Cells control gene expression by using molecular tags that lure an enzyme to insure the transcription of certain genes. they also use tags that repel the same enzyme for genes that are turned off. the enzyme that controls the transcription is

water is a polar molecule. a chemical bond is a force of attraction between atoms or ions. bonds form when atoms share or transfer valence electrons. atoms form chemical bonds to achieve a full outer energy level, which is the most stable arrangement of electrons. so, false

explanation:

in h2o molecule, two water molecules are bonded by a hydrogen bond but the bond between two h - o bonds within a water molecule are covalent. the greater the electronegativity difference, the more ionic the bond is. bonds that are partly ionic are called polar covalent bonds. nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.

1. efficient use of space

2. elimination of groundwater contamination

3. energy generation

4. lower carbon footprint

c is the correct answer hope this !