Biology (Part-IV) (UPSC)

Total Questions: 66

51. Consider the following: [2021-1]

1. Bacteria

2. Fungi

3. Virus

Which of the above can be cultured in an artificial/ synthetic medium?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Correct Answer: (a) 1 and 2 only

Solution:Statement 1 is correct.

Bacteria can be grown in synthetic culture media. The DNA of the bacteria Escherichia coli, has been rewritten by researchers, fashioning a synthetic genome four times larger and far more complex than any previously created.

Statement 2 is correct.

Fungi can be grown in synthetic culture media. In a pure synthetic medium, Four allergologically important fungi, viz. Aspergillus fumigatus, Alternaria Penicillium notatum, and Cladosporium herbarum, were cultured.

Statement 3 is incorrect.

Viruses can't be cultured in artificial medium due to lack of metabolic machinery of their own and depend totally on the host cell for replication.
Therefore, the correct answer is "(a)": 1 and 2 only.

52. Consider the following statements: [2021-1]

1. Adenoviruses have single-stranded DNA genomes whereas retroviruses have double-stranded DNA genomes.

2. Common cold is sometimes caused by an adenovirus whereas AIDS is caused by a retrovirus.

Which of the statements given above is/are correct?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer: (b) 2 only

Solution:Adenoviruses are double-stranded DNA genomes. Retroviruses are single-stranded RNA animal viruses that employ a double-stranded DNA intermediate for replication. Option #1 is incorrect.

Common cold is a symptom of adenovirus. The retrovirus known as human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS) in humans. Option #2 is correct.

Therefore, correct option is "2".

53. Consider the following kinds of organisms: [2021-1]

1. Copepods

2. Cyanobacteria

3. Diatoms

4. Foraminifera

Which of the above are primary producers in the food chains of oceans?

(a) 1 and 2
(b) 2 and 3
(c) 3 and 4
(d) 1 and 4

Correct Answer: (b) 2 and 3

Solution:Diatoms are found in fresh water as well as in marine environments. They are microscopic and float passively in water currents (plankton). Most of them are photosynthetic. Diatoms are the chief 'producers' in the oceans. #3 is right. We are 50:50 between B or C.

Cyanobacteria (also referred to as blue-green algae) have chlorophyll, a similar to green plants and are photosynthetic autotrophs. #2 is right.

Therefore correct answer B 2 and 3.

54. Consider the following animals [2021-1]

1. Hedgehog

2. Marmot

3. Pangolin

To reduce the chance of being captured by predators, which of the above organisms rolls up/roll up and protects/protect its/their vulnerable parts?

(a) 1 and 2
(b) 2 only
(c) 3 only
(d) 1 and 3

Correct Answer: (d) 1 and 3

Solution:Hedgehogs have a coat of stiff, sharp spines. If attacked they will curl into a prickly and unappetizing ball that deters most predators. Option #1 is correct. We are 50:50 between A or D.

A startled pangolin will cover its head with its front legs, exposing its scales to any potential predator. If touched or grabbed it will roll up completely into a ball, while the sharp scales on the tail can be used to lash out. Option #3 is correct.

Therefore, correct answer is "D": 1 and 3

Marmots live in burrows and hide themselves in holes when there is a predator. Option #2 is incorrect.

55. Which one of the following is a filter feeder? [2021-1]

(a) Catfish
(b) Octopus
(c) Oyster
(d) Pelican

Correct Answer: (c) Oyster

Solution:Filter feeding, in zoology, a form of food procurement in which food particles or small organisms are randomly strained from water.

Oysters like other shellfish have unique filter-feeding ability, in the sense it takes in water through its gills, which then filters it for nutrients like suspended fragments of plankton, while automatically draining out the rest of the water.

56. Which of the following are detritivores? [2021-1]

1. Earthworms

2. Jellyfish

3. Millipedes

4. Seahorse

5. Woodlice

Select the correct answer using the code given below :

(a) 1, 2 and 4 only
(b) 2, 3, 4 and 4 only
(c) 1, 3 and 5 only
(d) 1, 2, 3, 4 and 5

Correct Answer: (c) 1, 3 and 5 only

Solution:Detritivores (e.g., earthworm) break down detritus into smaller particles. This process is called fragmentation. Detritus consists of dead plant remains and dead remains of animals. And if earthworm belong to this group then jellyfish (#2) and seahorse (#4) cannot be part of this group. Thus A, B and D are eliminated & we are left with correct Option "C".

Alternatively you could apply some logic that earthworm and woodlice look like insects whereas Jellyfish and seahorses live in sea so 2 and 4 are 'odd men' so eliminate them.

57. Which of the following have species that can establish a symbiotic relationship with other organisms? [2022-1]

1. Cnidarians

2. Fungi

3. Protozoa

Select the correct answer using the code given below:

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Correct Answer: (d) 1, 2 and 3

Solution:A number of organisms live together and share both shelter and nutrients. This relationship is called symbiosis. Lichens: Lichens are symbiotic Algae prepare food for fungi and fungi provide shelter and absorb mineral nutrients and water for its partner. So close is their association that if one saw a lichen in nature one would never imagine that they had two different organisms within them. #2 is right. CNIDARIA: Some of these species live in colonies (corals), while others have a solitary like-span (Hydra). Coral exhibit symbiosis with Algae. So, #1 is right.

Protozoa also forms symbiotic relations with other organisms. Statement 3 is right.

58. Consider the following statements: [2022-1]

1. Biofilms can form on medical implants within human tissues.

2. Biofilms can form on food and food processing surfaces.

3. Biofilms can exhibit antibiotic resistance.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Correct Answer: (d) 1, 2 and 3

Solution:Biofilm is a complex structure of microbiome that adhere to the surface. They can form on medical implants as well as food surface and exibit antibiotic resistance. So, all three statements are correct.

59. Consider the following statements in respect of probiotics: [2022-1]

1. Probiotics are made of both bacteria and yeast.

2. The organisms in probiotics are found in foods we ingest but they do not naturally occur in our gut.

3. Probiotics help in the digestion of milk sugars.

Which of the statements given above is/are correct?

(a) 1 only
(b) 2 only
(c) 1 and 3
(d) 2 and 3

Correct Answer: (c) 1 and 3

Solution:Statement 1 is correct: Probiotics are defined as living bacteria that, when administered in adequate amounts, confer a health benefit on the host. (b) and (d) are eliminated. Statement 3 is correct: probiotics aid the digestion of lactose (milk sugar). So Answer is (c).

60. Which one of the following statements best describes the role of B cells and T cells in the human body? [2022-1]

(a) They protect the body from environmental allergens.
(b) They alleviate the body's pain and inflammation.
(c) They act as immunosuppressants in the body.
(d) They protect the body from the diseases caused by pathogens.

Correct Answer: (d) They protect the body from the diseases caused by pathogens.

Solution:T cells protect us from infection. In our daily lives, we're constantly exposed to pathogens, such as bacteria, viruses and fungi. Without T lymphocytes, also called T cells, every exposure could be life-threatening.

T cells can wipe out infected or cancerous cells. They also direct the immune response by helping B lymphocytes to eliminate invading pathogens. B cells create antibodies. B lymphocytes, also called B cells, create a type of protein called an antibody. These antibodies bind to pathogens or to foreign substances, such as toxins, to neutralize them.

For example, an antibody can bind to a virus, which prevents it from entering a normal cell and causing infection. B cells can also recruit other cells to help destroy an infected cell.

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