Under what circumstances will a recessive gene be expressed? a. when the gene is carried on the y chromosome b. when the gene is from the mother c. when it is paired with another recessive gene for the same trait or d when it is carried on the x chromosome.

I suggest you to choose this option: C. when it is paired with another recessive gene for the same trait. As it fits the best.

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