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