# Tutor profile: Sam B.

## Questions

### Subject: Biomedical Science

The brain is protected by the blood brain barrier (BBB) which is impermeable to hydrophilic molecules. Scientists used to treat dopamine related disorders by giving patients dopamine, which had no effect. However, when patients were given L-DOPA (a precursor to dopamine), they had a therapeutic response. We can infer that: A. Both dopamine and L-DOPA are hydrophilic molecules but dopamine is too big to pass through the BBB B. Dopamine is hydrophilic but L-DOPA is hydrophobic C. Lack of L-DOPA is the problem, not dopamine D. None of the above

B. Dopamine is hydrophilic but L-DOPA is hydrophobic

### Subject: Biology

You are a field biologist that just discovered an unknown organism in a sample you obtained from a nearby swamp. The unknown organism is a single cell, does not have a nucleus and moves around using a single flagella. The organism is most likely a: A. Eukaryote B. Prokaryote C. Non-living D. Virus

B. Prokaryote

### Subject: Algebra

If the cost of gummy bears in 2000 was $1.50 per bag and the cost of them now (2020) is $3.00 per bag, what is the rate of the price increase assuming a linear slope?

Because the question is asking for the rate, we need to find the slope of the line between these two points (slope=rate). The year 2000 is the starting point so we can represent that as x=0 with the x-axis measuring time. So, at time 0, the cost of gummy bears is $1.50 so the starting point is (0,1.5). Twenty years later, the cost of gummy bears is $3.00 so our new point is (20,3). To find the slope between these two points, we use the equation M=(y2-y1)/(x2-x1). so, M=(3-1.5)/(20-0)= 1.5/20= 0.075 This means that on average, the cost of gummy bears has gone up by 0.075 cents per year.