Day-569 | Daily MCQs | UPSC Prelims | ENVIRONMENT AND ECOLOGY

Answer. D
Explanation:
Mulches could be both organic (using straw, husk, grass, cover crops, saw dust, compost and manures) and synthetic (polyethylene plastic mulch).
• Statement 1 is incorrect: Mulching is beneficial for the soil health as it increases the water-retention capacity of the soil and decreases the soil compaction. Studies have shown that mulches can potentially reduce weed infestation and soil moisture losses through evaporation. They enhance the percolation and retention rate of soil. Straw mulch has been noticed to reduce evaporation losses of moisture from soil by up to 35%.
• Organic mulches act as sponge which helps retain irrigation and rainfall water in soil. The straw mulches can reduce run off by 43%.
• The problem of soil compaction in agriculture due to use of heavy machinery or implements is becoming severe, which can be addressed by addition of organic mulch materials such as bark. Also, the decomposition of organic mulches provides additional benefit of nutrient enrichment in the soil. This improves the fertility of the soil.
• Statement 2 is incorrect: Since mulches cover the soil surface, in general, they help in controlling the temperature of the soil. However, the type of materials used in mulching decide the effectiveness of mulches in controlling the soil temperature. Studies indicate that mulches can reduce soil temperature by 10 degrees Celsius in hot and dry conditions. But the mulches comprising cobbles can increase the overall soil temperature as compared to living mulches due to absorption of solar radiation.

Answer. A
Explanation:
• Most archerfish species live in freshwater habitats, including rivers, streams, and pools. A few species are euryhaline, which means that they can live in both freshwater and brackish waters. They are generally found in the lowlands of tropical countries like India, Sri Lanka, Bangladesh, and Southeast Asia. They also live in Northern Australia and Melanesia.
• Uniqueness: Archerfish are known for their ability to shoot water from their mouths at a target above the water’s surface. They do this by dilating and contracting their gill covers, which are controlled by a special lateral line organ. The archerfish may also move its tail back and forth to aim itself after its target.
• In addition, Archerfish have very sharp eyesight, which is a factor for their ability to shoot the water with great accuracy.

Answer. C
Explanation:
Options 1, 2 and 3 are correct.
• Butterflies and turtle: While butterfly drinks turtle tears to obtain nutrients like sodium which it needs for egg production and metabolism, this activity benefits the turtle by cleaning its eyes. It also helps turtle to get rid of the excess salt from its body. The behaviour is called ‘lachryphagy’.
• Clownfish and sea anemone: Sea anemones are marine predatory animals related to jellies and corals. They provide the clownfish with protection and shelter, while the clownfish provides the anemone nutrients in the form of waste while also scaring off potential predator fish.
• Sea anemones live attached to the surface of coral reefs. They trap their prey with stinging cells called nematocysts, which are located on their tentacles. Nematocysts release toxins when a small animal contacts an anemone’s tentacle. This paralyzes the stung animal, allowing the anemone to easily bring the animal into its mouth for ingestion. While other fish succumb to these toxic stings, clownfish secrete a substance in the mucus covering their bodies that suppresses the firing of nematocysts. This allows the clownfish to swim comfortably between the tentacles of anemones, creating a protected environment in which potential predators are killed off by anemone stings. This clearly benefits the clownfish, but how about the sea anemones? The brightly colored clownfish attract other fish looking for a meal. These unsuspecting would-be predators are then caught and eaten by the anemones.
• Aphids and ants: Aphids are sucking insects that are common on both outdoor and indoor plants. They feed on the sap of plants and secrete a substance called honeydew. This sticky resin is a favourite food of ants, who actually “milk” the aphids for it by stroking their abdomen.
• The unique relationship between these two organisms provides protection for the aphids and food for the ants. Ants protect the aphids from predators, such as lacewings and ladybugs.

Answer: A
Explanation:
• Statement 1 is correct: Compared to conventional fuels, green methanol can reduce carbon dioxide emissions by 60-95%, reduce nitrogen oxide emissions by 60-80%, and almost completely eliminate sulphur oxide and particulate matter emissions, according to the Methanol Institute.
• Statement 2 is correct: Green methanol is obtained by using CO2 captured from renewable sources (bioenergy with carbon capture and storage [BECCS] and direct air capture [DAC]) and green hydrogen, i.e., hydrogen produced with renewable electricity.
Additional information
• Renewable methanol can be produced from a variety of sustainable feedstocks, such as biomass, waste or CO2 and hydrogen.
• It is a versatile fuel that can be used in internal combustion engines, and in hybrid and fuel cell vehicles and vessels. It is compatible with existing distribution infrastructure and can be blended with conventional fuels.
• It is a liquid at ambient temperature and pressures.
• The production of green methanol also offers a range of environmental benefits. It can be blended with traditional gasoline or diesel fuel, offering a seamless transition for vehicle owners and minimizing the need for infrastructure upgrades. This makes it an attractive option for countries and industries looking to reduce their carbon footprint without disrupting their current operations.
• In the maritime sector, methanol is being considered as a potential alternative to traditional bunker fuels. With global shipping responsible for 90% of world trade and 3-4% of greenhouse gas emissions, the sector is under increasing pressure to decarbonize.
• It can be used not only as a transportation fuel but also as a feedstock for the production of other valuable chemicals and materials such as formaldehyde, acetic acid and plastics.

Answer. D
Explanation:
Eco Mark is a certification scheme for environment-friendly products which is administered by the Bureau of Indian Standards (BIS). It was first started in 1991. It is a voluntary non-binding scheme which labels consumer products as environment-friendly on the basis of certain environmental and quality parameters.
Any product which has less potential for pollution during its entire lifecycle (raw material, manufacturing, use and disposal) could be considered ‘environment-friendly’.
Logo- Earthen pot, which signifies that renewable resource like clay should be used so that it generates little or no hazardous waste and also consumes less energy in its making.
The BIS implements the Eco Mark scheme under the BIS Act,1986. It is awarded for minimum one year, after which it is re-assessed for renewal of license. The BIS can withdraw the certification at any time if any misleading information is found or if nay criterion is changed related to technology.
The Central Pollution Control Board (CPCB) administers the Ecomark Scheme in partnership with Bureau of Indian Standards (BIS), which is the national body for standards and certification.
The Eco Mark scheme is applicable for the following goods, as specified by the BIS:
• Soaps and detergents
• Paints
• Food items
• Lubricating oil
• Packing/packaging material
• Architectural paints and powder coatings
• Batteries
• Electrical and electronic goods
• Food additives
• Wood substitutes
• Cosmetics
• Aerosols and propellants
• Plastic products
• Textiles
• Fire extinguishers
• Leather
• Coir and coir products