Karen is classifying a group of organisms that are either primary producers or consumers. What is the direct source of energy for all of the consumers?
A either producers or other consumers
B. producers only
C nonliving sources, such as sunlight
OD
other consumers only

Milk production during breastfeeding is increased by the suckling of a newborn from his mother's nipple. this type of feedback mechanism best describes a positive or negative

What does polymerase chain reaction (pcr) do? o a. separates dna fragments by size o b. cuts a dna sample into fragments o c. provides an overall picture of a person's chromosomes o d. makes more copies of a sample of dna

The picture below shows two galaxies. spiral galaxy and elliptical galaxy which of these statements best describes a similarity between the two galaxies? (2 points) both have elongated centers. both have centers shaped like bars. both change their shape from time to time. both are held together by gravitational forces.