# Explain how vesicles are used to transport large molecules across the plasma membrane by exocytosis.

> IB DP Biology Standard Level (2023 syllabus) — B2.1 Membranes and membrane transport · Explain · 4 marks

## Mark scheme (4 marks)

1. Large molecules are packaged into vesicles (membrane-bound sacs) within the cell.
2. The vesicle moves to and fuses with the plasma membrane.
3. Fusion releases the contents of the vesicle to the outside of the cell.
4. Exocytosis requires energy (ATP) as it is an active process.

## Key terms

- [exocytosis](https://www.gradenine.co.uk/glossary/exocytosis)
- [vesicle](https://www.gradenine.co.uk/glossary/vesicle)
- [plasma membrane](https://www.gradenine.co.uk/glossary/plasma-membrane)

## Related

- [Revision notes for IB DP Biology Standard Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-vesicles-are-used-to-6c943ac1) · Published by Druglandscape Ltd.