chapter1
What are the five major unifying themes of biology?
Organization, information, energy and matter, interactions, and evolution.
What are the four most abundant elements found in living systems?
Nitrogen, carbon, sulfur, and oxygen
Hydrogen, oxygen, calcium, and nitrogen
Hydrogen, oxygen, nitrogen, and carbon dioxide
Hydrogen, oxygen, nitrogen, and carbon
Hydrogen, oxygen, nitrogen, and carbon
right answer. These four elements make up about 96% of living matter.
Water is a polar molecule. What does this statement mean?
That the atoms in water have equal electronegativities
That atoms in the molecule have partial charges as a result of unequal sharing of electrons in a covalent bond
That water is one of the many hydrophobic molecules
That water molecules are linear, like a pole
That atoms in the molecule have partial charges as a result of unequal sharing of electrons in a covalent bond
In the case of water, the oxygen is slightly negative, and the hydrogen atoms are slightly positive.
What are the six most important chemical elements of life?
Carbon, nitrogen, calcium, oxygen, phosphate, iron
Carbon, nitrogen, oxygen, calcium, phosphate, hydrogen
Carbon, nitrogen, oxygen, hydrogen, phosphate, sulfur
Carbon, nitrogen, sulfur, hydrogen, iron, magnesium
Carbon, nitrogen, oxygen, hydrogen, phosphate, sulfur
All of these elements are capable of forming strong covalent bonds, important in building large, complex molecules.
What is the process by which monomers are linked together to form polymers?
Monomerization
Hydrolysis
Coiling
Dehydration reaction
Protein formation
Dehydration reaction
When monomers are linked together to form a more complex polymer, a water molecule is removed by dehydration reactions.
A scientist records the height of plants in centimeters after giving them different amounts of fertilizer. Is the height measurement qualitative or quantitative data?
Quantitative, because it is expressed as a numerical measurement.
Which of the following subatomic particles has appreciable mass but no charge?
Proton
Neutron
Electron
Both proton and neutron
A neutrin
Correct. A neutron weighs about 1.7 × 10–24 grams (has a mass close to 1 dalton), and it is electrically neutral.
In a group of water molecules, hydrogen bonds form between which of the following?
The hydrogen atoms in a single water molecule
Two hydrogen atoms in different water molecules
The oxygen atom in one water molecule and a hydrogen atom in another water molecule
The oxygen atoms in different water molecules
The oxygen atom in one water molecule and a hydrogen atom in another water molecule
The slightly negatively charged region of an oxygen atom of one water molecule is attracted to the slightly positively charged region of a hydrogen atom of another water molecule.
Which of the following is an organic molecule?
Ne
NaCl
O2
CH4
CH4
Compounds containing carbon are said to be organic.
In a hydrolysis reaction, __________, and in this process, water is _________
a monomer is broken up into its constituent polymers; produced
monomers are assembled to produce a polymer; produced
monomers are assembled to produce a polymer; consumed
a polymer is broken up into its constituent monomers; consumed
a polymer is broken up into its constituent monomers; produced
a polymer is broken up into its constituent monomers; consumed
The meaning of hydrolysis is "to break with water."
A scientist wants to determine whether fertilizer causes plants to grow taller. She gives one group fertilizer and another group no fertilizer. what is the independent variable
The amount/presence of fertilizer, because that is what the researcher manipulates.
An uncharged atom of nitrogen (atomic number = 7) has _________
seven protons and seven neutrons
seven neutrons and six protons
seven protons and seven electrons
seven neutrons and seven electrons
seven protons and seven electrons
Correct. The atomic number is the number of protons, and this equals the number of electrons in an electrically neutral (uncharged) atom.
The tendency of water molecules to stay close to each other as a result of hydrogen bonding __________.
provides the surface tension that allows small animals to move across a water surface
helps to keep water moving through the vessels in a tree trunk
is called cohesion
is called cohesion, acts to moderate temperature, provides the surface tension that allows small animals to move across a water surface, and helps to keep water moving through the vessels in a tree trunk
is called cohesion, acts to moderate temperature, provides the surface tension that allows small animals to move across a water surface, and helps to keep water moving through the vessels in a tree trunk
All of the choices reflect results of the cohesiveness of water molecules.
The carbon atom possesses __________ valence electron(s).
2
3
1
4
4
Carbon's four valence electrons allow it to form four covalent bonds.
Generally, animals cannot digest (hydrolyze) the glycosidic linkages between the glucose molecules in cellulose. How then do cows get enough nutrients from eating grass?
They have to eat a lot of grass.
Cows and other herbivores are exceptions and make some cellulose-digesting enzymes.
Microorganisms in their digestive tracts hydrolyze the cellulose to individual glucose units.
The flat teeth and strong stomach of herbivores break the cellulose fibers so that the cows get enough nutrition from the cell contents.
All of the listed responses are correct.
Microorganisms in their digestive tracts hydrolyze the cellulose to individual glucose units.
Cows have digestive chambers populated by microorganisms that can produce certain hydrolytic enzymes that cows cannot. The enzymes hydrolyze (digest) the cellulose polymer into glucose monomers.
An experiment produces the expected result once, but when other scientists repeat the experiment using the same procedure, they cannot reproduce the result.
Why is this a problem scientifically, and what should happen to the original claim?
The result is not reliably repeatable, so the original claim needs to be questioned and potentially revised. Scientific knowledge is strengthened by reproducible evidence.
Some groups of chemical elements react similarly to one another. For example, the chemistries of sodium and of lithium are similar, as are the chemistries of chlorine and of iodine. These similarities in chemistry result when different elements have similar _________
atomic size
energy per electron
numbers of outer-shell electrons
total numbers of electrons
numbers of outer-shell electrons
Atoms with the same number of electrons in their valence shells exhibit similar chemical behavior or reactivity.
What do cohesion, surface tension, and adhesion have in common with reference to water?
All have to do with ionic interactions.
All are produced by covalent bonding.
All are properties related to hydrogen bonding.
All are results of the structure of the hydrogen atom.
All are properties related to hydrogen bonding.
The extraordinary qualities of water are emergent properties resulting from hydrogen bonding.
A straight-chain carbon compound constructed from __________ must contain at least one carbon-carbon double bond.
6 hydrogen atoms, 2 carbon atoms, and 1 oxygen atom
8 hydrogen atoms, 3 carbon atoms, and 3 oxygen atoms
6 hydrogen atoms and 2 carbon atoms
6 hydrogen atoms and 3 carbon atoms
6 hydrogen atoms and 3 carbon atoms
There must be a carbon-carbon double bond for this molecule to exist.
Which of the following molecules is a monosaccharide?
C22H49O10N5
C51H98O6
C45H84O8PN
C25H43O8
C6H12O6
C6H12O6
Monosaccharides have molecular formulas that are multiples of CH2O.
A company was testing a new drug it thought would help decrease the risk of transmission of viruses from mother to fetus. In an experiment to test the compound, an investigator gave 400 pregnant female rats a small dose of the experimental drug and inoculated each with a type of virus known to cause disease in rats. At the same time, 400 other pregnant rats were given only the virus. Of the rat pups born to the females that received both the virus and the drug, 197 showed no symptoms of the disease; 205 rat pups born to the virus-only females showed symptoms. From these data, we can best conclude __________.
nothing because no independent variable could be identified
nothing because no control group was used in the test of the drug
that the drug is effective and testing on humans should begin
that the drug seems to have little effect on viral transmission at the dosage given
"that the drug seems to have little effect on viral transmission at the dosage given"
right answer feedback:Correct. Approximately equal numbers of pups were affected in both groups (experimental group = 197, control group = 205), suggesting that the drug was probably not effective at the dosage given.
Copper has an atomic number of 29 and a mass number of 64. What would result if an uncharged copper atom lost two electrons?
The atom would have a double negative charge and be an ion.
The atomic number would remain 29, the mass number would remain 64, and the atom would be a cation with a +2 charge.
The atomic number would be reduced to 27, the mass number would remain 64, and the atom would be an anion with a +2 charge.
The atomic number of the atom would remain 29, the mass number would be reduced to 62, and the atom would be an anion.
The atomic number would remain 29, the mass number would remain 64, and the atom would be a cation with a +2 charge.
The loss or gain of electrons does not influence the atomic number (number of protons) or the mass number (number of protons plus neutrons) of an atom.
How does the polarity of water contribute to its ability to dissolve so many substances?
Natural water has a pH of approximately 5.6, which is slightly acidic. Acids can dissolve more substances than bases can.
Water's polarity allows it to form covalent bonds with many substances.
Because it is polar, water forms ionic bonds with the ions in substances such as NaCl (salt).
Because it is polar, water's negatively charged oxygen atoms and positively charged hydrogen atoms are attracted to positively and negatively charged ions and molecules.
Because it is polar, water's negatively charged oxygen atoms and positively charged hydrogen atoms are attracted to positively and negatively charged ions and molecules.
Polar water molecules surround the individual ions or charged molecules, separating and shielding the ions or molecules from one another.
Which of the following groups is capable of hydrogen bonding with an oxygen atom on another functional group?
Carboxyl group
Amino group
Hydroxyl group
All of the listed responses are correct.
All of the listed responses are correct.
All of the listed functional groups are polar and thus capable of hydrogen bonding with the oxygen of another molecule.
If a small droplet of triacylglycerol molecules is suspended in water, the fat molecules form a "ball of spaghetti" with no particular orientation. But if a droplet of phospholipid molecules is put in water, all the molecules point outward, toward the water. Phospholipids are forced into this orientation because phospholipids have __
a charged or polar end and an uncharged or nonpolar end
three fatty acid molecules, all pointing in different directions
two charged or polar ends
both a saturated fatty acid and an unsaturated fatty acid
two fatty acid molecules pointing in different directions
a charged or polar end and an uncharged or nonpolar end
The nonpolar hydrocarbon tails of phospholipids are hydrophobic—that is, they are excluded from water. The negatively charged phosphate group and its attachments form a hydrophilic head that is attracted to water.