I'm not sure what YOU already know about photosynthesis and cellular respiration.... however, you SHOULD know that the two are beautifully linked to one another!
Photosynthesis equation:
6CO2+6H2O -> C6H12O6+H2O
Cellular respiration
C6H12O6+H2O -> 6CO2+6H2O
Notice something? The substrates of one equation are the products of the other! We rely on plants for their photosynthetic reactions - and plants benefit from us (not really because there is already a TON of CO2 in the atmosphere) from our cellular respiration
***we like their oxygen and they like our carbon dioxide!
:) I hope that helps! Let me know if you need any more elaboration!
One sperm fertilizes the egg cell forming a diploid zygote, the other sperm fuses with the two polar nuclei forming a triploid cell that develops into endosperm
The answer is seeds and pollen. They allow for the free dispersion of plants in terrestrial environments hence allowing plants colonize new habitats. Additionally, the seeds and pollen can remain dormant for a period of time and sprout only in favourable conditions for plant growth