OPEN ENDED QUESTION
Suggest the reason why phospholipid
molecules are arranged in a bilayer form
with fatty acid tails facing inward

Interactions with water cause the phospholipids to form a bilayer, with hydrophobic fatty acid tails inside the bilayer and hydrophilic groups exposed to water. This basic structure makes the membrane a barrier to hydrophilic molecules. The interior of the membrane is fluid, with a viscosity about equal to olive oil. Since the tails are hydrophobic, they face the inside, away from the water and meet in the inner region of the membrane. Since the heads are hydrophilic, they face outward and are attracted to the intracellular and extracellular fluid.

Explanation:

the answer is d p: cell, q: organ, r: organ system, s: tissue