A carbon atom has four valence electrons. How do all living things depend on this property and other special chemical properties of the carbon atom?

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

Aflashlight produces light using energy from the batteries. in which order does the energy change form? a. from chemical to electric to light energy b. from electric to light to chemical energy c. from electric to chemical to light energy d. from light to electric to chemical energy

The embryos of a bird, a reptile, and a mammal are similar in appearance. how does comparing the physical appearance of embryos of different species support the theory of evolution? a. it shows that these organisms share a common ancestor. b. it provides evidence that these organisms eat the same foods.c. it shows that these organisms share the same habitat.d. it provides evidence that these organisms suffered a genetic mutation.