All Free Biology MCQs with Answers

1301. The Study of organisms inhabiting the sea and Ocean and the physical and chemical characteristics of their environment is:

• A. Social Biology
• B. Marine Biology
• C. Environmental Biology
• D. Fresh Water Biology

Explanation: Marine biology studies organisms living in seas and oceans along with the physical and chemical conditions of marine environments. Freshwater biology is limited to rivers, lakes, and other low-salinity habitats, while environmental biology covers environments more generally. The likely alternative is environmental biology because the question mentions environmental characteristics, but the sea and ocean make marine biology the specific field.

1302. What is Aquaculture?

• A. culture of finfish
• B. culture of shellfish
• C. culture of aquatic organisms
• D. culture of shrimp and Tilapia

Explanation: Aquaculture is the controlled cultivation or farming of aquatic organisms, including fish, shellfish, algae and other species. Finfish, shellfish, shrimp and tilapia are only particular examples, so none of those narrower choices gives the complete definition. Students may choose finfish because fish farming is common, but aquaculture covers more than fish.

1303. Chromic catgut is made up of ____________?

• A. Sheep gut
• B. Cat gut
• C. Kangaroo gut
• D. dog gut

Explanation: Chromic catgut is a surgical absorbable suture traditionally prepared from purified sheep intestinal tissue and treated with chromium salts to slow its absorption. It is not made from cats, despite the misleading name, and the listed dog and kangaroo sources are not the standard source. Students commonly choose cat gut because of the word catgut, which is a historical naming misconception.

1304. The expression of a transgene in the target tissue is identified by a ___________?

• A. Transgene
• B. Promoter
• C. Enhancer
• D. Reporter

Explanation: A reporter gene produces an easily detected signal, such as fluorescence or a coloured product, when the transgene is expressed in the target tissue. The promoter is the likely alternative because it controls transcription, but it does not itself provide the detectable output used to identify expression.

1305. ELISA is _________?

• A. Using radiolabelled second antibody
• B. Usage of RBCs
• C. Using complement-mediated cell lysis
• D. Addition of substrate that is converted into a coloured end product

Explanation: ELISA uses an enzyme-linked antibody and a substrate that the enzyme converts into a coloured product, allowing the antigen or antibody to be detected. The radiolabelled second antibody is the likely alternative because it describes radioimmunoassay-type detection, not the enzyme-based signal of ELISA.

1306. The DNA fragments have sticky ends due to___________?

• A. Endonuclease
• B. Unpaired bases
• C. Calcium ions
• D. Free methylation

Explanation: Restriction enzymes can cut the two DNA strands at staggered positions, leaving short single-stranded overhangs called sticky ends, which are unpaired bases. Endonuclease is the likely distractor because it makes the cut, but the sticky character specifically results from the exposed unpaired bases.

1307. Which of the following is the quality of improved transgenic basmati rice?

• A. Gives high yield but no characteristic aroma
• B. Gives high yield and is rich in vitamin A
• C. Does not require chemical fertilizers and growth hormones
• D. Resistant to insects and diseases

Explanation: The improved transgenic basmati rice described here combines increased yield with provitamin A enrichment, a trait associated with Golden Rice-type genetic modification. Students may choose insect and disease resistance because those are common benefits of transgenic crops such as Bt cotton, but they are not the stated improvement in this rice variety.

1308. The first transgenic plant to be produced is__________?

• A. Brinjal
• B. Tobacco
• C. Rice
• D. Cotton

Explanation: Tobacco was the first plant successfully transformed using recombinant DNA techniques, making it the earliest widely recognised transgenic plant. Cotton may be chosen because it is a familiar commercial transgenic crop, but it was produced later.

1309. RNA interference helps in__________?

• A. Cell proliferation
• B. Micropropagation
• C. Cell defence
• D. Cell differentiation

Explanation: RNA interference silences specific genes by using small RNA molecules to guide the destruction or blocking of complementary mRNA, providing a form of cellular defence against viruses and other genetic threats. Cell differentiation is the likely distractor because gene silencing can influence development, but defence is the direct function asked here.

1310. The first clinical application of gene therapy over a 4 year old girl was for_________?

• A. Adenosine deaminase deficiency
• B. Adenosine deficiency
• C. Growth deficiency
• D. Adenine deficiency

Explanation: The first widely recognised clinical gene-therapy trial treated severe combined immunodeficiency caused by adenosine deaminase deficiency by introducing a functional ADA gene into the patient's cells. Adenosine deficiency is the likely distractor because it sounds similar, but the disorder specifically involves the ADA enzyme.