Place the steps of the development of male external structure in chronological order. 1. Internal structures form

2. Testes secrete testosterone

3. External structures form

4. Testes descend

5. Testosterone is converted to DHT

Which of these is not a function of some membrane proteins ? a.allowing polar molecules to enter the cell b.recognizing other types of cells c.receiving messeges from other cells b.carrying messages to oher cells

Ras is a g-protein that is activated when a growth factor attaches to egfr. its activation results in the replacement of a gdp molecule with a gtp molecule, thus allowing a signal transduction pathway to be activated. considering the signal pathway illustrated on this page, what is one potential outcome of a mutation in the ras gene that leads to ras protein hyperactivity. be specific.

Agroup of organisms that changes over time is said to