Afarmer planted legumes and cabbage in the same field that is devoid of fertilizers. the yield from this field is better than the cabbage planted in another field without legumes. why?
a. nitrogen-fixing present in the roots of legumes aid enrichment of nitrogen in the soil.
b. nitrogen-fixing bacteria present in the roots of legumes inhibit the growth of weeds or unwanted plants.
c. nitrogen-fixing bacteria present in the roots of legumes prevent bacterial growth that cause root disease

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

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People with one sickle cell allele are not likely to get malaria. what is this an example of?