Epithelial cells are mainly used for protection; in the urinary tract, these tissue cells are used to protect the bladder from toxic urine. The tissue can also expand to hold larger quantities of urine.
Answer:
The answer should be 
Since the pedigree has two different letters, it will have one letter of each, but the DNA will still be A.
Answer:
DNA is double stranded, and the strands are antiparallel because they run in opposite directions.
Explanation:
Each DNA molecule has two strands of nucleotides. Each strand has sugar phosphate backbone, but the orientation of the sugar molecule is opposite in the two strands.