Natural selection directly affects which of the following?

a. alleles

b. genes

c. phenotypes

d. mutations

Which is the best description of an organelle? A) organelles are structures located in the cytoplasm B) an organelle is a structure that performs a specific job in the cell C) the mitochondria, golgi apparatus, and endoplasmic reticulum are examples

A biome is a group of ecosystems that share which of the following?

Ben was training for a cross-country bicycle race. During his practice run, Ben's tire went flat and he fell off of his bike, cutting both knees.

SuperMeds Corporation develops a new drug that controls severe acne. The drug is not approved bythe government for sale in the United States because one of its ingredients is a banned chemical. This chemical is not banned in Mexico.

When testing a person's skin for allergens using patch testing, tiny amounts of allergens are placed on stainless steel discs and applied to the back. How many hours later is the skin under the discs assessed for reaction?

What must happen before the cell can go through mitosis? Interphase.

Belle's grandfather lives in a region where the temperature drops below 0*F at night. When belle visited her grandfather, they hiked up a hill. Belle noticed that a lot of rock had cracks in them.

The genetic condition of an organism that has two identical alleles for a given trait.

Which level of biological classification is the lowest level that butterflies

What might happen if a continent stops rifting apart?