Question

8 which of the following best describes the components of an ecosystem?
a ecosystems consist of biotic and abiotic factors that interact within a defined area
b ecosystems only include plants and animals
c ecosystems are solely based on the physical environment
d only living organisms interact with each other
9 in an ecosystem, which organisms convert sunlight into energy-rich organic compounds?
a primary producers
b tertiary consumers
c decomposers
d consumers

1. what organisms play a vital role in breaking down organic matter and returning nutrients to the soil?

a primary producers
b decomposers
c tertiary consumers
d secondary consumers
11 what is the primary function of decomposers in an ecosystem?
a to compete with producers for resources
b to break down dead organic matter and return nutrients to the soil
c to prey on herbivores
d to convert sunlight into energy

1. which of the following is not a characteristic of a keystone species?

a it has a large population
b it plays a critical role in maintaining ecosystem structure
c it influences the types and numbers of other species
d its removal can lead to significant changes in the ecosystem
13 which level of ecological organization includes multiple individuals of the same species?
a population
b ecosystem
c community
d individual
14 why is efficiency in energy transfer important for ecosystems?
a it determines the number of species present
b it regulates the water cycle
c it influences population stability and supports higher trophic levels
d it affects the composition of the atmosphere

Explanation:

• Question 8: An ecosystem is a community of biotic (living) and abiotic (non - living) factors interacting in a defined area. Option a is correct as it includes both biotic and abiotic factors. Option b is wrong because ecosystems also include abiotic factors. Option c is incorrect as ecosystems are based on interactions between biotic and abiotic, not just physical environment. Option d is wrong as both living and non - living interact.
• Question 9: Primary producers (like plants) convert sunlight into energy - rich organic compounds through photosynthesis. Tertiary consumers eat secondary consumers, decomposers break down dead matter, and consumers eat producers or other consumers. So, option a is correct.
• Question 10: Decomposers (e.g., fungi, bacteria) break down organic matter and release nutrients back to the soil. Primary producers make food, tertiary consumers are high - level consumers, and secondary consumers eat primary consumers. So, option b is correct.
• Question 11: The primary function of decomposers is to break down dead organic matter and return nutrients to the soil. They do not compete with producers for resources (option a wrong), do not prey on herbivores (option c wrong), and do not convert sunlight into energy (option d wrong). So, option b is correct.
• Question 12: A keystone species has a disproportionately large effect on its environment relative to its abundance. It does not need to have a large population. Options b, c, and d are characteristics of keystone species. So, option a is correct.
• Question 13: A population is a group of multiple individuals of the same species. An ecosystem has biotic and abiotic components, a community has multiple species, and an individual is a single organism. So, option a is correct.
• Question 14: Efficiency in energy transfer (e.g., 10% rule in food chains) influences population stability and supports higher trophic levels. It does not determine the number of species (option a wrong), regulate the water cycle (option b wrong), or affect the composition of the atmosphere (option d wrong). So, option c is correct.

Answer:

1. A. Ecosystems consist of biotic and abiotic factors that interact within a defined area
2. A. Primary producers
3. B. Decomposers
4. B. To break down dead organic matter and return nutrients to the soil
5. A. It has a large population
6. A. Population
7. C. It influences population stability and supports higher trophic levels