EnvSci 7:1 What causes extinction and what are its impacts?

Human population growth can lead to increases in species extinctions by reducing the habitat available for many species.

• true

• false

The loss of orangutans from tropical rain forests would have few impacts on other species in those ecosystems.

• True

• False

If speciation occurs more rapidly than extinction, the result is a net increase in extinction.

• True

• False

How many mass extinctions has Earth experienced throughout its history?

• none

• one

• five

• six

• hundreds

Extinction rates began rising above the natural background rate after _____.

• Earth’s first recorded ice age

• the end of the last mass extinction

• the appearance of modern humans

• the global climate started to change

• the end of the twentieth century

Colony collapse disorder causes honeybees to _____.

• stop making honey

• abandon their hives

• become more aggressive

• stop living together in groups

• stop reproducing

An endangered species is best described as any species that _____.

• has fewer than two individuals remaining

• is in danger of becoming rare

• will soon become extinct in all or part of its range

• may eventually become threatened

• is considered economically important

Compared to previous mass extinctions, a sixth mass extinction would _____.

• be very unlikely to happen

• take several million years to occur

• involve a much more rapid return of biodiversity

• happen in the course of a human lifetime

• only happen in the absence of human activity

Orangutans are losing habitat in the tropical rain forests where they live, mainly because land there is being _____.

• cleared due to timber harvesting

• converted to cattle ranches

• developed for ecotourism

• converted to oil palm plantations

• destroyed by periods of drought

According to the IUCN, most of the endangered bird species on its Red List have declined primarily due to which human-related factor?

• exotic pet trade

• overhunting

• invasive species

• pollution

• pesticide use