What is meant by the following statement about the cell membrane

This is a type pf behavior that animals are born with and them to survive

In general, characteristics that an organism survive and reproduce become more common over time. what mechanism of evolution causes this?

What do isotopes of uranium have the same number of? what do they have a different number of? a) same number of protons; different number of electrons b) same number of protons; different number of neutrons c) same number of electrons; different number of protons d) same number of neutrons; different number of protons