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Ecology

📆 September 25, 2024

Total Questions: 88

31. Which of the following are the primary consumers in an ecosystem? Select the correct answer from the codes given below : [U.P.P.C.S. (Mains) 2006]

  1. Ants
  2. Deer
  3. Fox
  4. Tiger

Codes :

Correct Answer: (a) 1 and 2
Solution:Mainly herbivores, in a food chain, are considered as primary consumers. In the given options, Deer is herbivorous hence it is a primary consumer. Ants fall under decomposer and primary consumers both. It eats plants and receives energy from cellulose. Tiger is carnivorous and the fox is omnivorous. Significantly, primary consumers feed on primary producers (plants). Hence option (a) is the correct answer.

32. Due to some reasons, if there is a huge fall in the population of species of butterflies, what could be its likely consequence/consequences? [I.A.S. (Pre) 2017 ]

  1. Pollination of some plants could be adversely affected.
  2. There could be a drastic increase in the fungal infection of some cultivated plants.
  3. It could lead to a fall in the population of some species of wasps, spiders and birds.

Select the correct answer using the code given below :

Correct Answer: (c) 1 and 3 only
Solution:Butterflies play a vital role in the pollination of many flowering plants, so their declining number may have an adverse effect on the pollination of plants. Butterflies act as the lower member in the food chain. They are the meal of spider, bird, snake etc. Therefore, the drop in a number of butterflies can adversely affect the food chain.

33. In a food chain, man is : [U.P.P.C.S. (Pre) 2016 ]

Correct Answer: (d) primary as well as a secondary consumer
Solution:In food chain there are trophic levels i.e., Autotroph, Primary consumer, Secondary consumer and Tertiary consumer. The primary consumer is the herbivores (that feed on the plant), the secondary consumer is small carnivores (feeding on primary consumer) and the tertiary consumer is larger carnivores. So, in food chain, man is the primary as well as a secondary consumer who feeds on both plant, products and meat.

34. In the marine environment, the main primary producers are : [U.P.P.C.S. (Mains) 2005]

Correct Answer: (a) Phytoplanktons
Solution:Phytoplankton, also known as micro-algae, are similar to terrestrial plants in that they contain chlorophyll and require sunlight to live and grow. Most phytoplankton are buoyant and float in the upper part of the ocean, where sunlight penetrates the water. Phytoplankton also requires inorganic nutrients such as nitrates, phosphates, and sulfur which they convert into proteins, fats, and carbohydrates.

35. Among the biotic components of the ecosystem, the producer system is - [U.P.P.C.S. (Pre) 2013 ]

Correct Answer: (d) Green Plants
Solution:Plants are self-feeding organisms that produce complex organic compounds such as carbohydrates, fats and proteins generally using energy from light (photosynthesis). These are known as autotrophs and are fundamental to the food chain of all ecosystems. There are called primary producers.

36. Trophic level-I includes - [M.P.P.C.S. (Pre) 2016]

Correct Answer: (d) Green plants
Solution:Each step or level of the food chain forms a trophic level. Tropic level-I includes autotrophs or the producers (i.e. green plants) which fix up solar energy and make it available for heterotrophs or the consumers. The herbivores (primary consumer) come at second, small carnivores at third and tertiary consumer (large carnivores) form the fourth trophic level.

Herbivorous animals: These animals eat only plants. Examples include cows, sheep, goats, and elephants.

Carnivorous animals: These animals eat only meat. Examples include lions, tigers, and sharks.

Omnivorous animals: These animals eat both plants and animals. Examples include humans, bears, and pigs.

37. Work as intermediaries between biotic and abiotic components [R.O./AR.O. (Mains) 2017]

Correct Answer: (b) Decomposers
Solution:
  • Producers: These are autotrophs, organisms that can produce their own food from inorganic sources. They form the base of the food chain.
    Examples: Plants, algae, and some bacteria.
  • Consumers: These are heterotrophs, organisms that cannot produce their own food and must obtain it from other sources.
    Examples: Animals (herbivores, carnivores, omnivores), humans.
  • Decomposers: These organisms break down dead organic matter and waste, releasing nutrients back into the environment. They are essential for recycling matter in ecosystems. They act as intermediaries between biotic and abiotic components.
    Examples: Bacteria, fungi, worms.
  • Parasites: These are a specific type of consumer that lives on or in a host organism, feeding off of it. They can harm the host, but the parasite may not necessarily kill the host.
    Examples: Fleas, ticks, tapeworms.

38. Consider the following statements about eco-system : [U.P. R.O./A.R.O. (Pre) 2017 ]

  1.  The production at the autotroph level is said to be primary productivity.
  2. The secondary productivity refer to the production at the heterotroph level.

Of the above, the correct statement is/are :

Correct Answer: (c) Both 1 and 2
Solution:Autotrophs are organisms that undergo autotrophic mode of nutrition. These are the organisms that can prepare their own food from simple substances like carbon dioxide and water. All green plants are examples of autotrophs. These green plants contain chlorophyll pigment in the plant cell that helps in the synthesis of their own food by absorbing energy from the sunlight. All autotrophs are producers and are placed at the primary level in the food web.

Heterotrophs are organisms which cannot prepare their own food and depend upon producers or green plants and other animals for their food. This mode of nutrition is known as the heterotrophic mode of nutrition. Heterotrophs rely on autotrophs to provide a continuous supply of new organic molecules. Heterotrophs are considered as consumers in the food web and are placed at a secondary or tertiary level.

39. Which one of the following pairs is correctly matched? [U.P.P.C.S. (Pre) 2015 ]

Correct Answer: (c) Green plants - Ecosystem
Solution:All the pairs mentioned in the question are related to ecosystems but correctly matched is only (c). An ecosystem is a community of living organisms in conjunction with the non-living components of their environment. Since plants are living organism hence they are related to the ecosystem.

40. Concerning the food chains in ecosystems, which of the following kinds of an organism is/are known as decomposer organism/organisms? [I.A.S. (Pre) 2013]

  1. Virus
  2. Fungi
  3. Bacteria

Select the correct answer using the codes given below :

Correct Answer: (b) 2 and 3
Solution:Decomposers are nature's recyclers as they break down the organic matter found in the dead bodies of living beings. The term 'organic matter' refers to the matter that comes from living organisms. Decomposers are mainly the microorganisms such as bacteria and fungi in the form of yeasts and moulds that break down bodies of dead organisms and release compounds that can be used by producers.
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