The depletion of what results in higher levels of uv radiation reaching earth?
Options:
- (A) O3
- (B) O2
- (C) oil
- (D) pan
- (E) h2o
- (F) CO2
- (G) DNA
- (H) DDT
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Let's think first: Ozone depletion results in higher levels of UV radiation reaching Earth. Ozone is represented chemically as O3. O3 depletion results in higher levels of UV radiation reaching Earth.... So the answer is [(A)]

What creates active immunity from a parasite?
Options:
- (A) Cooking
- (B) memory cells
- (C) alpacas
- (D) peachleaf willow
- (E) Allergies
- (F) mammals
- (G) an organism's body
- (H) animals
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Let's think first: Active immunity results when an immune response to a pathogen produces memory cells. If the parasite causes harm, it is a pathogen. When a parasite produces memory cells, active immunity results.... So the answer is [(B)]

What is better able to dissolve oxygen and nutrients than standing water?
Options:
- (A) puddles
- (B) microorganisms
- (C) ponds
- (D) nitrogen
- (E) swamp vegetation
- (F) Veins and arteries.
- (G) streams and creeks
- (H) peachleaf willow
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Let's think first: Running water is better able to dissolve oxygen and nutrients than standing water. Streams and creeks provide running water. Streams and creeks are better able to dissolve oxygen and nutrients than standing water.... So the answer is [(G)]

What can be found in moist soil near rivers and streams in tropical regions?
Options:
- (A) storing water
- (B) a fish
- (C) insects
- (D) Most plants
- (E) shrub beds
- (F) bioaerosols
- (G) ferns
- (H) reptilians
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Let's think first: Caecilians can be found in moist soil near rivers and streams in tropical regions. Salamanders, frogs, toads, caecilians Class Reptilia. Reptilians can be found in moist soil near rivers and streams in tropical regions.... So the answer is [(H)]

What does the base of the food chain provide food for?
Options:
- (A) It helps them survive
- (B) sediments
- (C) Most plants
- (D) other organisms
- (E) our planet
- (F) energy systems
- (G) fruits
- (H) Animal survival
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Let's think first: Producers are organisms that produce food for themselves and other organisms. Producers are the base of the food chain. The base of the food chain help provide food for other organisms.... So the answer is [(D)]

What is the process by which living things give rise to offspring?
Options:
- (A) DNA
- (B) photosynthesis
- (C) bird
- (D) sex
- (E) subtraction
- (F) gametes
- (G) eggs
- (H) ovum
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Let's think first: Reproduction is the process by which living things give rise to offspring. Sex equals reproduction. Sex is the process by which living things give rise to offspring.... So the answer is [(D)]