Which is most likely to pass directly through a plasma membrane: aGroup of answer choicessteroidneurotransmitterproteinwater soluble hormone

The substance most likely to pass directly through a plasma membrane is a steroid.

Here's why:

1. The plasma membrane is composed of a phospholipid bilayer, which is hydrophobic (water-fearing) in its interior. This means it repels substances that are polar or charged (hydrophilic), and allows passage of nonpolar (hydrophobic) substances.

2. Steroids are lipophilic (fat-loving) and nonpolar, so they can easily dissolve in the hydrophobic interior of the membrane and pass through it by simple diffusion.

3. On the other hand, neurotransmitters, proteins, and water-soluble hormones are typically polar or charged, so they cannot easily pass through the hydrophobic interior of the plasma membrane. They usually require some form of transport protein to help them cross the membrane.