Biology Questions and Answers – Ecosystem – Decomposition – 1

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This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Ecosystem – Decomposition – 1”.

1. Which organism is said to be a farmer’s friend?
a) Rat
b) Earthworm
c) Bat
d) Leopard
View Answer

Answer: b
Explanation: The earthworm is said to be a farmer’s friend. The earthworm is a tubular, segmented invertebrate organism commonly found in soil that survives on eating live and dead organic matter. They improve the health of the soil by break down soil substances and loosening it.
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2. Which are the organisms called those who are responsible for the break down complex organic matter into inorganic substances?
a) Decomposers
b) Producers
c) Consumers
d) Herbivores
View Answer

Answer: a
Explanation: The organisms that are responsible for the break down complex organic matter (dead or decaying organisms) into inorganic substances are called decomposers (detritivores). The decomposers or detritivores may include invertebrates, fungus or bacteria.

3. What is the process of break down complex organic matter into inorganic substances called?
a) Organization
b) Decomposition
c) Production
d) Consumption
View Answer

Answer: b
Explanation: The physical and chemical process of break down complex organic remains (dead or decaying organisms) into inorganic substances is called decomposition. It is carried out by the organisms called decomposers (invertebrates, fungus or bacteria).
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4. What are the complex organic remains such as dead animal remains, dead plant remains, and fecal matter called?
a) Humus
b) Mucus
c) Excreta
d) Detritus
View Answer

Answer: d
Explanation: The organic remains such as dead plants remain, dead animal remains and fecal matter is called detritus. It acts as the raw material for various organisms such as decomposers. In terrestrial ecosystems, it is called “soil organic matter” while in the aquatic system it is known as “marine snow”.

5. Which organisms carry out the fragmentation of detritus?
a) Sponges
b) Vertebrates
c) Detritivores
d) Zooplankton
View Answer

Answer: c
Explanation: The process of fragmentation of detritus is done by detritivores. These are also known as decomposers and are the organisms responsible for the break down complex organic matter (dead or decaying organisms) into inorganic substances.
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6. Which of the following is an example of detritivore?
a) Monkey
b) Termites
c) Elephant
d) Flat-worm
View Answer

Answer: b
Explanation: Among the above-given options, a termite is one of the best examples of detritivores. They are essential as they keep the forests healthy. They feed on dead decaying plants and aerate the soil as they move through it.

7. What is the process of secretion of digestive enzymes by decomposers to convert insoluble complex organic molecules into simple soluble organic and inorganic molecules called?
a) Fragmentation
b) Decomposition
c) Humification
d) Catabolism
View Answer

Answer: d
Explanation: The process of secretion of digestive enzymes by decomposers to convert insoluble complex organic molecules into simple soluble organic and inorganic molecules is called catabolism. It is the catabolic metabolism in which degradation occurs.
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8. What is the process called when detritivores feed on larger pieces and leave smaller fragments behind?
a) Leaching
b) Catabolism
c) Fragmentation
d) Mineralization
View Answer

Answer: c
Explanation: The process called when detritivores feed on larger pieces and leave smaller fragments behind is called fragmentation. It is carried out by many detritivores such as carrion beetles, earthworms, termites, etc.

9. What is the process of the formation of a dark-colored amorphous substance called?
a) Leaching
b) Catabolism
c) Fragmentation
d) Humification
View Answer

Answer: d
Explanation: The process of formation of dark-colored amorphous substance is called humification. This substance is called humus that is highly resistant to any microbial action and decomposes at a slower rate.
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10. What is the dark amorphous organic matter rich in cellulose and lignin that is highly resistant to any microbial action and decomposes at a slower rate called?
a) Fragments
b) Enzymes
c) Humus
d) Minerals
View Answer

Answer: c
Explanation: The dark amorphous organic matter rich in cellulose and lignin that is highly resistant to any microbial action and decomposes at a slower rate is called humus. It is formed due to the decomposition of the organic remains such as dead plants remains dead animal remains and fecal matter.

11. What is the percolation of the soluble substances formed due to decomposition called?
a) Humification
b) Leaching
c) Mineralization
d) Catabolism
View Answer

Answer: b
Explanation: The percolation of the soluble substances formed due to decomposition into deeper layers of soil is called leaching. In this process, the water-soluble inorganic nutrients get precipitated as unavailable salts by going down into the soil horizon.

12. Which substances are formed along with humus due to the decomposition process?
a) Organic substances
b) Minerals
c) Inorganic substance
d) Fragments
View Answer

Answer: c
Explanation: The substances are formed along with humus due to the decomposition process are inorganic nutrients. This gives rise to many metal ions such as iron, cobalt, potassium, selenium, zinc, etc.

13. What is the process of release of inorganic substances both minerals and non-minerals from organic matter called?
a) Fragmentation
b) Mineralization
c) Humification
d) Leaching
View Answer

Answer: b
Explanation: The process of release of inorganic substances both minerals (H2O, CO2, etc.) and non-minerals from organic matter (e.g. Ca2+, NH4, Mg2+, K+, etc.) is called mineralization. It is the last step in the process of decomposition. These minerals are again used by plants for food production.

14. How many steps are involved in the process of decomposition?
a) 10
b) 2
c) 8
d) 5
View Answer

Answer: d
Explanation: The physical and chemical process of break down complex organic remains (dead or decaying organisms) into inorganic substances is called decomposition. The decomposition is a 5 step process. The steps are fragmentation, leaching, catabolism, humification, and mineralization respectively.

15. What does decomposition depend on?
a) Oxygen
b) Nitrogen
c) Ammonia
d) Carbon monoxide
View Answer

Answer: a
Explanation: The process of break down complex organic matter (dead or decaying organisms) into inorganic substances is called decomposition. It is an aerobic process and is largely dependent on the availability of oxygen.

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