Seeds that have a specific requirement for light for germination are referred to as photoblastic seeds. these seeds require a brief exposure to red light while imbibed. what is the photoreceptor involved in this response?

Phytochrome

Explanation:

The phytochrome is a photoreceptor which is responsible for detection of specific light in plants. It is sensitive to the red and far red portions of the visible spectrum. The phytochrome is very important for seed germination. As the phytochrome detects the light required for the germination of seeds.

the answer to your question is sperm

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.