B. Brain and spinal cord
The nervous system is an organ system in charge of sending messages to and from the brain<span> and </span>spinal cord<span> to and from all parts of the body. </span>
Invertebrates are what they can be classified as
Answer:
<u><em>DNA is made of repeating units called nucleotides.</em></u>
Explanation:
DNA can be described as a double helix molecule made up of long polymer chains of nucleotides. The nucleotides which are present in a DNA are:
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
The hydrogen bonds which occur in the pairing of nucleotides makes the double helix structure of DNA.
Adenine forms hydrogen bonds with Thymine.
Guanine forms hydrogen bonds with Cytosine.
The backbone of the DNA is made up of sugars and phosphates
Answer: Platelets release a vasoconstricting substance called <u>SEROTONIN.</u>
