Answer: Stomata plays very crucial roles in plants. During photosynthesis, gas exchange takes place via the stomata. Water also evaporates from plants through the stomata. In plants, most of the stomata are usually on the bottom of the leaf IN ORDER TO PREVENT EXCESSIVE LOSS OF WATER.
During the day, the sunlight falls on the leaf directly and draws water from the plants. Locating the stomata at the underside of the leave reduces the amount of water that can be lost through excessive evaporation. Also, locating the stomata on the underside of leaves prevent the leaves from taking in too much water during rainfall.
Answer: Antigens
Explanation: The ABO system of blood grouping is based on the basis of the type of antigens that are present in the red blood cells. Erythrocytes is another name for the red blood cells. Antigens are molecules that are capable of eliciting immune response. There are two types of antigens: antigen A and B. Blood type A has only antigen A, blood type B has only antigen B, blood type AB has both antigen A and B while blood type O has no antigen (neither A nor B antigen).
Similarly, Rh trait is determined by the presence or absence of rhesus antigen in the erythrocytes. Rhesus antigen is an antigen first discovered in rhesus monkey. Rh+ indicates the presence of rhesus antigen in the red blood cells while Rh- indicates the absence of rhesus antigen in the red blood cells.
It is A. Clay ....sand is not it