What is the purpose of having a positive and a negative control?

Some plants rely on the wind to reproduce an example is it’s important for plants to use the forces of nature to reproduce because 1. 1a white tuft of dandelion seeds 2a spiked burrs surrounding seeds 3a hard shell on a walnut? 2. 1b require pollination to reproduce 2b reproduce only asexually 3b cannot move about freely?

Mike was adopted, and his biological family history is unknown. although he is healthy, he would like some understanding of his genetic makeup, including potential health risks and genes that he could pass on to his children. mike has heard about commercial laboratories that can compare segments of your dna to those of people with common hereditary diseases in order to give you some idea of how susceptible you are to the diseases. the results of these types of tests are highly inconclusive. if mike's dna showed that he shares similarities in a segment of dna with people who have a given disease, his chances of developing that disease or passing it on to his children may be slightly elevated, but they are not 100 percent. these tests can cost more than $2,500 and are not covered by many insurance companies. do you think that mike should undergo the genetic tests? explain your answer. what are the potential pros and cons of having such tests done? describe how the availability of these genetic tests might affect the frequency of genetic diseases in individuals and populations.

The nervous system interacts with the endocrine system by a. using hormones as connections b. sending nerve impulses directly to glands c. using neuroendocrine cells as connections d. sending neurotransmitters directly to neurons