Threats to Biodiversity

_____________ extinctions occur naturally over time and do not concern scientists.  Many are worried that the current extinction rate is about 1,000 times higher.

• Background

• Extinction

What has occurred during each of the Earth's mass extinctions?

• Most of the Earth's islands have become uninhabited.

• A new dominant species has been introduced to the Earth.

• Humans hunted many animals for food and clothing.

• The Earth has lost at least three-quarters of its species.

Some people believe that the Earth is currently experiencing its sixth mass extinction

because_____________

• The background extinction rates are happening gradually

• the Earth's climate has stayed relatively unchanged

• The extinction rate has greatly increased due to human actions

• There are now laws to protect the habitats of many species

Identify the human action that could potentially lead to habitat fragmentation.

• recycling, reusing, and reducing waste to reduce pollution

• animals hunting as a sport

• cutting down some trees to build a road through a habitat

• accidentally introducing a nonnative species to the habitat

Select the effects of habitat fragmentation on biodiversity. (2 answers)

• increase in edge habitats

• chances of finding a mate increase

• carrying capacity increases

• carrying capacity decreases

• increase in interior habitats

Habitat fragmentation can negatively impact______ opportunities for species to find mates.  diversity by reducing

• Extinction

• genetic

• Background

In a typical food web, a(n)__________ of a pollutant in its body. is likely to have the lowest concentration

• producer

• genetic

Chemicals, like DDT, enter the tissues of animals by.

• feeding on other organisms

• living in an edge habitat

• interacting with populated areas

• breathing the chemicals in the air

Chemicals such as polychlorinated biphenyls (PCBs) enter ecosystems through__________

• industrial runoff

• producer

• genetic

Bonus

• LION

• RYAN

• SIMB