Science Unit 3 Test

The body of a polar bear is able to withstand extreme cold. Temperatures of 50 degrees Fahrenheit can be too warm for them.

Could a polar bear survive in another, very warm ecosystem?

• No, the polar bear could not meet its need for colder temperatures.

• No, the polar bear could not reproduce in warmer temperatures.

• Yes, the polar bear would lose fat layers and adapt to warm temperatures.

What are the characteristics of a healthy ecosystem?

Choose TWO

• Many species are able to meet all of their needs.

• There is a healthy and stable web of life.

• Decomposers are not present in the ecosystem's web of life.

• New species are able to take over resources and reproduce quickly.

What best describes an invasive species?

• • 
    

    a new species that is introduced to an ecosystem and causes harm

• a new species that is introduced to an ecosystem and benefits existing species

• a species in an ecosystem that competes with many species for resources

• • 
    

    a species in an ecosystem that eats other species for food

Some species, such as kudzu, can completely change an ecosystem.

Kudzu is a plant native to Asia. It was brought to the southeast United States where it grew very ​ (a)   . In its new home, Kudzu ​ (b)    resources such as food, water, and sunlight. It ​ (c)    native species in the environment.

• quickly
• competes for
• crowds out

Beavers build dams across streams to create ponds for their lodges.

Which statement about ecosystems is shown by the behavior of beavers?

• The beaver dams cause fish populations to die out.

• All animals need clean water to survive.

• • 
    

    Animals always help plant populations in an ecosystem.

• Animals can change the ecosystem where they live.

Match the following

• primary consumer

• hawk

• • 
    top consumer

• grass

• • 
    secondary consumer

• field mouse

• producer

• bacteria

• decomposer

• snake

How does matter cycle between an animal and its surroundings?

Select the three correct answers.

• The animal is eaten by another animal.

• The animal dies, and its matter is broken down by decomposers.

• The matter combines with oxygen to form carbon dioxide, and is breathed out.

• The matter is burned for energy, and no longer exists.

What is photosynthesis?

In the process of photosynthesis, plants take up ​ (a)    from the air and ​ (b)    from the soil. Using the energy from sunlight, they produce ​ (c)   and release ​ (d)    into the air.

• carbon dioxide
• water
• glucose
• oxygen

What was a problem created by removing the wolves?

• The elk had no predators and populations grew out of control.

• Populations of aspen trees were able to grow once the wolves were removed.

• Beaver populations grew too large because the wolves were no longer threats.

• Elk populations decreased due to the removal of the wolves.

What was a problem created by removing the wolves?

• The elk had no predators and populations grew out of control.

• Populations of aspen trees were able to grow once the wolves were removed.

• Beaver populations grew too large because the wolves were no longer threats.

• Elk populations decreased due to the removal of the wolves.