Which cell organelle directs all the cells activities and is commonly associated as the brains of the cell

Explain the difference between the geocentric and heliocentric models of the solar system.

Sickle cell anemia is a recessive trait in humans. In a cross between a father who has sickle cell anemia and a mother who is heterozygous for the gene, what is the probability that their first three children will have the normal phenotype

A cell forms glycogen from simple sugars when food is plentiful. Which statement describes this process? A It is a catabolic reaction that is endothermic. B It is an anabolic reaction that is endothermic.

Mucus membranes trap pathogens that are airborne. a. True b. False

Which of the following is most likely to be propagated by grafting? A An apple tree B An iris C A strawberry plant D a fern

Why are species like the lionfish considered "invasive"?

What process hollows out limestone caves?

Increasing levels of chemicals in freshwater is attributed to fertilizers why

Red blood cells maintain their shape in what solution

Describe the structure of a tRNA molecule.