Which would have the greatest effect on the rate of photosynthesis in a plant?
a) oxygen level
b) light intensity
c) sugar concentration
d) starch concentration

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link: