The Prayas ePathshala

Exams आसान है !

Q1. Plants prepare Glucose in the process of:

Solution: c)

In contrast to humans and other animals, plants can produce glucose through a process known as photosynthesis. The green parts of plants use sunlight, water, and the gas carbon dioxide from the air to produce glucose and oxygen.

Q2. Increased Snow cover on a water body can lead to:

Sudden spurt in phytoplankton population which are not dependent on photosynthesis.
Improved oxygen exchange and nutrient recycling in the lake.
A condition of winterkill causing large scale death of fishes and organisms.

How many of the above statements is/are correct?

(a) Only one

(b) Only two

(d) None

Solution: a)

Only statement 3 is correct.
Phytoplankton float on top surface of water bodies and require sunlight to thrive. Ice cover will reduce their breeding grounds and population.
The snow cover blocks exchange of nutrients and oxygen from the atmosphere, however the same may continue within the water stream. But it is worse than before.
Snow cover of ice on water body can effectively cut off light, plunging the waters into darkness.
Hence photosynthesis stops but respiration continues. Thus, in shallow lakes, oxygen gets depleted, and due to lack of oxygen there is large scale death of fishes and other organisms. This condition is known as winterkill.

Q3. Consider the following statements regarding Black Carbon:

Black carbon is a component of fine particulate matter, formed through the incomplete combustion of fossil fuels, biofuel, and biomass.
In the tropics, black carbon in soils significantly contributes to the soil fertility.
Black carbon significantly increases the albedo when deposited on snow and ice.

How many of the above statements is/are correct?

(a) Only one

(b) Only two

(d) None

Solution: b)

Statement 3 is incorrect.
Black carbon (BC) is a component of fine particulate matter. Black carbon consists of pure carbon in several linked forms. It is formed through the incomplete combustion of fossil fuels, biofuel, and biomass, and is emitted in both anthropogenic and naturally occurring soot. Black carbon causes human morbidity and premature mortality.
In climatology, black carbon is a climate forcing agent. Black carbon warms the Earth by absorbing sunlight and heating the atmosphere and by reducing albedo when deposited on snow and ice.
In the tropics, black carbon in soils significantly contributes to fertility as it is able to absorb important plant nutrients.

Q4. Consider the following statements:

Cold water corals, in general, have greater amount of zooxanthellae than warm water corals and does not build reef-like structures.
Cold-water corals differ from warm water corals because the former does not contain symbiotic algae for photosynthesis and grow more slowly.

Which of the above statements is/are incorrect?

Solution: a)

Corals that inhabit the colder deep waters of continental shelves and offshore canyons, ranging from 50 to over 1000m depths lack zooxanthellae and may build reef-like structures or occur solitarily.
Cold-water corals are different from their warm-water counterparts because they do not contain symbiotic algae for photosynthesis and grow more slowly. Cold-water corals obtain all their energy from organic matter and zooplankton, which they catch from the currents drifting past.
Cold-water corals can be found over a wide range of latitudes, from tropical to Polar Regions, and from the shallow to the deep seas.

Q5. Oil spills can be treated with bioremediation by using some species of:

How many of the above options are correct?

Solution: d)

Bioremediation refers to the use of specific microorganisms or plants to metabolize and remove harmful substances. These organisms are known for their biochemical and physical affinity to hydrocarbons among other pollutants. Various types of bacteria, archaea, algae, fungi, and some species of plants are all able to break down specific toxic waste products into safer constituents.