Biology Chapter 2: chemistry

Why are hydrophobic molecules such as fats and oils unable to dissolve in watery solutions?

Water molecules form hydrogen bonds with each other, excluding the hydrophobic molecules.

What is a hydrogen bond?

a weak bond between two partially charged atoms

What is the fundamental structural unit of all matter?

atom

Which of the following lists of terms is in the correct order of size, going from smallest to largest? molecule, atom, nucleus, proton, electron electron, proton, nucleus, molecule, atom proton, electron, nucleus, atom, molecule electron, proton, nucleus, atom, molecule nucleus, electron, proton, atom, molecule

electron, proton, nucleus, atom, molecule

What is contained in the nucleus of the atom?

protons and neutrons

In water, the chemicals HsPO4-, HPO42-, and HCO3- all act as buffers. In dry form, these chemicals are often ionically bound to another element. Which of the following is a good candidate for that element?

sodium (Na) Sodium can form a positive ion to bind to these chemicals and will not itself affect the pH of the solution.

Cancer is caused by mutating DNA. What exactly do cigarette smoke and radiation do that can cause cancer?

Cigarette smoke and radiation both cause free radicals, which damage DNA, leading to mutation.

How do atoms respond when they absorb energy?

Electrons move to a higher orbital.

How are ionic and covalent bonds related?

Ionic and covalent bonds both result in a full outer electron shell.

Because the specific heat of land is less than the specific heat of water, which of the following should be true?

Lakes should be warmer at night than the land around them.

Coffee has a pH of 5.0. Stomach acid has a pH of 2.0. How does coffee compare to stomach acid?

Stomach acid is 1,000 times more acidic than coffee

If electrons in water molecules were equally attracted to the hydrogen and oxygen atoms, how would this affect the bonds between them?

The bond would become less polar.

How do the hydrogen bonds between water molecules compare to the covalent bonds within water molecules?

The hydrogen bonds are more easily broken than the covalent bonds.

Why does ice float?

The hydrogen bonds in solid water force the molecules farther apart than the same bonds in liquid water.

How does water dissolve salt?

The partial positive charges of the hydrogen atoms on water surround the negative charge of a chlorine ion.