Daily Static MCQs for UPSC & State PSC Exams - Environment & Ecology (29 July 2023)

Daily Static MCQs Quiz for UPSC, IAS, UPPSC/UPPCS, MPPSC. BPSC, RPSC & All State PSC Exams

Subject : Environment & Ecology

1. Consider the following statements regarding Savanna type climate:

1. It is a transitional type of climate between the equatorial forest and the trade wind hot deserts.
2. It is characterized by high and year-round rainfall.
3. It covers much of Africa as well as large areas of Australia, South America, and India.

How many of the above statements are correct?

(a) Only one
(b) Only two
(c) Only three
(d) None

Answer: (B)

Explanation: Savanna or Sudan climate is a transitional type of climate found between the equatorial forests & trade wind hot deserts. It is best developed in Sudan, where dry & wet climate are most distinct, hence named Sudan climate. It covers much of Africa (Keya, Nigeria, Gambia) as well as large areas of Australia, South America (Brazilian highlands), and India. Sudan climate is characterized by an alternate & distinct hot, rainy season (from May to Sep) & cool, dry season (Oct – April) in Northern Hemisphere& vice versa in Southern Hemisphere. Hence, statement 2 is incorrect.

2. Consider the following statements:

1. Stenothermal organisms can tolerate and thrive in a wide range of temperatures.
2. Freshwater animals cannot live for long in sea water because of the osmotic problems.

Which of the above statements is/are correct?

(a) 1 only
(b) 2 only
(c) Both
(d) Neither 1 nor 2

Answer: (B)

Explanation:

  • A few organisms can tolerate and thrive in a wide range of temperatures (they are called eurythermal), but, a vast majority of them are restricted to a narrow range of temperatures (such organisms are called stenothermal). Hence, statement 1 is incorrect.
  • Many freshwater animals cannot live for long in sea water and vice versa because of the osmotic problems, they would face. Hence, statement 2 is correct.

3. Which of the following shows the symbiotic relationship (partially or fully) between Rhizobium bacteria and the plants they colonise?

1. Rhizobium bacteria colonize plant cells within root nodules, where they convert nitrous oxide from the soil into ammonia and provide organic nitrogenous compounds to the plants.
2. The plant, in turn, provides the Rhizobium bacteria with organic compounds made using photosynthesis.

Select the correct answer using the code given below:

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Answer: (C)

Explanation:

  • Rhizobium is a genus of Gram-negative soil bacteria that fix nitrogen. Rhizobium species form an endosymbiotic nitrogen-fixing association with roots of (primarily) legumes and other flowering plants.
  • Rhizobium forms a symbiotic relationship with certain plants such as legumes, fixing nitrogen from the air into ammonia, which acts as a natural fertilizer for the plants. The plant, in turn, provides the bacteria with organic compounds made by photosynthesis. This mutually beneficial relationship is true of all of the rhizobia, of which the genus Rhizobium is a typical example. Hence, both statements are correct.

4. The phenomenon of increasing concentration of a substance, such as a toxic chemical, in the tissues of tolerant organisms at successively higher levels in a food chain is known as:

(a) Bioaccumulation
(b) Biosparging
(c) Biomagnification
(d) Biodilution

Answer: (C)

Explanation: Biomagnification, also known as bioamplification or biological magnification, is the increasing concentration of a substance, such as a toxic chemical, in the tissues of tolerant organisms at successively higher levels in a food chain. Hencve, option (c) is correct.

5. Ecological Succession is generally characterized by:

1. Increased productivity
2. Decreased niche development
3. Increased complexity of food webs

Select the correct answer using the code given below:

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Answer: (C)

Explanation:

  • Ecological succession is the process by which the structure of a biological community evolves over time. The time scale can be decades (for example, after a wildfire), or even millions of years after a mass extinction.
  • The community begins with relatively few pioneering plants and animals and develops through increasing complexity until it becomes stable or self-perpetuating as a climax community.
  • Two different types of succession—primary and secondary—have been distinguished. Primary succession occurs in essentially lifeless areas—regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. Secondary succession occurs in areas where a community that previously existed has been removed; it is typified by smaller-scale disturbances that do not eliminate all life and nutrients from the environment.
  • Increased niche development is the characteristic feature of Ecological succession.

Hence, option (c) is correct.