Question

insulin binding to a receptor protein on the cell allows a cell to uptake glucose from the blood. in this scenario, insulin would be called a

protein.

ligand.

lock.

transporter.

glycolipid.

Explanation:

To solve this, we analyze each option:

• "Protein": Insulin is a protein, but the question is about its role in binding to a receptor, not just its structure. So this is not the best term for its role here.
• "Ligand": A ligand is a molecule that binds to a receptor (usually a protein). Insulin binds to a receptor protein, so it acts as a ligand.
• "Lock": The "lock - and - key" model has the receptor as the lock and the molecule binding to it (ligand) as the key. So insulin is not the lock.
• "Transporter": Transporters are involved in moving substances across membranes, while insulin's role here is binding to a receptor to trigger a response, not transporting.
• "Glycolipid": Glycolipids are lipid - carbohydrate complexes, and insulin is a protein, so this is incorrect.

Answer:

B. ligand