Multiple questions! Also, it would really help if you could explain your answer.

16. Explain how you would calculate the ecological footprint of the state that you live in if you knew the average ecological footprint of a resident in your state?

18. In gel electrophoresis, DNA fragments move across a gel. What causes them to move?

20. Explain the difference between chromatids and chromatin.

__5. When Gregor Mendel crossed true-breeding tall plants with true-breeding short plants, why was it impossible to observe segregation?
A. Alleles for height do not segregate in the F2.
B. Alleles segregate only in the F2 generation.
C. Alleles segregate best when two tall plants are crossed.
D. Alleles in the F1 must be Tt to have height variety in the F2.

_____2. Carbon-12 is the most common isotope of carbon. It has 6 protons, 6 neutrons, and 6 electrons. Of its 6 electrons, 4 are valence electrons. How many covalent bonds can a carbon atom form?
A. 1
B. 4
C. 6
D. 12