* not completed

. Which statement regarding brain phospholipids in fish is most accurate?

Tropical fish tend to have very unsaturated phospholipids in their brain synaptic membranes. correct incorrect

Fish in very cold habitats tend to have very saturated phospholipids in their brain synaptic membranes. correct incorrect

The colder the habitat, the greater the degree of phospholipid unsaturation in the brain synaptic membranes. correct incorrect

The degree of phospholipid saturation in brain synaptic membranes is independent of habitat temperature. correct incorrect

* not completed

. Which of the following is not a functional type of membrane protein?

Enzyme correct incorrect

Receptor correct incorrect

Structural correct incorrect

Resistance correct incorrect

* not completed

. Which cell‒cell junctions allow cytoplasmic flow between the connected cells?

Tight junction correct incorrect

Septate junction correct incorrect

Gap junction correct incorrect

Desmosome correct incorrect

* not completed

. When there are more substrate molecules than the enzyme molecules can accommodate, the reaction is

saturated. correct incorrect

subsaturated. correct incorrect

showing the highest enzyme–substrate affinity. correct incorrect

at its K_m. correct incorrect

* not completed

. The catalytic effectiveness of an enzyme molecule is expressed as the

half-saturation constant, K_m. correct incorrect

activation energy during a saturated reaction. correct incorrect

number of substrate molecules converted to product per second by each enzyme molecule when saturated. correct incorrect

maximum velocity, V_max. correct incorrect

* not completed

. The allosteric site is located

on the enzyme. correct incorrect

on the substrate. correct incorrect

on the cell surface. correct incorrect

on the modulator. correct incorrect

* not completed

. Human LDH-A₄ and rat LDH-A₄ together are a good example of

isozymes. correct incorrect

interspecific enzyme homologs. correct incorrect

allosteric modulators. correct incorrect

ligands. correct incorrect

* not completed

. An animal is exposed to halogenated aromatic hydrocarbons, and as a result, its levels of P450 enzymes rise. This is an example of the action of

transcription factors. correct incorrect

enhancers. correct incorrect

constitutive enzymes. correct incorrect

inducible enzymes. correct incorrect

* not completed

. When an allosterically modulated enzyme is the rate-limiting enzyme in a metabolic pathway, the entire pathway may be upregulated or downregulated by allosteric modulation. The result of downregulation of the entire pathway is called

feedback inhibition. correct incorrect

positive feedback. correct incorrect

covalent modulation. correct incorrect

phosphorylation. correct incorrect

* not completed

. Multiple-enzyme sequences in which each enzyme in the sequence activates another enzyme is an example of

covalent modulation. correct incorrect

allosteric modulation. correct incorrect

amplification. correct incorrect

feedback inhibition. correct incorrect

* not completed

. The example of killifish allele frequency distribution along the Atlantic coast describes enzyme changes over a(n) _______ time frame.

acute correct incorrect

chronic correct incorrect

evolutionary correct incorrect

developmental correct incorrect

* not completed

. In the most common protein-degradation mechanism, tagging occurs by the attachment of _______ to the protein targeted to be degraded.

a heat-shock protein correct incorrect

a molecular chaperone correct incorrect

a proteasome correct incorrect

ubiquitin correct incorrect

* not completed

. In a bioluminescent animal such as the hydromedusa jellyfish Aequorea victoria, the _______ consist(s) of luciferin, O₂, and a protein.

chromatophores correct incorrect

pigment granules correct incorrect

photocyte correct incorrect

photoprotein correct incorrect

* not completed

. Color change in fish depends on flattened pigment-containing cells called

photoproteins. correct incorrect

chromatophores. correct incorrect

photocytes. correct incorrect

chromocytes. correct incorrect

* not completed

. Which receptor protein brings about cascades of membrane proteins involving significant amplification?

Ligand-gated channel correct incorrect

G protein–coupled receptor correct incorrect

Enzyme/enzyme-linked receptor correct incorrect

Intracellular receptor correct incorrect

* not completed

. Which receptor protein changes membrane voltage immediately when activated?

Ligand-gated channel correct incorrect

G protein–coupled receptor correct incorrect

Enzyme/enzyme-linked receptor correct incorrect

Intracellular receptor correct incorrect

* not completed

. Which receptor proteins activate enzymes on the cell membrane?

Ligand-gated channel and G protein–coupled receptor correct incorrect

G protein–coupled receptor and enzyme/enzyme-linked receptor correct incorrect

Enzyme/enzyme-linked receptor and intracellular receptors correct incorrect

Ligand-gated channel, G protein–coupled receptor, and enzyme/enzyme-linked receptor correct incorrect

* not completed

. Which receptor protein interacts with DNA?

Ligand-gated channel correct incorrect

G protein–coupled receptor correct incorrect

Enzyme/enzyme-linked receptor correct incorrect

Intracellular receptors correct incorrect

* not completed

. When epinephrine attaches to a(n) _______, the process of _______ results in the formation of a large amount of intracellular _______.

G protein‒coupled receptor; amplification; glucose correct incorrect

ligand-gated receptor; amplification; glucose correct incorrect

G protein‒coupled receptor; metabolic pathways; glycogen correct incorrect

enzyme-enzyme‒linked receptor; amplification; glycogen correct incorrect

* not completed

. Which of the following is not involved at the cell membrane in a second messenger cascade?

Adenylyl cyclase correct incorrect

G protein‒coupled receptor correct incorrect

Protein kinase correct incorrect

Phospholipase C correct incorrect