Class 9 – Science Extra Questions – Ch. 12 – Improvement in Food Resources

Ans: B

Explanation: The question asks for the term describing a fishery located in saltwater environments. Inland fisheries are in freshwater environments. River water fisheries are also in freshwater environments. Marine refers to oceans and seas, which are saltwater environments. Therefore, a fishery in a saltwater environment is called a marine fishery.
Correct Option: B

Ans: A

Explanation: DDT (dichlorodiphenyltrichloroethane) is a synthetic organic compound that was widely used as an insecticide. It is known to persist in the environment for a very long time and does not break down easily through natural biological or chemical processes. This persistence leads to bioaccumulation and biomagnification in food chains, causing significant harm to ecosystems and wildlife. Therefore, it is classified as a non-biodegradable pollutant. Antibiotics are drugs that kill or inhibit the growth of bacteria, which is not the function of DDT.
Correct Option: A

Ans: D

Explanation: Rhizobium are a genus of gram-negative bacteria that live symbiotically in the root nodules of leguminous plants. They convert atmospheric nitrogen into ammonia, a form that plants can use for growth. This process is known as nitrogen fixation and is essential for plant health. Yeast is a type of fungus used in baking and brewing. Fungi are a broad kingdom of organisms, but not all are microscopic, and their role in nitrogen fixation is generally not as direct or primary as Rhizobium. Algae are photosynthetic organisms, primarily aquatic, and do not play a significant role in nitrogen fixation for soil plants.
Correct Option: D

Ans: D

Explanation: Broilers are a type of chicken specifically bred for meat production due to their rapid growth and efficient feed conversion. Layers are chickens bred for egg production, focusing on their high laying rate and longevity. The question asks which type is raised for meat and which is raised for eggs, so “Broiler” for meat and “Layer” for eggs is the correct pairing. Option A lists Broiler for meat and Chicken, which is too general as chickens can be either broilers or layers. Option B lists Layer for meat and Chicken, which is incorrect. Option C lists Layer for meat and Broiler for eggs, which is incorrect. Option D lists Broiler for meat and Layer for eggs.
Correct Option: D

Ans: B

Explanation: Organic farming emphasizes natural methods of soil enrichment and pest control, avoiding synthetic inputs. Green manure involves planting crops to be plowed back into the soil, improving fertility. Crop rotation is a technique to prevent soil depletion and pest buildup. Compost and farmyard manures are natural sources of nutrients for the soil. Chemical fertilizers, on the other hand, are synthetic and are intentionally excluded from organic farming practices.
Correct Option: B

Ans: B

Explanation: Pusa Lerma is a well-known improved variety of wheat. It was developed by the Indian Agricultural Research Institute (IARI) and has contributed significantly to wheat production in India.
Correct Option: B

Ans: D

Explanation: Animals are organisms that cannot produce their own food. They obtain nutrients by consuming other organisms, either plants or other animals. This mode of nutrition is called heterotrophic. Parasitic organisms live on or in another organism and get nutrients from it, but not all animals are parasitic. Saprophytic organisms obtain nutrients from dead or decaying organic matter, which is also a form of heterotrophic nutrition, but not descriptive of all animals. Autotrophic organisms, like plants, produce their own food through photosynthesis.
Correct Option: D

Ans: D

Explanation: Green manure crops are incorporated into the soil while still green, decomposing and releasing nutrients. They add organic matter, which improves soil structure and fertility. Leguminous green manures, in particular, fix atmospheric nitrogen, enriching the soil with this essential nutrient. The dense growth of green manure crops also helps to bind the soil particles together, preventing wind and water erosion. Leaching, on the other hand, is the process where soluble substances are washed out of the soil by water. While green manure improves soil structure which can affect water infiltration, it doesn’t inherently *allow* leaching; in fact, improved soil structure can sometimes reduce leaching by increasing water retention. Therefore, allowing leaching is not a benefit of green manure.
Correct Option: D

Ans: D

Explanation: Bio-fertilizers are natural products that contain living microorganisms which, when applied to seeds, plant surfaces, or soil, colonize the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant. Margosa and Pyrethrum are generally used as natural pesticides or insecticides, not bio-fertilizers. Green manure is a practice where crops are grown and then tilled back into the soil, but the term “green manure” itself refers to the crop residue, not the bio-fertilizer itself. Nitrogen-fixing bacteria and cyanobacteria are classic examples of bio-fertilizers because they directly fix atmospheric nitrogen into a usable form for plants, enhancing soil fertility.
Correct Option: D

Ans: A

Explanation: Apis mellifera is the scientific name for the Western or European honey bee. Various subspecies of Apis mellifera exist, including the Italian honey bee (Apis mellifera ligustica), which originates from Italy. Apis dorsata is the giant honey bee, Apis florae is the dwarf honey bee, and Apis cerana indica is the Indian honey bee.
Correct Option: A