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 58 of 103
Question #1141
The term for the death of brain tissue due to lack of blood flow is:
A. Stroke
B. Myocardial infarction
C. Aneurysm
D. Embolism
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
A stroke (cerebrovascular accident) occurs when blood supply to part of the brain is interrupted, causing tissue death. Myocardial infarction is heart attack, aneurysm is vessel ballooning, embolism is blockage by a traveling clot.
This question belongs to: Science Biology
Question #1142
The scientist who discovered the structure of chlorophyll was:
A. Richard Willstätter
B. Hans Fischer
C. Robert Woodward
D. Melvin Calvin
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Hans Fischer determined the structure of chlorophyll in the 1930s and synthesized hemin. Willstätter studied its composition, Calvin elucidated the carbon fixation pathway, Woodward synthesized chlorophyll.
This question belongs to: Science Biology
Question #1143
The process by which a bacterial cell takes up DNA from its environment is:
A. Transduction
B. Transformation
C. Lysogeny
D. Conjugation
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Transformation is the direct uptake and incorporation of naked DNA from the surroundings by a bacterium. Conjugation is DNA transfer via pilus, transduction via phage, lysogeny is phage DNA integration.
This question belongs to: Science Biology
Question #1144
The hormone that promotes the development of the mammary glands during pregnancy is:
A. Estrogen
B. Progesterone
C. Prolactin
D. Oxytocin
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Progesterone stimulates the development of alveolar tissue of the breasts during pregnancy. Estrogen promotes duct development. Prolactin initiates milk synthesis, oxytocin ejection.
This question belongs to: Science Biology
Question #1145
The organ that produces the hormone renin is the:
A. Kidney
B. Liver
C. Adrenal gland
D. Heart
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Renin is secreted by juxtaglomerular cells of the kidney in response to low blood pressure or sodium. It converts angiotensinogen to angiotensin I, initiating the RAAS. Liver produces angiotensinogen, adrenal aldosterone, heart ANP.
This question belongs to: Science Biology
Question #1146
The enzyme that catalyzes the synthesis of RNA primer during DNA replication is:
A. Primase
B. Helicase
C. Ligase
D. DNA polymerase
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Primase is an RNA polymerase that synthesizes short RNA primers complementary to the DNA template, providing a free 3'-OH for DNA polymerase to begin synthesis. Helicase unwinds, polymerase extends, ligase joins.
This question belongs to: Science Biology
Question #1147
The compound that is the main energy source for the brain is:
A. Ketone bodies
B. Amino acids
C. Fatty acids
D. Glucose
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Under normal conditions, the brain relies almost exclusively on glucose for energy. During prolonged fasting, it can adapt to use ketone bodies. Fatty acids cannot cross the blood-brain barrier.
This question belongs to: Science Biology
Question #1148
The disorder caused by the deficiency of antidiuretic hormone (ADH) is:
A. Diabetes mellitus
B. Cushing's syndrome
C. Addison's disease
D. Diabetes insipidus
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Diabetes insipidus results from ADH deficiency (or resistance), causing polyuria, polydipsia, and dilute urine. Diabetes mellitus is insulin-related, Addison's is adrenal insufficiency, Cushing's is excess cortisol.
This question belongs to: Science Biology
Question #1149
The structure that provides nutrients to the sperm and forms seminal fluid is the:
A. Prostate gland and seminal vesicles
B. Vas deferens
C. Epididymis
D. Testis
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Seminal vesicles produce a fructose-rich fluid (energy for sperm), and the prostate gland adds a milky, alkaline fluid to form semen. The testis produces sperm, epididymis stores them, vas deferens transports.
This question belongs to: Science Biology
Question #1150
The technique that uses antibodies to detect specific proteins in a sample is:
A. PCR
B. Southern blotting
C. ELISA
D. Northern blotting
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
ELISA (enzyme-linked immunosorbent assay) uses enzyme-linked antibodies to detect and quantify specific antigens or antibodies in a sample. PCR amplifies DNA, Northern blotting detects RNA, Southern blotting DNA.
This question belongs to: Science Biology
Question #1151
The element that is a component of the vitamin B₁₂ molecule is:
A. Cobalt
B. Iron
C. Magnesium
D. Zinc
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Vitamin B₁₂ (cobalamin) contains a cobalt ion at the center of its corrin ring. It is the only vitamin that contains a metal. Iron is in heme, zinc in enzymes, magnesium in chlorophyll.
This question belongs to: Science Biology
Question #1152
The scientist who discovered the 'transforming principle' in bacteria was:
A. Avery, MacLeod, McCarty
B. Watson and Crick
C. Hershey and Chase
D. Frederick Griffith
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Frederick Griffith in 1928 demonstrated the transformation of non-virulent pneumococci to virulent by heat-killed virulent strain, suggesting a transforming principle. Avery et al. later identified it as DNA. Hershey-Chase confirmed DNA is genetic material.
This question belongs to: Science Biology
Question #1153
The hormone that triggers the release of cortisol from the adrenal cortex is:
A. TSH
B. FSH
C. GH
D. ACTH
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Adrenocorticotropic hormone (ACTH), secreted by the anterior pituitary, stimulates the adrenal cortex to produce and release cortisol. TSH stimulates thyroid, FSH gonads, GH growth.
This question belongs to: Science Biology
Question #1154
The structure that separates the thoracic and abdominal cavities is the:
A. Peritoneum
B. Mediastinum
C. Pleura
D. Diaphragm
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
The diaphragm is a dome-shaped skeletal muscle that separates the thoracic cavity (lungs, heart) from the abdominal cavity. It is the primary muscle of inspiration. Pleura lines lungs, peritoneum lines abdomen.
This question belongs to: Science Biology
Question #1155
The process by which water enters the root hairs from the soil is:
A. Diffusion
B. Active transport
C. Transpiration pull
D. Osmosis
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Water moves from the soil (high water potential) into root hair cells (lower water potential due to solutes) by osmosis across the semipermeable membrane. Active transport is for minerals, transpiration pull is for upward movement.
This question belongs to: Science Biology
Question #1156
The vitamin that is a component of the coenzymes FMN and FAD is:
A. Pantothenic acid
B. Niacin
C. Thiamine
D. Riboflavin
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Riboflavin (vitamin B₂) is the precursor of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which are electron carriers in redox reactions. Thiamine is TPP, niacin NAD/NADP, pantothenic acid CoA.
This question belongs to: Science Biology
Question #1157
The disease caused by a prion that leads to spongiform degeneration of the brain is:
A. Parkinson's disease
B. Alzheimer's disease
C. Huntington's disease
D. Creutzfeldt-Jakob disease
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Creutzfeldt-Jakob disease (CJD) is a rare, fatal prion disease causing rapid neurodegeneration and sponge-like brain tissue. Alzheimer's involves amyloid plaques, Huntington's is genetic, Parkinson's involves dopamine deficiency.
This question belongs to: Science Biology
Question #1158
The organ that secretes the hormone atrial natriuretic peptide (ANP) is the:
A. Liver
B. Adrenal gland
C. Heart
D. Kidney
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
ANP is secreted by atrial muscle cells of the heart in response to stretching (high blood volume). It promotes sodium and water excretion, lowering blood pressure. Kidneys secrete renin, adrenal aldosterone, liver angiotensinogen.
This question belongs to: Science Biology
Question #1159
The process by which atmospheric nitrogen is converted to ammonia by industrial process is:
A. Ammonification
B. Nitrification
C. Haber-Bosch process
D. Denitrification
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
The Haber-Bosch process synthesizes ammonia from N₂ and H₂ under high temperature and pressure with a catalyst. It is the main industrial nitrogen fixation for fertilizers. Biological fixation is by microbes.
This question belongs to: Science Biology
Question #1160
The type of ecological pyramid that can be inverted in a parasitic food chain is the:
A. Pyramid of numbers
B. Pyramid of productivity
C. Pyramid of energy
D. Pyramid of biomass
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
A pyramid of numbers can be inverted when a single tree (producer) supports many herbivores, or many parasites live on a single host. Energy pyramids are always upright. Biomass pyramid can be inverted in aquatic systems.
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.'