What is similar between elements in horizontal rows in the periodic table?

Which of the following is a main difference in cell structure between an onion cell and a human cheek cell? a. an onion cell contains one nucleus, whereas a human cheek cell contains two nuclei. b. an onion cell has a cell wall. c. a human cheek cell contains chloroplasts. d. there is no difference between an onion cell and a human cheek cell. you for your.

Where can a dna be found in a prokaryotic cell

What is the problem in this article? what solution does the article propose?