What determines how many covalent bonds two atoms can make?

Which of the following occurs after a natural or unnatural disturbance in an ecosystem

Round peas are dominant to wrinkled. what would you cross a round pea with to determine if it were heterozygous or homozygous dominant? why? ?

Which of the following describes a negative feedback loop? when the heart rate is too high, the body sends hormones that continually increase the heart rate higher. when a pregnant woman is in labor, the body sends hormones that increase the intensity of contractions, which then increases the secretion of the same hormones. when blood sugar is too low, the body sends hormones that raise blood sugar until it reaches a typical level and hormone secretion slows. when a person is jogging, the body sends hormones that continually decrease the rate of oxygen supply to the legs.