Question

1. which proteins are primarily responsible for muscle contraction? a.hemoglobin and myosin b.actin and myosin c.collagen and keratin d.insulin and glucagon 8. nerve cells rely on which type of proteins to transmit signals? a. ion channels b. enzymes c. structural proteins d. transport proteins

Explanation:

• For question 7: Actin and myosin are the key proteins involved in muscle - contraction. Actin forms the thin filaments and myosin forms the thick filaments, and their interaction leads to muscle contraction. Hemoglobin is for oxygen - transport in blood, collagen and keratin are structural proteins, and insulin and glucagon are hormones related to blood - sugar regulation.
• For question 8: Nerve cells rely on ion channels to transmit signals. Ion channels allow the flow of ions (such as sodium, potassium, and calcium) across the cell membrane, which is essential for generating and propagating action potentials. Enzymes are for catalyzing biochemical reactions, structural proteins provide support, and transport proteins are mainly for moving substances across membranes.

Answer:

1. B. Actin and myosin
2. A. Ion channels