Kingdom, Microbiology, Human Diseases, Nutrition, Reproduction, Environmental Biology, and all other important topics. Includes chapter-wise and exam-oriented multiple-choice questions with detailed answers and explanations for JKSSB, SSC, Banking, Railway, UPSC, CUET, NEET, State PSCs, and other competitive exams.

2054
Total Questions

Practice Questions

Page 59 of 103
Question #1161
The scientist who first used the term 'antibiotic' was:
A. Gerhard Domagk
B. Selman Waksman
C. Paul Ehrlich
D. Alexander Fleming
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Selman Waksman coined the term 'antibiotic' in 1942 to describe chemical compounds produced by microorganisms that inhibit or kill other microbes. Fleming discovered penicillin, Ehrlich developed the concept of chemotherapy, Domagk discovered sulfa drugs.
This question belongs to: Science Biology
Question #1162
The structure that prevents food from entering the nasal cavity during swallowing is the:
A. Epiglottis
B. Pharynx
C. Tongue
D. Soft palate (uvula)
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
The soft palate, including the uvula, elevates during swallowing to close off the nasopharynx, preventing food from entering the nasal passages. The epiglottis closes the larynx, the tongue pushes food.
This question belongs to: Science Biology
Question #1163
The vitamin that is a coenzyme in the transfer of one-carbon units is:
A. Biotin
B. Riboflavin
C. Folic acid
D. Thiamine
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Folic acid (vitamin B₉) is reduced to tetrahydrofolate (THF), which carries one-carbon groups in amino acid and nucleotide metabolism. Biotin is for carboxylation, riboflavin for redox, thiamine for decarboxylation.
This question belongs to: Science Biology
Question #1164
The disease caused by the SARS-CoV-2 virus is:
A. COVID-19
B. MERS
C. SARS
D. Influenza
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
COVID-19 (coronavirus disease 2019) is caused by the novel coronavirus SARS-CoV-2. MERS is caused by MERS-CoV, SARS by SARS-CoV. Influenza is caused by influenza viruses.
This question belongs to: Science Biology
Question #1165
The hormone that stimulates the growth of the ovarian follicle is:
A. Estrogen
B. LH
C. Progesterone
D. FSH
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Follicle-stimulating hormone (FSH) from the anterior pituitary promotes the growth and maturation of ovarian follicles and stimulates estrogen secretion. LH triggers ovulation, estrogen proliferates endometrium, progesterone maintains it.
This question belongs to: Science Biology
Question #1166
The organ that stores excess glucose as glycogen is the:
A. Kidney
B. Muscle
C. Pancreas
D. Liver
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
The liver is the primary organ for glycogenesis (storing glucose as glycogen) and glycogenolysis, maintaining blood glucose levels. Muscles store glycogen for local use. Pancreas regulates via hormones, kidneys excrete excess glucose.
This question belongs to: Science Biology
Question #1167
The process of separating proteins based on their net charge is:
A. Gel filtration chromatography
B. Affinity chromatography
C. Ion exchange chromatography
D. SDS-PAGE
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Ion exchange chromatography separates proteins based on their net surface charge; positively charged proteins bind to cation exchangers, negatively to anion exchangers. Gel filtration separates by size, affinity by specific binding, SDS-PAGE by molecular weight.
This question belongs to: Science Biology
Question #1168
The organelle that converts fatty acids into sugars in plant seedlings is the:
A. Peroxisome
B. Mitochondria
C. Glyoxysome
D. Chloroplast
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Glyoxysomes are specialized peroxisomes found in germinating oil seeds. They contain enzymes of the glyoxylate cycle, converting fatty acids to carbohydrates until the seedling can photosynthesize.
This question belongs to: Science Biology
Question #1169
The vitamin that is required for the formation of collagen and wound healing is:
A. Vitamin D
B. Vitamin C
C. Vitamin A
D. Vitamin E
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Vitamin C is a cofactor for prolyl and lysyl hydroxylases, enzymes essential for collagen cross-linking and stability. Deficiency impairs wound healing and causes scurvy. Vitamin A is for epithelial integrity.
This question belongs to: Science Biology
Question #1170
The scientist who discovered the enzyme reverse transcriptase was:
A. Howard Temin and David Baltimore
B. James Watson
C. Francis Crick
D. Kary Mullis
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Howard Temin and David Baltimore independently discovered reverse transcriptase in retroviruses in 1970, an enzyme that synthesizes DNA from RNA. Watson and Crick DNA structure, Mullis PCR.
This question belongs to: Science Biology
Question #1171
Which of the following is an example of a coenzyme?
A. NAD⁺
B. Hemoglobin
C. Pepsin
D. Collagen
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
NAD⁺ (nicotinamide adenine dinucleotide) is a coenzyme derived from vitamin B₃, serving as an electron carrier in redox reactions. Pepsin is an enzyme, collagen a structural protein, hemoglobin a transport protein. Coenzymes are organic non-protein molecules that assist enzymes.
This question belongs to: Science Biology
Question #1172
The scientist who proposed the 'one gene-one enzyme' hypothesis using Neurospora crassa was:
A. Beadle and Tatum
B. Watson and Crick
C. Morgan
D. Mendel
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
George Beadle and Edward Tatum irradiated Neurospora crassa and showed that mutations in specific genes caused defects in specific enzymes, leading to the one gene-one enzyme concept. Watson and Crick discovered DNA structure, Mendel laws of inheritance, Morgan chromosome theory.
This question belongs to: Science Biology
Question #1173
Assertion (A): Mitochondria are called semi-autonomous organelles. Reason (R): They possess their own DNA and ribosomes and can synthesize some proteins.
A. A false, R true.
B. Both A and R are true, and R is the correct explanation.
C. A true, R false.
D. Both A and R are true, but R is not the correct explanation.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Mitochondria have circular DNA and 70S ribosomes, enabling them to transcribe and translate some proteins independently, hence semi-autonomous. They still depend on nuclear genes for most proteins. The reason correctly explains the assertion.
This question belongs to: Science Biology
Question #1174
Which of the following is a disaccharide?
A. Glucose
B. Glycogen
C. Fructose
D. Sucrose
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Sucrose (table sugar) is a disaccharide composed of glucose and fructose. Glucose and fructose are monosaccharides, glycogen is a polysaccharide. Other disaccharides include maltose and lactose.
This question belongs to: Science Biology
Question #1175
In a typical angiosperm, the male gametophyte is the:
A. Endosperm
B. Pollen grain
C. Embryo sac
D. Ovule
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
The pollen grain contains the male gametophyte, which produces two sperm cells. The ovule contains the female gametophyte (embryo sac). Endosperm is the triploid nutritive tissue formed after double fertilization.
This question belongs to: Science Biology
Question #1176
The disease caused by the deficiency of vitamin B₃ (niacin) is characterized by:
A. Bone deformities
B. Dermatitis, diarrhea, dementia
C. Bleeding gums
D. Night blindness
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Pellagra (niacin deficiency) presents with the three D's: dermatitis, diarrhea, and dementia. Bleeding gums is scurvy (vitamin C), bone deformities rickets (vitamin D), night blindness vitamin A deficiency.
This question belongs to: Science Biology
Question #1177
The process by which bacteria acquire genes from the environment is:
A. Translation
B. Transduction
C. Transformation
D. Conjugation
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Transformation is the uptake of free DNA from the surroundings and its incorporation into the bacterial genome. Conjugation requires cell-to-cell contact via pilus, transduction involves bacteriophage, translation is protein synthesis.
This question belongs to: Science Biology
Question #1178
The pigment that gives red algae their characteristic color is:
A. Phycoerythrin
B. Chlorophyll a
C. Fucoxanthin
D. Phycocyanin
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Phycoerythrin is a red phycobiliprotein that masks chlorophyll in red algae (Rhodophyta). Phycocyanin is blue in cyanobacteria, fucoxanthin brown in brown algae. These accessory pigments allow light absorption at depths.
This question belongs to: Science Biology
Question #1179
The technique used to separate DNA fragments based on size is:
A. Gel electrophoresis
B. PCR
C. DNA sequencing
D. Cloning
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Agarose gel electrophoresis separates DNA fragments by size under an electric field; smaller fragments migrate faster. PCR amplifies DNA, sequencing determines base order, cloning produces copies.
This question belongs to: Science Biology
Question #1180
The enzyme that catalyzes the synthesis of ATP in chloroplasts is:
A. ATP synthase
B. Rubisco
C. PEP carboxylase
D. NADP reductase
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
ATP synthase (CF₀-CF₁ complex) uses the proton gradient across the thylakoid membrane to synthesize ATP. Rubisco fixes CO₂, NADP reductase reduces NADP⁺, PEP carboxylase is in C4 plants.
This question belongs to: Science Biology

More Science Topics

chemistry MCQs
Physics MCQs
Today's Top Topics
Physics 1287 chemistry 1089 Biology 2054
Explore Subjects
Computer 5279 History GK 3374 English 15164 Static General Knowledge 6362 Reasoning 1120
Practice Mix
The term 'Deuce' is used when the score is tied in tennis. What specific score does it denote?
The 'Vittala Temple' is known for its:
Two stations A and B are 450 km apart. A train leaves station A at 4:00 PM at 60 km/h. Another train leaves station B at 5:00 PM at 70 km/h traveling towards A. At what time will they meet?
Which of the following is a characteristic of a distributed operating system?
Select the correct passive voice of: 'She gave me a book.'