Final answer:
Steroid hormones, which are lipid-soluble, can enter a cell by diffusion, as opposed to peptide and amino acid-derived hormones like epinephrine and oxytocin, which require surface receptors.
Step-by-step explanation:
The hormones that enter a cell by diffusion are steroid hormones. These hormones are lipid-soluble, meaning they can pass directly through the cell membrane without the need for a cell surface receptor. Examples of steroid hormones include estrogen and testosterone. On the contrary, peptide hormones and amino acid-derived hormones such as epinephrine, norepinephrine, and oxytocin require cell surface receptors because they are not lipid-soluble and cannot diffuse through the plasma membrane.