Chapter Wise Ecology & Environment MCQ’s With Explanation

Today’s Topic: Population, Biotic Community and Succession

These are most-important and most-expected Questions for IAS Prelims General Studies paper-1 (Ecology and Environment) of UPSC Civil Service exam. Every day Himalai is coming with different subjects questions and answers with explanation analysis, these Questions will be both theoretical and fact based. Every day preparation will make a way for success, keep up your daily IAS Exam preparation with Himalai subject wise, chapter wise and topic wise Mcq’s with answers and analysis. We are providing our daily program list so that aspirant can note it and keep a watch on Himalai Mock test blogs for updated questions and get prepare for the Exam.

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Wednesday- Indian Polity and Governance

Thursday- History of India and Indian National Movement

Friday- Economic and Social Development

Saturday- Indian and world Geography

 

Today’s Topic: Population, Biotic Community and Succession

 

 

Q1. Which of the following constitute a population?

  1. All individuals of the common grass, Cynodon, in a given area.
  2. A Group of snails of the same species present in a given area.
  3. All pine trees occurring in a habitat.

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

Ans.     D

Explanation:    In ecology, a population is a group of individuals of the same species, inhabiting the same area, and functioning as a unit of biotic community. For example, all individuals of the common grass, Cynodon, in a given area constitute its population. A group of snails of the same species present in a given area represent a population. Similarly, all pine trees occurring in a habitat, constitute a population.

Q2. Consider the following statements:

  1. Organisms in a population undergo the same life cycle.
  2. A set of local populations connected by dispersing individuals is called a meta population.

Which of the statements given above is/are correct?

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

Ans:     C

Explanation:    Organisms in a population undergo the same life cycle. They experience similar ecological processes at particular stage of the life cycle. Populations can be defined at various spatial scales. Local populations can occupy very small habitat patches, like a temporary pool of water. A set of local populations connected by dispersing individuals is called a meta population.

Q3. Consider the following statements:

  1. The size of the population is represented by its density.
  2. Density of plants is determined by counting individuals in sampling units of predetermined sizes.

Which of the statements given above is/are correct?

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

Ans:     C

Explanation:    The size of the population is represented by its density. Density is expressed as the total number of individuals present per unit area or volume at a given time. For example, 50 individuals of a tree species may occur per hectare, or 70 individuals of the grass Cynodon per square meter. Density of plants is determined by counting individuals in sampling units of predetermined sizes.

Q4. Consider the following statements:

  1. The increase in number of individuals in a population under given environmental conditions is called mortality.
  2. The loss of individuals due to death in a population under given environmental conditions is termed as nasality

Which of the statements given above is/are correct?

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

Ans:     D

Explanation:    The increase in number of individuals in a population under given environmental conditions is called natality. Birth, hatching, germination and even vegetative propagation cause increase in number of individuals. The loss of individuals due to death in population under given environmental condition is termed mortality.

Q5. Which of the following statements is/are correct?

  1. The majority of organisms disperse at one time or the other during their life cycles.
  2. Distribution of age groups of a population influences the population growth.

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

Ans:     C

Explanation:    The majority of organisms disperse at one time or the other during their life cycles. The individuals move into (immigration) and move out of the population (emigration), and these movements affect the size of age groups influences the population growth. Populations with more younger members grow rapidly, while the declining populations have a large proportion of older individuals.

Q6. Consider the following statements:

  1. The environmental check on population size or its biotic potential is called environmental resistance.
  2. With increase in population size, the environmental resistance tends to decrease.

Which of the statements given above is/are correct?

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

Ans:     A

Explanation:    The environmental check on population size, or its biotic potential, is called environmental resistance. With increase in population size, the environmental resistance (against the population) trends to increase (not decrease). The environmental resistance represents the limiting effect of abiotic and biotic factors that do not allow organisms to attain their biotic potential and keep the population size at a much lower level.

Q7. Consider the following statements:

  1. The inherent maximum capacity of an organism to reproduce or increase in number is termed biotic potential.
  2. The environmental resistance represents the limiting effect of abiotic and biotic factors.

Which of the statements given above is/are correct?

a) Only 1

b) Only 2

c) Both 1 and 2

d) Neither 1 nor 2

Ans:     C

Explanation:    The inherent maximum capacity of an organism to reproduce or increase in number is termed biotic potential. Biotic potential is realized only when the environmental conditions are non-limiting, so that natality rate is maximum and mortality rate is minimu. The environmental check on population size, or its biotic potential, is called environmental resistance. The environmental resistance represents the limiting effect of abiotic (e.g water, space) and biotic factors (e.g. food, competition) that do not allow organism to attain their biotic potential and keep the population size at a much lower level.

Q8. Consider the following statements:

  1. In J-shaped population growth form, the population grows exponentially and after attaining the peak value the population may abruptly crash.
  2. Biotic potential is realized only when the environmental conditions are non-limiting.

Which of the statements given above is/are correct?

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

Ans:     C

Explanation:    In J-shaped population growth form, the population grows exponentially and after attaining the peak value, the population may abruptly crash. The exponential growth cannot be sustained infinitely because not only environment is ever changing, food and space are limited. The inherent maximum capacity of an organism to reproduce or increase in number is termed biotic potential. Biotic potential is realized only when the environmental conditions are non-limiting so that natality rate is maximum and mortality rate is minimum.

Q9. Consider the following statements:

  1. S-shaped population growth form shows an initial gradual increase in population size, followed by an exponential increase and then a gradual decline to a near constant level.
  2. The maximum number of individuals of a population that can be sustained indefinitely in given habitat represent its carrying capacity.

Which of the statements given above is/are correct?

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

Ans:     S-shaped or signoid population growth form shows an initial gradual increase in population size, followed by an exponential increase and then a gradual decline to a near-constant level. This slow-down following the exponential phase, occurs due to increasing environmental resistance. In such cases, plotting of the rate of increase of population over time gives an S-shaped or signoid curveThe maximum number of individuals of a population that can be sustained indefinitely in a given habitat, represent its carrying capacity.

Q10. Which of the following statements is correct?

a) Members of the biotic community in an area are dependent on one another.

b) Plants and animals have well established interdependence for reproduction.

c) Birds and mammals help in the dispersal of seeds and fruits.

d) All of the above.

Ans.     D

Explanation:    Members of the biotic community in an area are dependent on one another. The inter-dependent on one another. The inter-dependence is reflected in their interactions mainly for food, space, reproduction and protection.

Plants and animals have well established interdependence for reproduction. It is best illustrated by the role of insects in the community. The insects are flower specific and have structures suitable for nectar sucking and pollination.

Birds and mammals help in the dispersal of seeds and fruits.

 

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