Answer:
1. Signaling molecule
2. Signaling receptors
Explanation:
Hormones, growth factors, neurotransmitters, etc. serve the function of signaling molecules for cells. These molecules are released by one cell and bind to the receptors present on/in the target cells to elicit the desired response. Thereby, the signaling molecules serve in cell-cell communication.
For example, insulin hormone synthesized and released from beta cells of pancreas binds to its cell surface receptors present on the surfaces of liver cells and muscle cells to stimulate the uptake of the glucose from the blood.
Likewise, neurotransmitters released from the presynaptic neuron bind to receptors present on the membrane of postsynaptic neuron and serve to carry the nerve impulse to the postsynaptic neuron.
The correct answer is option D
Both are made up of the same nucleotide, but in a different sequence
DNA is made up of same set of nucleotide only the sequence is different which generates different set of amino acids forming the proteins of different types.Proteins are the building blocks of DNA which are responsible for different characteristics of an individual.
The answer is pheromones. Hope that helps :)