The two major factors that contribute to the weathering of rock are climate and:

A) inorganic minerals.
B) atmospheric carbon dioxide.
C) organisms.
D) aeration.
E) atmospheric oxygen..

In the United States, oral contraceptives are the most common means of birth control.

Which statement best describes a lophophore?

A) It is a ciliated ring of tentacles surrounding the mouth.
B) It is a structure used for locomotion in the Lophophorata.
C) It is the opening also referred to as the anus in the Ecdysozoa.
D) It is a larval stage found in the Lophotrochozoa and the Ecdysozoa.
E) It is one of the openings to the excretory system of phylum Platyhelminthes.

Tension created by transpiration pulls on entire columns of water that fill xylem tubes because water has ____.

A) cohesion due to hydrogen bonds
B) cohesion due to ionic bonds
C) cohesion due to covalent bonds
D) pressure caused by the compression of xylem cells
E) osmotic pressure caused by differences in solute concentrations

Frequently, several different signals or molecules are needed in order to produce an immune response by a B cell or T cell. The second signal in this process is called ________.

A) opsonization
B) copresentation
C) complement activation
D) antigen processing
E) costimulation

Cytotoxic T cell

A) Quick and responsive to antigen, remembers previous exposure
B) After activation, differentiates to become plasma cell or memory B cell
C) Produces antibodies
D) Destroys cells by lysis or by production of cytokines
E) Activates B and effector T cells

mosses, liverworts

A) have rhizoids, cuticle, and protected embryo sporophyte; no xylem
B) produce fruit
C) nonseed-bearing, heart-shaped gametophytes; spore-bearing leaves with sori
D) Lycopodium; cone-bearing sporophyte; free-living gametophyte
E) gymnosperm; only one species left
F) pine and redwood; mostly evergreen
G) confined to tropics or warm, temperate zones; resemble squat cone-bearing palm trees
H) flowering plant with two seed leaves
I) flowering plant with only one seed leaf

In the following pairs, which lists the first messenger followed by a second messenger?

A) insulin; glucagon
B) ACTH; cortisol
C) TSH; thyroxin
D) glucose; insulin
E) peptide hormone; cAMP

Oxygen debt may be associated with

A) low oxygen demand by the cells.
B) lactic acid buildup.
C) too much oxygen in the body.
D) too little carbon dioxide in the body.
E) failure to convert potential energy into kinetic energy.

Okazaki fragments are complementary to the leading strand of DNA.