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Lactase persistence, the ability to digest lactose into adulthood, is a trait prevalent in some human populations but not others. Which of the following best explains the evolutionary advantage that led to the spread of lactase persistence in certain populations?

The enzyme hexokinase catalyzes the first step of glycolysis by adding a phosphate group to glucose. If N-Acetyl-d-glucosamine (NAG) is introduced into the cell, it occupies the active site of hexokinase, thereby preventing glucose from binding, and thus stopping glycolysis. NAG is therefore an example of what?

Consider cellular respiration and photosynthesis in a plant. In cellular respiration, the source of electrons is ______, whereas in photosynthesis, the source of electrons is ______.

A plant leaf performs photosynthesis. Which of the following is the most accurate definition of this process?

In the electron transport chain (ETC) of cellular respiration, the electron carriers NADH and FADH2 give up electrons to protein complexes of the ETC. What happens to these NADH and FADH2 molecules during this process?

Which of the following statements best describes the function of an enzyme and its effect on a chemical reaction?

Oxygenic photosynthesis is the type performed by plants, algae, and cyanobacteria, which releases oxygen. Anoxygenic photosynthesis, performed by other bacteria, does not release oxygen. What is a key similarity between these two processes?

CO2 fixation and nitrogen fixation are both essential processes for life. Why are these processes critical for the formation of biological macromolecules?

In human saliva, the enzyme amylase breaks down the starch in foods such as potatoes, rice, and pasta into smaller sugar subunits including its monomer glucose. This process begins in the mouth. If amylase were not present in saliva, the breakdown of starch would still occur, but at a much slower rate. What is the role of salivary amylase in this reaction?

Individuals with lactose intolerance can sometimes consume yogurt or cheese and experience fewer symptoms than with milk. Which of the following best explains why this is the case?