What two organelles are thought to have arisen from endosymbiosis?
1 point
a.
flagella and nucleus
b.
nucleus and mitochondria
c.
mitochondria and chloroplasts
d.
chloroplasts and ribosomes

Explain what a zygote is. use the terms egg cell, sperm cell, and fertilization in your explanation.

Select the correct answer from each drop-down menu. which phase of mitotic division is the highlighted cell undergoing? the cell is undergoing , which is the stage before .

Lactase is essential for digesting lactose in milk. this enzyme is specific for this sugar. why? molecules and active sites vary in size; only properly sized molecules can fit.there is a precise compatibility between the active site and the lactose molecule.specificity refers to the action of the enzyme, such as hydrolysis, and relatively few molecules can be hydrolyzed.reaction-specific enzymes assume a fit by folding around the most numerous substrate molecules.