Based on chargaff's rule, the percentage of cytosine in the dna of the bacterium s. lutea in figure 12-3 should be around _
a. 26.6 %
b. 73.2 %
c. 36.6 %
d. 29.4 %

Why does meiosis produce cells with half the chromosomes? o a. most of the chromosomes are not necessary to keep an organism alive. b. a gamete needs only half the number of chromosomes because two gametes join together. o c. it makes the gametes easier to move around in the organism. o d. it is faster to produce gametes with fewer chromosomes.

Which of the following statements about archaea and bacteria is true? a. neither is single-celled. b. they both have nuclear membranes. c. neither reproduces by binary fission. d. they both lack a nuclear membrane.

Why is it important to study each branch of earth science?