UPSC Civil Services Previous Year 2021 Question Papers With Answer Key

1 .

Consider the following statements :

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

(2) Common cold is sometime 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 : Option (B) - 2 only

Note :

It is actually the opposite the statement given. Adenoviruses have double stranded DNA genomes while Retroviruses have single stranded DNA genomes. So, statement 1 is not correct.

Common cold can sometimes be caused by adenoviruses while AIDS is caused by retrovirus. So, statement 2 is correct.

Year : 2021

Category : General Studies

2 .

Consider the following :

(1) Bacteria

(2) Fungi

(3) Virus

Which of the above can be cultured in 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 : Option (A) - 1 and 2 only

Note :

• Some bacteria can be grown in artificial medium but some cannot. So, statement 1 is correct.

• Fungi can be grown in artificial medium. So, statement 2 is correct.

• Unlike bacteria and fungi, viruses need living host to grow. So, statement 3 is not correct.

Year : 2021

Category : General Studies

3 .

In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the followings?

(1) Area of the hole in the lid

(2) Temperature of the flame

(3) Weight of the lid

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 : Option (A) - 1 and 2 only

Note :

• The larger hole will lead to increase in the steam going out leading to greater reduction in temperature. So, statement 1 is correct.

• As the temperature increases of the flame the temperature inside will also increase. So, statement 2 is correct.

• Weight of the lid has nothing to do with the temperature inside the pressure cooker. So, statement 3 is not correct.

Year : 2021

Category : General Studies

4 .

Bollgard I and Bollgard II technologies are mentioned in the context of

A)

Clonal propagation of crop plants

B)

Developing genetically modified crop plants

C)

Production of plant growth substances

D)

Production of bio-fertilisers

Correct Answer : Developing genetically modified crop plants

Note : Bollgard I and Bollgard II are technologies to produce genetically modified crop plants for example BT cotton. So, other can be easily eliminated.

Year : 2021

Category : General Studies

5 .

In the context of hereditary diseases, consider the following statements :

(1) Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilisation of egg.

(2) A child inherits mitochondrial diseases entirely from mother and not from father.

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 : Option (A) - 1 only

Note :

The mitochondrial replacement therapy can be done either before or after in vitro fertilization. Two mitochondrial replacement techniques have been developed, maternal spindle transfer and pronuclear transfer. In maternal spindle transfer, the chromosome spindle apparatus of the carrier mother is removed from her unfertilized oocyte and inserted into the donor mother’s unfertilized and enucleated oocyte that contains normal mtDNA. The hybrid oocyte is then fertilized in vitro by the father’s sperm and implanted into the carrier mother by standard in vitro fertilization (IVF) procedures. In pronuclear transfer, both carrier mother’s and donor mother’s oocytes are first fertilized in vitro. The carrier mother’s pronucleus is inserted into the donor mother’s enucleated oocyte containing normal mtDNA, and the embryo is implanted into the carrier mother by IVF. The mitochondrial replacement approach is generic; instead of targeting a specific mutation, MRTs replace nearly all mitochondria and their resident mtDNA and so could be applied to any inherited mtDNA disease. So, statement 1 is correct.

In most people, primary mitochondrial disease is a genetic condition that can be inherited (passed from parents to their children) in several ways. Under normal circumstances, a child inherits genes in pairs -- one gene from the mother and one from the father. A child with a mitochondrial disease does NOT receive a normal pair of genes from the parents. The gene has mutated – meaning it has become defective (changed). Learning the way a mitochondrial disease has been inherited helps predict the chance of passing on the disease(s) to future children. So, statement 2 is not correct.

Year : 2021

Category : General Studies

6 .

With reference to recent developments regarding ‘Recombinant Vector Vaccines’, consider the following statements :

(1) Genetic engineering is applied in the development of these vaccines

(2) Bacteria and viruses are used as vectors

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 : Option (A) - 1 only

Note :

They are genetically modified and involve use of genetic engineering to mimic the actual virus for which the vaccine is being produced. So, statement 1 is correct.

Viruses and not bacteria are used as vectors to produce the vaccine and hence this statement is wrong. So, statement 2 is not correct.

Year : 2021

Category : General Studies

7 .

The black cotton soil of India has been formed due to the weathering of

A)

Brown forest soil

B)

Fissure volcanic rock

C)

Granite and schist

D)

Shale and limestone

Correct Answer : Fissure volcanic rock

Note : Black soil is formed sue to weathering or basalt rock or volcanic rocks. While other rocks don’t have the properties found in black soil.

Year : 2021

Category : General Studies

8 .

Consider the following statements:

(1) Moringa (drumstick tree) is a leguminous evergreen tree

(2) Tamarind tree is endemic to South Asia

(3) In India, most of the tamarind is collected as minor forest produce

(4) India exports tamarind and seeds of moringa

(5) Seeds of moringa and tamarind can be used in the production of biofuels

Which of the statements given above are correct?

A)

1, 2, 4 and 5

B)

3, 4 and 5

C)

1, 3 and 4

D)

1, 2, 3 and 5

Correct Answer : Option (B) - 3, 4 and 5

Note :

• It can be evergreen or semi-deciduous. Because of which is is extensively eing grown in semi-arid regions in India. So, statement 1 is not correct.

• It is native to Africa or Indian-sub continent and grown in South-east Asia and Africa as well. So, statement 2 is not correct.

• Most of the tamarind is collected as minor forest produce. So, the statement 3 is correct.

• India is one of the largest exporters of both Tamarind and Seed of Moringa. So, Statement 4 is correct.

• Seeds of Moringa and Tamarind can be used for biofuel production. So, statement 5 is correct.

Year : 2021

Category : General Studies

9 .

With reference to the water on the planet Earth, consider the following statements :

(1) The amount of water in the rivers and lakes is more than the amount of groundwater.

(2) The amount of water in polar ice caps and glaciers is more than the amount of groundwater.

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 : Option (B) - 2 only

Note :

Water in groundwater is 0.62% while in lakes and rivers it is 0.008 (Salt lakes)+0.009(freshwater lakes) + 0.0001(rivers)=0.0171. So, the statement 1 is not correct.

Water in polar ice caps and glaciers is 2% while in groundwater it is 0.62%. So, the statement 2 is correct.

Year : 2021

Category : General Studies

10 .

The vegetation of savannah consists of grassland with scattered small trees, but extensive areas have no trees. The forest development in such areas is generally kept in check by one or more or a combination of some conditions. Which of the following are such conditions?

(1) Burrowing animals and termites

(2) Fire

(3) Grazing herbivores

(4) Seasonal rainfall

(5) Soil properties

Select the correct answer using the code given below :

A)

1 and 2

B)

4 and 5

C)

2, 3 and 4

D)

1, 3 and 5

Correct Answer : Option (C) - 2, 3 and 4

Note :

Here is depends on grazing intensity and not the burrowing animals or termites. So, statement 1 is not correct.

Bush fires are common in Savannah because of alternate wet and dry season which can modify the forest.

Grazing intensity is a major reason for type of Savannah, so Grazing herbivores do contribute in keeping a check on forest. So, statement 2 is correct.

It has seasonal rainfall based on which it is divided into wet, dry or thornbush. So, the statement 3 is correct.

Soil properties influence the type of Savannah and its vegetation but don’t contribute in checking it once formed. So, statement 5 is not correct.

Year : 2021

Category : General Studies

UPSC 2021 (Prelims & Mains) Questions