Answer: Cancer cells and embryonic stem cells.
- A Differentiated somatic cells throughout the body
- B Cancer cells and embryonic stem cells
- C Mainly neurons within the central nervous system
- D Mainly liver cells involved in regeneration
Correct answer: B. Cancer cells and embryonic stem cells
Explanation: Telomerase adds telomeric repeats to prevent shortening. Active in germ cells, stem cells, and most cancer cells (enabling their immortality).
The cell cycle: G1 (growth and preparation), S (DNA replication, chromosome number stays 2n but DNA content doubles), G2 (final checks before division), and M (mitosis itself) - together, G1+S+G2 make up interphase.
Concept context
Mitosis and meiosis: how cells divide for growth, repair, and reproduction.