Which microorganism is most closely related to plants? cyanobacteria green algae red algae brown algae?

green algea are closely related to plants. even though all living organisms that possess chloroplasts originated from cyanobacteria, their evolving order is as follows;The chloroplast of modern plants is thought to have undergone through the following sequence
cyanobacteria→green algea→plants. so it is clear that plants are closely related to green algea because plants evolved from them

Spherical shaped cell might increase the surface area and decrease the volume.

Since a female is both xx chromosome and the male passes down the x chromosome, than the offspring would be female since a female is xx.