Lack of nucleus is a feature in?

Step 1: Analyze the question The question asks which cell has no nucleus when mature.

Step 2: Explain the concept Most animal cells have a nucleus that holds the genetic material (DNA). Mature mammalian red blood cells are an exception. As they develop in the bone marrow, they expel their nucleus. This leaves more room for haemoglobin, so they can carry more oxygen. It also gives the cell its biconcave disc shape, which increases surface area for gas exchange.

Step 3: Check each option

• A. Osteocyte is a mature bone cell. It has a nucleus.
• B. Neurone is a nerve cell. It has a nucleus in its cell body.
• C. Erythrocyte is a red blood cell. It has no nucleus when mature.
• D. Leucocyte is a white blood cell. It has a nucleus, which is often lobed or irregular, and this helps in identifying the different types.

Step 4: Answer The correct answer is C. erythrocyte.

Exam tip: Remember "Erythrocytes are Empty" because the nucleus is Eliminated. Also, "Leuco" means white, and white blood cells keep their nuclei because they need them to make proteins like antibodies and enzymes for fighting infection.