1. Complete the table below.
| Structure | Function |
|---|---|
| Synthesises proteins | |
| Contains hydrolytic enzymes to break down worn-out organelles | |
| Golgi apparatus | |
| Smooth endoplasmic reticulum | |
| Chloroplast | |
| Produces ATP in aerobic respiration | |
| Rough endoplasmic reticulum | |
| Nucleus |
Answer
| Structure | Function |
|---|---|
| Ribosome | Synthesises proteins |
| Lysosome | Contains hydrolytic enzymes to break down worn-out organelles |
| Golgi apparatus | Modifies proteins and packages them for secretion |
| Smooth endoplasmic reticulum | Synthesis and transport of lipids/steroids/carbohydrates |
| Chloroplast | Carries out photosynthesis/uses light energy to produce carbohydrates |
| Mitochondrion | Produces ATP in aerobic respiration |
| Rough endoplasmic reticulum | Synthesises and transports proteins |
| Nucleus | Contains DNA which controls the cell's activities |
2. Electron microscopes and optical microscopes have different resolutions. Explain how their resolutions differ.
Answer
Electron microscope has a higher resolution than the light microscope (as electrons have a shorter wavelength than light).
3. Give two ways in which the structure of genetic material in prokaryotes differs from that in eukaryotes.
Answer
DNA is circular rather than linear. DNA is not associated with histones/proteins, eukaryotic DNA is.
4. Give some advantages of using an optical microscope rather than an electron microscope.
Answer
You can use live samples with a light microscope, the staining process is less complex, and you can see colour.
5. Describe and explain some features a specialised eukaryotic cell might have if it is adapted to carry out large amounts of active transport.
Answer
Many mitochondria to provide ATP. Large surface area/presence of microvilli. RER in order to synthesis the transport proteins. Golgi complex in order to process proteins.
6. A eukaryotic cell is specialized to produce and secrete a large amount of a specific enzyme. Explain why it is advantageous for this cell to have a large quantity of rough endoplasmic reticulum and Golgi apparatus.
Answer
Cells possess a large amount of rough endoplasmic reticulum, which enables them to synthesise proteins. They also contain many Golgi apparatus, which modify the proteins and prepare them for secretion.
7. Describe the process by which a student could obtain isolated mitochondria starting with fresh liver tissue.
Answer
Homogenise the tissue in a solution that is cold, buffered, and has the same water potential as the cells. Filter the mixture to remove debris and intact cell fragments. Spin the filtrate in a centrifuge at a low speed, remove the pellet containing nuclei, and then spin the supernatant again at a higher speed. The pellet formed will contain the mitochondria.
8. Name the two pieces of equipment in the figure below.
Answer
Eyepiece graticule and stage micrometer.
9. The student used the equipment shown above to find the length of an onion cell. Give one way that the student could ensure that her measurement of cell length was reliable.
Answer
Place stage micrometer on stage of microscope. Use eye piece graticule and align the two. Calculate how many known values on the stage micrometer equal 1 eye piece graticule unit.
10. The figure below shows a diagram of two organelles of the same type from the same eukaryotic cell. Identify and explain the function of this organelle.
Answer
Mitochondrion. It is the site of aerobic respiration and the organelle where ATP is produced.
11. The organelles above are the same size and shape. Explain why they appear different in this diagram.
Answer
Mitochondria are 3D. When cut at different positions in the cytoplasm or along different planes, they appear in different shapes.