Biology Miscellaneous (Part-I)

Total Questions: 50

21. A group of archaebacteria is used in the production of- [R.A.S./R.T.S. (Pre) 1997]

(a) Ethane
(b) Methane
(c) Acids
(d) Alcohols

Correct Answer: (b) Methane

Solution:Methanogens (a group of archaebacteria) are microorganisms that produce methane as a metabolic by-product in hypoxic conditions. They are prokaryotic and belong to the domain of archaea.

Methanogens thrive in oxygen-free environments, meaning they cannot survive in the presence of oxygen. They produce methane (CH₄) as a final product of their metabolism, often using hydrogen gas and carbon dioxide as substrates.

This methane production occurs in hypoxic environments where other electron acceptors like oxygen, nitrate, or sulfate have been depleted. Methanogens play a vital role in the carbon cycle and the breakdown of organic matter in anaerobic environments.

22. An organism involved in the fermentation of toddy is : [U.P.P.C.S. (Mains) 2010]

(a) Lactobacillus
(b) Acetobacter
(c) Saccharomyces
(d) Penicillium

Correct Answer: (c) Saccharomyces

Solution:Saccharomyces is a genus of fungi that include many species of yeasts. It is used in fermentation of toddy (a type of raw alcoholic beverage).

Lactobacillus is a genus of bacteria that is primarily known for producing lactic acid, which is used in the production of yogurt, sauerkraut, and other fermented foods.

Acetobacter is a genus of bacteria that oxidizes ethanol into acetic acid, which is the main component of vinegar.

Penicillium is a genus of fungi that is known for producing penicillin, a well-known antibiotic.

23. Which yeast is used for commercial production of ethanol? [U.P. P.C.S. (Pre) 2016]

(a) Candida albicans
(b) Saccharomyces cerevisiae
(c) Candida sloofi
(d) Leucosporidium frigidum

Correct Answer: (b) Saccharomyces cerevisiae

Solution:

Many yeasts such as the commonly used baker’s yeast Saccharomyces cerevisiae prefer fermentation to respiration. These yeasts will produce ethanol under aerobic conditions if they are provided with the right kind of nutrition.

24. A microbe commonly used for alcoholic fermentation in wine industry is: [U.P.P.C.S. (Mains) 2005]

(a) Yeast
(b) Bacterium
(c) Cyanobacterium
(d) Actinomycete

Correct Answer: (a) Yeast

Solution:Yeasts have two main uses in food production:

baking, 2. making alcoholic beverages.
The alcohol in wine is formed by the fermentation of the sugars in grape juice, with carbon dioxide as a byproduct. Yeast is commonly used for alcoholic fermentation in the wine industry.

25. Consider the following statements: [I.A.S. (Pre) 2023]

1. Some microorganisms can grow in environments with temperature above the boiling point of water.

2. Some microorganisms can grow in environments with temperature below the freezing point of water.

3. Some microorganisms can grow in highly acidic environments with a pH below 3.

How many of the above statements are correct?

(a) Only one
(b) Only two
(c) All three
(d) None of these

Correct Answer: (c) All three

Solution:Organisms that grow at optimum temperatures of 50°C to a maximum of 80°C are called thermophiles (heat loving). Higher up on the extreme temperature scale we find the hyperthermophiles, which are characterized by growth ranges from 80°C to a maximum of 110°C, with some extreme examples that survive temperatures above 121°C.

Some bacteria grow at the bottom of the ocean in sea vents, where temperatures can reach 340°C (700°F). The organisms retrieved from arctic lakes such as Lake Whillans are considered extreme psychrophiles (cold loving). Psychrophiles are microorganisms that can grow at 0°C and below, have an optimum growth temperature close to 15°C, and usually do not survive at temperatures above 20°C. They are found in permanently cold environments such as the deep water of the oceans. Acidophiles are microorganisms that show optimal growth in highly acidic environments. The extreme acidophiles dwell in environments with a pH value below 3. Hence, all 3 statements are correct.

26. Biomagnification means- [R.A.S./R.T.S.(Pre) 2008]

(a) Fast spreading of cancer cells in the body
(b) Increasing amount of pesticides in the organisms of successive tropic level
(c) To see the microscopic parts of the body by microscope
(d) Sudden increase in the number of the individuals of a species in a specific area

Correct Answer: (b) Increasing amount of pesticides in the organisms of successive tropic level

Solution:Biomagnification is the process in which the concentration of toxic substances increases as they move up the food chain. These harmful substances, such as pesticides, heavy metals, and chemicals, accumulate at progressively higher levels in organisms, especially apex predators.

As predators consume prey that has already accumulated toxins, these substances accumulate in their bodies. This phenomenon can cause severe health effects, particularly for species at the top of the food chain, including humans. Biomagnification effects wildlife and humans by accumulating toxins in food chains, leading to reproductive, behavioural, and health issues, including species decline and increased human health risks.

27. Assertion (A): Herbicides can destroy weeds without harming useful plants. [U.P.P.C.S. (Mains) 2002]

Reason (R): Herbicides are absorbed in different rates by weeds and crop plants.

Select the correct answer using the code given below:

(a) Both (A) and (R) are true and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true but (R) is not the correct explanation of (A).
(c) (A) is true but (R) is false
(d) (A) is false but (R) is true

Correct Answer: (a) Both (A) and (R) are true and (R) is the correct explanation of (A).

Solution:Herbicides, also commonly known as weedkillers are used to kill unwanted plants. Herbicides are absorbed in different rates by weed and crop plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. It is clear that (A) and (R) both are correct and (R) is the correct explanation of (A).

28. Generally, Orobanche weed is found in — [U.P.R.O./A.R.O. (Pre) 2014]

(a) Tobacco field
(b) Gram field
(c) Rice field
(d) Wheat field

Correct Answer: (a) Tobacco field

Solution:Generally, Orobanche weed is found in a tobacco field. Orobanche weed is a parasitic weed which is also found in tomato and potato fields. It’s 150 species are spread over much of the world’s temperate and subtropical regions.

29. Information about local flora can be obtained from : [R.A.S./R.T.S. (Pre) 2010]

(a) Herbarium
(b) Auditorium
(c) Sanitarium
(d) Planetarium

Correct Answer: (a) Herbarium

Solution:A herbarium is a collection of preserved plants stored, catalogued and arranged systematically for study by professionals and amateurs from many walks of life. A collection like this is a vital reference when you need to identify a plant and also serves to fix forever the identity of thousands of plant names.

Auditorium: This refers to a large room or building designed for public gatherings, often for presentations, performances, or meetings.

Sanitarium: This term is typically used to describe a medical institution or facility that provides long-term care and treatment, often for chronic or mental illnesses.

Planetarium: A planetarium is a specific type of theater or building that displays the night sky and celestial objects using a special projector and a domed ceiling. The Kalpana Chawla Memorial Planetarium in Panipat is equipped with modern projectors, 5.1 surround sound, and a large dome for full-dome planetarium programs. It also features an exhibit gallery with interactive displays and an Astro Park with various outdoor exhibits.

30. ICAR Day is celebrated on : [Jharkhand P.C.S. (Pre) 2023]

(a) 23rd December
(b) 16th July
(c) 22nd April
(d) 23rd November

Correct Answer: (b) 16th July

Solution:The Indian Council of Agricultural Research (ICAR) celebrates its foundation day every year on 16th July. ICAR was established on 16 July, 1929 as a registered society under the Societies Registration Act, 1860 in pursuance of the report of the Royal Commission on Agriculture. From 2023 it has been decided to observe this day as the ‘Foundation and Technology Day’ of ICAR. ICAR celebrated its 95th Foundation and Technology Day on 16 July, 2023 at National Agriculture Science Complex, Pusa, New Delhi. The ICAR has its headquarters at New Delhi.

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