Question

Aleurone layer of maize grain is especially rich in
A. Proteins
B. Starch
C. Lipids
D. Auxins

Answer 1

Hint: Aleurone layer is the outermost layer of the endosperm. It is a special one cell thick layer. It is present in the monocotyledonous endospermic seeds. This layer plays an important role in the seed development.

Complete answer:
The aleurone layer of maize grain is especially rich in proteins. Aleurone is a protein found in protein granules of mature seeds and tubers. The aleurone layer is the outermost layer is the outermost layer of the endosperm. It lies between the pericarp and the hyaline layer of the endosperm. The aleurone cells remain alive at maturity.
The aleurone layer is important for the developing seed and the mature plant. The aleurone layer contains a large amount of oils and lipids which is useful during seed development. It contains several pathogen protective proteins.
The starchy endosperm present in the cereals. Starchy endosperm cells are large, irregular and contain starch grains whereas aleurone cells are cuboidal in shape and contain aleurone grains.
In cereals, the aleurone layer releases phosphoric acids to maintain the pH of the endosperm between 3.5 to 4. During seed germination, embryos produce gibberellins which stimulate the aleurone cells to release alpha-amylase for the hydrolysis of starch and storage proteins into the endosperm. The secretion of alpha-amylase is considered to be the most important role of an aleurone layer.

So the correct answer is option A.

Note: In most cultivated cereals such as wheat, rye, oats, rice and maize the aleurone is single layered and it is multicellular in barley. The ploidy of the aleurone is 3n because it is the result of double fertilization.