8 Environmental Change and Ecological Interactions Free Online FlashCards

What makes an ecological system an ecosystem?

An ecosystem consists of a community of organisms and the nonliving environment with which they interact.

How do abiotic and biotic factors differ?

Abiotic factors are nonliving conditions, such as temperature and light. Biotic factors are living influences, such as predators, competitors, and food sources.

What is carrying capacity, and why can it change?

Carrying capacity is the population size an environment can support under particular conditions. It can change when resources or habitat conditions change.

How do density-dependent and density-independent pressures differ?

Density-dependent pressures, such as competition or disease, intensify as a population becomes more crowded. Density-independent events, such as severe storms, can affect populations regardless of density.

How does energy move through an ecosystem?

Energy usually enters as sunlight captured by producers, then passes through consumers and decomposers. Less energy is available at higher trophic levels because some is released as heat at each transfer.

How does matter move through ecosystems?

Matter is recycled through ecosystems: decomposition returns materials to the environment, and elements such as carbon and nitrogen move among organisms, soil, air, and water.

How can fertilizer runoff harm aquatic life?

Excess nitrogen or phosphorus can trigger rapid algal growth. When algae die and decompose, oxygen can be depleted, harming aquatic organisms.

What is ecological succession?

Ecological succession is community change after a disturbance as species colonize and replace one another over time. Recovery may produce a different community if conditions have changed or disturbances recur.

How might removing a major predator affect plants?

Removing a major predator may increase its prey, which can then consume more plants. The actual effects depend on the food web and other limiting factors.

What forms of variation does biodiversity include?

Biodiversity includes variation within species, among species, and among ecosystems. It also reflects the variety of ecological roles in a community.

At what level does evolution occur, and what makes it possible?

Populations evolve when heritable traits affect survival and reproductive success across generations. Individual organisms do not evolve.

How can habitat fragmentation affect populations?

Fragmentation divides habitat, potentially limiting access to food, shelter, and mates and isolating populations.