Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane?
a. intracellular receptor
b. g protein-coupled receptor
c. phosphorylated receptor tyrosine kinase dimer
d. ligand-gated ion channel

d. Ligand-gated ion channels

Explanation:

a.Intracellular receptor: it's activated through second messengers since its activation and actions happen only inside the cell there's no distribution of ions on opposite sides of the membrane.

b.G-protein-coupled receptor: these receptors bind specific ligands at the cell surface (hormones and neurotransmitters) to relay the signal across the membrane. This means they act as a messager, there's no distribution of ions.

c.Phosphorylated receptor tyrosine kinase dimer: works as a messenger as well, it propagates a signal through the plasma membrane when it allows tyrosine to be trans phosphorylated.

d. Ligand-gated ion channels open to allow ions such as Na+, K+, Ca2+ or Cl- in response to the binding of a chemical messenger, one example of this kind of channel in action is when a neurotransmitter binds to a receptor located on the postsynaptic neuron, opening ion channels, this lead to a flow of ions across the cell membrane that turns into a depolarization or a hyperpolarization by changing the distribution of ions on opposite sides of the membrane.

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answer; i believe the correct answer is (sporophyte);

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.