Chapter Exam

Chapter 7: Ecosystem — Online MCQ Test

Q: Who coined the term 'Ecosystem' in the year 1935?

Answer: B. A.G. Tansley — The term 'Ecosystem' was first proposed by the British ecologist A.G. Tansley in 1935.

Q: Net primary productivity (NPP) is calculated using which of the following equations?

Answer: A. NPP = GPP - Respiration loss (R) — Net Primary Productivity (NPP) is the remaining organic matter stored by producers after accounting for respiratory utilization (R). Thus, NPP = GPP - R.

Q: Read the biological definitions below: X: The amount of living organic matter present in a trophic level of an ecosystem at a given time. Y: The total amount of inorganic nutrients (such as carbon, nitrogen, phosphorus) present in the soil/abiotic environment of an ecosystem at a given time. Identify X and Y correctly:

Answer: A. X = Standing Crop, Y = Standing State — Standing crop refers to the mass of living material (biomass) present at each trophic level. Standing state is the amount of inorganic nutrients present in the abiotic components of the ecosystem.

BOTANY · CLASS 12th · Tamil Nadu State Board

Practice Chapter 7: Ecosystem with a free chapter-wise online MCQ test for Tamil Nadu State Board CLASS 12th BOTANY. This chapter covers: This chapter details ecosystem structure functions energy flow and biogeochemical cycles. Students examine primary and secondary productivity food chains food webs ecological pyram.... AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 7: Ecosystem — Important Questions & Answers (FAQ)

Frequently asked questions from Tamil Nadu State Board CLASS 12th BOTANY — Chapter 7: Ecosystem, with answers and explanations. These are sample questions; the exam has its own separate question set.

Who coined the term 'Ecosystem' in the year 1935?

A. E.P. Odum
B. A.G. Tansley ✓
C. Ernst Haeckel
D. Karl Mobius

Answer: B. A.G. Tansley
The term 'Ecosystem' was first proposed by the British ecologist A.G. Tansley in 1935.

Net primary productivity (NPP) is calculated using which of the following equations?

A. NPP = GPP - Respiration loss (R) ✓
B. NPP = GPP + Respiration loss (R)
C. NPP = GPP / Respiration loss (R)
D. NPP = Gross Primary Productivity only

Answer: A. NPP = GPP - Respiration loss (R)
Net Primary Productivity (NPP) is the remaining organic matter stored by producers after accounting for respiratory utilization (R). Thus, NPP = GPP - R.

In a lithosere succession on bare rock, which of the following represents the correct sequence of pioneer and early seral stages?

A. Foliose lichens -> Crustose lichens -> Mosses -> Herbs
B. Crustose lichens -> Foliose lichens -> Mosses -> Herbs ✓
C. Mosses -> Crustose lichens -> Foliose lichens -> Shrubs
D. Blue-green algae -> Mosses -> Crustose lichens -> Trees

Answer: B. Crustose lichens -> Foliose lichens -> Mosses -> Herbs
On bare rock, crustose lichens act as the pioneer species. They disintegrate rocks to form soil, paving the way for foliose lichens, mosses, and subsequently herbs.

Why is the pyramid of biomass in a pond ecosystem generally inverted, unlike the upright pyramid of biomass in a forest ecosystem?

A. The trophic levels in a pond ecosystem are fewer than those in a forest ecosystem.
B. The standing crop biomass of phytoplanktons (producers) is much lower than the consumers at any given time due to their rapid turnover rate. ✓
C. Phytoplanktons have a much lower rate of reproduction compared to the fish.
D. Aquatic consumers are physiologically smaller and lighter than terrestrial consumers.

Answer: B. The standing crop biomass of phytoplanktons (producers) is much lower than the consumers at any given time due to their rapid turnover rate.
The biomass of phytoplanktons is low at any single point in time, but they reproduce and grow extremely fast to continuously support a larger biomass of zooplanktons and fish.

Read the biological definitions below: X: The amount of living organic matter present in a trophic level of an ecosystem at a given time. Y: The total amount of inorganic nutrients (such as carbon, nitrogen, phosphorus) present in the soil/abiotic environment of an ecosystem at a given time. Identify X and Y correctly:

A. X = Standing Crop, Y = Standing State ✓
B. X = Standing State, Y = Standing Crop
C. X = Biomass, Y = Humus
D. X = Productivity, Y = Detritus

Answer: A. X = Standing Crop, Y = Standing State
Standing crop refers to the mass of living material (biomass) present at each trophic level. Standing state is the amount of inorganic nutrients present in the abiotic components of the ecosystem.