Question

receive external chemical messages
store excess energy for short-term use
function as cell-surface identity markers
transport specific ions and molecules across the membrane
catalyze specific chemical reactions on the surface of the membrane
eliminate viruses that are attempting to enter the cell
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Explanation:

To determine the correct functions of membrane proteins:

1. Receive external chemical messages: Receptor proteins (a type of membrane protein) bind to ligands (chemical messengers) to receive signals, so this is a function.
2. Store excess energy for short - term use: Membrane proteins are not involved in energy storage (this is more related to molecules like glycogen or fat). So this is not a function of membrane proteins.
3. Function as cell - surface identity markers: Glycoproteins on the cell membrane act as identity markers (e.g., for immune recognition), so this is a function.
4. Transport specific ions and molecules across the membrane: Channel and carrier proteins (membrane proteins) are responsible for transporting substances across the membrane, so this is a function.
5. Catalyze specific chemical reactions on the surface of the membrane: Enzymatic membrane proteins can catalyze reactions on the membrane surface, so this is a function.
6. Eliminate viruses that are attempting to enter the cell: Membrane proteins do not directly eliminate viruses; the immune system (e.g., antibodies, immune cells) is responsible for this. So this is not a function of membrane proteins.

Answer:

• Receive external chemical messages (checked)
• Store excess energy for short - term use (un - checked)
• Function as cell - surface identity markers (checked)
• Transport specific ions and molecules across the membrane (checked)
• Catalyze specific chemical reactions on the surface of the membrane (checked)
• Eliminate viruses that are attempting to enter the cell (un - checked)