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A Levels Biology (9700)•9700/13/O/N/22
Question 20 from 9700/13/O/N/22

Explanation

Stem Cells and Organelles in Skin Epidermis

Steps:

  • Identify stem cells in the skin epidermis: basal keratinocytes act as stem cells, dividing to replenish the epidermis.
  • Recognize that keratinocytes, including basal ones, differentiate into mature skin cells producing keratin.
  • Determine the organelle needed for keratin production and secretion: Golgi bodies modify and package proteins like keratin.
  • Match the choice that correctly includes both cell types and the appropriate organelle.

Why B is correct:

  • Basal cells (stem-like keratinocytes) and keratinocytes require Golgi bodies for processing and secreting keratin, per cellular biology definitions of organelle function in protein modification.

Why the others are wrong:

  • A: Centrioles aid cell division, not keratin secretion; excludes keratinocytes.
  • C: Excludes keratinocytes; Golgi body misspells the plural form but mainly wrong on cells.
  • D: Includes cells correctly but misspells organelle as singular "golgi body" instead of "golgi bodies."

Final answer: B

Topic: Replication and division of nuclei and cells

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