IAS Exam: Prelims Environment and Ecology Questions: Principles of Ecology Set II

Environment and Ecology has become indispensable for IAS Prelims Exam. Candidates cannot dispense with this section. In future also Importance of Environment and Ecology cannot be underestimated. Following are some MCQs that would help candidates to understand the kinds of questions they are going to face from Environment and Ecology section in IAS Prelims Exam:

Q1.Consider the following statements

1. In predation one organism kills other and benefits itself
2. In parasitism one species inhibits the other and benefits itself.
3. In amensalism one species harms the other and benefits itself.

Select the correct answer from the following codes

a.Only 1
b.Only 1 and 2
c.Only 2 and 3
d.1,2 and 3

Answer: a

Explanation: In parasitism one species harms the other and benefits itself. In amensalism one species inhibits the other and benefits itself.

Q2. With reference to competition, which of the following are true?

 1. In competition between two species, only one species is harmed.
 2. Competition is always Intraspecific.

Select the correct answer from the following codes

a.    Only 1
b.    Only 2
c.    Both 1 and 2
d.    Neither 1 nor 2

Answer: d

Explanation: Competition is an interaction between two populations in which both species are harmed to some extent. Competition can be interspecific and intraspecific.

Q3. Community that invade bare land, where soil is initially absent is called

a. Pioneer community
b. climax community
c. xerach
d.hydrarch

Answer: a

Explanation: Terminal stage of succession is climax community. Succession on bare rock is xerarch, succession in water body is hydrarch.

Q4. An association in which one species harms or restricts, other species without itself being adversely affected or harmed by other species is called

a. Amensalism
b. Predation
c. competition
d. commensalism

Answer: a

Explanation: A negative association in which organisms that secrete antibiotics and the species that get inhibited by antibiotics are examples of amensalism.

Q5. An association in which pencillium produce pencillin, an antibiotic substance and inhibiting growth of bacteria is example of

a. Commensalism
b. Neutralism
c. Amensalism
d. Competition

Answer: c

Explanation: In amensalism Pencilium doesn’t harm bacteria; it only inhibits its growth.

Q6.which of the following is/are not possible association of parasitism?

1. Animals as parasite of plant
2. Plant as parasite of plant
3. Tapeworm as parasite of Human

Select the correct answer from the following codes

a.Only 2
b.Only 2 and 3
c.Only 1 and 3
d.None

Answer: d

Explanation:  Plants like fodder plant and mistletoe are parasites that live on flowering plants. Tapeworm, roundworm, malarial parasite, bacteria, fungi, and viruses are common parasites of humans.

Q7. Which of the following pairs are correctly matched?

1. Commensalism    -    sea anemone with hermit crab
2. Mutualism        -    shark with Sucker fish
3. Parasitism        -    dodder plants with grass tree

Select the correct answer from the following codes

a. Only 3
b. Only 1 and 2
c. Only 2 and 3
d. 1,2 and 3

Answer: a

Explanation: commensalism- shark with Sucker fish, Mutualism-sea anemone attached to shell is inhabited by hermit crab.

Q8. Association of epiphytes on the surface of other plants like ferns, mosses and orchids is

a. Mutualism
b. Commensalism
c. Competition
d. Amensalism

Answer: b

Explanation: Epiphytes live on the surface of other plants like ferns, mosses and orchids and use the surface of trees for support and for obtaining sunlight and moisture. The tree gets no benefit from this relationship nor are they harmed.

Q9. Consider the following statements?

1. Mutualism and symbiosis can be used interchangeably.
2. Association of termite and intestinal flagellates is called symbiosis.
3. The relationship between two species which do interact but do not affect each other is mutualism.

Select the correct answer from the following codes

a. Only 2
b. Only 1 and 2
c. Only 2 and 3
d. 1,2 and 3

Answer: a

Explanation: some mutualisms are so intimate that the interacting species can no longer live without each other as they depend totally on each other to survive. Such close associations are called symbiosis. The relationship between two species which do interact but do not affect each other is neutralism.

Q10. pollination of flowers by the bees is example of

a. Mutualism
b. Symbiosis
c. Neutralism
d. Commensalism

Answer: b

Explanation: Symbiosis is seen in pollination of flowers where flowering plants are cross pollinated by bees which benefit by getting nectar from plants and both cannot survive without the other.

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