Which equation was used by Albert Einstein to explain the photoelectric effect? [E = energy, h = Planck’s constant, and v = frequency.] E =
E = hv
E =
E = h - v

How do the sperm cells get from the stigma to the ovules? a. they slide down the petals to the bottom of the flower. b. they travel through pollen tubes. c. they travel along filaments. d. insects carry the sperm cells from the stigma to the ovules.