1.   Biologists prefer to cite biochemical reactions and swelling cells to explain the turning.

2.   But eliminating all free radicals would kill us, because they perform certain necessary intermediary steps in biochemical reactions.

3.   Fast fibers derive the energy required to contract from biochemical reactions that occur in the absence of oxygen.

4.   If, in addition, the woman starts estrogen replacement at menopause, her blood levels of testosterone drop even further as a result of a biochemical reaction.

5.   It is a naturally occurring part of many biochemical reactions, including the manufacture of joint cartilage and the maintenance of nerve cell membranes.

6.   Rather, they use solvents the way people use oxygen, for the cycle of biochemical reactions known as respiration.

7.   When the sun hits the molecules in a sunflower stem, it sets off a series of biochemical reactions that move hormones away from that part of the plant.

8.   Enzymes are complex proteins produced by living cells that catalyse specific biochemical reactions at body temperature.