# Explain how the ultrastructure of a pancreatic acinar cell is adapted for the secretion of digestive enzymes.

> IB DP Biology Higher Level (2023 syllabus) — B2.3 Cell specialisation · Explain · 4 marks

## Mark scheme (4 marks)

1. Abundant rough endoplasmic reticulum (RER) provides the site for synthesis/translation of digestive enzymes (secretory proteins).
2. A prominent Golgi apparatus modifies, packages, and directs the enzymes into vesicles for secretion.
3. Zymogen (secretory) granules accumulate at the apical surface, storing inactive enzyme precursors ready for exocytosis.
4. Numerous mitochondria supply ATP to power the energy-demanding processes of synthesis, vesicle transport, and exocytosis.

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