Which best describes the big bang theory? a. the universe is 4.6 billion years old. b. the universe is shrinking. c. our universe is not the only universe. d. the universe is expanding.

Assume that a student is given two different models of bacteria, with one model consisting of big bacteria and the other consisting of small bacteria. how can the student demonstate the theory of endosymbiosis using the models

What causes temperature extremes in the desert

What would be the result if crossing over did not happen during meiosis in humans? a. there would be less genetic variation in humans. b. parents would be more likely to look like their children. c. the human population could not reproduce. d. children would have more chromosomes.