C. a rise in blood carbon dioxide concentration
Explanation:
Negative feed back mechanism refers to the control mechanism in which a product of a particular pathway controls the switch on and switch off of that particular pathway.
Since breathing increases the blood oxygen concentration and lowers carbon dioxide concentration and pH. The sensors that regulate the breathing should respond to oxygen concentration as the carbon dioxide is the by-product of respiration and is responsible for increasing blood pH. Thus increased Carbon dioxide levels in blood is the only factor which will trigger breathing.
Answer:
C. 444 Ma
Explanation:
The first plants that managed to colonize the land appeared around 470 million years ago, while the first arthropods on land appear i the fossil records around 450 million years ago, so we can say that around the period of 444 million years ago they were well established on land. The first arthropods that started to have terrestrial life were almost identical to those in water, with only minor changes that enabled them to breathe and move more easily. The first plants on land were non-vascular plants. They were small as they initially didn't had deep and well established roots.
You can find the response on google
The correct answer is Mollusks, Echinoderms, Chordates, and Annelids.
This is basically how evolution works, at a certain point in the past,
there was a transitional organism that eventually developed into
roundworms and the other part of his species that was exposed to other
things evolved into other transitional organisms who evolved eventually
into these 4 groups.
