Questions: The phospholipid-based membrane need to be a because otherwise it forms a - bilayer; solid sphere single layer; bilayer solid sphere; bilayer

The answer is the first one: bilayer; solid sphere.

Explanation:

• The phospholipid-based membrane needs to be a bilayer because otherwise, it forms a solid sphere.
• Phospholipids naturally arrange themselves into a bilayer in aqueous environments due to their hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails. This bilayer structure is essential for forming the flexible and semi-permeable membranes of cells.
• If phospholipids were to form a single layer, they would not be able to create a stable boundary between the inside and outside of the cell. Instead, they would tend to form a solid sphere (micelle) to minimize the exposure of their hydrophobic tails to water.

Thus, the correct answer is: bilayer; solid sphere.