Factors Affecting Decomposition

Q. The rate of decomposition is faster in the ecosystem due to following factors EXCEPT:

1. Detritus rich in sugars
2. Warm and moist environment
3. Presence of aerobic soil microbes
4. Detritus richer in lignin and chitin

Q. Most important climatic factors that regulate the rate of decomposition are

1. temperature and soil moisture
2. soil pH and aeration
3. aeration and temperature
4. moisture and soil pH

Q. Why moist and warm conditions favours decomposition?

Q. Decomposition is an ___ dependent process.

1. None of the above
2. Oxygen
3. Nitrogen
4. Carbon dioxide

Q. Match column I with column II, and choose the correct
combination from the options given below.

	Column I		Column II
a.	Detritus	1.	Partially decomposed leaves
b.	Catabolism	2.	Dark coloured amorphous substance
c.	Humus	3.	Bark and faecal matter
d.	Litter	4.	Enzymatic process

1. $\begin{array}{cccc}a& b& c& d\\ 1& 4& 3& 2\end{array}$
2. $\begin{array}{cccc}a& b& c& d\\ 1& 4& 2& 3\end{array}$
3. $\begin{array}{cccc}a& b& c& d\\ 4& 2& 1& 3\end{array}$
4. $\begin{array}{cccc}a& b& c& d\\ 2& 3& 4& 1\end{array}$

Q. 1)Figure shows the effect of light on the rate of photosynthesis. Based on the graph, answer the following questions:
1)At which point/s (A, B or C) in the curve is light a limiting factor?

2)What could be the limiting factor/s in region A?

3) What do C and D represent on the curve?

Q.

What could be the reason for the faster rate of decomposition in the tropics?

Q.

The chemical energy trapped in the dead bodies is released through

1. decomposition

2. fungi and bacteria

3. botha and b

4. none of these

Q.

Among the following, where do you think the process of decomposition would be the fastest?

1. Antarctic

2. Dry arid region

3. Alpine region

4. Tropical rain forest

Q. ___ soil reduces the rate of decomposition.

1. Neutral
2. Slightly alkaline
3. Alkaline
4. Acidic

Q. Regarding the assertion and reason choose the right option.
Assertion [A]: Warm and moist environment can enhance the rate of decomposition.
Reason [R]: Anaerobic condition can enhance the rate of decomposition.

1. Both A and R are true and R explains A
2. Both A and R are true R does not explain A
3. A is true and R is false
4. Both A and R are false

Q. Figure shows the effect of light on the rate of photosynthesis. Based on the graph, answer the following questions:
At which point/s (A, B or C) in the curve is light a limiting factor?

Q. Most important climatic factors that regulate the rate of decomposition are

1. temperature and soil moisture
2. soil pH and aeration
3. aeration and temperature
4. moisture and soil pH

Q. Given below is a simplified model of phosphorus cycling in a terrestrial ecosystem with four blanks (A-D). Identify the blanks.

	A	B	C	D
(1)	Rock minerals	Detritus	Litter fall	Producers
(2)	Litter	Producers	Rock minerals	Detritus
(3)	Detritus	Rock minerals	Producer	Litter fall
(4)	Producers	Litter fall	Rock minerals	Detritus

1. (3)
2. (4)
3. (2)
4. (1)

Q. When the temperature is warm and the soil is moist, the rate of decomposition will

1. decrease
2. increase
3. not be affected
4. initially decrease and then becomes stable

Q. Methanogens are

1. aerobic bacteria that can produce methane from carbon dioxide and hydrogen
2. anaerobic bacteria that can produce methane from carbon dioxide and hydrogen
3. facultative aerobic bacteria that can produce methane from carbon dioxide and hydrogen
4. facultative anaerobic bacteria that can produce methane from carbon dioxide and hydrogen

Q. Choose correct option w.r.t. significance of fermentation

1. Regenerates $NA{D}^{+}$ needed for glycolysis
2. Liberates large amount of energy
3. Allow survival of roots under waterlogged soils.
4. More than one option is correct

Q. What will happen if decomposers are not there in the environment?

Q. State whether true or false
Detritivores are found in abundance in neutral and slightly alkaline soils.

1. True
2. False

Q. When two plants L and M were exposed to different light intensities and temperatures, they showed changes in their rates of photosynthesis, which have been represented in the following graph.


The graph indicates that:

1. Plant L is a $C_3$ plant for which the light saturation point is 100% of full sunlight
2. Plant M is a $C_4$ plant for which the optimum temperature is around ${20}^{\circ }C$
3. Plant M is a $C_3$ plant which is more affected at higher temperature and higher light intensity as compared to plant L
4. Plant L is a $C_4$ plant and cannot function at light intensities above the saturation point

Q. The slow rate of decomposition of fallen logs is due to

1. poor nitrogen content
2. anaerobic environment
3. low cellulose contents
4. low moisture contents

Q. Regarding assertion and reason, choose the right option.

Assertion [A]: The rate of decomposition of detritus is reduced in the regions of higher altitude.
Reason: At higher altitudes the temperature becomes very low

1. Both A and R are correct and R does not explain A
2. Both A and R are incorrect

3. Both A and R are correct and R explains A

4. A is correct, R is incorrect

Q. Regarding the assertion and reason choose the right option.
Assertion [A]: Warm and moist environment can enhance the rate of decomposition.
Reason [R]: Anaerobic condition can enhance the rate of decomposition.

1. Both A and R are true and R explains A
2. Both A and R are true R does not explain A
3. A is true and R is false
4. Both A and R are false

Q. Slow rate of decomposition of fallen log is due to

1. poor nitrogen content
2. anaerobic environment
3. low moisture content
4. low cellulose contents

Q. Name two climatic factor that influence decomposition through their effect on soil microbes.

Q. ___ soil reduces the rate of decomposition.

1. Alkaline
2. Acidic
3. Neutral
4. Slightly alkaline

Q. Given is a table of factors affecting microbial decomposition. (${}^{\prime }{+}^{\prime }$ means 'favouring' and ${}^{\prime }{-}^{\prime }$ means inhibiting or lowering). Select the correct option.

1. High temperature- $+$, Lack of oxygen- $+$, Moist environment- $+$, Lignin and chitin in detritus- $-$
2. High temperature- $+$, Lack of oxygen- $-$, Moist environment- $+$, Lignin and chitin in detritus- $-$
3. High temperature- $-$, Lack of oxygen- $-$, Moist environment- $+$, Lignin and chitin in detritus- $-$
4. High temperature- $-$, Lack of oxygen- $+$, Moist environment- $+$, Lignin and chitin in detritus- $-$

Q. Choose the factor(s) affecting decomposition:

1. Chemical nature of decomposition products.
2. pH of the soil.
3. Temperature of the decomposition site.
4. Consumers living in the decomposition site.

Q. Figure shows the effect of light on the rate of photosynthesis. Based on the graph, answer the following questions:
What could be the limiting factor/s in region A?

Q. .......... are organisms that break down dead or decaying organisms.