Carbon Cycle

Q.

Fill in the blanks.

(a) Plants are called as ___ because they fix carbon dioxide.

(b) In an ecosystem dominated by trees, the pyramid (of numbers) is___ type.

(c) In aquatic ecosystems, the limiting factor for the productivity is ___

(d) Common detritivores in our ecosystem are ___

(e) The major reservoir of carbon on Earth is ___

Q. The main role of bacteria in carbon cycle involves

1. Breakdown of organic compounds
2. Chemosynthesis
3. Fixation of atmospheric nitrogen
4. Photosynthesis

Q. How many molecules of CO${}_2$ are released in one turn of Krebs cycle?

1. 2
2. 3
3. 4
4. 6

Q.

Outline salient features of carbon cycling in an ecosystem.

Q. Why is carbon called the basis for life on earth?

1. Carbon can form stable bonds with other elements
2. Both b and c
3. Carbon is inert and does not react with other elements
4. Carbon dioxide is abundant in the atmosphere

Q. Biogeochemical cycle means

1. cycling of nutrients in an ecosystem
2. cycling of organic compounds only
3. cycling of energy in an ecosystem only
4. cycling of gases between plants and atmosphere only

Q.

On an annual basis, approximately what percentage of all the carbon dioxide in the atmosphere is fixed by photosynthesis?

1. 100%

2. 70%

3. 10%

4. 1%

Q. In the carbon cycle, the human body directly returns carbon to the atmosphere through this way:

1. Photosynthesis
2. Formation of glucose
3. Urination
4. Cellular respiration

Q. How does photosynthesis help to maintain the percentage of oxygen and carbon dioxide in the atmosphere?

1. By giving off carbon dioxide and absorbing oxygen
2. By giving off oxygen and absorbing carbon dioxide
3. By releasing oxygen and carbon dioxide
4. By absorbing oxygen and carbon dioxide.

Q. Why photorespiration occurs?for what purpose?

Q.

Human activities interfere with carbon cycle. List any tow such activities.

Q.

Fill in the blanks.

(a) Plants are called as_________ because they fix carbon dioxide.

(b) In an ecosystem dominated by trees, the pyramid (of numbers) is _________ type.

(c) In aquatic ecosystems, the limiting factor for the productivity is _________.

(d) Common detritivores in our ecosystem are_________.

(e) The major reservoir of carbon on earth is_________.

Q. Which one of the following plants is considered as a potential petro-crop?

1. Jatropha curcas
2. Euphorbia tirucalli
3. Ricinus communis
4. Pongamia glabra

Q. If the energy transferred to a tertiary consumer in a food chain is 10 J, how much energy was available to the primary consumer?​

Q. Which of the following cycles involve photosynthesis and cellular respiration?

1. Sulphur cycle
2. Carbon cycle
3. Nitrogen cycle
4. Phosphorus cycle

Q. Which is correct about GPP and NPP in ecosystem?

1. NPP = GPP – Plant respiration
2. NPP = GPP + Plant respiration
3. NPP = GPP – Animal respiration
4. NPP = GPP + Animal respiration

Q. Fill in the blanks.
(a) Plants are called as .......... because they fix carbon dioxide.
(b) In an ecosystem dominated by trees, the pyramid (of numbers) is .......... type.
(c) In aquatic ecosystems, the limiting factor for the productivity is ..........
(d) Common detritivores in our ecosystem are ..........
(e) The major reservoir of carbon on earth is ..........

Q.

How is carbon dioxide added in atmosphere?

Q. Assertion :Oceans are a low productivity ecosystems despite occupying about $70\%$ of the earth's surface. Reason: In aquatic ecosystems, productivity is limited by light which decreases with increasing water depth.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. During the carbon cycle, which of the following carbon compounds would be utilized as an energy source by heterotrophs?

1. Carbon dioxide
2. Carbon monoxide
3. Carbonic acid
4. Organic molecules

Q. There are nearly 10 million carbon compounds in living things.

1. True
2. False

Q. Global warming and climate change is altering environmental niches, causing:

1. Movement of thousands of ocean species poleward from the equator
2. Terrestrial organisms to adapt and become marine
3. Species to rapidly increase in number
4. Accumulation of helium gas in organisms

Q. There are nearly 10 million carbon compounds in living things.

1. True
2. False

Q. During the carbon cycle, hetrotrophs utilise carbon in forms.

1. gaseous
2. inorganic
3. acidic
4. organic

Q. Explain carbon cycle.

Q. A non-biological source of carbon dioxide is

1. Volcanic eruptions
2. Hot springs
3. Weathering
4. All of the above

Q. Give schematic representation of carbon cycle.

Q. Why is carbon called the basis for life on earth?

1. Carbon is inert and does not react with other elements
2. Carbon dioxide is abundant in the atmosphere
3. Carbon can form stable bonds with itself and other elements
4. Both b and c

Q. (a)Why is Charcoal considered better fuel than wood?
(b)Write one disadvantage of converting wood into Charcoal.

Q. Which of the following cycles involve photosynthesis and cellular respiration?

1. Sulphur cycle
2. Carbon cycle
3. Nitrogen cycle
4. Phosphorus cycle