Answer: Valves in the veins
Explanation: The flow of the blood inside the body takes place through the veins and arteries. The oxygenated blood from the heart is supplied to the different parts of the body.
The blood flows from the capillaries to the venules and from there to the veins. The blood moves in the veins by the rhythmic movement of the smooth muscles in the body.
Most of the blood moves against the gravity so there is a chance that it can backflow so to prevent this there are valves in the veins known as one way valves.
I don't know if this question is missing some multiple choice options that go along with it, but...
One plate will subduct (go under the other plate), creating a trench or subduction zone. The other plate goes over the subducted plate, creating raised ground. This is how mountains and volcanoes are made.
Answer: Abiotic factor for polar: Ice
Abiotic for desert: Sand
Biotic for polar: Polar bears
Biotic for desert: Cacti
The types of factors are different because there are different set conditions for each ecosystem. A cactus is built for it's hot, dry ecosystem. If it were to move to a polar ecosystem it would not survive there. Same for the polar bear. It's built for polar regions. It has white fur to blend with the white ice to help it blend in and it's adapted to swim to get it's food source.
Explanation:
Zero; myocardial infarction. The posterior interventricular artery supplies much of the left ventricle, the systemic pump .
