Biology MCQs

Question #121

Share Report

Which of the following is an example of a genetically modified crop?

A. Brassica napus

B. Triticale

C. Bt cotton

D. Sugarcane

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Bt cotton is genetically modified by inserting the cry gene from Bacillus thuringiensis, which produces an insecticidal protein toxic to bollworms. Triticale is a hybrid of wheat and rye (not GM per se), Brassica napus is rapeseed (canola) which may have GM varieties, but Bt cotton is a classic example. GM crops include Bt brinjal, herbicide-tolerant soybeans.

This question belongs to: Science Biology

Question #122

Share Report

The technique of producing genetically identical individuals from a single cell is:

A. Hybridization

B. Cross breeding

C. Cloning

D. Mutation breeding

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Cloning produces genetically identical copies of an organism or cell. In animals, somatic cell nuclear transfer (like Dolly the sheep) is used. Plant cloning occurs via vegetative propagation or tissue culture. Hybridization combines different genomes; mutation breeding induces mutations; cross breeding involves mating. Cloning has applications in therapeutics, conservation, and agriculture.

This question belongs to: Science Biology

Question #123

Share Report

Which of the following is a correct statement about biofertilizers?

A. They are toxic to soil organisms.

B. They are synthetic growth regulators.

C. They are chemical fertilizers that enhance crop yield.

D. They are living organisms that enrich soil nutrient content.

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Biofertilizers contain living microorganisms like bacteria, cyanobacteria, and fungi that increase nutrient availability (e.g., nitrogen fixation, phosphorus solubilization) for plants. They are eco-friendly and sustainable. Chemical fertilizers are synthetic inorganic salts. Biopesticides control pests. Examples: Rhizobium, Azotobacter, mycorrhiza. Biofertilizers improve soil health without chemical residue.

This question belongs to: Science Biology

Question #124

Share Report

In fish farming, 'induced breeding' is commonly achieved by injecting:

A. Thyroxine

B. Insulin

C. Pituitary extract containing gonadotropins

D. Adrenaline

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
In pisciculture, induced breeding is carried out by injecting fish with pituitary gland extract from donor fish containing gonadotropic hormones (FSH and LH), which stimulate spawning. This allows controlled production of fish seed. Hypophysation is the technique used in Indian major carps. Insulin and thyroxine are not involved in reproduction. Adrenaline is a stress hormone.

This question belongs to: Science Biology

Question #125

Share Report

Louis Pasteur is famous for developing the first vaccine for:

A. Tuberculosis

B. Smallpox

C. Rabies

D. Polio

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Louis Pasteur developed the first vaccine against rabies in 1885, using a weakened strain of the virus. He also invented pasteurization and made significant contributions to microbiology, disproving spontaneous generation. Jenner developed smallpox vaccine. Salk developed polio vaccine. BCG for TB was developed later. Pasteur's work laid the groundwork for modern immunology.

This question belongs to: Science Biology

Question #126

Share Report

The animal that exhibits 'canine' teeth adapted for tearing flesh is characteristic of:

A. Omnivores

B. Carnivores

C. Herbivores

D. Detritivores

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Carnivores have well-developed, sharp, pointed canines for piercing and tearing flesh. Herbivores have reduced or absent canines, with well-developed molars for grinding. Omnivores like humans have moderate canines. Detritivores feed on detritus. Dental formula and tooth type are adaptations to diet. Dogs, cats, and lions have prominent canines.

This question belongs to: Science Biology

Question #127

Share Report

In which part of the human body is the pituitary gland located?

A. Brain (hypothalamus region)

B. Pelvis

C. Abdomen

D. Neck

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
The pituitary gland is a pea-sized endocrine gland located at the base of the brain, in a bony cavity called sella turcica, attached to the hypothalamus by a stalk (infundibulum). It is divided into anterior and posterior pituitary, secreting hormones that regulate growth, reproduction, metabolism, and other endocrine glands. Thus, it's in the head, not neck or abdomen.

This question belongs to: Science Biology

Question #128

Share Report

Which part of the human digestive tract is primarily responsible for the absorption of digested food?

A. Stomach

B. Large intestine

C. Small intestine

D. Esophagus

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
The small intestine, especially the jejunum and ileum, is the major site for absorption of nutrients due to its large surface area from villi and microvilli. Stomach absorbs some water, alcohol, and drugs. Large intestine absorbs water and electrolytes. Esophagus is a conduit. The small intestine receives bile and pancreatic juice for digestion.

This question belongs to: Science Biology

Question #129

Share Report

The average life span of human red blood cells is about:

A. 30 days

B. 1 year

C. 120 days

D. 24 hours

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Mature human RBCs have a lifespan of approximately 120 days, after which they are phagocytosed by macrophages in the spleen and liver. They lack nuclei and organelles, thus cannot repair themselves. New RBCs are produced in the bone marrow at a rate of about 2 million per second. Erythropoietin stimulates RBC production.

This question belongs to: Science Biology

Question #130

Share Report

Which type of joint is present between the skull bones?

A. Fibrous joint (suture)

B. Hinge joint

C. Ball and socket joint

D. Pivot joint

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
The joints between skull bones are immovable fibrous joints called sutures, where bones are tightly connected by dense connective tissue. Hinge joint (elbow, knee) allows movement in one plane. Ball and socket (shoulder, hip) allows multi-directional movement. Pivot joint (atlas-axis) allows rotational movement. Sutures fuse completely in old age.

This question belongs to: Science Biology

Question #131

Share Report

Which of the following is the primary target organ for the hormone insulin?

A. Kidney

B. Liver

C. Heart

D. Brain

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Insulin acts primarily on liver, muscle, and adipose tissue. The liver is a key target where insulin promotes glycogenesis (glucose to glycogen), glycolysis, and lipogenesis, and inhibits gluconeogenesis, lowering blood glucose. Muscle and adipose tissue also respond. Brain takes up glucose independently of insulin via GLUT1 transporters. Thus liver is a principal target.

This question belongs to: Science Biology

Question #132

Share Report

Which of the following diseases is caused by a deficiency of insulin?

A. Diabetes mellitus

B. Diabetes insipidus

C. Addison's disease

D. Graves' disease

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Diabetes mellitus is characterized by hyperglycemia due to insufficient insulin secretion (Type 1) or insulin resistance (Type 2). Diabetes insipidus is due to deficiency of ADH (vasopressin) affecting water reabsorption. Graves' disease is hyperthyroidism, Addison's is adrenal insufficiency. Insulin deficiency leads to inability of cells to uptake glucose.

This question belongs to: Science Biology

Question #133

Share Report

The nephron structure that measures the concentration of sodium chloride in the filtrate and regulates GFR is the:

A. Proximal convoluted tubule

B. Juxtaglomerular apparatus

C. Bowman's capsule

D. Collecting duct

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
The juxtaglomerular apparatus (JGA) is formed by the macula densa cells of the distal tubule and granular cells of the afferent arteriole. It detects NaCl concentration in the filtrate and releases renin, which regulates GFR and systemic blood pressure via the renin-angiotensin-aldosterone system. Bowman's capsule collects filtrate, PCT reabsorbs, collecting duct concentrates urine.

This question belongs to: Science Biology

Question #134

Share Report

Which of the following is an example of an insectivorous plant?

A. Drosera

B. Cuscuta

C. Rhizobium

D. Monotropa

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Drosera (sundew) is an insectivorous plant that captures insects with sticky tentacles on leaves to supplement nitrogen in nutrient-poor soils. Cuscuta is a parasitic plant, Monotropa is saprophytic, Rhizobium is a bacterium, not a plant. Insectivorous plants include pitcher plant (Nepenthes), Venus flytrap, and bladderwort. They are autotrophic but supplement nitrogen.

This question belongs to: Science Biology

Question #135

Share Report

The pigment that absorbs light energy in the photosystems of plants is:

A. Chlorophyll a

B. Carotene

C. Phytochrome

D. Xanthophyll

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Chlorophyll a is the primary photosynthetic pigment that acts as the reaction center in photosystem I (P700) and II (P680), converting light energy to chemical energy. Accessory pigments like chlorophyll b, carotenes, and xanthophylls absorb light and transfer energy to chlorophyll a. Phytochrome is involved in photoperiodism. Without chlorophyll a, photosynthesis cannot occur.

This question belongs to: Science Biology

Question #136

Share Report

The phenomenon by which plants lose water in the form of liquid droplets through hydathodes is:

A. Guttation

B. Translocation

C. Bleeding

D. Transpiration

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Guttation is the exudation of water droplets containing dissolved salts from hydathodes at leaf margins, occurring under high humidity and low transpiration, due to root pressure. Transpiration is loss of water vapor through stomata. Bleeding is oozing of sap from cut plant parts. Translocation is transport of organic solutes. Guttation is visible as morning dew drops.

This question belongs to: Science Biology

Question #137

Share Report

Which of the following is an advantage of seed dispersal?

A. Reduces genetic diversity

B. Increases soil erosion

C. Avoids overcrowding and competition with parent plant

D. Competition between offspring

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Seed dispersal spreads seeds away from the parent plant, reducing competition for light, water, nutrients, and space. It also aids in colonization of new habitats and increases species distribution. Dispersal agents include wind, water, animals, and explosive mechanisms. Overcrowding would lead to resource limitation. Genetic diversity is promoted by cross-pollination, not directly by dispersal.

This question belongs to: Science Biology

Question #138

Share Report

In genetic engineering, the enzyme used to cut DNA at specific sequences is:

A. Ligase

B. Helicase

C. Restriction endonuclease

D. DNA polymerase

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Restriction endonucleases (restriction enzymes) recognize specific palindromic DNA sequences and cleave the phosphodiester bonds, producing sticky or blunt ends. They are essential tools for recombinant DNA technology. DNA polymerase synthesizes DNA, ligase joins fragments, helicase unwinds. Examples: EcoRI, HindIII. These enzymes are naturally present in bacteria as a defense against viruses.

This question belongs to: Science Biology

Question #139

Share Report

The vector commonly used for cloning genes in plants is:

A. pBR322

B. Ti plasmid

C. Bacteriophage lambda

D. Cosmid

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
The Ti (tumor-inducing) plasmid from Agrobacterium tumefaciens is a natural plant genetic engineer. It transfers T-DNA into the plant genome, making it an effective vector for introducing foreign genes in plant genetic engineering. pBR322 is a common E. coli cloning vector. Bacteriophage lambda and cosmids are used in animal/bacterial systems. Ti plasmid has revolutionized GM crop development.

This question belongs to: Science Biology

Question #140

Share Report

Which of the following is a biopesticide?

A. Bacillus thuringiensis

B. DDT

C. Lindane

D. Malathion

View Answer & Solution Discuss

Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Bacillus thuringiensis (Bt) is a bacterium producing crystal (Cry) proteins toxic to specific insect larvae, used as a biological insecticide. DDT, malathion, and lindane are synthetic chemical pesticides. Biopesticides are eco-friendly, target-specific, and biodegradable. Bt formulations are used in organic farming. The cry gene is also used in GM crops like Bt cotton.

This question belongs to: Science Biology

Practice Questions

More Science Topics