A controlled experiment is: 1. always conducted using only one sample group
2. one in which a scientist leads another group of scientists
3. hard to design and rarely leads to any conclusion
3. one involving two groups, where the variable being tested is the only difference

After which event could you say that evolution has occurred? question 1 options: an allele frequency changes in a population. a white-eyed fly is born into a population of brown-eyed flies. a new predator comes into an environment. an animal gets fat.

What evidence did mendel find that supported his law of independent assortment? a. some traits are controlled by several different genes. b. a trait can be passed on from a parent to an offspring. c. most traits have a dominant form and a recessive form. d. different traits are passed on independently of each other.

You are observing different types of cells in your science lab. one cell has many chloroplasts. what is the most likely function of this cell? a. energy production b. photosynthesis c. reproduction d. digestion