Type the word that appropriately completes each statement.

All fish reproduce sexually, but fertilization may occur in one of two ways.

In fertilization, the female fish releases eggs in the water or on a surface. The male fish spreads sperm over the eggs to fertilize them.

In fertilization, the eggs are fertilized inside the female's body. The young develop there until the female gives birth.

Consider the following reaction: 2h2 + o2 —> 2h2o a) what are the reactants in this reaction? b) what are the products in this reaction? c) how many molecules of oxygen are used in this reaction?

Juan and carol were studying invertebrates in biology. they knew that segmented or earth worms preferred a dark, moist habitat. during this lab, they would be investigating the responses of organisms called planaria or dugesia tigrina. these were simple flatworms that still had a one-way digestive system and a very simple nervous system. juan and carol placed the planaria in a petri dish containing cool, distilled water that was partially covered with black paper. they shined a light on the dish. next, they removed the paper and placed a small amount of chicken liver at one end of the dish. they added a few large salt crystals to the water. finally, they added drops of hot water to the cool water in the petri dish. their results can be seen in the data table. according to their experiment, all but one conclusion is valid.

Natural selection changes allele frequencies because some survive and reproduce more successfully than others.