Are the backbones of the dna molecule identical in all living things?

Astudent observes a star from two positions of earth in its orbit, in summer and winter, and measures the change in the position of the star. which of these can be best calculated by this method?

Amino acids contain the elements carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. of the 20 amino acids found in humans, 11 are called "nonessential" because they can be manufactured by the body when needed. which elements in these 11 amino acids are commonly obtained from the metabolism of sugar molecules?

Which of the following organisms are capable of self-fertilization? a. plants b. tigers c. humans