The punnett square predicts a 9: 3: 3: 1 ratio for phenotype. explain what the ratio means.

This occurs in dihybrid crosses
There is a 9/16 chance of the offspring have all dominant traits
A 3/16 chance of the offsprings traits being dom/rec or rec/dom
A 1/16 chance of the traits being all recessive.

For example if Tall is dominant to short and Red is dominant to green
9/16ths of the offspring will be Tall and Red
3/16ths will be either Tall and green OR short and Red
1/16ths chance the offspring will be short and green

Eukaryotic cells are theorized to have evolved from prokaryotes called the endosymbiotic theory. this explains that the most primitive eukaryotic cell engulfed a prokaryotic cell (by the process of phagocytosis) that is capable of cellular respiration and another prokaryotic cell that is capable of photosynthesis. these prokaryotic cells eventually became organelles and these organelles are the mitochondria and the chloroplast