Cell wall is the outer envelop structure which cover a plant cell. It provides a plant cell it's structure and rigidity. It is made up of rigid polysaccharide such as cellulose, pectin or hemicellulose. It protects the cell from the external environment. It prevents the entry of large molecules that can be toxic to cell.
Chloroplast is an organelle in the plant cell which consists of green pigement chlorophyll. This pigment absorbs the light energy from sun which is necessary for the process of photosynthesis in green plants.
Both cell wall and chloroplast are specialized structures present plants but not in animals.
The metabolite called lactic acid causes the body, specifically the muscles to ache after performing exercises. During exercise, respiration takes place which converts glucose substituents to be converted into metabolites such as lactic acid.
