All Free Biology MCQs with Answers

461. Cloning is the production of

• A. organisms genetically identical to the original
• B. hybrids between two species
• C. organisms with random mutations
• D. gametes in the laboratory

Explanation: A clone shares the exact nuclear genome of its source, whether produced by cuttings, bacteria dividing or nuclear transfer. Hybrids and mutations increase variation, the opposite of cloning.

462. The Human Genome Project determined the sequence of roughly how many base pairs?

• A. 3 million
• B. 3 billion
• C. 300 thousand
• D. 3 trillion

Explanation: Completed in 2003, the project read about three billion base pairs spanning the human genome's roughly 20,000 to 25,000 genes. Confusing billions of bases with thousands of genes is the trap.

463. Genetically engineered vaccines are considered safer than older vaccines because they

• A. contain live pathogens
• B. are never tested before use
• C. contain only specific proteins of the pathogen, not the whole organism
• D. provide immunity without any immune response

Explanation: Recombinant vaccines such as hepatitis B present one safe protein to the immune system, removing any risk of the disease itself. An immune response is still required; that is how the memory is made.

464. The antibiotic resistance gene carried on a plasmid vector serves to

• A. cut the DNA at specific points
• B. digest the bacterial cell wall
• C. colour the bacterial colonies
• D. identify the bacteria that have successfully taken up the plasmid

Explanation: Only bacteria carrying the plasmid survive on antibiotic containing medium, so the marker selects the transformed cells. The cutting is done by the restriction enzyme before the plasmid enters the cell.

465. Single cell protein refers to

• A. a single essential amino acid
• B. protein rich biomass grown from microorganisms for food and feed
• C. a strand of DNA
• D. an industrial enzyme

Explanation: Bacteria, yeasts and algae can be farmed on cheap substrates to yield protein far faster than crops or livestock. The name refers to the single celled producers, not to a molecule.

466. The use of microorganisms to break down pollutants in soil and water is called

• A. bioremediation
• B. vaccination
• C. fermentation
• D. electrophoresis

Explanation: Oil spills and industrial wastes can be cleaned by microbes that feed on the contaminants, a gentle alternative to chemical treatment. The prefix bio plus remediation, repairing, captures the idea.

467. The technique in which an egg is fertilised by sperm outside the body in the laboratory is called

• A. cloning
• B. hybridisation
• C. pollination
• D. in vitro fertilisation

Explanation: IVF brings gametes together in a dish, and the resulting embryo is then placed in the uterus. Cloning makes copies without fertilisation, so the presence of sperm marks IVF.

468. In IVF, the early embryo is transferred into the mother's

• A. ovary
• B. vagina
• C. uterus
• D. kidney

Explanation: The uterus is the organ of implantation and pregnancy, so the embryo must reach it to develop. Transfer to any other site cannot support the pregnancy.

469. A sample of the amniotic fluid surrounding a fetus can be tested to detect

• A. genetic disorders of the fetus
• B. the mother's blood pressure
• C. the father's blood group
• D. the colour of the fetus's eyes

Explanation: Amniocentesis collects fetal cells from the fluid for karyotyping and biochemical tests, revealing chromosome disorders before birth. It examines the fetus, not the parents' physiology.

470. A crop engineered for herbicide tolerance allows farmers to

• A. grow the crop without water
• B. spray herbicide to kill weeds without damaging the crop
• C. skip photosynthesis
• D. avoid all insect pests

Explanation: The crop carries a gene that withstands a broad spectrum herbicide, so spraying clears weeds while the crop survives. Insect protection is a different modification, provided by Bt genes.