In a water molecule,which bond connects the hydrogen and oxygen atoms?

Which substance is most abundant in a cell?

Find the mismatched pair.

$A$ mixture of oil in water forms an emulsion. If a protein is shaken up with such an emulsion,what happens?

How many of the following biological molecules possess the ability to undergo duplication?
$RNA, DNA,$ Protein,Enzyme,Lipid,Carbohydrate

$\beta$-carotene is a ...... .