Answer:
When you sit on a plane for 6 hours without moving, blood accumulates in your veins, and the moment you get up, gravitational forces affect venous return, cardiac output, blood pressure, and venous pressure. That way, when you're sitting on a plane, the gravitational force is the same at the upper and lower extremities, such as the chest, abdomen, and legs, causing venous blood pressure and volume to be evenly distributed throughout the body. However, when one gets up, one becomes dizzy because of abnormal regulation of blood pressure. This is because gravity causes blood to accumulate in the lower extremities (veins of the legs and trunk). This lowers the blood pressure and the blood that the heart pumps. By causing blood to accumulate in the lower extremities, and as venous compliance increases, the veins expand with blood that causes the volume of blood to shift in the veins. This increases the volume and venous pressure in the lower extremities when standing. And the volume of thoracic venous blood is less and less central venous pressure. This leads to a decline in stroke volume. Cardiac output and mean arterial pressure also decrease as left ventricular stroke volume decreases, reducing pulmonary venous return. Decreased standing blood pressure, referred to as orthostatic or postural hypotension. Thus, lowering blood pressure decreases cerebral blood flow, which means less range of blood in the brain causing dizziness.
Explanation:
I'm not sure but it might be C
Both photosynthesis and respiration require specific catalyst.
Why not the other answer?
(1) only photosynthesis require the sun as a source of energy,respiration use glucose.
(2) photosynthesis result in the formation of glucose,respiration result in the formation of carbon dioxide.
(3)Only respiration occur in the mitochondria,photosynthesis occur in the stroma of the chloroplast.
Answer is 2 because both of them require specific enzyme and as you know enzymes are biological catalyst.
The correct answer is A: adaptive radiation
Well thats ur opinion some people might not think it is hard
