Chapter 02 Homework

Why is a denatured enzyme no longer functional?

A denatured protein has lost its normal three-dimensional shape; if that protein is an enzyme, denaturing can change the shape of its active site.

What type of chemical reaction is used by liver cells when synthesizing glycogen from glucose?

Dehydration synthesis.

Atoms that have lost or gained electrons during chemical bonding are known as isotopes.

False

Phospholipids have a hydrophobic region (the "head") and a hydrophilic region (fatty acid chains, or nonpolar "tails").

False

Which carbohydrate is also known as blood sugar?

Glucose

An atom of magnesium has lost two electrons. It is known as a(n) ________.

Cation

Which of the following lipids is formed of four interlocking carbon rings?

Cholesterol

Water is the single most abundant inorganic compound in the human body.

True

Polar molecules, like water, result when electrons are shared ________.

Unequally between atoms

Which nitrogen-containing base is found only in RNA?

Uracil

Which of these vitamins is produced in skin upon exposure to ultraviolet (UV) radiation?

Vitamin D

What organic molecule provides an immediate source of chemical energy within all cells?

Adenosine triphosphate.

Why are salts referred to as electrolytes?

After salts dissolve in a solution, the resulting ions can conduct an electrical current.

What is an ion?

An atom that has either gained or lost electron(s)

What type of bond is formed when electrons are transferred from one atom to another?

An ionic bond.

In a covalent bond,

Atoms share one or more pairs of electrons.

A salt is an ionic compound containing cations other than hydrogen and anions other than the hydroxylion. In writing the formula for a salt, the symbol of the cation is listed first, and the symbol for the anion is listed second. Which one of these is a salt?

CaPO4

A chemist experiments on a molecule with the formula of C5H10O5. This compound is likely a(n) ________.

Carbohydrate

Trans fats are oils that have been solidified by the addition of ________.

Hydrogen atoms

Which of the following leads to an increase in the rate of a chemical reaction?

Increased temperature.

Covalent bonds:

Involve the sharing of one to three pairs of electrons.

How do ions form ionic bonds?

Ions of opposite electrical charges are attracted to each other to balance the charges.

Which statement best describes energy?

It does not have mass or occupy space.

Which subatomic particles contribute to an atom's mass number but not its atomic number?

Neutrons.

The number of protons always equals the ________ in a neutral atom.

Number of electrons

What ion is found in bone, nucleic acids, and ATP?

Phosphorous

A molecule of water (H2O) is formed by what type of bond?

Polar covalent bonds

Glycogen and starch are examples of a specific category of carbohydrates called ________.

Polysaccharides

During a synthesis reaction, amino acids join to form ________.

Proteins

The atomic number of an atom is equal to the number of ________ an atom contains.

Protons

An acid is a molecule that releases (donates) ________.

Protons (hydrogen ions)

Which type(s) of subatomic particles can be located within the nucleus of an atom?

Protons and neutrons.

A molecule with the sequence of AUCGUCA should be categorized as ________.

RNA

Which of the following is true of polar covalent bonds?

The electrons are shared unequally.

What does the molecular formula CO2 mean?

The molecule contains one atom of carbon (C) and two atoms of oxygen (O).

When an ionic bond forms, which part(s) of the atoms are directly involved?

The outermost electrons

What occurs when acid is added to a solution with a pH of 7?

The pH drops below 7.

Which of these events occurs when salts dissolve in body fluids?

They easily dissociate into their ions.

The complementary base to adenine in a molecule of DNA is ________.

Thymine

Which organic molecule or molecules are found in subcutaneous tissues and around organs, and are the major source of stored energy in the body?

Triglycerides.

The lower the pH, the greater the number of hydrogen ions released by a chemical into solution.

True