Question

1.
a) When and why do trees use their peroxisomes?

b) Which vegetable has a high concentration of carotenoids which when ingested can aid in maintaining good vision?

c) Which fruit has a high concentration of the pigment, whose color is that of the plant pigment xanthophyll?

Answer 1

Answer (a).Peroxisome is membrane bound organelle occurring in the cytoplasm of eukaryotic cells. Peroxisomes play a key role in the oxidation of specific biomolecules. They also contribute to the biosynthesis of membrane lipids known as plasmalogens. In plant cells, peroxisomes carry out additional functions, including the recycling of carbon from phosphoglycolate during photorespiration. Specialized types of peroxisomes have been identified in plants, among them the glyoxysome, which functions in the conversion of fatty acids to carbohydrates. Peroxisomes contain enzymes that oxidize certain molecules normally found in the cell, notably fatty acids and amino acids. Those oxidation reactions produce hydrogen peroxide, which is the basis of the name peroxisome. However, hydrogen peroxide is potentially toxic to the cell, because it has the ability to react with many other molecules. Therefore, peroxisomes also contain enzymes such as catalasethat convert hydrogen peroxide to water and oxygen, thereby neutralizing the toxicity. In that way peroxisomes provide a safe location for the oxidative metabolism of certain molecules.

Answer( b). Carrot has a high concentration of carotenoids which when ingested can aid in maintaining good vision.Carrots are rich in beta- carotene,which is converted into vitamin A in liver. Vitamin A is transformed in the retina, to rhodopsin , a Purple pigment necessary for night vision.

Answer (c).papaya and banana has a high concentration of the pigment, whose color is that of the plant pigment xanthophyll.