All Free Biology MCQs with Answers

2771. These are the first eukaryotes to be used by genetic engineers:

• A. Lichen
• B. Yeast
• C. Mycorrhizae
• D. Rhizopus

Explanation: Answer is "Yeast"Explanation: Various yeast species have been genetically engineered to produce various drugs; Saccharomyces cervisiae is a simple eukaryotic cell, serving as a model for all eukaryotes. It is easy to genetically engineer. Its physiology, metabolism and genetics are amendable for use in harsh industrial conditions. A wide variety of chemicals of different classes can be produced by engineered yeast, including phenolics, isoprenoids, alkaloids and polyketides. About 20% biopharmaceuticals are produced by Saccharomyces cervisiae, including insulin, vaccine for hepatitis and human serum albumin.

2772. A functional artificial chromosome was made in:

• A. Aspergillus fumigatus
• B. Saccharomyces cerevisiae
• C. Penicillium notatum
• D. Penicillium griseofulvin

Explanation: Answer is "Saccharomyces cervisae"Explanation: Yeast artificial chromosomes (YACs) are genetically engineered chromosomes derived from the DNA of the yeast Saccharomyces cervisae, which is then ligated into a bacterial plasmid.

2773. Fungi are responsible for many serious plant diseases because they produce several enzymes that can break down the following substances, EXCEPT:

• A. Cellulose
• B. Cutin
• C. Lignin
• D. Chitin

Explanation: Answer is "Chitin"Explanation: Fungi have battery of enzymes to decompose cellulose, lignin and cutin but chitin cannot be broken down by it.

2774. Extensive damage due to _ and _ diseases of wheat, corn, and rice prompted mass displacement and starvation to death many people.

• A. Rusts, Smuts
• B. Ergot of eye, red rot of sugarcane
• C. Brown rot of plums and apricots
• D. Cotton seed rot and apple scab

Explanation: Answer is "Rusts, Smuts"Explanation: The most devastating parasitic fungi for cereal crops.

2775. Ringworm and athlete's foot are superficial fungal infections caused by certain:

• A. Club fungi
• B. Sac fungi
• C. Conjugating fungi
• D. Imperfect fungi

Explanation: Answer is "Imperfect Fungi" Explanation:

2776. Candida albicans cause:

• A. Oral thrush
• B. Vaginal thrush
• C. Oral and vaginal thrush
• D. Ringworm

Explanation: Candida albicans can cause the following conditions:1. Oral Thrush: Candida albicans can infect the mouth, resulting in a condition called oral thrush. It typically appears as white, creamy patches on the tongue, inner cheeks, and the back of the throat. It is more common in infants, the elderly, and individuals with weakened immune systems.2. Vaginal Thrush: Candida albicans can also cause vaginal yeast infections, often referred to as vaginal thrush or candidiasis. Symptoms may include itching, burning, and unusual discharge in the vaginal area. This condition is common in women.3. Oral and Vaginal Thrush: It is possible for Candida albicans to simultaneously affect both the mouth and the vaginal area, leading to symptoms of both oral and vaginal thrush.4. Ringworm: Candida albicans is not responsible for ringworm. Ringworm is a fungal infection caused by a different group of fungi known as dermatophytes, not Candida albicans. Ringworm typically affects the skin, scalp, and nails and appears as circular, red, itchy rashes.So, to clarify, Candida albicans can cause oral thrush, vaginal thrush, or both at the same time, but it is not responsible for causing ringworm.

2777. Histoplasmosis becomes fatal:

• A. Usually
• B. Always
• C. Never
• D. Very occasionally

Explanation: Very Occasionally Fatal: This option is more accurate. Histoplasmosis is very occasionally fatal, primarily in cases where it spreads to other parts of the body and when individuals have weakened immune systems, such as those with HIV/AIDS or organ transplant recipients. With timely diagnosis and appropriate treatment, the risk of fatality is significantly reduced.

2778. Pick up the correct sequence:

• A. Aspergillus ⎯⎯→ Aspergillosis ⎯⎯→ AIDS ⎯⎯→ Death
• B. Aspergillosis ⎯⎯→ Aspergillus ⎯⎯→ AIDS ⎯⎯→ Death
• C. AIDS ⎯⎯→ Aspergillosis ⎯⎯→Aspergillus ⎯⎯→ Death
• D. AIDS ⎯⎯→Aspergillus ⎯⎯→Aspergillosis ⎯⎯→Death

Explanation: Answer is "AIDS - Aspergillus -Aspergillosis - Death"Explanation: Aspergillosus occurs in those persons who suffers from any type of immune deficiency e.g. AIDS

2779. Improperly stored grains such as peanuts and corn etc. are contaminated by:

• A. Aspergillus
• B. Candida
• C. Neurospora
• D. Agaricus

Explanation: Answer is "Aspergillus"Explanation: It is decomposer and saprobic fungus.

2780. It is caused by eating bread made from purple ergot-contaminated rye flour:

• A. Histoplasmosis
• B. Ergotism
• C. Ringworm
• D. Aspergillosis

Explanation: Answer is "Egotism"Explanation: Ergot fungi refers to a group of fungi of genus Claviceps. The most prominent member in Claviceps pupurea. This fungus grows on rye and related plants and produces alkaloids that can cause ergotism in humans and other mammals who consume grains contaminated with its fruiting structure called ergot sclerotuim.