Tutor profile: Ritisha G.

A solution of which of the 20 essential amino acids will NOT rotate plane polarized light?

Glycine; A molecule that has an atom that is bonded to four DIFFERENT chemical groups is said to be chiral. Solutions of chiral molecules rotate plane polarized light when this light is shone through it. Amino acids contain an amino group, a carboxylate group and a hydrogen atom bonded to an alkyl carbon, also known as the alpha carbon. Each of them also has their own R-group, that is unique to each of the amino acids. If the R-group is different than the other 3 different subsituents, the amino acid is chiral. Glycine has an R-group of a single hydrogen atom, which means it matches the other hydrogen atom that is linked to the same alpha carbon. That makes glycine achiral, because it doesnt have 4 different substituents, it has 3. That means glycine will not rotate plane polarized light like a chiral molecule does.

As the two anatomical divisions of the adrenal gland, the adrenal cortex and adrenal medulla share a common feature in that both: A. synthesize steroid hormones B. regulate the synthesis of bone mast cells C. secrete hormones that alter blood pressure 4. release signaling molecules into the ovaries

The answer here is C, secrete hormones that alter blood pressure. The adrenal CORtex deals with the CORticosteroids, that are split into glucocorticoids (sugar), mineralocorticoids (salt), and the cortical sex hormones. These hormones regulate glucose levels, salt and water homeostasis, and androgens and estrogens, respectively. The mineralocorticoids, while regulating salt and water, also regulate blood pressure, because when sodium reabsorption in the nephron increases, this also increases blood volume and pressure because water will follow these sodium cations into the blood stream. The adrenal medulla is responsible for your fight or flight - therefore, it produces epinephrine and norepinephrine. If you think about how you feel when you are scared or stressed, you can feel the blood rushing in your veins. This is because epinephrine and norepinephrine maximize blood flow to the essential organs, and they do so by either narrowing blood vessels or widening them to change blood pressure.

Zoe earns $14 per hour for the first 6 hours of her shift. For each additional hour she works beyond the first six hours, she earns $16 per hour. If Zoe earned $244 from a single shift, how many hours long was that shift?

First, lets figure out what we want to find out. We want to find the number of hours that Zoe worked for that entire shift, and since that is the unknown we are trying to solve, we can call that "x". We can split the problem into two parts since there are two different wages that Zoe earns here. We know the first 6 hours of the shift has one wage, $14/hour and the rest of the shift has another wage, $16/hour. The difference here is also that we know EXACTLY how many hours Zoe earns $14/hour for (six), but not how many hours Zoe earns $16/hour for. So for the first 6 hours, we can multiply to find out the total $ from that part of the shift: $14 x 6 = 84. We can do the same for the rest of the hours, but since we don't know the # of hours, we need to create an expression for it. Since x is the total hours, and 6 hours is the first part of the shift, the rest of the shift is x - 6 hours. Therefore, we can multiply this with the wage like we did for the first part to find the total $ from that part of the shift, giving us $16 x ( x - 6 hours). We know that she earned $244 from the whole shift, which is more than $84, so we can put both our earnings expressions together to form: $84 + $16 ( x - 6 ) = $244. Now, we solve for x. 1) $84 + $16 ( x - 6 ) = $244 2) $16 ( x - 6 ) = $244 - $84 = $160 3) ( x - 6 ) = $160 / $16 4) ( x - 6 ) = $10 5) x = 10 + 6 6) x = 16 hours Zoe worked 16 hours for that shift. Wow, looks like she needs some time off :)