Q: Index fossils help scientists estimate the age of a rock because index fossil species only existed for a relatively short time. What happened to the species that are now used as index fossils? OPTIONS:
- They became extinct.
- They changed their diets.
- They hid in marine sediments.
- They migrated to new environments.
A: They became extinct.

As the population of small fish in a lake decreases, the population of large fish that depend on the small fish for food will
OPTIONS:
- reproduce faster
- begin to produce their own food
- decrease in number
- increase in number

decrease in number

Q: Which three systems of the human body function together to move and control body parts? ---- OPTIONS:
- nervous, skeletal, and muscular
- muscular, endocrine, and excretory
- digestive, excretory, and reproductive
- circulatory, endocrine, and respiratory

A: nervous, skeletal, and muscular

Which of the following best describes the number of chromosomes in a normal human liver cell?
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OPTIONS:
- 23 pairs of chromosomes
- 46 different types of chromosomes
- 46 male chromosomes and 46 female chromosomes
- 23 original chromosomes and 23 duplicate chromosomes

23 pairs of chromosomes

Question:
All animals need food to survive. Immediately after an animal eats food, the food is
OPTIONS:
- stored for later use
- converted into waste
- transported by the bloodstream
- digested into simpler substances
Answer:
digested into simpler substances

Question:
In the human body, which system functions primarily to defend the body against disease?
OPTIONS:
- digestive
- immune
- nervous
- respiratory
Answer:
immune