Venn diagram of respiratory and circulatory system

Which of the following sex and generation combinations directly produces the pollen tube of angiosperms? a) male gametophyteb) female gametophytec) male sporophyted) female sporophyte

What is the difference between a scientific hypotheses and a scientific theory?

Apond, rich in various micro-organisms, dries up due to drought. how will the amoeba in the pond protect themselves from this unfavorable condition?