Cells Practice Exam
KEY
Honors Biology
1 Identify the following structures:
Golgi body
Endocytic Pocket
Cell Membrane
Nuclear Membrane
Vesicle
DNA or Chromatin
Smooth ER
Rough ER
Centrioles
Nucleolus
Vesicle
Mitochondria
Is this an animal, plant, or prokaryotic cell? How can you tell?
This is an animal cell—no cell wall or large vacuole, it is undergoing endocytosis
(probably pinocytosis because there is no solid food in the pocket) and it has an irregular
shape.
On the diagram above, label a vesicle, an endocytic pocket, the nucleolus and the
centrioles (which are very poorly drawn and may be hard to see).
If you didn’t know this was an animal cell from the question above, the fact that I want
you to find centrioles gives away the answer.
1. What type of cell (prokaryotic, plant or animal) is described below?
This cell lacks mitochondria, ER, and Golgi bodies.
No membrane-bound organelles, so this a prokaryote
This cell contains plasmodesmata.
Plant cell
This cell has ribosomes.
All known cells have ribosomes
This cell moves via pseudopodia
Must be an animal
This cell contains structures with cristæ.
Must be a eukaryote
2. Can these particles cross the cell membrane without a transport protein?
A molecule of water
Yes, because it is so small.
A steroid
Yes, because it is hydrophobic.
A fluoride ion (F-)
No, because it is charged.
A 345 amino-acid long protein
No, because it is too big.
Carbon dioxide
Yes, because it is so small.
3. Sketch the cell membrane. Label the phospholipids, integral proteins, peripheral
proteins, cholesterol, and carbohydrate chains.
It would be a good idea also to know all the functions of these components.
4. Neurons (nerve cells) contain many vesicles that contain neurotransmitters—molecules
that send a signal from one nerve cell to another. Neurons must have large numbers of
what organelles to create all of these filled vesicles?
They would need large numbers of ribosomes to make all the neurotransmitter proteins,
large amounts or ER to move them, and many Golgi bodies to package them.
5. Describe the structure of the nucleus, especially its membrane or envelop.
The nucleus is a large, membrane bound sac that contains the DNA in eukaryotes. It has
a double phospholipid membrane, punctured by pores. The nuclear membrane is
attached to the ER.
6. Identify the organelle
This structure contains thylakoids and chlorophyll.
Chloroplast
This is made up of RNA and protein, though the RNA does all the work. Ribosome
This comes in two varieties, with and without attached ribosomes.
ER
This contains peroxide, and kills things.
Peroxisomes
Amebas and white blood cells use this to move.
Pseudopods
These structures produce vesicles that will ultimately fuse with the cell membrane.
Golgi Bodies
This darkish blob is because the genes for the ribosomes are read so often they always
have high concentrations of DNA-reading proteins present.
Nucleolus
This structure requires glucose and makes ATP
Mitochondria
7. In a fit of teen-aged angst (which we grown-ups call stupidity) you have shaved your
head. Your hair is mainly composed of the protein keratin. Assume that keratin is an
exported protein. Briefly describe the process that must occur inside a hair cell to
produce and export this protein to begin re-carpeting your bald head.
mRNA encoding keratin is produced in the nucleus. It leaves through a pore, and is
translated by a ribosome on the rough ER into the keratin protein. The keratin protein
travels first through the rough then smooth ER until it buds off in a vesicle and travels to
the Golgi bodies. There, it undergoes final modifications before being packaged in a
vesicle and budded off for a trip to the cell membrane. There, the vesicle fuses with the
cell membrane, pushing the keratin outside the cell. Eventually, it will incorporated into
a growing strand of hair.
8. What are some differences between a cell membrane and a cell wall?
Cell membranes are semi-permeable membranes made of phospholipids, proteins, and
other assorted molecules. They are found in all cells.
Cell walls are structures found in bacteria, fungi, and plants that are made out of
peptidoglycan, chitin, and cellulose (respectively) that offer support and osmotic
protection, but cannot prevent chemicals from entering or leaving.
9. You put a bunch of amebas into a beaker and then leave for lunch. When you come
back, all of your amebas have shriveled up and died. This beaker contained what type
of solution?
Water left the amebas, so they were hypotonic and the solution was hypertonic.
You have placed a cell inside a hypotonic solution, but it did not explode. Why not?
It may have had a cell wall or a contractile vacuole.
10. Against all odds, you pass honors biology, graduate from college, complete medical
school, and grow up to be a doctor. Unfortunately, you are not a very good one. You
accidentally give a patient with type A blood a unit of type B blood. He dies. Why?
The patient’s immune system didn’t recognize the B-type carbohydrates on the new
blood cells. As a result, they attacked and destroyed them, unfortunately damaging
many other A-type blood cells at the same time.
After your insurance company pays out the award in the wrongful death lawsuit for the
blood mix-up, you return to the hospital. While in the pharmacy, you accidentally make
up the saline IV solutions with 9% salt instead of the isotonic 0.9% salt. What happened
to the blood of the poor patient who got your mixed-up IV?
The water would have left the blood cells, leaving them crenellated.