ENVIRONMENT FOR UPSC PRELIMS 2020 , TEST-29

Q 1 . Consider the following w.r.t ‘Ecotones and Ecoclines’:
1. an ecocline describes a variation in species prevalence and is often not strictly dependent on a major physical factor separating an ecosystem from another, with resulting habitat variability.
2. an ecotone is a variation of the physicochemical environment dependent of one or two physico-chemical factors of life, and thus presence/absence of certain species.
Select the correct code:
(a) Only 1
(b) Only 2
(c) Both
(d) None

Q 2 .  Consider the following regarding ‘Keystone Species’:
1. Keystone species have lower levels of biomass in the trophic pyramid relative to the importance of their role.
2. Sea Otters are example of keystone species
Select the correct code:
(a) Only 1
(b) Only 2
(c) Both
(d) None

Q 3 . In Equatorial rainforest, the undergrowth on the floor is very less. The correct reason behind this is:
(a) Very less sunlight reaches the ground for survival of plants due to thick canopies.
(b) The hardwood trees excrete toxic resins which do not allow the plants to grow.
(c) Due to high population of herbivorous species.
(d) The soil of rainforest is less fertile due to heavy leaching of minerals.

Q 4 .  Which of the following statements are correct about life processes of plants?
1. The process of making of food with the help of photosynthesis takes place only during the day.
2. The process of respiration takes place during day and night both.
Which of the above statements are incorrect:
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Q 5 .  Consider the following statements:
1. Despite various external conditions, the organisms maintain constant internal environment like temperature and osmotic pressure. This process is called Homeostasis.
2. During winters the human body shivers to generate heat and maintain the body temperature of 37 degree Celsius.
3. During summers the body sweats profusely to maintain the temperature.
4. Plants also have the same mechanism as animals to maintain homeostasis.
Which of the above statements are correct:
(a) 1 only
(b) 1,2 and 3
(c) 1, 3 and 4
(d) All of the above

Q 6 . Consider the following statements:
1. The exchange of air (breathing) in plants takes place only through stomata present in the leaves.
2. Many desert plants have their stomata in deep pits to minimize water loss by evaporation.
3. Desert plants have a mechanism that their stomata remain closed during day time.
Which of the above statements are incorrect:
(a) 1 and 2
(b) 2 and 3
(c) 1 and 3
(d) None of the above

Q 7 . At higher elevations, people generally have breathing problems due to low pressure and lack of oxygen. This is called altitude sickness. Soon the body acclimatise this situation and and breathing becomes normal. Which of the following functions does the body take to adapt to this situation:
1. The body increases red blood cell production.
2. Body decreases the binding capacity of hemoglobin.
3. Body increases the breathing rate.
Select the correct code from the following:
(a) 1 only
(b) 2 and 3
(c) 1 and 3
(d) All of the above

Q 8 .  Consider the following statements:
1. Detrivores like earthworm, breakdown detritus into smaller particles. This process is called fragmentation.
2. Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called as catabolism.
Which of the above statements are correct:
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Q 9 . Consider the following statements regarding ‘Humus’:
1. Humus is a finely divided partially decomposed organic material in soil, whose origin cannot be traced by looking at it.
2. Humus is colloidal and helps in binding minerals in the top soil and making them available to the roots of trees.
3. It is highly resistant to microbial action and decomposes at a very slow rate.
Which of the above statements are correct:
(a) 1 and 2
(b) 2 and 3
(c) 1 and 3
(d) All of the above

Q 10 . Consider the following statements regarding energy flow from one trophic level to other trophic level:
1. The energy flow is always unidirectional, i.e. from lower trophic level to higher trophic level.
2. The energy transfer in trophic levels follows a 10% law, i.e. only 10 percent energy is transferred from lower trophic level to the next trophic level.
Which of the above statements are correct:
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2