The fitness of one's cardiorespiratory system is assessed by measuring the a. Length of time you can hold your breath while exercising b. Strength needed to sustain a muscular contraction during exercise c. Increase in blood pressure during exercise. d. Volume of oxygen the muscles consume during exercise.

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.