In the seeds of cereals, the outer covering of endosperm separates the embryo by a protein-rich layer called: 

The correct answer is Aleurone layer

Explanation:

Aleurone layer:

• The aleurone layer is a single layer of specialized cells found at the interface of the endosperm and the seed coat.
• The outer covering of the endosperm separates the embryo by a proteinous layer called the aleurone layer.
• It is rich in proteins and plays a crucial role during seed germination by secreting enzymes such as amylase and protease.
• These enzymes break down starch and proteins stored in the endosperm into simpler compounds, which are then utilized by the growing embryo.
• The aleurone layer also contributes to the seed's nutritional value in cereal grains.

Incorrect Options:

• Coleoptile: This is a protective sheath that covers the emerging shoot or plumule of monocot seeds during germination.
• Coleorhiza: The coleorhiza is a protective covering that encloses the emerging radicle (root) in monocot seeds.
• Integument: The integument is the protective outer layer of the ovule that eventually develops into the seed coat.