Photosynthesis and Ecosystems Flashcards

Which human activity most directly contributes to increased atmospheric CO₂ and disrupts the carbon cycle?

Answer: Burning fossil fuels

Burning fossil fuels releases CO₂ that was stored underground for millions of years, significantly increasing atmospheric CO₂ levels.

Deforestation leads to soil erosion primarily because:

Answer: Tree roots that previously held soil in place are removed

Tree roots bind soil particles together; when trees are removed, soil becomes loose and is easily washed or blown away.

Which term describes the maximum number of individuals of a species that an ecosystem can sustainably support?

Answer: Carrying capacity

Carrying capacity is the maximum population size an environment can sustain indefinitely given available resources.

An invasive species introduced into a new ecosystem often causes harm primarily because:

Answer: It lacks natural predators to control its population

Invasive species often thrive unchecked because the new ecosystem lacks predators, parasites, or competitors that kept them in balance in their native range.

In a stable ecosystem, what keeps the populations of both predators and prey from growing without limit?

Answer: Limiting factors such as food, space, and predation

Limiting factors — including food availability, habitat space, disease, and predation — prevent any population from growing indefinitely.

Which process in the water cycle is directly driven by solar energy and moves water from the ocean into the atmosphere?

Answer: Evaporation

Solar energy heats water at the ocean surface, causing evaporation that transfers water vapor into the atmosphere.

A farmer uses pesticides that kill insects in a field. Which unintended effect on the local ecosystem is most likely?

Answer: Decline of insect-eating birds due to reduced food supply

Reducing insect populations removes a key food source for insect-eating birds, causing their numbers to decline in the area.