Download Answers to Progress 2 Practice Questions

Answers to Progress 2 Practice Questions
1. D. Remember, a hydrogen bond occurs between two different molecules.
2. D.
3. D. Saturated fatty acids have ALL single bonds between their carbons. This constitutes all animal fat,
which is solid at room temperature (think of that juicy steak before it is grilled, the white marbling of fat
stays solid at room temp).
4. C. You are looking at two amino acids bonding together via dehydration synthesis (or condensation
reaction). you MUST be able to recognize an amino acid. It always has a carboxyl group (an end carbon
with a double-bonded oxygen and a hydroxyl group [OH]) and an amino group (NH2).
5. C. The hydroxyl group is polar on serine whereas the methyl group (CH3) on alanine is nonpolar.
Recall from your protein-building activity that hydrophobic interactions between nonpolar side-chains of
amino acids typically point inwards in a protein where polar groups bond with each other and tend to
point outwards towards the aqueous environment of the protein (where it can interact with water and
potentially form hydrogen bonds).
6. A
7. B
8. B. Hydrogen Peroxide is H2O2. If you remove hydrogens from a toxic material, they must go
somewhere. Oxygen is used as that ‘somewhere’.
9. D
10. E
11. A. Based on just concentrations of the two solutes, side B has a higher molar concentration of the
two solutes combined together than side A.
12. D. Salt can move so it will become isotonic in its concentrations thus it won’t affect the movement of
water. That leaves glucose. It is higher on side B, thus lowering B’s water potential. Water moves from
an area of high water potential to low water potential.
13. D
14. E. If you only want certain cells to allow a material in, it would be controlled by a transport protein.
Thus the drug you create must match the shape of transport protein’s attachment site.
15. B. All cells have some solute in them, lowering their water potential. Distilled water is 100% pure
water, thus water will move from the blood into the cells.
16. D. Plant cells must maintain a fluid cell membrane. However, in colder temperatures their cell
membranes can become stiff. To counteract this activity, they increase the number of unsaturated fatty
acids by forming double bonds between the carbons in the fatty acid tails of the phospholipids. This
forms kinks in the fatty acid chains, forming more space between them, making them less dense and
staying fluid.
17. A. Similar question to #14.
18. A. Cells MUST have a high surface area to volume ratio. This increases as the size of the cell
decreases.
19. B. There is an inverse relationship between rate of contraction and osmolarity of the solution.
Basically as osmolarity increases, the solution’s water potential becomes similar to the interior of the
paramecium, meaning less water will naturally diffuse in, thus less effort is needed to pump water out.
20. D. Typo! Sorry, choice D should read “protein tertiary structure”. PROTEIN REVIEW! First, know
which bonds determine what structure in a protein. Primary structure is the peptide bonds formed
between the amino acids. Secondary structure are the hydrogen bonds formed between the amino
acids that BEGIN to form the 3-dimensional shape of the protein. Typically this forms alpha-helices and
beta-pleated sheets. Tertiary structure of a protein is a result of the interactions between the Rgroups/side-chains of the amino acids such as disulfide bonds (very strong), acid-base bonds, more
hydrogen bonds, and hydrophobic interactions of all the non-polar R-groups that go to the interior of
the protein. Quaternary structure only occurs when two different amino acid chains bond together and
form the same bonds mentioned for tertiary structure. A protein will lose its shape via denaturation
(breaking of bonds) if its environment changes (change in pH, temperature, water concentration).