Decomposers
Producers
Primary consumers
Secondary consumers
Tertiary consumers
Genetic variation<span> occurs </span>mainly<span> through DNA mutation, gene flow (movement of genes from one population to another) and sexual reproduction</span>
Answer:
Aa
Explanation:
The dominant gene is purple and usually represented with the capital letter while the recessive gene is white
Endorphins are brain chemicals
known as neurotransmitters which are released when the body feels a certain
amount of stress and pain. Endorphins alter the communication of pain in the
body by interacting with the opiate receptors and blocking the synapse so that signals
cannot be sent to the brain in order to reduce an individual perception of pain.
The main responsible for the delay among the atrial and
ventricular contractions is the action potential conduction velocity of the AV
node cells. If the atria and ventricles contract simultaneously, atria cannot
give any help in filling the ventricles, which is needed, especially in those
with stiff ventricles as in the elderly. Hence atria have to contract first and
then the ventricles.
