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. receptor tyrosine kinase
b. g protein-coupled receptor
c. ligand-gated ion channel
d. intracellular receptor

c. ligand-gated ion channel

Explanation:

As soon as a signaling molecule binds a ligand-gated ion channel it leads to the opening of these ion channels which in turn causes ions to either rush inside or outside of the cell on which they are located leading to the disruption of distribution of initial ion concentration.  

As the name suggests, these kind of receptors are also known as ionotropic receptors.

For example: Binding of acetylcholine hormone to it's receptor which is a ligand gated cation channel located at post synaptic muscle cells leads to the opening of Na⁺ ion channels. As a result of this, Na⁺ rushes into muscle cell leading to the change in the concentration of Na⁺ inside the muscle cells. This is known as depolarisation.

1: most common garden plants prefer loam — soils with a balance of different-sized mineral particles (approximately 40% sand, 40% silt, and 20% clay) with ample organic matter and pore space. however, some plants grow better in sandy soils, while others are well-adapted to clay soils.

2: available water capacity is the maximum amount of plant available water a soil can provide. it is an indicator of a soil's ability to retain water and make it sufficiently available for plant use. available water capacity is the water held in soil between its field capacity and permanent wilting point.

3: it is the same for all living things (plants and animals). it also includes very tiny organisms that our eyes cannot see. they are known as microorganisms, and include viruses, bacteria and fungi.