Ques:Answer the following question given this paragraph: Humans could not live on Earth if it were not for protists. Why? Plant-like protists produce almost one-half of the oxygen on the planet through photosynthesis. Other protists decompose and recycle nutrients that humans need to live. All protists make up a huge part of the food chain. Q: What produces almost one-half of the earth's oxygen through photosynthesis? Choices: - prokaryotes - algae - arthropods - protists A:

Ans:protists
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Ques:Answer the following question given this paragraph: Water pollution happens when contaminants enter water bodies. Contaminants are any substances that harm the health of the environment or humans. Most contaminants enter the water because of humans. Surface water (river or lake) can be exposed to and contaminated by acid rain, storm water runoff, pesticide runoff, and industrial waste. This water is cleaned somewhat by exposure to sunlight, aeration, and microorganisms in the water. Groundwater (private wells and some public water supplies) generally takes longer to become contaminated, but the natural cleaning process also may take much longer. Groundwater can be contaminated by disease-producing pathogens, careless disposal of hazardous household chemical-containing products, agricultural chemicals, and leaking underground storage tanks. Q: What "kind" of water may take longer to become contaminated than surface water, while the natural cleaning process may take longer? Choices: - lake water - spring water - dam water - groundwater A:

Ans:groundwater
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Ques:Answer the following question given this paragraph: Microtubules guide the formation of the plant cell wall. Cellulose is laid down by enzymes to form the primary cell wall. Some plants also have a secondary cell wall. The secondary wall contains a lignin, a secondary cell component in plant cells that have completed cell growth/expansion. Q: The secondary wall contains _________ , a secondary cell component in plant cells that have completed cell growth/expansion. Choices: - cytoplasm - glucogen - cellulose - lignin A:

Ans:lignin
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Ques:Answer the following question given this paragraph: Fermat's Principle states that light will always take the path of least amount of time (not distance). This principle governs the paths light will take and explains the familiar phenomena of reflection, refraction, lenses and diffraction. Light rarely travels in a straight-line path. When photons interact with electrons in matter the time it takes for this interaction determines the path. For example, higher frequency blue light is refracted more than red because blue wavelengths interacts more frequently with electrons than red wavelengths and the path of least time is for blue to bend more then red in order to get out of this 'slow' area faster. The rainbows we see are a result of this. Fermat's Principle explains the many fascinating phenomena of light from rainbows to sunsets to the haloes around the moon. Q: Fermat's principle states that light will always take the path of least amount of? Choices: - energy - momentum - resistance - time A:

Ans:
time
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