Answer:Exercise increases the rate at which energy is needed from food, increasing the need for both food and oxygen by the body. This is why when we exercise both pulse/heart rate and breathing rate increase.
Explanation: Hope this helps
D. It occurs before an organism can reproduce. Meiosis is the replication of sex cells required for sexual reproduction to occur.
Antigens; they are molecules that are foreign to the body, thus stimulating a response by the b- and t-cells that aim to defend the body against harmful and mostly foreign bacteria.
