D bacteria are the main nitrogen transporters
The gene which is produced once or twice in a lifetime is the milk producing hormone after childbirth. This is because it is produced only after the birth of the child. The growth of the mammary glands takes place during pregnancy. The breast continue to increase in size after giving birth to a child. After delivery only copious milk is produced which is generally done with the help of milk hormone. During pregnancy the secretion of the milk is inhibited by the estrogen and progesterone which circulates in the blood stream which in turn inhibits the release of prolactin from the pituitary gland thus making the mammary glands unresponsive. Where as insulin is a hormone which helps the body to utilise the sugar or glucose from different sources like carbohydrates that we get while we eat food and adrenaline is secreted when we are scared or when we feel that we are in danger. Therefore, milk producing hormone is the gene that are turned once or twice in a lifetime.
The study of the relationship between structures and functions is at the very heart of biology. This relationship is expressed in living beings by the adaptation of the first to the second and poses a series of absolutely fundamental problems, such as the relationship between causality and finality, analogy and homology, structural improvement and evolutionary level, etc.
For example, the structure of the hand is related to its function, thanks to the fingers and the thumb it is easy to wear and store objects.
The zigzag structure of the intestine is related to its absorption function, as this makes it possible to increase the contact surface between the alimentary bolus and the intestinal wall, and thus to increase the absorption.
It sends an impulse back to the cell body of a neuron
B. The area's climate
Specific plants need specific climate conditions in order to survive. The other answer choices have little to no impact on the growth of plants.