Which of the following is the best example of natural selection? A)A population of a rabbits decreases in number as some move to another area.
B)The shell of a crab becomes harder over time as a result of being hunted by a predator.
C)A person's muscles become firmer from riding a bike for exercise.
D)A cheetah living in a zoo lives 10 years longer than average.

Forces that are equal in strength but opposite in direction are a.) balanced b.) unbalanced c.) always result in motion d.) do not exist

What is the period of cell life when it is conducting

Which of these is true of the cytoplasm of an unfertilized egg? a. it is an unevenly distributed mixture of mrna, proteins, organelles, and other substances. b. it does not contain substances that are important in directing development. c. these substances are supplied by the sperm. d. it does not contain substances that are important in directing development. e. development is directed solely by the surrounding cells. f. it is a homogeneous mixture of mrna, proteins, organelles, and other substances. g. it does not contain substances that are important in directing development. h. these substances are produced by the dna of the fertilized zygote.