Explain why gene expression may be decreased when histones are deacetylated/dna is methylated.

DNA acetylation and methylation are important for the proper gene expression. These modification works as epigenetics modification in the genome of the organism.

The histone deacetylation means the removal of acetyl group at particular amino acid residues. The deactylation of histones maintains the positive charge on the histone and bind them tightly with neighboring nucleosome result in decrease in gene expression. The methylation of DNA is the addition of methyl group at particular site on DNA molecule. The methylation results in the lack of gene expression and decreases the gene expression.

the answer would be d

both anaerobic and aerobic respiration use glucose (or other carbohydrates), proteins and lipids to produce atp and nadh. cell uses those energy molecules, obtained from food and   breaks them down during the chemical reactions of respiration. in anaerobic respiration, nadh is regenerated to nad+ by enzymes lactate dehydrogenase (lactate is produced, e.g. in muscle cells) or by alcohol dehydrogenase where ethanol is produced (alcohol fermentation), while in aerobic respiration, electrons from nadh are deposited in the mitochondria to regenerate nad+ (electron transport chain. anaerobic respiration produces 2 atp per molecule of glucose compared to aerobic respiration where about 38 atp molecules are produced.