All Free Biology MCQs with Answers

1311. Plasmids are used as cloning vectors for which of the following reasons?

• A. Can be multiplied in culture
• B. Self-replication in bacterial cells
• C. Can be multiplied in laboratories with the help of enzymes
• D. Replicate freely outside bacterial cells

Explanation: Plasmids are useful cloning vectors because they contain an origin of replication and can replicate independently inside bacterial cells, producing many copies of inserted DNA. The option saying they can be multiplied in culture is incomplete, while plasmids cannot replicate freely outside living bacterial cells.

1312. Which is a genetically modified crop?

• A. Bt-cotton
• B. Bt-brinjal
• C. Golden rice
• D. All

Explanation: Bt cotton, Bt brinjal and Golden Rice are all genetically modified crops because each contains introduced genetic material that gives a desired trait. A student may hesitate over Golden Rice because its modification improves nutrition rather than insect resistance, but nutritional improvement is also a genetically engineered trait.

1313. PCR technique was invented by__________?

• A. Karry Mullis
• B. Boyer
• C. Sanger
• D. Cohn

Explanation: Kary Mullis developed the polymerase chain reaction, which repeatedly copies a selected DNA segment through cycles of denaturation, primer binding and extension. Sanger is the likely distractor because he developed a major DNA sequencing method, not PCR.

1314. --- is used as a vector for cloning into higher organisms.

• A. Retrovirus
• B. Baculovirus
• C. Salmonella typhimurium
• D. Rhizopus nigricans

Explanation: Retroviruses can be modified to carry genes into higher-organism cells because their normal life cycle includes entry into host cells and integration of their genetic material. Baculovirus may be chosen because it is also used as a vector, but it is mainly associated with insect-cell expression systems.

1315. Which bacterium is used in the production of insulin by genetic engineering?

• A. saccharomyces
• B. Rhizobium
• C. Escherichia
• D. Mycobacterium

Explanation: Escherichia coli is commonly engineered to contain the human insulin gene and then used to produce recombinant insulin in bacterial cultures. Saccharomyces is a yeast rather than the bacterium traditionally associated with this production method.

1316. What is the Pathogen that causes Acne?

• A. staphylococcus
• B. Mycobacterium
• C. Streptococcus
• D. Propionibacterium

Explanation: Acne is commonly associated with Cutibacterium acnes, formerly called Propionibacterium acnes, a bacterium living in skin follicles. Students may choose Staphylococcus because it is another common skin bacterium, but it is not the usual pathogen linked with acne.

1317. A line on map connecting places that receives equal solar radiation is called:________?

• A. Isobar
• B. Isohel
• C. Isochore
• D. None of these

Explanation: An isohel is a line joining places that receive equal amounts of sunshine or solar radiation. An isobar joins places with equal atmospheric pressure, so students may choose it because both terms begin with 'iso' and describe lines on maps.

1318. Epiphytes are plants which depend on other plants for________?

• A. food
• B. mechanical support
• C. shade
• D. None of these

Explanation: Epiphytes grow on other plants mainly to obtain mechanical support and better access to light, while they make their own food by photosynthesis. Students may choose food because the epiphyte is attached to a living plant, but it is not normally parasitic and does not obtain food from its support.

1319. "Athlete's Foot" is a disease caused by_________?

• A. Bacteria
• B. Fungus
• C. Protozoan
• D. Nematode

Explanation: Athlete's foot, or tinea pedis, is caused by dermatophyte fungi that grow in warm, moist skin areas. Students may choose bacteria because athlete's foot can cause irritated or infected skin, but the primary disease-causing organisms are fungi.

1320. 2. Which one of the following organisms can serve as a biofertilizer for rice crop?

• A. Blue-green algae
• B. Rhizobium sp.
• C. Mycorrhizal fungi
• D. None of these

Explanation: Blue-green algae, especially cyanobacteria such as Anabaena, can fix atmospheric nitrogen and enrich flooded rice fields. Rhizobium is also a nitrogen-fixing organism, but it mainly forms root nodules in legumes, not rice plants, so students may choose it by overgeneralizing nitrogen fixation.