Chapter Wise Ecology & Environment MCQ’s With Explanation

Today’s Topic: Organisms and the Environment-4

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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Today’s TopicOrganisms and the Environment-4

Q1. Which of the following are the characteristics of Xerophytes?

  1. Large leaves
  2. Sunken Stomata
  3. Leathery leafy surfaces
  4. Waxy cuticle

a) Only 1 , 2 and 3        b) Only 1, 2 and 4         c) Only 2, 3 and 4         d) 1, 2, 3 and 4

Ans:     C

Explanation:     Exerophyte is a species of plant that has adapted to survive in an environment with little water such as desert or an ice or snow-covered region in the Alps or the Arctic. In Xerophytes, small leaves, sunken stomata, leathery leaf surfaces and waxy cuticle help in reducing transpiration.

 

Q2. Consider the following statements:

  1. Many tropical plants possess C4 pathway of photosynthesis.
  2. Plants having C4 pathway perform bad in low soil water environments.

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:     Many tropical plants, particularly grasses which grow in hot and arid climates, possess C4 pathway of photosynthesis. Plants having this pathway perform better in low soil water environments. Such plants, therefore, use less water to achieve higher rates of photosynthesis, particularly at higher temperatures.

 

Q3. Consider the following statements:

  1. Cacti and Succulents possess CAM pathway of photosynthesis.
  2. Cacti and succulents close their stomata during the day and open them in the night to reduce transpiration.

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:     Many desert plants, such as cacti and succulents, close their stomata during the day and open them in the night to reduce transpiration. Such plants possess CAM, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but open at right to collect carbon dioxide.

 

Q4. Consider the following statements:

  1. The plants which have a long life span are known as ephemerals.
  2. The heat shock proteins, chaperonins, provide physiological adaptations to plants to high temperatures.

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:     The plants which have a short (not long) life span are known as ephemerals. For example, in desert areas of Rajasthan, many annual plants germinate from seeds, complete their life cycle quickly during the rainy season. Chaperonins, the heat shock proteins provide physiological adaptations to plants to high temperatures. These proteins help other proteins to maintain their structure and avoid denaturisation at high temperatures.

Q5. Which of the following are the examples of hydrophytes?

  1. Wolffia
  2. Salvinia
  3. Cerataphyllum
  4. Hydrilla

a) Only 1 , 2 and 3         b) Only 1, 2 and 4         c) Only 2, 3 and 4         d) 1, 2, 3 and 4

Ans:     D

Explanation:     Plants which remain permanently immersed in water are called hydrophytes. They may be submerged, or party submerged and show the presence of aerenchyma in the leaves and petioles. Wolffia, Salvinia, Ceratophyllum and Hydrilla are the examples of hydrohytes.

 

Q6. Which of the following statements is/are correct?

  1. Roots are poorly developed or absent in free floating hydrophytes like Ceratophyllum and Hydrilla.
  2. Nymphaea is an example of an emergent and rooted hydrophyte.

a) Only 1 , 2 and 3        b) Only 1, 2 and 4         c) Only 2, 3 and 4         d) 1, 2, 3 and 4

Ans:     C

Explanation:     In free floating hydrophytes like Woffia, Salvinia, Ceratophyllum and Hydrilla, roots are poorly developed or absent. Nymphaea is an example of an Nymphaea is an example of an emergent and rooted hydrophyte, which is seen growing in a pond. This plant, as well as other emergent hydrophytes have a continuous system of air passages, which help the submerged plant organs to exchange gases from the atmosphere through the stomata in the emergent organs.

 

Q7. Which one of the following statements is/are correct?

a) The oligotrophic soils contain low amounts of nutrients.

b) In nutrient-poor soils, nutrient accumulation in vegetation is high.

c) Many plants growing in nutrient-poor soils, possess mycorrhizae.

d) All of the above.

Ans.     D

Explanation:     The oligotrophic soils contain low amounts of nutrients. These soils generally develop in old and geologically stable areas, such as soils found in most of the tropical rain forest region. Due to intense weathering and high rates of leaching, these soils have a poor nutrient retention capacity. In nutrient-poor soils, nutrient accumulation in vegetation is high. Many plants growing in nutrient-poor soils possess mycorrhizae which have mutualistic association of roots with fungi.

 

Q8. Match the following:

List-I                            List-II

  1. Sciophytes 1. Sun adapted plants.
  2. Heliophytes 2. Plants permanently immersed in water.
  3. Hydrophytes 3. Plants of saline environments
  4. Halophytes 4. Shade tolerant plants.

Code:

A         B          C          D

a) 3         4          1          2

b) 1         2          3          4

c) 4         1          3          2

d) 4         1          2          3

Ans:     D

Explanation:     Individual plants, as well as plant communities adapt to different light intensities. Schiophytes are shade tolerant plants whereas heliophytes are sun-adapted plants. Plants which remain permanently immersed in water are called hydrophytes. Halophytes are plants of saline environments, which are adapted to grow in high concentration of salt in soil or water.

 

Q9. Consider the following statements:

  1. Dunaliella species are green and halophytic algae found in hyper saline lakes.
  2. Avicennia and Rhizophora are dominant species in mangrove forests.

Which of the statements given above is/are correct?

a) Only 1 , 2 and 3         b) Only 1, 2 and 4         c) Only 2, 3 and 4         d) 1, 2, 3 and 4

Ans:     C

Dunaliella species, green and halophytic algae found in hyper saline lakes, can tolerate saline conditions by accumulating glycol in the cells, which helps in osmorejulation.

Avicennia and Rizophora (red mangrove) are dominant species in mangrove forest.

 

Q10. Which of the following special adaptations are developed by halophytes as a result of their exposure to saline and anaerobic conditions in wetlands?

  1. Pneumatophores
  2. Prop
  3. Stilt roots
  4. Vivipary

a) Only 1 , 2 and 3         b) Only 1, 2 and 4         c) Only 2, 3 and 4         d) 1, 2, 3 and 4

Ans:     D

Explanation:     Since halophytes are exposed to saline and anaerobic conditions in wetlands, they have developed special adaptations, like pneumatophores, prop and stilt roots, and vivipary. The presence of pneumatophores (the respiratory roots) help to take up oxygen from the atmosphere and transport it to the main roots. Prop and stilt roots, in many species of mangrove, give support to the plants in wet substratum. Vivipary permits plants to escape the effect of salinity on seed germination.

 

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