In 1939, the use of ddt (a powerful synthetic chemical) as an insecticide was discovered. the united states adopted its widespread use, producing up to 100 million kilograms per year (200 million pounds per year). twenty years later, severe side effects started to be reported as a result of ddt use. which was an advantage of using ddt?
insect and pest populations decreased
birth defect rates increased
cancer rates increased
fertility rates decreased

Ihave made a synthetic cell by placing a solution that is 10% sodium chloride inside a semipermeable membrane through which water can pass but not sodium chloride. if i place this cell into a solution that is 20% sodium chloride what will happen to the size of the cell? will it increase, decrease, or stay the same in size?

Npiranha, fish with large teeth represent the dominant trait. because the dominant trait masks the recessive trait, in a population of 1,000 piranhas, all with large teeth, we could expect about the next generation of fish to have small teeth.

Apopulation of bears has genetic diversity. some of the bears have an allele that gives them thicker fur. due to climate change, the winters have gotten colder in their habitat. now the bears with thicker fur are becoming more common in the population. a.) which type of bear is selected for in the coldest ecosystem? b.) what must be the other allele for the type of fur, and what term would you use to describe the fact that the allele is becoming less common in the colder climate? c.) describe the change in the bear population in terms of changing allele frequencies and phenotypes d.) is this an example of natural selection