Biology Study Module #2

Which of the following are the reactants in the chemical reaction that results in 2 molecules of water (2H2O)?

2 molecules of hydrogen gas and 1 molecule of oxygen gas

The cells of the human body are about __________% water. Six elements together make up about 99% of the body. These are oxygen, carbon, hydrogen, __________, __________, and __________.

70; nitrogen; calcium; phosphorus

What is radon?

A radioactive gas from the decay of uranium that can cause lung cancer

Water molecule A has two hydrogens, called HA1 and HA2. Its oxygen atom is called OA. The same naming rules apply to water molecules B, C, D, and E. How does Molecule A form its hydrogen bonds?

HA1 bonds with OB, HA2 bonds with OC, and OA bonds with HD1 and HE1.

What happens when water is heated?

Hydrogen bonds are broken.

Sodium chloride (NaCl, table salt) is a compound but not a molecule. Why?

It does not contain covalent bonds.

Which of the following is a characteristic of Carbon-14, but not of Carbon-12 or Carbon-13?

Its nucleus is unstable.

In Sweden (a cold country) one year, there was sunshine from July 1 to July 10, followed by several days of very cold, rainy weather. If you wanted to stay warm that year during your late-July camping trip, where was the best place to pitch your tent? Why?

Near the coast: Water stores heat from the sun and releases it gradually.

Little Freddie is a bored child at home on a rainy day. He stirs sugar into his water until it dissolves. Match the components of Freddie's new "drink" to their appropriate chemistry terms. Sugar, Water, and Sugar & Water mixture Solute -> Solvent -> Solution ->

Solute -> Sugar Solvent -> Water Solution -> Sugar & Water mixture

Examine the graph. The x-axis shows increasing concentrations of carbonate ions (CO32-) in seawater, while the y-axis shows the rate of calcification of animals on coral reefs. What does this graph tell you about the relationship between the two variables?

The more carbonate ions in seawater, the higher the rate of calcification.

Drinking a buffering solution, such as milk of magnesia, after eating a very acidic meal would be likely to have which of the following effects on the pH of a person's stomach contents?

The pH would increase.

Which of the following is not a true statement regarding radioactive isotopes?

They can be used to diagnose, but not to treat, certain diseases.

Hydrogen and helium are the only elements in the first row of the periodic table. What characteristic(s) do they share that determine(s) their position?

They have only one electron shell.

Which of the following is the best definition of a polar molecule?

a molecule with an unequal distribution of charges

The process whereby coral animals form their skeletons is called __________.

calcification

Of what substance are coral reefs mainly composed?

calcium carbonate skeletons of coral animals

A radioactive tracer called PIB can be used to detect beta-amyloid plaques in the brains of some people with Alzheimer's disease. This represents the medical use of radioactive isotopes to __________.

diagnose disease

Which subatomic particles are directly involved in an atom's chemical activity?

electrons

Water has different properties from its components hydrogen and oxygen. Such properties are called __________.

emergent

Which of the following is a disease caused by an excess of a trace element and what is the element?

fluorosis; fluoride

Scientists have found several lines of evidence pointing to the existence of water on Mars. Which of the following have they observed?

ice caps at both poles soil samples containing water

A deficiency of __________ is the world's most common nutritional deficit.

iron

What information is provided by a molecule's structural formula that is not provided by its molecular formula?

number of covalent bonds and whether they are single, double, or triple

An atom's mass number equals which of the following?

number of protons + number of neutrons

In a covalent bond, electrons are __________. In an ionic bond, electrons are __________. Which is the stronger type of bond?

shared; transferred; covalent

The atomic number of neutral sulfur = 16. How many electrons does a sulfur atom have in its valence shell?

six