Timothy made the model shown below to represent the steps in the formation of a tornado. The diagram has four boxes. The first box on the top left has the symbol '?' in it, an arrow points from it, over to the left to a box with the text 'Severe thunderstorm'; this box has an arrow pointing down from it to a box with the text 'High winds push clouds'; and this box has an arrow pointing to the left to a box with the text 'Rotation within thunderstorm's

Which of these best fits the empty cell in Timothy's model?

Why do you think the puppy litter was all dark-haired?

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

Which statement is the best summary of the model? a-a series of aerobic and anaerobic reactions take place in cells b- the sun's energy moves through trophic levels in a food chain c-light energy is converted into stored chemical energy plants. d- food molecules are broken down in the cells if living things.