Dr. Reichler’s Bio 301L 1-2pm
In-class Exam #3 November 11, 2002
Answer each question as succinctly as possible in the
space provided. If needed, continue on the back. If you use a
drawing as part of your answer, be sure to also include a written explanation.
Read each question carefully and don’t hesitate to ask if a question seems
unclear. These questions have specific answers, although for some,
more than one answer is possible. To receive full credit you must clearly
and fully answer the question being asked. Each question is worth 6
pts, unless otherwise noted, for a total of 100 points possible for this
1. a. Some fungi, yeast, are unicellular. Could you tell the
difference between a yeast cell and bacterial cell by looking at them under
a microscope? Why or why not?
Yes, look for nucleus or other organelle. Bacteria do not have a
nucleus or other organelles.
b. How could viruses be used to treat a bacterial infection? Would
this be advisable? Explain.
Viruses infect and destroy bacteria.
Yes, the virus is specific for bacteria and unlikely to infect people.
OR No, the virus might mutate and infect the person.
2. a. How does HIV, the virus that causes AIDS, remain dormant in the
human body for many years?
It enters the lysogenic/integrative cycle. The HIV DNA inserts into
the human DNA, and only later enters the lytic cycle.
b. How do viruses with membranes get their membranes?
They leave the cell individually, each one taking some cell membrane as
c. If blood containing HIV is treated with restriction enzymes, which cut
up DNA, would that blood be safe to give to another person? Why or
why not? (4 pts)
No, HIV uses RNA as its genetic material. Restriction enzymes will
have no effect on DNA.
3. a. Looking back in geological time, would it be likely that flowering
plants (angiosperms) existed prior to land animals? Explain.
No, flowering plants use animals to spread their pollen.
b. What part of a plant is analogous to the above ground parts of a mushroom?
Flower. Both are reproductive structures.
c. Why can woody plants support more leaves than non-woody plants?
Any of: Wood is xylem. More xylem means more ability to transport
water, and each leaf is transpiring water.
Wood gives the plant support to hold up the leaves.
d. What are three differences between transport in plants and in animals?
Any three of: Animals have central heart that pumps fluid, plants
do not. Plants transport water and sugar separately, animals transport
them together in blood. Plants can add additional transport, wood,
animals can not. Animals transport gases, plants do not. Plants
get nutrients from ground, animals eat/absorb. Animals have 4 types
of vessels (arteries, capillaries, veins, lymph), plants have 2 types (xylem,
phloem). Animals have cells (red blood cells etc) in transport system,
plants do not.
e. Do you get more nutrients from eating a bean or the leaves of a bean plant?
From beans. Beans are seeds, and in the seed the plant is storing
energy for the future plant.
4. Why are animals so much easier to digest than plants?
Plants have cellulose, which is indigestible, so the nutrients are harder
5. a. Besides being multicellular and eukaryotic, what is one characteristic
fungi share with animals, one they share with plants, and one unique to the
fungi? (3 pts)
Fungi-animals: heterotrophic/only do cellular respiration
Fungi-plants: non-mobile, have cell wall
Unique to fungi: cell wall of chitin, form mycorrhizae, produce antibiotics,
grow by filaments (pseudo-parenchymotous),
b. Without fungi humans would not be able to exist. Describe three
reasons why this statement is true?
Any three of: Plants would grow smaller due to lack of mycorrhizae,
lack of antibiotics, dead material would build up
6. a. What is the function of the small intestine, and how does the
structure of the small intestine allow it to perform its function?
Digest and absorb food/nutrients. The small intestine is undulated/has
villi that increase surface area and allow for absorption.
b. Studies have shown that a high fat/lipid diet can lead to heart disease.
Why does a high fat/lipid diet affect the heart more than other organs?
Lipids/fats are transported via the lymphatic system that returns fluids
to the blood right before the heart. Therefore, the heart is the first
organ to be exposed to the lipids/fats.
7. a. How do cells not in contact with a capillary get nutrients and get
rid if cellular waste?
Interstitial fluid leaks from the capillaries and bathes the cells exchanging
nutrients and wastes.
b. What is the connection between blood pH and oxygen transport, and what
causes blood pH to change?
CO2 levels combine with H2O in blood to make carbonic acid (H2CO3).
At acid pH, hemoglobin binds O2 less well and O2 is released. When
CO2 leaves the blood, there is less carbonic acid and blood pH goes up (is
c. Describe one structural feature of each blood vessel (arteries, capillaries,
and veins) that allows it to carry out its function.
Artery: Thick walls to hold in high pressure blood. Large diameter
to transport a lot of blood.
Capillary: Thin/leaky walls to exchange nutrients/wastes. Small
diameter but many to be in contact with many cells.
Vein: Has one-way valves to move blood via muscle movement due to lack
of pressure. Large diameter to move large quantity of blood.
Thick walls to hold in blood for transport.