Why some molecules can pass through a certain membrane, but other molecules can not

If you answer this i"ll give you brainiest and all these points me if you do i love you 7. a doctor is at work taking care of sick patients. she spends a few minutes trying to figure out why a particular patient is sick. she taps the patient's knee to test his reflexes. while she is examining him, the patient coughs on her. a) describe the function of the skeletomuscular system in this situation. (3 points) b) describe the function of the circulatory and respiratory systems in this situation. (3 points) c) describe the function of the immune system in this situation. (3 points) d) describe the function of the nervous system in this situation. (3 points) e) describe one way that any two of the doctor's body systems worked together in this situation. (3 points)

Suppose you are estimating the size of a blue crab population. what is the population size if the number marked in the first catch is 40, the total number in the second catch is 200, and the number marked in the second catch is 50?

What are the characteristics of living things