Chapter 2 Biology

Which number represents the atomic weight of oxygen?

16

What is the maximum number of single covalent bonds a carbon atom can form with other elements?

4

How many neutrons are in a typical oxygen atom?

8

The typical carbon atom is described in the periodic table by the accompanying box. How many protons are in a typical oxygen atom?

8

While the maximum number of electrons required to fill the outermost shell of an atom varies depending on the size of the atom, almost all of the smaller atoms (atomic numbers 2-20) are considered stable, and thus nonreactive, when they contain ________ electron(s) in the outermost shell.

8

What is an organic compound?

A compound that contains carbon bonded to other elements

What is a trace element?

An element that is required in miniscule amounts for life

Imagine that you have been employed as a technical consultant for a new television program in which the main character is a doctor who works with anabolic steroids. The writers have asked you for a short description to provide them with background about this class of drugs. How would you best describe them?

Anabolic steroids are synthetic versions of the male sex hormone testosterone. They can increase muscle mass and strength, but they also have dangerous side effects and are illegal without a prescription.

Why is life based on carbon-based molecules?

Because a single carbon can bond with up to four other atoms

How do buffers minimize change in the pH of biological systems?

By donating H+ ions when there is a shortage and By absorbing H+ ions when there is an excess

Identify the reactants in the following chemical reaction: C10H8 + 12 O2 10 CO2 + 4 H2O

C10H8 and 12 O2

Which of the following large organic molecules include table sugar?

Carbohydrates

What are the four classes of large organic molecules important to life on Earth?

Carbohydrates, proteins, lipids, and nucleic acids

________ is the polysaccharide most commonly found in highly fibrous foods such as celery.

Cellulose

Which of the following statements regarding chemical reactions is false?

During a chemical reaction, atoms of one element can be converted into a different element.

Why is one side of a single water molecule partially negative while the other side is partially positive?

Electron pairs are unevenly shared between the oxygen atom and the two hydrogen atoms.

__________ are substances that CANNOT be broken down into other substances by chemical reactions.

Elements

Proteins are diverse molecules that perform a wide variety of functions. Which of the following is not a typical function of proteins?

Energy Storage

Which of the following represents a simple sugar (also called a monosaccharide)?

Glucose

Which of the following bonds is the weakest?

Hydrogen

What do we call the sum total of all the chemical reactions that take place in your body?

Metabolism

What is the most common element in your body?

Oxygen

Which four elements make up the bulk of living cells?

Oxygen, carbon, hydrogen, and nitrogen

What kind of bond joins amino acids together to form a protein?

Peptide Bond

__________ bonds hold the oxygen and hydrogen atoms in a molecule of water together.

Polar Covalent

Water "beads up" on synthetic fabric such as polyester but binds to cotton. What is the most likely explanation for this?

Polyester is nonpolar, whereas cotton is polar.

Which of the following molecules is solid at room temperature?

Saturated Fats

Which of the following properties of water molecules has important implications to life?

The ability to dissolve polar substances, The ability of ice to float in water, High surface tension

What makes one protein capable of a different function than other proteins?

The amino acid sequence of a protein determines its function.

A needle can be made to "float" on the surface tension of water. What causes this surface tension to form?

The cohesion of water molecules to each other

Select the most complete explanation of what the pH scale measures.

The concentration of hydrogen ions in an aqueous solution

Which of the following accurately describes the pH scale?

The pH scale runs from 0 (most acidic) to 14 (most basic), with 7 as a neutral.

What might happen if a protein has a change in one amino acid?

The protein has a new shape.

What do you think might happen if you put a mixture of proteins and starch in a solution containing trypsin, an enzyme that breaks down proteins?

The protein would be broken down into amino acids.

What will be accomplished by lowering the activation energy of a reaction?

The reaction will proceed more quickly.

To a large extent, a protein's function is dependent upon its shape. What determines a protein's shape?

The sequence of amino acids

What are the ecological consequences of acidification of rain and oceans?

They damage the health of ecosystems.

Oil hydrogenation can produce a product, such as vegetable shortening or margarine, that is spreadable at room temperature because of an unusual bond that does not occur naturally. What is the name of this category of lipid?

Trans fat

Evaluate this statement: Cholesterol is a type of lipid, and thus all cholesterol lipids are bad for human health.

True, because high levels of cholesterol lead to obesity.

What are isomers?

Two molecules that have the same atoms arranged differently

How can we explain that water is a solvent?

Water is very dense in its liquid state, which allows it to bind to different substances as a solvent.

What is responsible for the unusual chemical properties of water?

Water molecules can form an extensive network of hydrogen bonds with one another. Submit

Something with a pH of 5 would be ________.

acidic

What are the monomers of proteins?

amino acids

Organic compounds are distinguished by molecules that contain ________ bonded to other elements.

carbon

The number of electrons of an atom determines its ________.

chemical element

What are inhibitors?

chemicals that selectively inhibit the action of specific enzymes

The chemical name for table salt is sodium chloride, or simply NaCl. What type of chemical is NaCl?

compound

The bond in which bonded atoms share electrons is called a(n) ________.

covalent

The building of a large organic molecule from small subunits involves multiple ________.

dehydration synthesis reactions

Starch and glycogen are complex carbohydrates made by joining together long chains of __________ molecules.

glucose

The 2+ in Cu2+ tells us that this atom ________.

has two more protons than electrons

The breaking of a large organic molecule into smaller, individual subunits involves multiple ________.

hydrolysis reactions

All lipids are ________.

hydrophobic

In an atom, the number of neutrons determines most specifically the ________.

isotope

All sodium atoms have 11 protons. The nuclei of some sodium atoms contain 12 neutrons and others contain 11. These different forms of sodium are called __________.

isotopes

Enzymes are a type of ________.

protein

During digestion, __________ are broken down into __________ through __________ reactions.

proteins; amino acids; hydrolysis

The atomic number corresponds to the number of ________ in a specific element, while the atomic weight corresponds to the number of ________ in a specific element.

protons; protons and neutrons

During a chemical reaction, atoms are ________.

rearranged