Which internal system of communication—the endocrine system or nervous system—would be responsible for the growth spurt that occurs at puberty? which system would control the quick withdrawal of your foot when you step on a tack?

Hummingbirds drink nectar from flowers, while robins eat plant seeds. what does this reduce?

How can you tell the difference between rough er from smooth er?

You are working in the lab and are working with the same element but with varying isotopes of the element. you are working with c-11, c-13, c-14, and c-15. what is the average atomic mass of this element? (use periodic table) a- 12 b-15 c-14 d-13