Please help i don't understand

Which element is found in both dna and proteins

How does buring fossil fuels impact does carbon cycle? what large impact does this have on the envirnment?

Question 3(multiple choice worth 4 points) (02.04 lc) which best describes the function of chloroplast? allows certa molecules to enter and exit the cell makes food during photosynthesis detoxifies waste products o packages proteins into vesicles