Biology

71. Consider the following statements : Adenoviruses have single-strand

Consider the following statements :

  • Adenoviruses have single-stranded DNA genomes whereas retroviruses have double-stranded DNA genomes.
  • Common cold is sometime caused by an adenovirus whereas AIDS is caused by a retrovirus.

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=”option2″]

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Statement 1 is incorrect, while statement 2 is correct.
– Statement 1: Adenoviruses are non-enveloped viruses with a *double-stranded* linear DNA genome. Retroviruses are enveloped viruses with a *single-stranded* RNA genome (typically two copies). They are called retroviruses because they use an enzyme called reverse transcriptase to convert their RNA genome into double-stranded DNA after infecting the host cell. Therefore, statement 1 is incorrect.
– Statement 2: Adenoviruses are one of the common causes of the common cold, along with rhinoviruses and coronaviruses. AIDS (Acquired Immunodeficiency Syndrome) is caused by the Human Immunodeficiency Virus (HIV), which is a well-known example of a retrovirus. Therefore, statement 2 is correct.
Adenoviruses can also cause other illnesses like conjunctivitis, bronchitis, and gastroenteritis. HIV primarily infects components of the human immune system, such as CD4+ T cells, macrophages, and dendritic cells, leading to progressive failure of the immune system.

72. Consider the following : Bacteria Fungi Virus Which of the ab

Consider the following :

  1. Bacteria
  2. Fungi
  3. Virus

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

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

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Bacteria and Fungi can be cultured in artificial/synthetic medium.
– Bacteria and Fungi are generally heterotrophic organisms that can obtain nutrients from their environment. They can be grown in laboratory settings using various artificial media (like nutrient broth, agar plates, etc.) that provide the necessary nutrients, carbon sources, and growth factors.
– Viruses, on the other hand, are obligate intracellular parasites. They lack the cellular machinery required for replication and must infect living host cells to reproduce. They cannot replicate or be cultured in artificial/synthetic media alone. Instead, viruses are cultured using techniques involving live cells or tissues, such as cell cultures, embryonated eggs, or living animals.
Artificial media are typically composed of a defined mixture of salts, sugars, amino acids, vitamins, and sometimes complex organic substances like peptone or yeast extract. The composition of the medium can be adjusted to suit the specific nutritional requirements of different types of bacteria or fungi.

73. Bollgard I and Bollgard II technologies are mentioned in the context

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

[amp_mcq option1=”clonal propagation of crop plants” option2=”developing genetically modified crop plants” option3=”production of plant growth substances” option4=”production of biofertilizers” correct=”option2″]

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Bollgard I and Bollgard II technologies are used in the context of developing genetically modified crop plants.
– Bollgard I and Bollgard II are trade names for genetically modified (GM) cotton seeds developed by Monsanto (now part of Bayer).
– These technologies involve introducing genes from the bacterium *Bacillus thuringiensis* (Bt) into the cotton plant’s genome.
– The Bt genes (specifically *cry1Ac* in Bollgard I and *cry1Ac* and *cry2Ab* in Bollgard II) produce proteins that are toxic to certain insect pests, particularly the cotton bollworm (Helicoverpa armigera) and other lepidopteran pests.
– This genetic modification makes the cotton plant resistant to these pests, reducing the need for chemical insecticides and improving yields. This is a classic example of genetic modification for pest resistance in crops.
Bollgard cotton is widely cultivated in India and other parts of the world. While beneficial for pest control, its use has also raised concerns about pest resistance evolution and environmental impacts.

74. In the context of hereditary diseases, consider the following statemen

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

  • Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of egg.
  • A child inherits mitochondrial diseases entirely from mother and not from father.

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″]

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Statement 1 is correct, and statement 2 is correct.
– Statement 1: Mitochondrial Replacement Therapy (MRT), including Pronuclear Transfer or Maternal Spindle Transfer techniques, aims to prevent the transmission of mitochondrial diseases from mother to child. These procedures involve transferring the nucleus from the affected mother’s egg (or zygote) into a donor egg (or zygote) that has had its nucleus removed but retains healthy mitochondria. This can be performed either before or after fertilization (in vitro fertilization).
– Statement 2: Mitochondria, organelles responsible for energy production within cells, contain their own DNA (mtDNA). In humans, mtDNA is almost exclusively inherited from the mother because the egg contributes the vast majority of cytoplasm (containing mitochondria) to the zygote, while the sperm contributes primarily nuclear DNA. Therefore, mitochondrial diseases are maternally inherited.
Mitochondrial diseases are a group of chronic, genetic disorders that occur when mitochondria fail to produce enough energy for the body to function properly. MRT is a relatively new and complex technique with ethical and regulatory considerations, approved in some countries under specific conditions.

75. With reference to recent developments regarding Recombinant Vector Vac

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

  • Genetic engineering is applied in the development of these vaccines.
  • Bacteria and viruses are used as vectors.

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″]

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The correct answer is C) Both 1 and 2.
– Statement 1 is correct. Recombinant vector vaccines are developed using genetic engineering techniques. A gene from the target pathogen (e.g., the spike protein gene of SARS-CoV-2) is inserted into the genome of a harmless vector organism (usually a virus or bacterium). This process involves genetic manipulation.
– Statement 2 is correct. Both viruses (e.g., adenoviruses, vaccinia virus) and bacteria (e.g., attenuated Salmonella, Listeria) are used as vectors in the development of recombinant vector vaccines. The vector delivers the pathogen’s genetic material into host cells to trigger an immune response.
– Recombinant vector vaccines are one of the modern approaches to vaccine development. They combine elements of traditional vaccine approaches with genetic engineering, offering advantages in terms of safety and the ability to elicit strong immune responses. Several COVID-19 vaccines (e.g., AstraZeneca, Sputnik V, Johnson & Johnson) are examples of viral vector vaccines.

76. Which of the following have species that can establish symbiotic relat

Which of the following have species that can establish symbiotic relationship with other organisms?

  1. Cnidarians
  2. Fungi
  3. Protozoa

Select the correct answer using the code given below.

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

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Option D is the correct answer. All three groups listed – Cnidarians, Fungi, and Protozoa – include species that are known to establish various types of symbiotic relationships with other organisms, including mutualism, commensalism, and parasitism.
Symbiosis refers to a close and long-term interaction between two different biological species. This can include mutualistic relationships (both benefit), commensalistic relationships (one benefits, the other is unaffected), or parasitic relationships (one benefits, the other is harmed).
Examples: Cnidarians like corals have mutualistic symbiosis with zooxanthellae (algae). Fungi form mycorrhizae with plant roots (mutualism) or are components of lichens (mutualism with algae/cyanobacteria). Protozoa include parasitic forms like Plasmodium (malaria) and mutualistic forms like those in termite guts that digest cellulose.

77. Which one of the following is a filter feeder?

Which one of the following is a filter feeder?

[amp_mcq option1=”Catfish” option2=”Octopus” option3=”Oyster” option4=”Pelican” correct=”option3″]

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Option C is the correct answer. Oysters are filter feeders, meaning they obtain nutrition by filtering suspended food particles from water.
A filter feeder is an animal that feeds by straining suspended food particles from water. Examples include bivalve molluscs like clams and oysters, as well as some fish, whales, and birds.
Catfish are generally bottom feeders or predators. Octopuses are predatory cephalopods. Pelicans are birds that typically catch fish directly with their beaks, rather than filtering.

78. Consider the following animals : 1. Hedgehog 2. Marmot 3. Pangolin

Consider the following animals :

  • 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?

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

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Animals use various defense mechanisms against predators. Rolling up into a ball is a common defense strategy among certain species to protect their soft, vulnerable underbellies or heads.
1. Hedgehog: Hedgehogs are well-known for their ability to roll into a tight, spiny ball when threatened. Their strong back muscles allow them to pull their skin, covered in spines, over their head and legs, presenting a formidable defense.
2. Marmot: Marmots are large ground squirrels. Their primary defense mechanisms include loud alarm calls to alert others and retreating quickly into their burrows. They do not roll up into a ball for defense.
3. Pangolin: Pangolins are mammals covered in large, protective keratin scales. When threatened, they roll up into a tight ball, tucking their head under their tail and using their scales as armor against predators.
Therefore, both Hedgehogs and Pangolins employ the strategy of rolling up into a ball to protect themselves.
Hedgehogs use their spines and Pangolins use their scales as protection when rolling into a ball.
Other animals that roll up for defense include armadillos (some species), pill bugs (rolly pollies), and certain millipedes.

79. Consider the following kinds of organisms : 1. Copepods 2. Cyanobac

Consider the following kinds of organisms :

  • 1. Copepods
  • 2. Cyanobacteria
  • 3. Diatoms
  • 4. Foraminifera

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

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

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Primary producers in any ecosystem are organisms that produce organic compounds from inorganic carbon sources, usually through photosynthesis. In the oceans, the primary producers are mainly phytoplankton, which are microscopic photosynthetic organisms.
1. Copepods: These are small crustaceans belonging to zooplankton. They are consumers, typically feeding on phytoplankton or other smaller zooplankton.
2. Cyanobacteria: Also known as blue-green algae, these are photosynthetic bacteria. They are significant primary producers in both freshwater and marine environments, contributing substantially to global oxygen production.
3. Diatoms: These are a major group of algae and are among the most common types of phytoplankton. They are responsible for a large percentage of the world’s oxygen production and are a primary food source in marine food chains.
4. Foraminifera: These are single-celled protists with shells. While some species host symbiotic algae (which are primary producers), Foraminifera themselves are heterotrophic, meaning they consume other organisms (like bacteria or algae) or detritus. They are consumers, not primary producers.
Therefore, Cyanobacteria and Diatoms are primary producers in ocean food chains.
Primary producers in the ocean are photosynthetic organisms, primarily phytoplankton like cyanobacteria and diatoms, which form the base of the marine food web.
Other important groups of marine primary producers include dinoflagellates, coccolithophores, green algae, and larger seaweeds (macroalgae) in coastal areas.

80. Which one of the following is used in preparing a natural mosquito

Which one of the following is used in preparing a natural mosquito repellent?

[amp_mcq option1=”Congress grass” option2=”Elephant grass” option3=”Lemongrass” option4=”Nut grass” correct=”option3″]

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Lemongrass (Cymbopogon species) is widely known for its natural mosquito repellent properties. It contains citronella oil, a volatile oil commonly used as an ingredient in mosquito repellents, candles, and lotions. The strong citrusy scent of lemongrass is effective in deterring mosquitoes and other insects.
– Congress grass (Parthenium hysterophorus) is an invasive weed notorious for causing allergies and has no repellent properties; in fact, it can be harmful.
– Elephant grass (Pennisetum purpureum) is a tall, fast-growing grass primarily used as fodder or for biomass energy; it is not used as a mosquito repellent.
– Nut grass (Cyperus rotundus) is a common weed with some traditional medicinal uses, but it is not widely known or used as a mosquito repellent.
Lemongrass contains citronella oil, a well-established natural insect repellent.
Other plants known for mosquito repellent properties include Citronella (closely related to lemongrass), Lemon Eucalyptus, Catnip, Basil, Lavender, and Peppermint.
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