human biology chapter 2 chem

the pH of human blood is normally

7.4

The nucleotide most closely associated with energy is

ATP

________ reactions release energy.

Catabolic, exergonic, and decomposition

. Which of the following is a molecule, but not a compound? a. H2O b. 2H c. H2 d. H+

H+

cellulose is

a material found in plant cell walls

Proteins may function as a. structural units. b. hormones. c. storage molecules. d. transport molecules. e. all of these

all of these

Which of the following are lipids? a. steroids b. triglycerides c. oils d. waxes e. all of these

all of these

steriods are a. compounds that are related to lipids. b. sex hormones. c. components of membranes. d. troublesome on walls of arteries. e. all of these

all of these

A hydrogen bond is

an attractive force that involves a hydrogen atom and an oxygen or a nitrogen atom that are either in two different molecules or within the same molecule.

When an atom donates an electron to another atom, it becomes

an ion

Glycogen is a polysaccharide used for energy storage by

animals

Cellular pH is kept near a value of 7 because of

buffers

Which of the following is NOT a compound? a. salt b. a carbohydrate c. carbon d. a nucleotide e. methane

carbon

Organic compounds consist mainly of ________ atoms.

carbon and hydrogen

water is an example of a(n)

compound

DNA

contains protein building instructions

What kind of bond is formed when two atoms share a pair of electrons?

covalent

The disruption of a protein's three-dimensional shape is called

denaturation

Proteins that speed up chemical reactions are

enzymes

True or False? A solution with a low pH is more basic than a solution with a high pH.

false

True or False? Isotopes differ by the number of protons in their atoms.

false

Triglycerides are

fats

Select the carbohydrate. a. amino acid b. enzyme c. glucose d. peptide e. water

glucose

What organic compound do brain cells primarily rely on for fuel?

glucose

Which of the following is a building block of carbohydrates? a. glycerol b. nucleotide c. amino acid d. lipid e. glucose

glucose

A phospholipid ________.

has both polar and nonpolar regions

The shape (or tertiary form) of large molecules is often controlled by what kind of bonds?

hydrogen

What kind of bond is a weak attraction formed between a slightly positive atom on one molecule and a slightly negative atom on a different molecule?

hydrogen

the pH scale measures the

hydrogen ion concentration

In a lipid bilayer, __________ tails point inward and form a region that excludes water.

hydrophilic

What kind of bond is formed by the attraction of oppositely charged particles?

ionic

A salt will dissolve in water to form

ions

glucose dissolves in water because it

is polar and forms many hydrogen bonds with the water molecules

Organisms consist mostly of four elements. They are carbon, hydrogen, oxygen, and

nitrogen

CH4 is methane. This compound is ________. a. inorganic b. organic c. reactive d. a crystal

organic

Together, just four elements make up more than 95 percent of the body's mass. These include ________.

oxygen, carbon, hydrogen and nitrogen

The formation of buffers is important mainly in the regulation of the ________ of a solution.

pH

Which pH in a solution has the greatest concentration of hydrogen ions?

pH1

Which of the following is the most basic pH? a. pH 1 b. pH 5 c. pH 7 d. pH 9 e. pH 13

pH13

Which of the following is a neutral pH? a. pH 1 b. pH 4 c. pH 7 d. pH 10 e. pH 14

pH7

Select the element that is not one of the four most common elements in living matter. a. carbon b. hydrogen c. nitrogen d. oxygen e. phosphorous

phosphorous

A molecule of ammonia contains one atom of nitrogen and three atoms of hydrogen. These are linked with ________.

polar covalent bonds

A large molecule built of three to millions of subunits is a(n)

polymer

An enzyme is mainly

protein

All atoms of an element have the same number of

protons

The atomic number is determined by the number of

protons

The nucleus of an atom contains

protons and neutrons

How do hydrophobic molecules interact with water?

repelled by

Chewing a bite of bread mixes it with saliva and facilitates its chemical breakdown. This is most likely due to the fact that ________.

saliva contains enzymes

A substance dissociates into K+ and Cl- in solution. The substance is a(n) ________.

salt

lipids

serve as food reserves in many organisms

Which of the following is a "building block" of carbohydrates? a. glycerol b. nucleotide c. simple sugar d. monosaccharide e. simple sugar or monosaccharide

simple sugar or monosaccharide

The ability of an enzyme's active sites to bind only substrates of compatible shape and charge is known as ________.

specificity

Adenosine triphosphate (ATP) is an important molecule because it ________.

stores energy for use by body cells

A neutron is best described as a(n)

subatomic particle

The atomic number refers to the

the number of protons in an atom

Covalent bonding involves

the sharing of electrons

Radioactive iodine tends to concentrate in the

thyroid glands

True or False? A solution has a pH of 6.8. This pH is acidic.

true

True or False? Water is an example of a polar molecule.

true

an antioxidant

would protect DNA from damage