Answer:B. the population size that can be sustained by an ecosystem
Explanation:
<span>The autumnal equinox takes place on the same date in the southern hemisphere as the spring equinox, since the seasons are in "opposite" order as the calendar falls. In this case, the autumnal equinox would fall on March 21, since this is the date of the spring equinox in the northern hemisphere.</span>
Answer:
Low phenylalanine concentration:
- If the enzyme is inactive, PAH will look like its inactive form, with phenylalanine located in the allosteric site / inactive site so that PAH is a different shape. This will not allow as much phenylalanine to be converted into tyrosine, as we wait for Phe levels to increase.
High phenylalanine concentration:
- If the enzyme is active, PAH will look like its regular form, with an open active site that's the size of phenylalanine so that reactions can occur. (Like a hand fitting into a glove, or a lock into a key.) Phenylalanine will be the substrate, the thing acted upon by the enzyme. This will eventually raise the amount of tyrosine that's created and lower the concentration of phenylalanine.
Think about it like this. Ever heard of homeostasis? That's how the body likes to be the same, keep everything regulated, all the time. So if there are high levels of something, the body is going to try to keep that something down, and if there are low levels, it's going to try to increase the concentration of that thing.
