Final answer:
Steroid hormones are non-polar and can diffuse through cell membranes to bind with intracellular receptors. This allows them to directly influence gene transcription within the cell. So, the correct answer is option a.
Step-by-step explanation:
The steroid class of hormones, because of their non-polar, lipophilic (fat-loving) nature, have receptors located intracellularly. These hormones are derived from cholesterol and can readily diffuse through the lipid bilayer of the cell membrane to reach their receptors inside the cell.
Examples of steroid hormones include estrogen and testosterone. The intracellular hormone receptors are found either in the cytoplasm or in the nucleus of the target cells. Once a steroid hormone reaches its receptor, it can directly influence the transcription of specific genes, affecting the cell's function.
In contrast, peptide and amino acid-derived hormones are not lipid-soluble and cannot diffuse through the cell membrane. Their receptors are located on the cell surface. Communication by these hormones involves a signaling pathway that typically includes a second messenger within the cell.
So, the correct answer is option a.