Sperm develop from stem cells called

Assume that a student is given two different models of bacteria, with one model consisting of big bacteria and the other consisting of small bacteria. how can the student demonstate the theory of endosymbiosis using the models

How does the study of genetic disorders such as pku biologists understand normal alleles?

Which of the following would be a body response when stepping outside without a coat on a snowy day? a. senaceous glands. secrete more senum b. more liquid is transported by the body to the skin fir insulation c. blood vessels in the skin narrow and contract d. blood vessels in the skin expand