Biology

51. With reference to the role of biofilters in Recirculating Aquaculture

With reference to the role of biofilters in Recirculating Aquaculture System, consider the following statements:

  • 1. Biofilters provide waste treatment by removing uneaten fish feed.
  • 2. Biofilters convert ammonia present in fish waste to nitrate.
  • 3. Biofilters increase phosphorus as nutrient for fish in water.

How many of the statements given above are correct?

[amp_mcq option1=”Only one” option2=”Only two” option3=”All three” option4=”None” correct=”option1″]

This question was previously asked in
UPSC IAS – 2023
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The correct option is A, indicating that only one of the given statements is correct.
Recirculating Aquaculture Systems (RAS) use biofilters as a key component for water treatment.
Statement 1 is incorrect. Biofilters primarily treat dissolved waste products, particularly nitrogenous compounds. Solid wastes, such as uneaten fish feed and feces, are typically removed by mechanical filters (like drum filters or settling tanks) *before* the water reaches the biofilter. While the decomposition of uneaten feed *produces* substances that the biofilter treats, the biofilter itself does not remove the solid feed.
Statement 2 is correct. The main function of a biofilter in RAS is nitrification, which is the biological process where beneficial bacteria convert toxic ammonia (excreted by fish and from decomposition) first into nitrite and then into much less toxic nitrate. This is essential for maintaining water quality suitable for fish.
Statement 3 is incorrect. Biofilters are designed to remove or convert waste products, not increase nutrients for fish. While phosphorus is present in fish feed and waste, biofilters are primarily focused on managing nitrogen. Systems for nutrient addition for fish involve providing high-quality feed, not manipulating waste products in the water circuit.
RAS significantly reduces water usage compared to traditional aquaculture by recycling water. Effective biofiltration is crucial for removing metabolic wastes and maintaining a healthy environment for the fish. Other components of RAS often include mechanical filtration, oxygenation/aeration, pH control, and temperature control.

52. ‘Microsatellite DNA’ is used in the case of which one of the foll

‘Microsatellite DNA’ is used in the case of which one of the following?

[amp_mcq option1=”Studying the evolutionary relationships among various species of fauna” option2=”Stimulating ‘stem cells’ to transform into diverse functional tissues” option3=”Promoting clonal propagation of horticultural plants” option4=”Assessing the efficacy of drugs by conducting series of drug trials in a population” correct=”option1″]

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The correct answer is A) Studying the evolutionary relationships among various species of fauna.
Microsatellite DNA (also known as Short Tandem Repeats or STRs) consists of repeating sequences of a few nucleotides (typically 2-6 bp) found throughout the genome. These regions are highly variable in length among individuals and even among closely related species due to differences in the number of repeat units. This high variability makes microsatellites excellent genetic markers for population genetics studies, genetic diversity analysis, parentage testing, individual identification, and studying evolutionary relationships, particularly among populations within a species or among closely related species where there is sufficient variability.
Options B, C, and D are not primary applications of microsatellite DNA analysis. Stem cell differentiation (B) involves gene expression and signaling pathways. Clonal propagation (C) involves vegetative reproduction techniques, although microsatellites could be used for verifying clonality. Drug efficacy assessment (D) is part of clinical trials and often involves patient response, pharmacokinetics, and sometimes pharmacogenomics (which might use various genetic markers, but microsatellites are not typically the primary tool for drug *efficacy* assessment itself).

53. ‘Aerial metagenomics’ best refers to which one of the following situ

‘Aerial metagenomics’ best refers to which one of the following situations?

[amp_mcq option1=”Collecting DNA samples from air in a habitat at one go” option2=”Understanding the genetic makeup of avian species of a habitat” option3=”Using air-borne devices to collect blood samples from moving animals” option4=”Sending drones to inaccessible areas to collect plant and animal samples from land surfaces and water bodies” correct=”option1″]

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The correct answer is A) Collecting DNA samples from air in a habitat at one go.
Metagenomics is the study of the collective genetic material (DNA and RNA) from a community of organisms in an environmental sample, bypassing the need to isolate and culture individual species. “Aerial” refers to the air. Therefore, “aerial metagenomics” is the technique of collecting samples from the air (which contains DNA from airborne microorganisms like bacteria, fungi, viruses, pollen, spores, environmental DNA from insects, etc.) and analyzing the extracted genetic material to understand the biodiversity and composition of the airborne biome in a specific habitat at a particular time.
This technique allows for the broad-scale monitoring of biodiversity and ecological dynamics in the air, potentially detecting invasive species, monitoring allergens (pollen, spores), or studying pathogen distribution without extensive fieldwork or culturing.

54. ‘Wolbachia method’ is sometimes talked about with reference to which o

‘Wolbachia method’ is sometimes talked about with reference to which one of the following?

[amp_mcq option1=”Controlling the viral diseases spread by mosquitoes” option2=”Converting crop residues into packing material” option3=”Producing biodegradable plastics” option4=”Producing biochar from thermo-chemical conversion of biomass” correct=”option1″]

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The correct answer is A) Controlling the viral diseases spread by mosquitoes.
The Wolbachia method involves introducing the naturally occurring bacteria *Wolbachia* into mosquito populations, particularly *Aedes aegypti*, which transmit diseases like dengue, Zika, chikungunya, and yellow fever. *Wolbachia* can prevent these viruses from replicating effectively inside the mosquito, thereby reducing the mosquito’s ability to transmit the disease to humans. It can also affect mosquito reproduction, potentially suppressing populations over time.
This method is being explored and implemented by organizations like the World Mosquito Program as a sustainable, long-term approach to control mosquito-borne viral diseases, as an alternative or complement to traditional methods like insecticides.

55. Consider the following trees: 1. Jackfruit (Artocarpus heterophyllus)

Consider the following trees:
1. Jackfruit (Artocarpus heterophyllus)
2. Mahua (Madhuca indica)
3. Teak (Tectona grandis)
How many of the above are deciduous trees?

[amp_mcq option1=”Only one” option2=”Only two” option3=”All three” option4=”None” correct=”option2″]

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1. Jackfruit (Artocarpus heterophyllus) is generally considered an evergreen tree, although it might shed some leaves in certain conditions, it does not exhibit complete seasonal leaf shedding typical of deciduous trees.
2. Mahua (Madhuca indica) is typically described as a deciduous or semi-deciduous tree, shedding most or all of its leaves during the dry season (usually February-March in central India).
3. Teak (Tectona grandis) is a well-known large deciduous tree, shedding its leaves annually during the dry season.
Therefore, Mahua and Teak are deciduous trees among the options.
– Deciduous trees shed leaves seasonally.
– Jackfruit is evergreen.
– Mahua and Teak are deciduous trees commonly found in India.
Mahua is economically important for its flowers and seeds. Teak wood is highly valued for its durability and is widely used in furniture and construction. Jackfruit is the national fruit of Bangladesh and Sri Lanka, and a state fruit of Kerala and Tamil Nadu in India.

56. Consider the following statements: 1. Some microorganisms can grow i

Consider the following statements:

  • 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 environment with a pH below 3.

How many of the above statements are correct?

[amp_mcq option1=”Only one” option2=”Only two” option3=”All three” option4=”None” correct=”option3″]

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All three statements are correct.
1. **Some microorganisms can grow in environments with temperature above the boiling point of water:** This is correct. Thermophiles and hyperthermophiles are types of extremophilic microorganisms (often Archaea and Bacteria) that thrive at very high temperatures, such as those found in hydrothermal vents or hot springs, where temperatures can exceed 100°C and even reach above 120°C under pressure.
2. **Some microorganisms can grow in environments with temperature below the freezing point of water:** This is correct. Psychrophiles are extremophilic microorganisms that are capable of growth and reproduction in cold temperatures, typically between -15°C and 10°C. They are found in environments like polar ice, glaciers, permafrost, and the deep sea.
3. **Some microorganisms can grow in highly acidic environment with a pH below 3:** This is correct. Acidophiles are extremophilic microorganisms that thrive in highly acidic environments, with optimum pH levels typically between 0 and 3. Examples include species found in acid mine drainage or volcanic sulfur springs.
The ability of microorganisms to survive and proliferate in a vast range of extreme environmental conditions (extremophiles) highlights their remarkable metabolic and physiological diversity, adapted through evolutionary processes.

57. Consider the following statements regarding the Indian squirrels: 1.

Consider the following statements regarding the Indian squirrels:

  • 1. They build nests by making burrows in the ground.
  • 2. They store their food materials like nuts and seeds in the ground.
  • 3. They are omnivorous.

How many of the above statements are correct?

[amp_mcq option1=”Only one” option2=”Only two” option3=”All three” option4=”None” correct=”option2″]

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Only two of the above statements are correct.
1. **They build nests by making burrows in the ground:** This is generally incorrect for the common Indian squirrels (like the Indian Palm Squirrel). Tree squirrels, which are prevalent in India, typically build nests called ‘dreys’ high up in trees using twigs, leaves, and other plant materials. While some squirrel species (ground squirrels) do burrow, this is not characteristic of the squirrels commonly referred to in India in this context.
2. **They store their food materials like nuts and seeds in the ground:** This is correct. Burying or ‘caching’ nuts and seeds is a common behaviour among many squirrel species, including Indian squirrels, to store food for later consumption, particularly during scarcity.
3. **They are omnivorous:** This is correct. While their diet primarily consists of plant material like nuts, seeds, fruits, and buds, Indian squirrels are known to also eat insects, larvae, bird eggs, and occasionally small vertebrates, making them omnivorous.
The most common squirrel species in India are tree squirrels like the Indian Palm Squirrel (*Funambulus palmarum*) and the Indian Giant Squirrel (*Ratufa indica*). Their habits align with statements 2 and 3, but not statement 1.

58. Consider the following statements: 1. Some mushrooms have medicinal

Consider the following statements:

  • 1. Some mushrooms have medicinal properties.
  • 2. Some mushrooms have psycho-active properties.
  • 3. Some mushrooms have insecticidal properties.
  • 4. Some mushrooms have bioluminescent properties.

How many of the above statements are correct?

[amp_mcq option1=”Only one” option2=”Only two” option3=”Only three” option4=”All four” correct=”option4″]

This question was previously asked in
UPSC IAS – 2023
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All four statements are correct.
1. **Some mushrooms have medicinal properties:** Many mushroom species have been traditionally used for medicinal purposes and are being researched for compounds with potential benefits, including anti-cancer, immune-modulating, and antibiotic effects (e.g., Reishi, Shiitake, Turkey Tail).
2. **Some mushrooms have psycho-active properties:** Certain mushrooms contain psychoactive compounds like psilocybin and psilocin (e.g., Psilocybe species), which affect the mind and perception.
3. **Some mushrooms have insecticidal properties:** Some fungi, including certain mushroom species, produce compounds that are toxic or deterrent to insects. *Amanita muscaria*, for example, contains ibotenic acid, which has insecticidal properties.
4. **Some mushrooms have bioluminescent properties:** Several species of fungi, including certain mushrooms (e.g., some *Mycena* species, *Panellus stipticus*), are bioluminescent, meaning they produce light through a chemical reaction.
Fungi are a diverse kingdom, and mushrooms, being the fruiting bodies of many fungi, exhibit a wide range of biological and chemical properties, including those mentioned in the statements.

59. Which of the following organisms perform waggle dance for others of th

Which of the following organisms perform waggle dance for others of their kin to indicate the direction and the distance to a source of their food?

[amp_mcq option1=”Butterflies” option2=”Dragonflies” option3=”Honeybees” option4=”Wasps” correct=”option3″]

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Honeybees perform the waggle dance to indicate the direction and distance to a source of food.
The waggle dance is a specific figure-eight dance performed by honeybees (Apis mellifera) to communicate the location of food sources, water sources, or new nest sites to other members of the colony. The direction and duration of the “waggle” run within the dance correlate directly to the direction and distance of the resource from the hive relative to the sun’s position.
This remarkable form of communication was extensively studied by Nobel laureate Karl von Frisch. While other insects like ants also use chemical trails and other signals, the waggle dance is uniquely associated with honeybees for complex spatial information transfer.

60. Consider the following fauna: 1. Lion-tailed Macaque 2. Malabar C

Consider the following fauna:

  • 1. Lion-tailed Macaque
  • 2. Malabar Civet
  • 3. Sambar Deer

How many of the above are generally nocturnal or most active after sunset?

[amp_mcq option1=”Only one” option2=”Only two” option3=”All three” option4=”None” correct=”option2″]

This question was previously asked in
UPSC IAS – 2023
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Only two of the listed fauna are generally nocturnal or most active after sunset.
1. **Lion-tailed Macaque:** These are diurnal animals, meaning they are primarily active during the day.
2. **Malabar Civet:** This species is known to be strictly nocturnal, active mainly during the night.
3. **Sambar Deer:** While they can be active during the day, Sambar deer are often crepuscular (most active during dawn and dusk) and their activity often extends into the night, especially in areas with human disturbance. Thus, they are frequently most active after sunset.
Therefore, the Malabar Civet is nocturnal, and the Sambar Deer is often crepuscular/nocturnal, fitting the description “generally nocturnal or most active after sunset”. The Lion-tailed Macaque is diurnal. This makes a total of two species out of the three listed.
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