Biology

91. The word ‘Denisovan’ is sometimes mentioned in media in reference to

The word ‘Denisovan’ is sometimes mentioned in media in reference to

[amp_mcq option1=”fossils of a kind of dinosaurs” option2=”an early human species” option3=”a cave system found in North-East India” option4=”a geological period in the history of Indian subcontinent” correct=”option2″]

This question was previously asked in
UPSC IAS – 2019
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The correct answer is B) an early human species.
Denisovans are an extinct species or subspecies of archaic humans. Their existence was first suggested in 2010 based on mitochondrial and nuclear DNA analysis of a fossil found in Denisova Cave in Siberia. Genetic studies have shown that Denisovans interbred with modern humans and Neanderthals.
The discovery of Denisovans, Neanderthals, and their interbreeding with Homo sapiens has significantly advanced our understanding of recent human evolution and migration patterns. Traces of Denisovan DNA are found in the genomes of present-day populations, particularly in parts of Southeast Asia and Oceania.

92. Consider the following statements: Some species of turtles are herbi

Consider the following statements:

  • Some species of turtles are herbivores.
  • Some species of fish are herbivores.
  • Some species of marine mammals are herbivores.
  • Some species of snakes are viviparous.

Which of the statements given above are correct?

[amp_mcq option1=”1 and 3 only” option2=”2, 3 and 4 only” option3=”2 and 4 only” option4=”1, 2, 3 and 4″ correct=”option4″]

This question was previously asked in
UPSC IAS – 2019
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Option D is correct. All four statements are correct.
– Statement 1: Some species of turtles are herbivores (e.g., Green Sea Turtle as adults, many tortoise species).
– Statement 2: Some species of fish are herbivores (e.g., Parrotfish, Surgeonfish, grass carp).
– Statement 3: Some species of marine mammals are herbivores (e.g., Dugongs and manatees are Sirenians and feed on seagrass).
– Statement 4: Some species of snakes are viviparous (give live birth, e.g., many pit vipers like rattlesnakes, boas, anacondas, some sea snakes).
– The animal kingdom exhibits a wide diversity of diets and reproductive strategies. Not all individuals or species within a group share the same characteristics.
– Herbivory is relatively common across various animal groups.
– Viviparity (live birth) occurs in some species within groups where egg-laying (oviparity) is more common, like reptiles (snakes, some lizards).

93. Consider the following : 1. Birds 2. Dust blowing 3. Rain 4. Wind blow

Consider the following :
1. Birds
2. Dust blowing
3. Rain
4. Wind blowing

Which of the above spread plant diseases ?

[amp_mcq option1=”1 and 3 only” option2=”3 and 4 only” option3=”1, 2 and 4 only” option4=”1, 2, 3 and 4″ correct=”option4″]

This question was previously asked in
UPSC IAS – 2018
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All the listed items can act as vectors or facilitators in the spread of plant diseases. Birds can carry pathogens externally or internally. Dust particles in the air can transport fungal spores or bacteria. Rain splash can move pathogens from infected plant parts or soil to healthy tissues. Wind is a primary agent for the long-distance dispersal of airborne plant pathogens.
Plant diseases are spread by various means, including abiotic factors (wind, rain, dust) and biotic factors (insects, birds, other animals, human activities).
For example, birds can spread diseases like bacterial blight of coffee. Wind is crucial for spreading spores of rusts and powdery mildew. Rain splash helps in the spread of bacterial leaf spots and anthracnose. Dust storms can carry pathogens over vast areas.

94. With reference to the Genetically Modified mustard (GM mustard) develo

With reference to the Genetically Modified mustard (GM mustard) developed in India, consider the following statements :

1. GM mustard has the genes of a soil bacterium that give the plant the property of pest-resistance to a wide variety of pests.
2. GM mustard has the genes that allow the plant cross-pollination and hybridization.
3. GM mustard has been developed jointly by the IARI and Punjab Agricultural University.

Which of the statements given above is/are correct?

[amp_mcq option1=”1 and 3 only” option2=”2 only” option3=”2 and 3 only” option4=”1, 2 and 3″ correct=”option2″]

This question was previously asked in
UPSC IAS – 2018
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The Genetically Modified mustard variety DMH-11 (Dhara Mustard Hybrid-11) was developed in India.
Statement 1 is incorrect. GM mustard DMH-11 contains three genes: two from the soil bacterium *Bacillus amyloliquefaciens* (*barnase* and *barstar*) and one from the soil bacterium *Streptomyces hygroscopicus* (*bar*). The *barnase* and *barstar* genes are used in a male sterility/fertility restoration system to facilitate hybrid seed production. The *bar* gene confers tolerance to the herbicide glufosinate ammonium. It does not provide pest-resistance to a wide variety of pests.
Statement 2 is correct. The barnase-barstar system is a genetically engineered method to create male sterility in one parent line and restore fertility in the hybrid progeny, enabling the production of hybrid seeds through cross-pollination in a crop like mustard, which is often self-pollinating. This system allows the plant to undergo effective cross-pollination and hybridization to produce higher-yielding hybrids.
Statement 3 is incorrect. DMH-11 was developed by the Centre for Genetic Manipulation of Crop Plants (CGMCP) at Delhi University South Campus (DUSC), led by Dr. Deepak Pental, and in collaboration with the National Dairy Development Board (NDDB). It was not developed jointly by the IARI and Punjab Agricultural University.
GM mustard DMH-11 is a herbicide-tolerant hybrid developed to boost India’s domestic edible oil production. It is a hybrid of the Indian mustard variety ‘Varuna’ and the East European variety ‘Early Heera-2’. While approved by the GEAC in 2017 and again in 2022 for environmental release (field trials), its commercial cultivation is currently stayed by the Supreme Court.

95. Which of the following leaf modifications occur(s) in the desert areas

Which of the following leaf modifications occur(s) in the desert areas to inhibit water loss ?

  1. Hard and waxy leaves
  2. Tiny leaves
  3. Thorns instead of leaves

Select the correct answer using the code given below :

[amp_mcq option1=”2 and 3 only” option2=”2 only” option3=”3 only” option4=”1, 2 and 3″ correct=”option4″]

This question was previously asked in
UPSC IAS – 2018
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All three listed leaf modifications are adaptations found in plants in desert areas to minimize water loss through transpiration.
1. Hard and waxy leaves: A thick, waxy cuticle on the leaf surface reduces evaporation of water.
2. Tiny leaves: Reducing the surface area of leaves directly reduces the total surface area available for transpiration.
3. Thorns instead of leaves: Thorns are often modified leaves or branches. If they are modified leaves (e.g., in cacti), they drastically reduce the surface area for transpiration. Thorns also deter herbivores, protecting the plant.
– Desert plants (xerophytes) have adaptations to conserve water.
– Adaptations include reducing leaf surface area and preventing water loss through barriers.
– Waxy cuticle, reduced leaf size, and modifications like thorns are common water-conserving adaptations.
Other adaptations in desert plants include sunken stomata, fleshy stems for water storage, and extensive root systems.

96. What is the application of Somatic Cell Nuclear Transfer Technology?

What is the application of Somatic Cell Nuclear Transfer Technology?

[amp_mcq option1=”Production of biolarvicides” option2=”Manufacture of biodegradable plastics” option3=”Reproductive cloning of animals” option4=”Production of organisms free of diseases” correct=”option3″]

This question was previously asked in
UPSC IAS – 2017
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The correct answer is C) Reproductive cloning of animals. Somatic Cell Nuclear Transfer (SCNT) is the technology most famously associated with cloning animals.
– Somatic Cell Nuclear Transfer (SCNT) involves taking the nucleus from a somatic cell (any body cell other than sperm or egg) and transferring it into an enucleated egg cell (an egg cell from which the nucleus has been removed).
– This reconstructed egg cell is then stimulated to divide, forming an embryo.
– If this embryo is implanted into the uterus of a surrogate mother and develops to term, it results in the birth of an organism genetically identical to the donor of the somatic cell nucleus. This is reproductive cloning.
– SCNT can also be used for therapeutic cloning, where the embryonic stem cells derived from the resulting embryo are used for research or potential therapy, rather than implanting the embryo.
Dolly the sheep, cloned in 1996, was the first mammal created using SCNT from an adult somatic cell. While SCNT has potential applications in conservation (cloning endangered species), agriculture (cloning livestock), and medicine (therapeutic cloning), its most direct and well-known application is reproductive cloning of animals.

97. With reference to agriculture in India, how can the technique of ‘geno

With reference to agriculture in India, how can the technique of ‘genome sequencing’, often seen in the news, be used in the immediate future ?

  • 1. Genome sequencing can be used to identify genetic markers for disease resistance and drought tolerance in various crop plants.
  • 2. This technique helps in reducing the time required to develop new varieties of crop plants.
  • 3. It can be used to decipher the host-pathogen relationships in crops.

Select the correct answer using the code given below :

[amp_mcq option1=”1 only” option2=”2 and 3 only” option3=”1 and 3 only” option4=”1, 2 and 3″ correct=”option4″]

This question was previously asked in
UPSC IAS – 2017
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The correct answer is D) 1, 2 and 3.
Genome sequencing provides the complete genetic blueprint of an organism.
1. By sequencing genomes of different crop varieties and wild relatives, researchers can identify genes or genetic markers associated with desirable traits like resistance to diseases or tolerance to drought. This information is crucial for marker-assisted selection and breeding programs. Thus, statement 1 is correct.
2. Knowing the genetic basis of traits allows breeders to make more informed selections early in the breeding process, reducing the need for extensive field trials for each generation. This targeted approach, enabled by genomic data, can significantly shorten the time required to develop new, improved crop varieties compared to traditional breeding methods. Thus, statement 2 is correct.
3. Genome sequencing can be applied to both the host plant and the pathogens that infect it (e.g., fungi, bacteria, viruses, insects). By sequencing the genomes of pathogens, scientists can understand their virulence factors, mechanisms of infection, and evolution. Sequencing the host genome reveals genes involved in defense responses. Comparing and analyzing these genomes helps decipher the complex interactions and relationships between the host plant and its pathogens, which is vital for developing resistant varieties or disease management strategies. Thus, statement 3 is correct.
Genome sequencing is a powerful tool in modern agriculture, contributing to increased yield, improved nutritional content, enhanced resilience to environmental stresses, and reduced reliance on pesticides and herbicides through the development of superior crop varieties. These applications are already in use or are in advanced stages of research and development, making them relevant for the “immediate future” of agriculture.

98. Consider the following statements: 1. In tropical regions, Zika viru

Consider the following statements:

  • 1. In tropical regions, Zika virus disease is transmitted by the same mosquito that transmits dengue.
  • 2. Sexual transmission of Zika virus disease is possible.

Which of the statements given above is/are correct?

[amp_mcq option1=”1 only” option2=”2 only” option3=”Both 1 and 2″ option4=”Neither 1 nor 2″ correct=”option3″]

This question was previously asked in
UPSC IAS – 2017
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Both statements 1 and 2 are correct.
– Statement 1 is correct. Zika virus is primarily transmitted to people through the bite of an infected Aedes species mosquito (Ae. aegypti and Ae. albopictus), which are the same types of mosquitoes that spread dengue, chikungunya, and yellow fever.
– Statement 2 is correct. Zika virus can be transmitted through sexual contact, from an infected person to their partner.
Other modes of Zika virus transmission include transmission from mother to fetus during pregnancy, through blood transfusion (though less common), and potentially through organ transplantation.

99. Which of the following statements is/are correct? Viruses can infect

Which of the following statements is/are correct?
Viruses can infect

  • bacteria
  • fungi
  • plants

Select the correct answer using the code given below.

[amp_mcq option1=”1 and 2 only” option2=”3 only” option3=”1 and 3 only” option4=”1, 2 and 3″ correct=”option4″]

This question was previously asked in
UPSC IAS – 2016
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The correct option is D, as viruses can infect bacteria, fungi, and plants.
– Viruses are obligate intracellular parasites that infect a vast range of living organisms across all domains of life.
– Statement 1 is correct: Viruses that infect bacteria are called bacteriophages.
– Statement 2 is correct: Viruses that infect fungi are called mycoviruses.
– Statement 3 is correct: Viruses that infect plants are called plant viruses and cause numerous plant diseases.
Viruses are highly specific in their hosts, with different types of viruses infecting different types of organisms. However, collectively, viruses can infect virtually all forms of cellular life, including bacteria, archaea, protists, fungi, plants, and animals.

100. Recently, our scientists have discovered a new and distinct species of

Recently, our scientists have discovered a new and distinct species of banana plant which attains a height of about 11 metres and has orange-coloured fruit with pulp. In which part of India has it been discovered?

[amp_mcq option1=”Andaman Islands” option2=”Anaimalai Forests” option3=”Maikala Hills” option4=”Tropical rain forests of northeast” correct=”option1″]

This question was previously asked in
UPSC IAS – 2016
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The new and distinct species of banana plant, *Musa markkuaensis*, known for its height of about 11 metres and orange-coloured fruit with pulp, was discovered by scientists in the Andaman Islands.
The discovery of *Musa markkuaensis*, a giant banana species, occurred in the Andaman Islands.
This discovery was significant due to the plant’s impressive size and unique fruit characteristics (orange pulp, numerous seeds). The scientific team included researchers from the Botanical Survey of India. The finding highlights the rich biodiversity of the Andaman and Nicobar Islands.
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