State two reasons why some molecules can pass through a certain membrane, but other molecules can not.

Molecules with bigger charge or size can not pass through every membrane but other molecules can.

1. bigger size

2. bigger charge

3. electronegativity

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.