RAD BIO EXAM 4

What term is used to describe chemical secretions that are manufactured by various endocrine glands and carried by the bloodstream to influence the activities of other parts of the body?

Hormones

DNA regulates cellular activity indirectly by transmitting its genetic code information outside the cell nucleus by reproducing itself into the form of __________________.

Messenger RNA

Which of the following is another way to refer to lipids?

Fats

Which of the following is the primary energy source of the cell?

Glucose

Which of the following terms is described as the relative capabilities of radiation with differing linear energy tranfers to produce a particular biologic reaction.

Relative Biologic Effectiveness (RBE)

Which of the following structures do the nitrogenous base pairs form?

Steps, or rungs, of the DNA ladder-like structure

Which of the following statements is true regarding inorganic compounds?

They do not contain carbon

Which of the following terms is used to describe to ionization of a water molecule?

Radiolysis

Gamma Rays

Low-LET Radiation

Electrons

Low-LET Radiation

X-rays

Low-LET Radiation

Beta Particles

High-LET Radiation

Alpha Particles

High-LET Radiation

Low-Energy Neutrons

High-LET Radiation

How does the presence of oxygen affect tissue sensitivity to radiation?

Oxygen increases tissue sensitivity to radiation.

How do free radicals primarily cause damage in living cells?

By interacting with and damaging vital cellular components like DNA and proteins

When ionizing radiation irreparably damages the molecules essential for cell synthesis, what do cells do?

Stop dividing and eventually die

Why does high-LET radiation pose a greater risk of irreparable cell damage?

It produces multiple-strand breaks in DNA, which are difficult or impossible to repair.

When germ cells divide, which process do they undergo?

Meiosis

During which stage of the cell cycle is irradiation most likely to cause chromosome aberrations?

Interphase, before DNA synthesis

Which of the following is/are considered low-LET radiation(s)?

X-rays and gamma rays

Which of the following substances makes up approximately 80-85% of the human body?

Water

Direct action may occur after exposure to any type of radiation, but it is much more likely to occur after exposure to which of the following radiation types?

High-LET radiation such as alpha particles

Why do most effects of low-LET (Linear Energy Transfer) radiation in living cells result from indirect action?

Because the human body is 80% water and less than 1% DNA.

Which of the following accurately describes the radiosensitivity of ova?

It varies considerably throughout the lifetime of the germ cell.

Which of the following can cause an increase in cellular activity that in turn causes biochemical reactions to occur more rapidly to meet the needs of the cell in stressful situations?

Enzymes

What distinguishes indirect action of ionizing radiation from direct action at the molecular level?

Indirect action is a multistage process involving free radicals created from water molecules.

What happens to a cell if its master molecule is damaged by radiation and can't repair itself?

Normal cell function will cease, and the cell will die.

For an atom to become ionized, what happens?

An x-ray photon knocks out an electron of the atom it interacts with

Which statement about double-strand breaks in DNA is correct?

They occur more commonly with high-LET radiation.

When LET increases, the chance of a significant biologic response in the radiosensitive DNA macromolecule ___________.

Also increases

Why are free radicals considered dangerous in radiation biology?

They are chemically unstable and highly reactive, attacking DNA, proteins, and membranes.

During mitosis, which phase of the cellular life cycle is the actual DNA synthesis period?

S

Since repair enzymes can mend damaged molecules, what are they capable of helping the cell do?

Recover from a small amount of radiation-induced damage

Which of the following serves as a prototype for messenger RNA (mRNA)?

Deoxyribonucleic acid (DNA)

What are the two main possible outcomes when a cell can no longer function normally after radiation damage?

The cell behaves abnormally or dies

Which inorganic substances are the most important in protoplasm?

Water and mineral salts

Why are lymphocytes particularly important in radiation biology, and what happens when they are damaged?

Lymphocytes defend the body against antigens by producing antibodies; they are highly radiosensitive, and damage from radiation reduces the body's ability to fight infections.

Which of the following terms can be used to refer to fraternal twins?

Dizygotic Twins

Biologic damage produced by radiation escalates as the Linear Energy Transfer (LET) of radiation increases.

True

Which of the following occurs when the sequence of nitrogenous bases in the DNA chain is lost or altered?

Mutation

Which of the following groups of cells is most radiosensitive?

Lymphocytes

Biologic damage from exposure to ionizing radiation can occur at which of the following levels in living systems?

1, 2 and 3

What is the primary way low-LET radiation causes cell damage?

Indirect action through the production of free radicals

What is the primary role of DNA in a cell?

To carry all the information the cell needs to function

What is the annual effective dose (EfD) limit for an occupational worker?

50 mSv

Through which process do somatic cells divide?

Mitosis

What are genes?

Segments of DNA that serve as the basic units of heredity

In a DNA macromolecule, what determines the characteristics of every living thing?

The sequence of nitrogenous bases

Which of the following statements correctly describes the radiosensitivity of human cells?

Immature, undifferentiated cells that divide rapidly are more radiosensitive, while mature, specialized cells that divide slowly or not at all are less radiosensitive.

Which of the following terms is defined as the average energy deposited per unit length of track.

Linear Energy Transfer (LET)

Single-strand breaks in a DNA molecule are most likely to lead to which of the following?

Repair without negative effects to the DNA molecule

In radiation biology, what does the term "target" refer to, and why is a single hit usually not lethal?

A vital molecule or structure (often DNA); single hits usually don't cause lasting harm due to the cell's repair mechanisms.

Which of the following best describes how the indirect action of radiation interacts with a cell?

It first interacts with water molecules in the cell.

Radiation-induced chromosome damage may be evaluated during which of the following processes?

Metaphase

Which of the following is synonymous with apoptosis?

Programmed cell death

What do the steps, or rungs, of the DNA ladder-like structure consist of?

Paired nitrogenous bases

Which of the following groups of cells would be considered least radiosensitive?

Adult nerve cells

What is the primary consequence of ionizing radiation damaging the components of a cell involved in molecular synthesis beyond repair?

The cell loses its ability to carry out normal processes

Interphase consists of which of the following phases?

G1, S, and G2

compounds that do not contain carbon

organic compounds

Process of protein production within a cell

protein synthesis

The frail, semipermeable, flexible structure encasing and surrounding the human cell that functions as a barricade to protect cellular contents from the outside environment and also controls the passage of water and other materials into and out of the cell

cell membrane

Multiplication process whereby one cell divides to form two or more cells

mitosis

Chemical secretions manufactured by various endocrine glands and carried by the bloodstream to influence the activities of other parts of the body

hormones