Cells are _____.
characteristic of prokaryotic and eukaryotic organisms
In comparison to eukaryotes, prokaryotes _____.
Which of the following types of cells utilize deoxyribonucleic acid (DNA) as their genetic material but do not have their DNA encased within a nuclear envelope?
To understand the chemical basis of inheritance, we must understand the molecular structure of DNA. This is an example of the application of which concept to the study of biology?
A localized group of organisms that belong to the same species is called a _____.
When a person gets dehydrated while exercising on a hot day, their pituitary gland releases ADH, a hormone that signals the kidneys to retain more water. This is an example of
Negative feedback regulation
Agrobacterium infects plants and causes them to form tumors. You are asked to determine how long a plant must be exposed to these bacteria to become infected. Which of the following experiments will provide the best data to address that question?
Measure the number of tumors formed on plants, which are exposed to Agrobacterium for different lengths of time.
Which of these provides evidence of the common ancestry of all life?
near universality of the genetic code
How does a scientific theory differ from a scientific hypothesis?
Theories are usually an explanation for a more general phenomenon; hypotheses typically address more specific issues.
The best experimental design _____.
includes a large sample size and a control, and alters only one condition between the controls and the experimental condition
What is the difference between atomic mass and atomic weight?
Atomic mass is the mass of a single atom or an individual isotope. The atomic weight is the average mass of all naturally occurring isotopes of an element.
About twenty-five of the ninety-two natural elements are known to be essential to life. Which four of these twenty-five elements make up approximately 96 percent of living matter?
carbon, hydrogen, nitrogen, oxygen
Knowing the atomic mass of an element allows inferences about which of the following?
the number of protons plus neutrons in the element
Carbon-12 is the most common isotope of carbon and has a mass number of 12. However, the average atomic mass of carbon found on a periodic table is slightly more than 12 daltons. Why?
Some carbon atoms in nature have more neutrons.
Fluorine has an atomic number of 9. Which of the following would you do to a neutral fluorine atom to complete its valence shell?
add 1 electron
Oxygen has an atomic number of 8 and most commonly, a mass number of 16. Thus, what is the atomic mass of an oxygen atom?
approximately 16 daltons
If you change the number of neutrons in an atom, you create _____.
A covalent chemical bond is one in which _____.
outer-shell electrons of two atoms are shared so as to satisfactorily fill their respective orbitals
What is the difference between covalent bonds and ionic bonds?
Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between charged atoms.
How many electrons are involved in a single covalent bond?
In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by _____.
polar covalent bonds
The partial negative charge in a molecule of water occurs because _____.
the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus
Water molecules can form hydrogen bonds with _____.
compounds that have polar covalent bonds
The cities of Portland, Oregon, and Minneapolis, Minnesota, are at about the same latitude, but Minneapolis has much hotter summers and much colder winters than Portland. Why?
The ocean near Portland moderates the temperature.
Water has many exceptional and useful properties. Which is the rarest property among compounds?
Solid water is less dense than liquid water.
Which of the following effects can occur because of the high surface tension of water?
A raft spider can walk across the surface of a small pond.
What is the pH of a solution with a hydroxyl ion (OH-) concentration of 10-12 M?
A beaker contains 100 milliliters (mL) of NaOH solution at pH = 13. A technician carefully pours into the beaker 10 mL of HCl at pH = 1. Which of the following statements correctly describes the result of this mixing?
The pH of the beaker's contents will decrease.
Increased atmospheric CO2 concentrations might have what effect on seawater?
Seawater will become more acidic, and carbonate concentrations will decrease.
Differences among organisms are caused by differences in the _____.
elemental composition from organism to organism
Stanley Miller's 1953 experiments supported the hypothesis that _____.
organic molecules can be synthesized abiotically under conditions that may have existed on early Earth
Which of the following is true of carbon?
It can form both polar and nonpolar bonds.
How many electron pairs does carbon share to complete its valence shell?
A carbon atom is most likely to form what kind of bond(s) with other atoms?
Which of the following statements correctly describes cis-trans isomers?
They have variations in arrangement around a double bond.
Research indicates that ibuprofen, a drug used to relieve inflammation and pain, is a mixture of two enantiomers; that is, molecules that _____.
are mirror images of each other
Which two functional groups are always found in amino acids?
carboxyl and amino groups