Question 1

One micron (mm) = __________.

Accepted Answer

One micron (mm) equals 10-6 meters, which is represented by choice A.

Question 2

The normal white blood cell count for an adult ranges from:

Accepted Answer

The normal white blood cell count for an adult ranges from 5000 to 10,000/mm3 of blood.

Question 3

Direct action may occur after exposure to any type of radiation,but it is much more likely to happen after exposure to:

Accepted Answer

High-LET radiation such as alpha particles deposit a large amount of energy in a small area of tissue, which can cause direct damage to DNA and other cellular structures. This increases the likelihood of direct action occurring. Low-LET radiation such as x-rays and gamma rays have a lower probability of causing direct damage to DNA through direct action. Non-ionizing radiation such as microwave does not have enough energy to cause ionization and direct damage to DNA.

Question 4

Which of the following is/are considered low-LET radiation(s)?
1)X-rays
2)Alpha particles
3)Gamma rays

Accepted Answer

1 and 3 only. X-rays and gamma rays are considered low-LET (Linear Energy Transfer) radiations because they have a relatively low rate of energy transfer to the surrounding medium. Alpha particles, on the other hand, are high-LET radiation due to their high mass and charge, leading to a higher rate of energy transfer.

Question 5

While passing through a human cell,an x-ray photon interacts with and inactivates the cell's master molecule.What is the consequence for the cell?

Accepted Answer

The inactivation of the cell's master molecule would severely disrupt the cell's ability to carry out essential functions such as DNA replication, transcription, and protein synthesis. This would likely lead to the death of the cell.

Question 6

Which of the following groups of cells is most radiosensitive?

Accepted Answer

Lymphocytes are rapidly dividing cells that are among the most radiosensitive cells in the body. Adult nerve cells, erythrocytes, and muscle cells are not rapidly dividing and are more radioresistant.

Question 7

As LET increases,the ability of ionizing radiation to cause biologic effects:

Accepted Answer

The answer of As LET increases,the ability of ionizing radiation...

Question 8

Which of the following humans is most radiosensitive?

Accepted Answer

Embryos and fetuses during the first trimester of pregnancy are the most radiosensitive due to the rapid division and differentiation of cells during this developmental stage. Mature adults and 5-year-old children have more developed and differentiated cells, making them less sensitive to radiation. A fetus during the third trimester of gestation is still developing but is less radiosensitive than during the first trimester.

Question 9

The term apoptosis is synonymous with:

Accepted Answer

Apoptosis is a process of programmed cell death, in which a cell is systematically dismantled to ensure that it does not damage surrounding cells. It is a normal part of development and occurs in response to a range of physiological and environmental triggers. Meiosis is a type of cell division that occurs in sex cells, while mitosis is a type of cell division that occurs in all other types of cells. Point mutation refers to a change in a single nucleotide base in a DNA molecule.

Question 10

Which of the following groups of cells is least radiosensitive?

Accepted Answer

Adult nerve cells are the least radiosensitive because they have completed their cell division and differentiation. They are less likely to undergo changes or mutations when exposed to ionizing radiation.

Question 11

Based on current data,which of the following would be considered a safe radiation dose for the gonads of both males and females?

Accepted Answer

There is no safe radiation dose for the gonads of both males and females as any amount of radiation exposure can lead to genetic damage and reproductive harm. Therefore, the best choice is 0 Gyt.

Question 12

A biologic reaction is produced by 4 Gyt of a test radiation.It takes 16 Gyt of 250-kVp x-rays to produce the same biologic reaction.What is the relative biologic effectiveness (RBE) of the test radiation?

Accepted Answer

The relative biologic effectiveness (RBE) is calculated as the dose of the reference radiation (250-kVp x-rays) divided by the dose of the test radiation, both required to produce the same biologic effect. Thus, RBE = 16 Gyt / 4 Gyt = 4.

Question 13

Which of the following curves illustrates the radiation sensitivity of a particular type of cell?

Accepted Answer

The survival curve illustrates the radiation sensitivity of a particular type of cell by showing the relationship between the dose of radiation and the percentage of cells that survive.

Question 14

The radiation dose required to produce mitotic death is:

Accepted Answer

The answer of The radiation dose required to produce mitotic...

Question 15

Which of the following statements is true concerning patients who receive radiation exposure from a routine radiographic procedure such as a chest x-ray?

Accepted Answer

Routine radiographic procedures such as a chest x-ray deliver a small amount of radiation and are considered safe. Patients are not expected to sustain appreciable damage to either the blood or the blood-forming organs as a consequence of the examination.

Question 16

A periodic blood count is not recommended as a method for monitoring occupational radiation exposure because:
1)biologic damage from ionizing radiation cannot be determined from a blood test.
2)biologic damage has already been sustained when an irregularity is seen in the blood count.
3)a traditional blood count is a relatively insensitive test that is unable to indicate exposures of less than 10 cGy.

Accepted Answer

2 and 3 are correct because biologic damage from ionizing radiation indeed may have already occurred by the time changes are observed in a blood count, and traditional blood counts are relatively insensitive, often unable to detect exposures below 10 cGy.

Question 17

Which of the following gonadal radiation doses may cause permanent sterility in a male human?

Accepted Answer

A dose of 6.0 Gyt is likely to cause permanent sterility in a male human as it is a high dose of radiation to the gonads. Lower doses, such as 0.01 Gyt and 1.0 Gyt, are unlikely to cause permanent sterility but may still have temporary effects on fertility.

Question 18

Which of the following means the loss or change of a nitrogenous base in the DNA chain?

Accepted Answer

Mutation refers to any change in the DNA sequence, including the loss or change of a nitrogenous base. Aneuploidy refers to a condition where there is an abnormal number of chromosomes, Bleb refers to a bulge in the cell membrane, and Free radical refers to a molecule with an unpaired electron.

Question 19

OH* + OH* = __________.

Accepted Answer

The reaction between two hydroxyl radicals (OH*) typically forms hydrogen peroxide (H2O2).

Question 20

_________ of the effects of x-radiation and gamma in macromolecules of living systems (in vivo) occur as a result of indirect action.

Accepted Answer

Most of the effects of x-radiation and gamma in macromolecules of living systems (in vivo) occur as a result of indirect action. This is because when x-radiation or gamma rays pass through living cells, they ionize the water molecules present in the cells, leading to the formation of free radicals and reactive oxygen species (ROS). These free radicals and ROS are responsible for most of the damage caused to the macromolecules like DNA, proteins, and lipids, which can lead to cell death, mutations, and cancer. Therefore, the majority of the effects of x-radiation and gamma in macromolecules are due to indirect action.

Quiz 7: Molecular and Cellular Radiation Biology