12.4 Processes to maintain stable ecosystem

(a)   ​and ​ (b)   are both important processes involved in maintaining a stable ecosystem.​

• Photosynthesis
• respiration
• Decomposition
• parasitism

Which type of organisms can carry out photosynthesis?

• producers

• primary consumers

• secondary consumers

• tertiarty consumers

During which process does glucose (sugar) react with oxygen release energy that can be used for growth?

• Photosynthesis

• Cellular respiration

• Decomposition

• Combustion

Which energy in food is used by a consumer during respiration?

• Elastic potential energy

• Kinetic energy

• Gravitational potential energy

• Chemical potential energy

In an ecosystem, the flow of ​ (a)   occurs together with the flow of ​ (b)   .

• energy
• nutrients
• water
• light

_________ feed on the remains of dead organisms and faeces.

• Primary consumers

• Secondary consumers

• Tertiary consumers

• Decomposers

At each stage of a food chain, what percentage of energy is released as heat?

• 10%

• 50%

• 75%

• 90%

Producers absorb light energy from the sun, which is used to produce food through photosynthesis. The food produced stores chemical potential energy.

What would happen to the energy stored in the food produced by producers?

(3 correction options)

• When producers respire, the energy stored in the food is released and used for life processes.

• The energy stored in the food is passed on to consumers that feed on the producers.

• When consumers feed on producers, 90% of the energy stored in the food is released into the environment as heat.

• After consumers feed on producers, the energy stored in the food is recycled to be used by producers again.

Energy that is released as heat by each organism in a food chain cannot be reused as it is lost to the surroundings.

Thus, the flow of energy in a food chain is said to be _________.

• cyclical

• non-cyclical

Nutrients are transferred from producers to consumers through eating.

Decomposers break down dead organisms and faeces, and return the nutrients to the environment.

Thus, the flow of nutrients in an ecosystem is said to be ________.

• cyclical

• non-cyclical