1. Which structure carries out translation?
- Golgi membrane alone
- Ribosome
- Cell wall
Check the answer and reasoning
Ribosome
Ribosomes assemble polypeptides using information carried by mRNA.
Biology / AS level
Cell structure and microscopy
Eukaryotic cells compartmentalise reactions in membrane-bound organelles.
Learning objectives
- Compare prokaryotic and eukaryotic organisation.
- Relate organelles to their functions.
- Distinguish magnification from resolution.
The big idea
Eukaryotic cells compartmentalise reactions in membrane-bound organelles. Ribosomes synthesise proteins, rough endoplasmic reticulum supports processing and transport, and the Golgi apparatus modifies and packages products. Prokaryotes lack a membrane-bound nucleus but have DNA and ribosomes.
Electron microscopy resolves smaller structures than conventional light microscopy, but preparation can introduce artefacts. Magnification enlarges an image; resolution determines whether nearby details can be distinguished. Scale bars remain useful when images are resized.
Worked example
A 40 mm image represents a 20 µm structure. Find magnification.
Follow the solution
Convert 40 mm to 40000 µm, then divide by 20 µm: magnification is 2000.
Investigate and explain
Using the worked example as supplied data, predict the effect of changing one condition. Draw a labelled model, record your reasoning and identify a variable that would need controlling. No human, animal or microbial experiment is required.
No exact PhET model is claimed for this topic. Use diagrams and supplied-data reasoning instead.
Check your understanding
2. A 40 mm image represents a 20 µm structure. Find magnification.
- ×2
- ×800
- ×2000
Check the answer and reasoning
×2000
Convert 40 mm to 40000 µm, then divide by 20 µm: magnification is 2000.
3. Does enlarging a blurred image necessarily reveal new detail?
- No
- Yes
- Only on a large screen
Check the answer and reasoning
No
Magnification cannot recover features that the original imaging system failed to resolve.