Skin darkens when exposed to sunlight because _____ produce more pigment
a. melanocytes c. neuroglial cells
b. keratinocytes d. neurons
A
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Acetylcholine released into the junction between a motor neuron and a skeletal muscle binds to a sodium channel and opens it. This is an example of _____
A) a voltage-gated sodium channel B) a voltage-gated potassium channel C) a ligand-gated sodium channel D) a second-messenger-gated sodium channel E) a chemical that inhibits action potentials
When many genes of an organisms are globally regulated, those genes are considered as regulon genes. What is the common theme of such genetic regulation?
A) Genes of regulons are silenced by a common repressor. B) Genes of regulons are able to transcribe mRNA independent of regulation. C) Genes of regulons are much more stable than non-regulon genes. D) Genes of regulons are much less stable than non-regulon genes. E) Individual genes of regulons are regulated independently of each other.
The concentration of iron in a cell is an important regulator of gene expression. Explain two mechanisms through which iron concentration regulates gene expression in mammalian cells
What will be an ideal response?
Which is mismatched?
A. Scavengers - feed on live to dead cells and wastes B. Competition - one organism gives off substances that inhibit or kill other organisms C. Predator - seeks out and ingests live prey D. Parasitism - one organism benefits and the other receives no benefit E. Omnivores - feed on plants and flesh