Chapter Wise Ecology & Environment MCQ’s With Explanation

Today’s Topic: Organisms and the Environment-3

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.

EveryDay Program List

Monday-General issues on Environmental Ecology, bio-diversity and Climate Change

Tuesday- General Science

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 TopicOrganisms and the Environment-3

 

Q1. With reference to ‘Soil’, consider the following statements:

  1. It is the uppermost weathered layer of Earth’s crust.
  2. It is composed of minerals and partly decomposed organic mater.

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:     Soil is the uppermost weathered layer of Earth’s crust and is composed of minerals and partly decomposed organic meter. It is formed due to interactions among parent rock, climate, living organisms, time and topography. Soil plays an important role in plant growth by providing water, nutrients and andravage.

 

Q2. Consider the following statement:

  1. In desert soils, the top horizon is a rich mixture of humus and inorganic soil components.
  2. In temperate forest soils, the top soil has little or no humus.

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:     Soil in grassland, forest and desert biomes differ markedly in colour, clay, organic matter content, and depth. In desert soils, the top soil has little or no humus. In temperate forest soils, the top horizon is a rich mixture of humus and inorganic soil components.

 

Q3. Match the following:

Mineral particles in soil – Size

  1. Coarse sand 1. Less than 0.002 mm
  2. Fine sand 2. 0.00 2 mm – 0.02 mm
  3. Silt 3. 0.02 mm – 0.02 mm
  4. Clay 4. 0.2 mm – 2mm

Code:

A         B          C          D

a) 4         3          2          1

b) 4         3          1          2

c) 3         4          1          2

d) 3         4          2          1

Ans:     A

Explanation:     The proportion of mineral particles of different sizes in soil represents its texture. Mineral particles in soil vary greatly in size. Those between 0.2 and 2mm are called coarse sand, 0.02 and 0.2 mm fine sand, 0.002 and 0.02 mm silt, and those less than 0.002 mm clay.

 

Q4. What percent by volume mineral particles is filled in a soil?

a) 5 percent             b) 15 percent                c) 45 percent                d) None of the above

Ans:     C

Explanation:     Soils are made up of four components. The two solid substances are small mineral particles and organic matter. The small mineral particles come from weathering of rocks. The organic matter is of plant and animal origin, both from dead and living organisms. In an average soil, about 45 percent of the volume is filled with mineral particles and about 5 percent by organic matter.

 

Q5. Match the following:

Soil Component – Volume (percent)

  1. Miner Particles – 1. 50 percent
  2. Organic Matter – 2. 05 percent
  3. Air and Water – 3. 45 percent

Code:

A         B          C

a) 2         1          3

b) 1         3          2

c) 1         2          3

d) 3        2          1

Ans.     D

Explanation:     In an average soil, about 45 percent of the volume is filled with mineral particle and about 5 percent by organic matter. The other 50 percent of the volume is filled with air and water.

 

Q6. Consider the following statements:

  1. Low temperature limits plant growth at higher elevations.
  2. Water availability limits plant growth in deserts.

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:     Biological species show a range of tolerance to environmental factors. These factors vary in their effects, and any one which is present in least amount may become limiting. For example, low temperature limits plant growth at higher elevations; water availability limits plant growth in deserts; and low phosphorous availability limits the growth of phytoplankton in deep lakes.

 

Q7. Consider the following statements:

  1. The physical expression of the interaction between genotype of an organism and its environment is known as phenotype.
  2. Phenotypic plasticity is the variation among individuals, produced by the influence of the local conditions of the habitat.

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 phenotype is the physical expression of the interaction between genotype of an organism and its environment. The phenotypes show variations due to differences in the environmental conditions within the local habitat. Such variation among individuals, produced by the influence of the local conditions of the habitat, is known as phenotypic plasticity.

 

Q8. Consider the following statements:

  1. Sciophytes have higher temperature optima for photosynthesis.
  2. Heliphytes have high rates of respiration.

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:     B

Explanation:     Individual plants, as well as plant communities, adapt to different light intensities by becoming shadetolerant (sciophytes) or sun adapted (heliophytes). Heliophytes are adapted to high intensity of light, and have higher temperature optima far photosynthesis, as well as have high rates of respiration.

 

Q9. Which one of the following statements is incorrect?

  1. a) Heliphytes are adapted to high intensity of light.
  2. b) Sciophytes have low respiratory and metabolic activities.
  3. c) Ferns are shade tolerant plants.
  4. d) None of the above.

Ans:     D

Explanation:     Heliphytes are adapted to high intensity of light, and have higher temperature optima for photosynthesis. Sciophytes generally have low photosynthetic, respiratory and metabolic activities. Plants such as ferns and several herbaceous plants growing on the ground under the dense canopy of trees are shade tolerant plants.

 

Q10. Consider the following stamens:

  1. Prosopis and palms are the plants having deep root systems.
  2. In cacti, leaves are reduced to spines, whereas stems are modified into fleshy and spongy structures.

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:     Some plants have deep top roots, which can reach even up to water table, in arid climates, and therefore, are capable of absorbing water from deep soil. Some prominent examples of plants having deep root systems are Prosopis (mesquite), palms and some species of Acacia. In cacti, leaves are reduced to spines, whereas stems are modified into fleshy and spongy structures. Some cacti have expandable stems for storing water, and have spreading root systems in the surface layer of the soil.

 

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