PO,LMINUYBVTCXEWZQ.P,OMINUYBTVCXEWZQ
<span>These protrusions will only bind to </span>certain<span> receptors on the host cell; they are essential for both host specificity and viral infectivity.</span>
Answer:
Pollen grains are produced by meiosis of microspore mother cells that are located along the inner edge of the anther sacs (microsporangia). ... The tube cell (also referred to as the tube nucleus) develops into the pollen tube. The germ cell divides by mitosis to produce two sperm cells.
Answer:
B is INCORRECT
Explanation:
Action potential in contractile cells can be divided into 3 phases
1. Rapid depolarization; caused by fast influx of sodium ions into the cells. Last a few milliseconds.
2. Plateau phase: This is a sustained positive membrane potential, after rapid depolarization, caused by a balance between calcium ion influx and slow potassium ion efflux.
3. Rapid repolarization: Eventually there's a closure of all other ion channels except the potassium ion channels causing rapid efflux of potassium ions, returning the membrane potential back to negative.
A refractory period usually occurs after undergoing an action potential. During this time no action potential can occur.
