SCI 135 - Second Exam Fall 2017
Answer Key


On the line to the left, place the letter of the choice that best answers the question.
Three Points Each. NOTE: "e" answers are never the correct answer.

        1. In the lab, replacing the “regular” water with salt solution

___C___    a. Raises the concentration of water above the cell’s
                b. Changes the permeability of the cell membrane
                c. Lowers the concentration of water below the cell’s
                d. Changes the permeability of the cell wall
                e. Is a pretty rude thing to do to the leaf

           water leaves the cell (higher concentration) for the surroundings
                        (lower concentration).

        2. What is measured by looking at tiny gaps between objects?

___A___    a. Resolution         b. Clarity         c. Magnification        d. Repulsion         e. Gappiness

                    ...the smallest gap visible = best clarity of focus = resolution.

        3. On the lab table is a flask with a whitish liquid labeled “STARCH.”  The whitish liquid is a

___B___    a. Solvent         b. Solution         c. Solvent        d. Hydration         e. Bad substitute for lunch

                    ...because it's the whole mixture,  starch (solute) and water (solvent).

        4. To get into a cell, a particle must pass by/through which layers in order:

___B___    a. Hydrophobic, hydrophilic, hydrophilic, hydrophobic
                b. Hydrophilic, hydrophobic, hydrophobic, hydrophilic
                c. Hydrophilic, hydrophobic, hydrophilic, hydrophobic
                d. Hydrophobic, hydrophilic, hydrophobic, hydrophilic
                e. That is way too many layers

                    ...there are two double layers, with the water-repellent layers sandwiched between the
                        water-attractant layers facing the outside water and the inside water.

        5. Two atoms bond because one has a full positive charge and the other has a full negative charge.
                                What kind of bond is it?

___D___    a. Covalent         b. Balancing         c. Neutral        d. Ionic         e. Deeply personal

                    ...the attraction between opposite-charged ions.

        6. The main reason that plants produce digestible starches is that

___C___    a. They supply nutrients to animals                                b. They provide structure to the plant
                c. They will need to be broken down for later use        d. All of the above
                                        e. It’s one of the few fun things plants can do

                    ...the plants will need to "digest" them to use to component sugars for stuff later,
                        as opposed to indigestible starches, not easily broken down, giving plants structure.

        7. Hormones could be

___A___    a. Lipids or proteins         b. Proteins only        c. Carbohydrates or lipids         d. Carbohydrates only
                                                            e. The cause of all of our misery

          's on the "use list" for both types of molecules.

        8. Which would be a dehydration synthesis process?

___B___    a. Water freezing        b. Amino acids linking together        c. Hormones connecting to receptors
                d. Breakdown of lipids                    e. I sort of recognize the words…but not together…

                    ...the "synthesis" part should be the big clue here.

        9. Which Kingdom(s) do not have cell walls?

___B___    a. They all have them         b. Animals only        c. Bacteria and fungi         d. Plants only
                                    e. What’s that Kingdom in Game of Thrones-?

                    ...cell walls give stiff structure, not good for animal movement.

        10. Pure water is most dense at what Celsius temperature?

___D___ a. 100o         b. 0o         c. 12o         d. 4o        e. There’s a Celsius temperature?

                    ...cooling has packed the molecules close together, but they start to organize and repel,
                        moving apart if it gets colder.

        11. The pressure in root pressure is produced by

___A___    a. Osmosis         b. Photosynthesis         c. Living cells        d. Gravity
                            e. The GPS thingy – no, wait, that’s route pressure

                    ...soil water (very dilute) moves into roots (less dilute) and up the plant, where the water gets
                        used, dropping its concentration.  Until gravity's pull won't let it climb any higher.

        12. Sectioning is something that is done

___C___    a. When molecules break down         b. During evaporation        c. To microscope specimens
                d. Inside eukaryotes                                        e. When oranges grow

                    ...the specimens are sliced thin to let the transmission beam come through them.


Answer any eight of the following questions for 4 Points Each.

Note: if you answer more than eight, only the first eight will be corrected.
You can get partial credit on these answers.

1. For each, what ions are most common?
ACIDS      H+ BASES         OH-

2. What is the basic function of an enzyme?

           help start up / speed up chemical reactions.

3.  Given here is one side (strand) of DNA. Starting with this strand, show:
Strand     T  G  C  T  A  C  C  G  T  A  T  T  G  G  C  G  A  G  T  C  A  T  C  G

             A  C  G  A  T  G  G  C  A  T  A  A  C  C  G  C  T  C  A  G  T  A  G  C                   
                                                        Other DNA strand

4. What are two different types of proteins that can be found embedded in a cell membrane?

5. You put the corner of a paper towel into a water spill, and the water moves into the towel. What property of water is in action there?

                    ...adhesion, attraction of water for the starches in the paper.

6. What are two basic types of molecules that are always some sort of polymer?
Nucleic Acids.

7. In the term polyunsaturated fat, what does the term polyunsaturated mean?

           has more than 1 (poly) double bond / place where more hydrogens could be attached.

8. What, technically, is a gene?

          's a DNA code for a particular protein.

9. What process produces simple carbohydrates?

                    ...photosynthesis.  or chemosynthesis.

10. An element in the second column of the Periodic Table is almost always found as a +2 ion. Briefly explain why.

          's uncharged form has 2 outer electrons in a level that should have 8.  It dumps those off (leaving 2 unbalanced positive protons), and now the outer level (that was below) is full and stable.

11. The two pieces of a lipid molecule, including how many of each piece -
1 glycerol 3 fatty acids

12. What are two things that non-coding DNA is or does?
Used for chromosome structure.

Old unused genes.

Genes from old invaders (bacteria, viruses, etc.)
Codes for functional RNA molecules.

DNA parasites.

13. What is the non-mathy explanation for why there seems to be a maximum size limit on cells?

                    ...using multiple cells for a larger organism, with more separation of chemistry / function, is more efficient than trying to do it in one big cell.

14.  Label the following chemical reaction with the general terms for each part –
      A               +               B                        x           >                       C


15. Actin and myosin -
Are what kind          Proteins
of molecules?
Are found       Muscle  (provide the pull)

16. What is the basic molecular formula for a simple sugar?



Answer any four of the following questions for Eight Points Each.

Note: if you answer more than four, only the first four will be corrected.
You can get partial credit on these answers.

1.  Using the numbers of bonds as a guide, fill in the symbols for either Carbon, Hydrogen, Nitrogen, or Oxygen.
 Can't recreate the original hand drawing.  Count the bonds sticking out of each circle and apply HONC -
                                                                 H=1 bond, O=2 bonds, N=3 bonds, C=4 bonds.

                 O           O           O

          O              O           O           O
                    O                                       O           O
          O               O

2.  Name and give a brief description for the four levels of protein structure.
Primary Order of amino acids in the protein string.
Secondary Local patterns inside the molecule.
Tertiary Overal 3-dimensional shape.
Quaternary If functional protein is more than one string, how they fit together.

3.  What are three different ways that fresh-water organisms deal with osmosis? Waterproof outer surfaces
Casing around cells (won't let it swell and pop) Pump extra water back out

4.  Give four rules from the Cell Theory.
All living things are made up of at least one cell.
Cells are the smallest thing considered alive.
Cells only come from other related cells. Cells are more alike than different.

5.  Name the two basic types of cells, and give three sets of differences between them:
Much smaller Much larger
Have no internal membrane chambers / nucleus Have chambers, including nucleus
Have single chromosome Have pairs of homologous chromosomes
Chromosomes are loop-shaped Chromosomes are 2-ended
Can make and share plasmids Don't make plasmids

6. Give the terms for each of the two groups in each microscope category -
Nature of the
Imaging Beam
How the Beam Interacts
with the specimen
(Goes through)
(Reflects off surface)

7.  What are four different types of proteins involved in communication and/or signaling?
Hormones Pheromones
Alarmones Neurotransmitters


Answer as many as you are able. Wrong answers will not result in points being lost from the main exam. You can get partial credit on these answers.

What is it about free oxygen radicals that makes them so reactive? Three Points.

What happens on the atomic level as the temperature goes up? Three Points.

What is the main purpose of stomach acid? (Before you write, it’s not breakdown!) Three Points.

Organic molecules, by definition, should have carbon, hydrogen, and oxygen in them, but the definition leaves out the oxygen. Why? Three Points.

When a cell process requires energy, what molecule usually comes in and supplies it? Three Points.

Why is it useful for a poison to be a lipid? Three Points.

What molecule type, previously thought to have just a couple of roles, is now being found to have a much bigger number of things that it does? Three Points.

Some microscope specimens must be coated with what material? Three Points.

Prokaryotes can all be kind of accu