All Free Biology MCQs with Answers

451. DNA fingerprinting is routinely used for

• A. measuring blood glucose
• B. treating cancer
• C. establishing paternity and identifying criminals
• D. increasing crop yield

Explanation: Because the pattern of non coding repeats is unique to each individual, a sample of blood or tissue can link a person to a crime or a child to a parent. It diagnoses identity, not disease.

452. Which of the following is an application of the polymerase chain reaction?

• A. Taking X ray images
• B. Transfusing blood
• C. Dialysing a patient's blood
• D. Detecting a virus from a tiny sample of its DNA

Explanation: PCR amplifies trace DNA millions of times, making it detectable in diagnosis, forensics and research. The other options are medical procedures that involve no DNA amplification.

453. The nucleus used to clone Dolly the sheep was taken from

• A. an adult mammary gland cell
• B. a red blood cell
• C. a sperm cell
• D. an unfertilised egg's own nucleus

Explanation: Dolly proved that the nucleus of an adult, specialised cell still contains a complete genome able to direct development. A red blood cell has no nucleus, and the egg's own nucleus was removed first.

454. Golden Rice has been genetically modified to produce

• A. an antibiotic
• B. beta carotene, which the body converts to vitamin A
• C. human insulin
• D. nitrogen fertiliser

Explanation: Genes from other organisms enable the rice grain to make beta carotene, aiming to reduce vitamin A deficiency in populations that live mainly on rice. It illustrates biotechnology aimed at nutrition rather than yield.

455. The first genetically engineered product approved for human medical use was

• A. Bt cotton
• B. Golden Rice
• C. Dolly the sheep
• D. human insulin produced by bacteria

Explanation: Approved in the early 1980s, bacterial human insulin transformed diabetes care and opened the era of biopharmaceuticals. Crops and cloned animals came later and are not medicines.

456. Gene therapy has been used in attempts to treat

• A. broken bones
• B. malaria
• C. severe combined immune deficiency, SCID
• D. appendicitis

Explanation: By inserting a working copy of the defective gene into the patient's cells, gene therapy targets single gene disorders such as SCID. Injuries and infections are treated by other means.

457. Embryonic stem cells are described as pluripotent because they

• A. can divide only once
• B. can differentiate into any cell type of the body
• C. produce blood cells only
• D. never divide

Explanation: Pluripotency means the ability to become nerve, muscle, blood or any other tissue, which is why these cells hold regenerative promise. Adult stem cells are usually more restricted in their options.

458. A practical use of monoclonal antibodies is

• A. treating some cancers and detecting pregnancy
• B. sterilising surgical instruments
• C. filtering blood in dialysis
• D. grinding food in digestion

Explanation: Because each monoclonal antibody recognises one target, it can mark cancer cells for destruction or detect the hormone hCG in pregnancy tests. Their value lies in precision, not in physical processes.

459. A goat engineered to secrete a human protein in its milk is an example of

• A. a clone
• B. a hybrid
• C. a transgenic animal
• D. a mutant

Explanation: The animal carries a gene from another species and expresses it in milk, from which the medicine is purified. Cloning copies an existing genome, whereas transgenesis introduces a new gene.

460. Which of the following is an advantage of genetically modified crops?

• A. They never cross breed with wild plants
• B. They eliminate all insects from the farm
• C. They require no sunlight
• D. They can resist pests or herbicides, reducing the need for sprays

Explanation: Bt crops make their own insecticidal protein and herbicide tolerant crops simplify weed control, both cutting chemical inputs. The absolute claims in the other options are false and designed to tempt.