Question 1

Which of the following best explains why controlled medical radiation therapy can be effective in treating cancer?

Accepted Answer

Radiation provides a large and deadly dose to cancerous cells while mostly sparing surrounding healthy tissues.

Question 2

Which four elements make up about 96% of the weight of the human body?

Accepted Answer

Oxygen, carbon, hydrogen, and nitrogen

Question 3

A patient develops a goiter due to a deficiency in which trace element?

Accepted Answer

Iodine

Question 4

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 5

A radioactive isotope is useful as a tracer in medical diagnostics because:

Accepted Answer

It can be detected due to the radiation it emits after being taken up by cells.

Question 6

Which type of chemical bond is the strongest and holds atoms together in a molecule?

Accepted Answer

Covalent bond

Question 7

What is the main reason water is considered a polar molecule?

Accepted Answer

Oxygen has a much higher electronegativity than hydrogen, causing unequal sharing of electrons.

Question 8

Which property of water allows trees to transport water from their roots to their leaves?

Accepted Answer

Cohesion due to hydrogen bonding

Question 9

Why does ice float on liquid water?

Accepted Answer

Hydrogen bonds in ice hold molecules apart, making it less dense than liquid water.

Question 10

Which of the following best describes a solution in which water is the solvent?

Accepted Answer

An aqueous solution

Question 11

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-6}$$ M. What is its pH?

Accepted Answer

$$pH = 6$$

Question 12

If the pH of a solution changes from 7 to 5, how does the hydrogen ion concentration change?

Accepted Answer

It increases by a factor of 100.

Question 13

Which of the following is a function of buffers in biological systems?

Accepted Answer

Buffers minimize changes in pH by accepting or donating hydrogen ions.

Question 14

Which of the following best describes the process of radiometric dating?

Accepted Answer

It measures the ratio of radioactive isotopes to stable isotopes to estimate the age of a fossil.

Question 15

Which of the following is true about chemical reactions in cells?

Accepted Answer

Chemical reactions rearrange matter by breaking and forming chemical bonds.

Question 16

Which of the following is an example of an ionic compound?

Accepted Answer

NaCl

Question 17

What is the main difference between a nonpolar covalent bond and a polar covalent bond?

Accepted Answer

Nonpolar covalent bonds have equal sharing of electrons, while polar covalent bonds have unequal sharing.

Question 18

Which property of water is most responsible for its ability to moderate Earth's climate?

Accepted Answer

Water's high heat capacity due to hydrogen bonding

Question 19

A molecule of water (H$$_2O) is $$held together by which type of bond between the hydrogen and oxygen atoms?

Accepted Answer

Covalent bond

Question 20

Which of the following best explains why fluorine is added to drinking water?

Accepted Answer

To help maintain healthy bones and teeth

Essential Chemistry of Biology – Study Notes

Study Guide - Practice Questions