Q2. Scientific evidence indicates that CO2 added to the air by the burning of wood and fossil fuels is contributing to global warming, a rise in the global temperature. Tropical rain forests are estimated to be responsible for approximately 20% of the global photosynthesis, yet the consumption of large amounts of CO2 by living trees is thought to make little or no net contribution to the reduction of global warming. Why might this be?

Aresearcher designed an investigation to test what effect eating different types of food would have on blood insulin levels. she selected 10 male subjects who were all 25 years of age and in good health. the experiment took place over 3 days. at 8: 00 a.m. on each day, the subjects ate a meal consisting of only 1 type of food. they had their blood insulin levels measured after consuming the meal. on day 1 they ate a high fat diet, on day 2 they ate a high protein diet, and on day 3 they ate a high sugar diel what is the independent variable in this experiment? a the age of the subjects b the blood insulin level c the type of food consumed d the time of day the meal was consumed