Question 11:
The term “standing crop” refers to:
(A) The total biomass of living organisms in a specific trophic level at a given time
(B) The rate of energy flow in an ecosystem
(C) The reproductive capacity of a population
(D) The total number of species in an ecosystem
Answer: (A) The total biomass of living organisms in a specific trophic level at a given time
Explanation:
Standing crop refers to the total biomass present in a given trophic level at a particular time. It reflects the amount of living material available in the ecosystem at that specific moment.
Question 12:
In a typical pyramid of energy, what percentage of energy is transferred from one trophic level to the next?
(A) 1%
(B) 10%
(C) 30%
(D) 50%
Answer: (B) 10%
Explanation:
According to the 10% law, only about 10% of the energy at one trophic level is passed on to the next trophic level, while the remaining 90% is lost as heat, metabolism, and other biological processes.
Question 13:
Which type of biome is characterized by high temperatures and heavy rainfall throughout the year?
(A) Desert
(B) Tundra
(C) Tropical rainforest
(D) Grassland
Answer: (C) Tropical rainforest
Explanation:
Tropical rainforests are characterized by consistently high temperatures and heavy rainfall year-round. These biomes are home to diverse species and exhibit complex and dense vegetation due to the favorable conditions for plant growth.
Question 14:
The relationship between a bee and a flowering plant is an example of:
(A) Parasitism
(B) Mutualism
(C) Commensalism
(D) Competition
Answer: (B) Mutualism
Explanation:
In mutualism, both species benefit from the relationship. A bee obtains nectar (food) from a flowering plant, and in return, the bee helps in pollination, which is essential for the plant’s reproduction. Both the bee and the plant gain from this interaction.
Question 15:
Which of the following nutrient cycles does not have an atmospheric component?
(A) Carbon cycle
(B) Nitrogen cycle
(C) Phosphorus cycle
(D) Water cycle
Answer: (C) Phosphorus cycle
Explanation:
The phosphorus cycle lacks a significant atmospheric component because phosphorus does not typically exist as a gas under normal environmental conditions. It primarily cycles through rocks, soil, water, and living organisms.
Question 16:
Which of the following processes in the carbon cycle is primarily responsible for removing CO₂ from the atmosphere?
(A) Respiration
(B) Photosynthesis
(C) Decomposition
(D) Combustion
Answer: (B) Photosynthesis
Explanation:
Photosynthesis, carried out by plants and other autotrophs, is the primary process that removes carbon dioxide (CO₂) from the atmosphere. During photosynthesis, CO₂ is converted into organic compounds such as glucose, which can be used for growth and energy storage.
Question 17:
Which trophic level contains the highest amount of energy in an ecosystem?
(A) Producers
(B) Primary consumers
(C) Secondary consumers
(D) Tertiary consumers
Answer: (A) Producers
Explanation:
Producers, such as plants, contain the highest amount of energy because they convert solar energy into chemical energy through photosynthesis. This energy is then transferred to consumers at higher trophic levels, but with decreasing amounts due to energy loss at each step.
Question 18:
What does “keystone species” refer to in an ecosystem?
(A) The most abundant species in an ecosystem
(B) A species that plays a critical role in maintaining the structure of an ecosystem
(C) A species at the top of the food chain
(D) A species that is highly susceptible to extinction
Answer: (B) A species that plays a critical role in maintaining the structure of an ecosystem
Explanation:
A keystone species has a disproportionately large impact on its ecosystem relative to its abundance. It plays a critical role in maintaining the structure, diversity, and balance of the ecosystem, and its removal can lead to significant changes in the ecosystem’s composition.
Question 19:
What does the term “biomagnification” refer to?
(A) Increase in population size
(B) Accumulation of pollutants in organisms at higher trophic levels
(C) Transfer of energy between trophic levels
(D) Growth of plant biomass
Answer: (B) Accumulation of pollutants in organisms at higher trophic levels
Explanation:
Biomagnification refers to the process by which certain toxic substances (such as pesticides or heavy metals) become more concentrated as they move up the food chain. Organisms at higher trophic levels accumulate more of these toxins, leading to harmful effects.
Question 20:
Which of the following represents a climax community in ecological succession?
(A) A barren rock
(B) A mature forest
(C) A pond with algae
(D) A grassland
Answer: (B) A mature forest
Explanation:
A climax community is the final, stable stage of ecological succession, where the ecosystem has reached equilibrium. A mature forest is an example of a climax community, where species diversity and population sizes are relatively stable over time.
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