• humans bitten by snakes.

• roads built on the island.

• lizards living in the trees.

• hours of sunlight each day.

If humans over-hunted a population of insect-eating birds, what immediate change would likely be seen in the area?

• Severe loss of vegetation.

• Migration of small mammals.

• Increased seedling germination.

• Increasing populations of insects.

If humans cleared a forest and built homes where the forest once was, we would expect which of the following?

• More development of soil.

• Fewer tree-dwelling animals.

• More frequent thunderstorms.

• Increased insect populations.

If a factory polluted the water supply in an area, what change would likely be observed in that ecosystem?

• New insects moving in to the region.

• More birds nesting in trees.

• Local trees growing taller.

• Fewer pond plants and animals.

Humans brought the first pigs to Hawaii more than 1,000 years ago. The pigs have no predators and eat nearly anything. Which of the following is a negative impact that might result from the introduction of pigs to the Hawaiian rainforest ecosystem?

• Fewer plants to hold soil in place.

• More kinds of insect species.

• Less rainfall throughout the year.

• Increased destruction by volcanoes.

• Birds depend on humans to provide food in bird feeders.

• Humans often hunt and kill animals that prey on birds.

• Many humans enjoy observing birds in the environment.

• Building more houses for humans removes trees birds need.

The ecosystem of some dairy cows includes the fields in which they graze, eating the grass they need. Too many cows can be harmful to their ecosystem because they could -

• produce too much milk.

• scare away predators .

• raise the temperature.

• remove all the vegetation .

A private landowner buys a large field in west Texas. She hires a snake catcher, who

removes all the bull snakes from her property. Which of the following will most likely

result?

• The number of spiders in the field will increase.

• The number of mice in the field will increase.

• The number of trees in the field will decrease.

• The number of deer in the field will decrease.

To protect their cows and sheep, ranchers killed every wolf, mountain lion, and

coyote they could find. Soon after, why did farmers start losing their crops to rabbits

and deer?

• There were no natural predators to keep the deer and rabbit populations under

  control.

• The farmers were able to also raise rabbits and deer and used their crops to feed

  them.

• Before the ranchers killed them all, the large predators guarded crops for the

  farmers.

• The deer and rabbits were starving because the ranchers had destroyed their food

  sources.

• Gradual cooling of the global climate

• An increase in the number of species on Earth

• Deforestation and other environmental destruction

• Less dependence on fossil fuels and increased use of alternative fuel sources