They breathe through their skin. Air dissolves on the mucus of their skin, so they MUST stay moist to breathe. If worms dry out, they suffocate. As fresh air is taken in through the skin, oxygen is drawn into the worm's circulatory system, and the worm's hearts pump the oxygenated blood to the head area.
Answer:
Mechanical isolation
Explanation:
mechanical isolation is a form of prezygotic reproductive barrier, whereby similar species organisms become isolated and unable to successfully interbreed with each other to form zygote, as a result of incompatibility of their reproductive organ or structure, which prevents them from copulating. As a result of this, both species become separated as there is no gene flow between both.
The two species of juniper can be said to be kept separate by <em>mechanical isolation</em>, due to the differences and incompatibility of their reproductive structure.
Question #1: D
Question #2: B
These are the correct answers hopefully. I knew the second one, but the first one I had to look up and do a wee bit of research
PH meter, which is a device used to measure hydrogen-ion activity in the solution. A PH meter is a voltmeter stuck to a pH electrode and a reference electrode. -maclittleseed
Suppose that part of an amino acid sequence of a protein changed from tyrosine-proline-glycine-alanine to tyrosine-histidine-glycine-alanine. This change was most likely caused by a point mutation called a <u>substitution</u>.
<u>Explanation:</u>
Any protein is synthesized by joining a number of amino acids together. This amino acid is placed based on the sequences of the DNA , for every 3 sequence there is an amino acid that is synthesized and therefore it is called as a triplet codon, since there may be many sequence for a single amino acid we call it as degenerate codon.
