RT 230 - First Exam 2005

Multiple Choice.

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

_______ 1. Single-target theory and Poisson distribution is used to figure the D₃₇, which is
then used to determine

                    a. Cells’ radiosensitivity                                             b. How many people will die
                    c. The average number of chromosome breaks            d. Cancer rates
                                        e. Something no one can really understand

_______ 2. When a cell has copied its DNA, it then has

                    a. 2 new copies and the old one is recycled
                    b. 1 totally new copy and the old copy
                    c. 2 copies that are half old and half new
                    d. Actually pulled an old copy out of storage
                    e. Something it can sell on eBay

_______ 3. There is some evidence that radiation may damage cell membranes through its effect on

a. Proteins b. Carbohydrates c. Lipids d. Minerals e. Slime

_______ 4. Which blood component typically shows the effects of radiation last?

                    a. Red blood cells                           b. White blood cells
                    c. Platelets                                     d. They’re roughly equal
                                    e. The ones that ducked at the right time

_______5. Erythema is a term applied to

                    a. Cancer changes                                         b. Blood cell changes
                    c. Skin changes                                             d. All of these
                                    e. Whatever you want to scare people about

_______6. Protraction is a radiation delivery rate

                    a. Increases effects by occurring in a quick dose
                    b. Increases effects through chemical additives
                    c. Decreases effects by occurring over a longer time
                    d. Decreases effects through chemical additives
                    e. Aimed with one of those half-circle thingees

_______7. Which cancer type is most connected to low-level radiation exposure?

a. Bone cancer b. Brain cancer c. Thyroid cancer
d. Leukemia e. The kind I hope not to get

_______8. Some studies suggest that a little radiation exposure may be good for people.
This idea is called

a. Minirads b. Homeopathic reaction c. Antithreshold
d. Hormesis e. Nutty by many people

_______9. Scission of a molecule produces

                    a. Totally new chemistry                     b. New connections
                    c. Genetic abnormalities                      d. Pieces
                        e. That feeling you get when a word is just bizarre

_______10. Which material, when exposed to radiation, is most likely to produce damage?

a. Water b. Carbohydrate c. Lipid d. Mineral
e. The ones that heat up and glow

_______11. When a cancer becomes malignant, the cells begin to

a. Divide b. Move c. Produce toxins
d. Attack normal cells e. Hog the remote control

_______12. DNA is found in a cell in the

                    a. Nucleus and membrane                         b. Nucleus and mitochondria|
                    c. Ribosomes and membrane                     d. Ribosomes and mitochondria
                                                    e. Special DNA drawer

Short Answer.

Pick SIX questions to answer in the spaces provided.
NOTE: if you answer MORE than six, only the first six will be corrected.
Four Points each. Partial credit is possible.

1. What are two different functions that proteins have in the body?

2. What is a codon? Be fairly specific.

3. Pick two parts of LD_50/60 (the LD, the 50, the 60) and explain what the term stands for.

4. Briefly explain why induced cross-linking can have a powerful effect on protein molecules.

5. Briefly explain why many tumors are less sensitive to radiation than the tissues they came from.

6. During the cell cycle -

When is radiation

most damaging?

Why then?

7. Why are some cancers treated with radiation beams from several different angles?

8. Briefly explain why cancers are particularly sensitive to radiation.

9. What two aspects of the prodromal period is used to guess how severe a radiation dose a person has received?

10. There are many chemicals that could be radioprotectors, except for two problems - what are the two shortcomings of these materials?

11. Briefly explain why gonad effects of radiation exposure are so different between men and women. Be fairly specific, but you don’t need specific terms.

12. Briefly explain why a multiple major radiation "hit" on a cell’s DNA is unlikely to affect that particular cell’s day-to-day performance.

13. What are two reasons why there may be no threshold for certain radiation effects?

Long Answer.

Select and answer completely any four of the following questions.
Note: if you answer more than four, only the first four will be corrected.
Ten Points Each. Partial credit is possible.

1. For three general types of tissue, name the type, give the general radiosensitivity (low / medium / high), and explain why it has that sensitivity.
TISSUE TYPE	RADIOSENSITIVITY	Explanation



2. You know enough to tell someone that radiation will not mutate them so that they won’t develop a new feature. But why shouldn’t a diagnostic x-ray mutate a cell so as to damage or kill it? Explain what happens on the cell - molecule level (there are a couple of possible different ways to answer this).





3. Briefly explain, in general, why absorption of radiation can cause chemical changes in a wide range of atoms and/or molecules.

4. For the following life-time periods, rate the radiosensitivity (low, moderate, high) and give a brief explanation for why it has that sensitivity.
STAGE	RADIOSENSITIVITY	Explanation
Embryo
Child
Adult
Elderly
5. Answer the following concerning the irradiation of foods -
What is it supposed to do to the foods?
Is there any danger? Why / why not?
Why doesn’t it make the foods radioactive?
6. For the three acute radiation syndromes, give the name of the syndrome, then briefly explain the reason why it has its effects (types of tissue affected & result of effects).

Link to Answer Key

BONUS QUESTIONS. Answer as many or as few as you wish. You can't lose points on the rest of the exam by getting these wrong. Partial credit is possible.

What is it about free radicals that makes them so chemically active? Three Points.

Many types of high Linear Energy Transfer (LET) radiation that a human could be exposed to are not that dangerous to us. Why? Three Points.

Why is it reasonable to expect that humans can withstand a decent amount of exposure to radon? Three Points.

In the Russian nuclear reactor disaster at Chernobyl, which workers were most severely affected? Three Points.

How is it thought that radiation will affect astronauts on a lengthy trip to Mars? Three Points.

On the book’s table showing effects of many factors on life-span shortening, what had the greatest effect? Three Points.

Radium settles into a particular part of the body - what is it? Three Points.

Why is blood vessel "recruitment" so important in the development and treatment of cancer? Three Points for each reason.

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