Question 1

During the preimplantation stage of development,the fertilized ovum divides and forms a ball-like structure containing undifferentiated cells.If this structure is irradiated with a dose in the range of 0.05 to 0.15 Gyt which of the following will result?

Accepted Answer

Irradiation with a dose in the range of 0.05 to 0.15 Gyt during the preimplantation stage can cause embryonic death. Congenital abnormalities, delayed bone growth, and microcephaly are potential outcomes of exposure to radiation during other stages of development.

Question 2

Which of the following late effects caused by exposure to ionizing radiation is considered to be most important?

Accepted Answer

While all the late effects listed are a concern with exposure to ionizing radiation, cancer is generally considered the most important due to its potential for significant morbidity and mortality.

Question 3

Radiation-induced cataracts in humans follow a ______ dose-response relationship.

Accepted Answer

D

Question 4

After the Chernobyl disaster in 1986,an attempt was made to prevent thyroid cancer in Poland and some other countries,resulting from the accidental overdose of iodine-131._______________ was administered to children as a substitute to block the gland's uptake of iodine-131.

Accepted Answer

Potassium iodide can saturate the thyroid gland with stable iodine, which prevents the uptake of radioactive iodine-131 and reduces the risk of thyroid cancer. Potassium bromide has no effect on the thyroid gland, while sodium chloride and sodium bicarbonate do not contain iodine and cannot reduce the uptake of radioactive iodine-131.

Question 5

What is the mean value of the radiation doubling equivalent dose for humans,as determined from studies of the children of the atomic bomb survivors of Hiroshima and Nagasaki?

Accepted Answer

The mean value of the radiation doubling equivalent dose for humans, as determined from studies of the children of the atomic bomb survivors of Hiroshima and Nagasaki, is 1.56 Sv. This value takes into account the increased risk of developing radiation-induced cancer or other diseases due to exposure to ionizing radiation.

Question 6

Epidemiologic studies are of significant value to radiobiologists who use the information from these studies to formulate dose-response curves for making predictions of the risk of ____________ in human populations exposed to low levels of ionizing radiation.

Accepted Answer

Epidemiologic studies provide valuable data on the risk of cancer in human populations exposed to low levels of ionizing radiation.

Question 7

During the 1950s and 1960s,the Navajo people of Arizona and New Mexico who mined uranium for fuel for nuclear weapons and power plants developed lung cancer years after their exposure.This provides an example of which of the following?

Accepted Answer

Late stochastic effects refer to the long-term consequences of exposure to radiation, such as cancer, which may not appear until many years after the exposure. In this case, the Navajo uranium miners developed lung cancer years after their exposure, making this an example of a late stochastic effect.

Question 8

Genetic effects from exposure to ionizing radiation occur as a result of radiation-induced damage to the DNA molecule in which of the following?
1)Sperm of a man
2)Ova of a woman
3)Somatic cells of men and women

Accepted Answer

Genetic effects from exposure to ionizing radiation occur due to damage to the DNA in the germ cells, which are the sperm in men and the ova in women. Somatic cells, when mutated, can lead to cancer but do not contribute to hereditary changes.

Question 9

Radiation-induced abnormalities are caused by unrepaired damage to

Accepted Answer

Radiation-induced abnormalities, especially those that can be passed on to offspring, are primarily caused by damage to the DNA molecules in the sperm or ova of an adult, as these are the cells involved in reproduction.

Question 10

The human body can incorporate radium into bone because it is chemically similar to

Accepted Answer

Radium has similar chemical properties to calcium and can replace it in bone tissue, leading to potential health risks.

Question 11

In general,laboratory experiments with mice prove that cataracts may be induced with doses of ionizing radiation as low as

Accepted Answer

The answer of In general,laboratory experiments with mice prove that...

Question 12

Among the atomic bomb survivors,the number of leukemia victims has _______________ since the late 1940s and early 1950s.However,the occurrence rates of other radiation-induced malignancies have continued to ___________since the late 1950s and early 1960s.

Accepted Answer

The sentence states that the number of leukemia victims has "slowly declined" since the late 1940s and early 1950s, while the occurrence rates of "other radiation-induced malignancies" have continued to "escalate" since the late 1950s and early 1960s. Therefore, the best choice is A, which accurately reflects these opposing trends.

Question 13

What do agents such as specific chemicals,viruses,and ionizing radiation have in common?

Accepted Answer

All of these agents are known mutagens, meaning they have the potential to increase the frequency of mutations in DNA. This can ultimately lead to changes in an organism's genetic material or even diseases such as cancer.

Question 14

In which of the following human populations is the risk for causing a radiation-induced cancer not directly measurable?
1)All patients in diagnostic radiology subjected to a radiation dose below 0.1 Sv
2)Chernobyl radiation accident victims living in contaminated villages
3)Atomic bomb survivors

Accepted Answer

The risk for causing a radiation-induced cancer is not directly measurable in patients subjected to a radiation dose below 0.1 Sv in diagnostic radiology because the doses are too low and the statistical noise in epidemiological studies is too high to directly attribute any specific cancer cases to such low doses. In contrast, Chernobyl accident victims and atomic bomb survivors were exposed to much higher doses, making it possible to measure and study the effects directly.

Question 15

Some mutations in genetic material occur spontaneously,without a known cause.In humans,a hereditary disorder is present in approximately _________ of all live births in the United States.

Accepted Answer

Approximately 10% of all live births in the United States are affected by a hereditary disorder, indicating that a significant portion of the population carries or is affected by genetic mutations that can lead to such conditions.

Question 16

To assess the magnitude and severity of late effects on the exposed population from the 1986 nuclear power station accident at Chernobyl

Accepted Answer

Long-term follow-up studies are necessary to assess the magnitude and severity of late effects on the exposed population from the 1986 nuclear power station accident at Chernobyl. The low doses of radiation received by the population may cause delayed health effects that can only be observed after several years or even decades. Therefore, long-term follow-up studies are crucial to understanding the health impacts of the Chernobyl disaster.

Question 17

Mutations in genes and DNA that occur at random as natural phenomena are called

Accepted Answer

Spontaneous mutations are those that occur naturally, without exposure to any external mutagenic agent. They happen as a result of errors during DNA replication, repair, or recombination, or from spontaneous chemical changes in DNA bases. The other options are not accurate since carcinogenic mutations are caused by environmental agents that increase the risk of cancer, sporadic mutations are those that appear in a single individual or a small number of individuals without any apparent cause, and stochastic mutations are those that occur randomly but follow a probabilistic pattern.

Question 18

Existing data on radiation-induced genetic effects in humans

Accepted Answer

Existing data on radiation-induced genetic effects in humans are contradictory and inconclusive. There is evidence of major genetic effects such as increased rates of genetic mutations and chromosomal abnormalities in populations exposed to high levels of radiation, such as survivors of atomic bombings and nuclear accidents. However, the extent of the genetic effects at lower, occupational exposure levels is still a subject of debate and research. Some studies have reported no significant genetic effects, while others suggest possible increased risks of certain diseases associated with radiation exposure. Overall, the existing data do not provide conclusive evidence for either major or minor genetic effects of radiation in humans.

Question 19

When a prediction is made that the number of excess cancers rises as the natural incidence of cancer increases with advancing age in the population,the risk is considered to be

Accepted Answer

The risk is considered to be relative because it compares the risk of cancer in one group (exposed to a certain factor) to the risk of cancer in another group (not exposed to the factor), showing how the risk increases with age.

Question 20

Which of the following are sources of low-level radiation exposure?
1)X-rays and radioactive materials used for diagnostic purposes.
2)Employment-related exposure in medicine and industry.
3)Natural background radiation.

Accepted Answer

All three options are sources of low-level radiation exposure. 1) X-rays and radioactive materials are used in medical diagnostics and can expose individuals to low levels of radiation. 2) Certain occupations in medicine and industry involve exposure to radiation. 3) Natural background radiation comes from cosmic rays, radon gas, and other natural sources.

Quiz 9: Stochastic Effects and Late Tissue Reactions of Radiation in Organ Systems