Ques:Q: When lactose is present in the cell, what allows the lac genes to be expressed? Choices: - concentration of repressor protein - binding of expressor protein - the addition of water - nonbinding of repressor protein A:

Ans:nonbinding of repressor protein
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Ques:Q: Water and chemical elements that organisms need keep recycling through biogeochemical what? Choices: - mutations - levels - effects - cycles A:

Ans:cycles
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Ques:Q: Cycling, shoveling snow and cross-country skiing are examples of what kind of heart-strengthening activity? Choices: - metabolism - anaerobic - exercise - aerobic A:

Ans:aerobic
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Ques:Q: What are the proteins called that speed up biochemical reactions in cells? Choices: - peptides - hormones - carbohydrates - enzymes A:

Ans:
enzymes
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