In the formation of biofilms, such as those forming on unbrushed teeth, cell signaling serves which function?

A) Formation of mating complexes

B) Secretion of apoptotic signals

C) Aggregation of bacteria that can cause cavities

D) Secretion of substances that inhibit foreign bacteria

E) Digestion of unwanted parasite population

C) Aggregation of bacteria that can cause cavities

In yeast signal transduction, the yeast cells

A) Must physically and directly interact

B) Produce signal molecules that change themselves so they can interact with one another

C) Produce response molecules that diffuse to other yeast cells

D) Secrete molecules that result in response by other yeast cells

E) Mate, after which the new cells secrete hybrid signals

D) Secrete molecules that result in response by other yeast cells

In which of the following ways do plant hormones differ from hormones in animals?

A) Plant hormones interact primarily with intracellular receptors

B) Plant hormones may travel in air or through vascular systems

C) Animal hormones are found in much greater concentration

D) Plant hormones are synthesized from two or more distinct molecules

E) Animal hormones are primarily for mating and embryonic development

B) Plant hormones may travel in air or through vascular systems

In an experiment to track the movement of growth factor molecules from secretion to the point of receptor binding in a particular species of mammal, a student found a 20-fold reduction in mm traveled when in the presence of an adrenal hormone. This is an in part attribute to which of the following?

A) The growth factor is a paracrine signal

B) The growth factor depends on osmosis

C) The mammal only carries growth factor through the lymph

D) The growth factor is an exocrine signal

E) The growth factor is an endocrine signal

A) The growth factor is a paracrine signal

When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway?

A) Receptor

B) Relay molecule

C) Transducer

D) Signal molecule

E) Endocrine molecule

D) Signal molecule

Of the following, a receptor protein in a membrane that recognizes a chemical signal is most similar to

A) The active site of an allosteric enzyme that binds to a specific substrate

B) tRNA specifying which amino acids are in a polypeptide

C) a metabolic pathway operating within a specific organelle

D) an enzyme having an optimum pH and temperature for activity

E) an antibody in the immune system

A) The active site of an allosteric enzyme that binds to a specific substrate

Which of the following is true for the signaling system in an animal cell that lacks the ability to produce GTP?

A) It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane

B) It could activate only the epinephrine system

C) It would be able to carry out reception and transduction but would not be able to respond to a signal

D) It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane

E) It would employ a transduction pathway directly from an external messenger

A) It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane

Testosterone functions inside a cell by

A) Acting as a signal receptor that activates tyrosine kinases

B) Binding with a receptor protein that enters the nucleus and activates specific genes

C) Acting as a steroid signal receptor that activates ion channel proteins

D) Becoming a second messenger that inhibits adenylyl cyclase

E) Coordinating a phosphorylation cascade that increases spermatogenesis

B) Binding with a receptor protein that enters the nucleus and activates specific genes

Which of the following is true of transcription factors?

A) They regulate the synthesis f DNA in response to a signal

B) The transcribe ATP into cAMP

C) They initiate the epinephrine response in animal cells

D) They control gene expression

E) They regulate the synthesis of lipids in the cytoplasm

D) They control gene expression

One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and the activating relay proteins. which type does this?

A) G protein-coupled receptors

B) Ligand-gated ion channels

C) Steroid receptors

D) Receptor tyrosine kinases

D) Receptor tyrosine kinases

E

B

C

D

A

E

C

A

E

A

D

C

C

C

D

D

E

C

A

C

C

E

A

B

C

D

C

D

C

B

D

C

B

A

A

E

C

D

C

B

E

D

B

B

Human have receptors for two kinds of beta adrenergic compounds such as catecholamines to control cardiac muscle contractions. Some are beta 1 receptors that promote increased heart rate. Other drugs, called beta blockers, slow heart rate. Smooth muscle cells, however, have beta 2 receptors, which mediate muscle relaxation. Blockers of these effects are sometimes used to treat asthma.

A

Human have receptors for two kinds of beta adrenergic compounds such as catecholamines to control cardiac muscle contractions. Some are beta 1 receptors that promote increased heart rate. Other drugs, called beta blockers, slow heart rate. Smooth muscle cells, however, have beta 2 receptors, which mediate muscle relaxation. Blockers of these effects are sometimes used to treat asthma.

C

Human have receptors for two kinds of beta adrenergic compounds such as catecholamines to control cardiac muscle contractions. Some are beta 1 receptors that promote increased heart rate. Other drugs, called beta blockers, slow heart rate. Smooth muscle cells, however, have beta 2 receptors, which mediate muscle relaxation. Blockers of these effects are sometimes used to treat asthma.

D

C

D

A

B

A

D

C

C