Topic 2.3

Question 1

Explain the pathways of solar radiation as it passes through the atmosphere.

Answer 1

Solar radiation can be reflected, scattered, absorbed, or transmitted as it passes through the atmosphere. Some of it reaches the Earth’s surface, where it is absorbed by land, water, and living organisms.

Question 2

Define and explain productivity – gross and net.

Answer 2

• Productivity refers to the rate at which energy or biomass is produced in an ecosystem.
• Gross productivity is the total energy or biomass produced by plants through photosynthesis.
• Net productivity is the energy or biomass remaining after plants have used some for their own respiration

Question 3

Calculate net primary productivity, gross primary productivity, net secondary productivity, and gross secondary productivity from given data and diagrams.

Answer 3

• (NPP) can be calculated by subtracting the energy lost through respiration from the gross primary productivity (GPP).
• Net secondary productivity (NSP) can be calculated by subtracting the energy lost through respiration and waste production by consumers from the energy gained through consumption.

Question 4

Explain the link between net primary and net secondary productivity of a system and maximum sustainable yield.

Answer 4

• The net primary productivity (NPP) of an ecosystem sets the limit for the maximum sustainable yield of herbivores.
• While the net secondary productivity (NSP) of herbivores sets the limit for the maximum sustainable yield of carnivores or higher trophic levels.

Question 5

Describe the differences between energy flow and nutrient cycling.

Answer 5

• Energy flow involves the transfer and transformation of energy through the trophic levels of an ecosystem.
• Nutrient cycling involves the recycling of nutrients through biotic and abiotic components of an ecosystem.

Question 6

Explain how energy and matter may transfer and transform in ecosystems.

Answer 6

Energy can transfer from one organism to another through feeding relationships, while matter can be transformed and cycled through processes like photosynthesis, respiration, decomposition, and nutrient uptake.

Question 7

Discuss the impacts of human activity on energy flows and the carbon and nitrogen cycles.

Answer 7

Human activities such as deforestation, burning fossil fuels, and industrial agriculture can disrupt energy flows, increase carbon dioxide levels in the atmosphere, and lead to nitrogen pollution through excessive use of fertilizers.