In cell biology, mitosis is defined as the division of the ______.

• A. nucleus (separation of duplicated chromosomes into two nuclei)
• B. cytoplasm (cytokinesis)
• C. ribosomes to increase protein synthesis capacity
• D. endoplasmic reticulum to form two identical organelle networks

Answer: (A)

Verified step by step guidance

1. Understand the definition of mitosis in cell biology: it is a process related to cell division.
2. Recall that mitosis specifically involves the division of the nucleus, where duplicated chromosomes are separated into two nuclei.
3. Differentiate mitosis from cytokinesis, which is the division of the cytoplasm following mitosis.
4. Recognize that mitosis does not involve the division of ribosomes or the endoplasmic reticulum directly.
5. Conclude that the correct completion of the sentence is 'nucleus', as mitosis is the division of the nucleus.