Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Biology OCR AS
| Question | Answer |
|---|---|
| Define: Magnification | - Degree to which size of an image is larger than the object size |
| Define: Resolution | - Degree to which it is possible to distinguish between two objects that are very close together - the higher the resolution, the greater the detail that you can see |
| Define: Staining | Coloured stains - chemicals that bind to chemicals on or in specimen allowing specimen to be seen. Some stains bind the cell structures |
| Define: Sectioning | - Specimens embedded in wax - thin sections are cut without distortion of the structure of the specimen |
| Formula for Image Size | Image size = Actual Size x Magnification |
| Why do we need to stain molecules | Most biogical molecules are not coloured and are transparent so we need to add stains to make them visible under a microscope |
| Three rules of cell theory developed by Schwann | - All living things consist of cells - New cells form from the division of pre-existing cells - Cells contain information that acts as the instruction for growth - this information can be passed onto new cells |
| What is a graticule and describe it | A graticule is tiny transparent thing with a ruler etched on it which can be used to work out structure sizes. Stage Micrometer required to calibrate it (EPU) |
| Describe Transmission Electron Microscope | - Electron beam passes through a very thin prepared sample - Electrons pass through denser parts less easily giving contrast - Thus image is 2 D |
| Describe a Scanning Electron Microscope | - Electron beam directed onto a sample - electrons don't pass through - They bounce off - Final image is 3D |
| Advantages of Electron Microscopes | - Resolution is 0.1nm - Can produce detailed images of organelle structure - SEM produces 3D images which can reveal details of contours and cellular tissue arrangements |
| Limitations of Electron Microscopes | - Electron deflected by molecules of air so sample needs to be in vacuum - Expensive - Preparing samples and using it is very expensive requiring a high degree of skill and training |
| What is the resolution for a light microscope | 200nm |
| What is the magnification for a light microscope | 1500X |
| What is the resolution of an electron microscope | 0.2nm |
| What is the magnification of a Transmission Electron Microscope | x500,000 |
| What is the magnification of a Scanning Electron Microscope | x100,000 |
| What is the function of the plasma membrane | Regulates movement of substances into and out of the cell - Have receptor molecules on them which allow them to respond to chemicals like hormones |
| Describe structure of the plasma membrane | -membrane found on surface of namimal cells and inside cell wall of plant cells and prokayotic cells - Made mainly of lipids and proteins |
| What is the function of the cell wall | Supports the plant cell and keeps the cells turgid |
| Describe structure of the cell wall | Rigid structure made mainly of the carbohydrate cellulose |
| Describe the function of the nucleus | - Chromatin made from proteins and DNA (DNA controls cell activity) - Pores allow substances like RNA to move between the nucleus and the cytoplasm - Nucleolus makes ribosomes |
| Describe the structure of the nucleus | - Large organelle - Contains a nuclear envelope - Contains many nuclear pores - Contains chromatin - Often a structure called a nucleolus |
| Describe the function of a lysosome | Contains digestive enzymes kept separate from cytoplasm - Can be used to digest invading cells or to break down worn out components of the cell |
| Describe the structure of a lysosome | - Round organelle - Surrounded by a membrane with no clear internal structure |
| Describe the function of a ribosome | The site where proteins are made or synthesised |
| Describe the structure of a ribosome | Very small organelle that either floats free in cytoplasm or is attached to the rough endoplasmic reticulum |
| Describe the function of the Rough Endoplasmic Reticulum | Folds and processes proteins that have been made at the ribosomes |
| Describe the structure of the rough endoplasmic reticulum | - System of membranes enclosing a fluid filled space - Surface covered in ribsomes |
| Describe the function of the smooth endoplasmic reticulum | Synthesizes and processes lipids |
| Describe the structure of the smooth endoplasmic reticulum | - System of membranes enclosing a fluid filled space - Surface has no ribosomes |
| Describe the function of a vesicle | Transports substances in and out of the cell via the plasma membrane and between organelles - Some formed by Golgi apparatus or the endoplasmic reticulum, while others formed at cell surface |
| Describe the structure of a vesicle | A small fluid filled sac in the cytoplasm surrounded by a membrane |
| Describe the function of the golgi apparatus | It processes and packages new lipids and proteins and also makes lysosomes |
| Describe the function of the mitochondria | Site of aerobic respiration - where ATP is produces - Large numbers found in active cells like muscle or sperm |
| Describe the structure of a mitrochondria | - Usually oval shaped - Have a double membrane with the inner one folded to form cristae - Inside is the matrix which contains enzymes involved in respiration |
| Describe the function of the chloroplasts | - Site where photosynthesis takes place - Some parts take place in the grana while the other parts take place in the stroma |
| Describe the structure of the chloroplasts | - Small, flattened structure in plant cells - Surrounded by a double membrane - Also has membranes inside called thylakoid membranes which are stacked up in some parts of the chloroplast to form grana - Grana linked together by Lamellae |
| Describe the function of the centriole | Involved with the separation of chromosomes during cell division |
| Describe the structure of the centriole | Small, hollow cylinders, containing a ring of microtubules |
| Describe the function of the cilia | - The microtubules allow the cilia to move - Movement is used by the cell to move substances along the cell surface |
| Describe the structure of the cilia | - Small hair like structures found on the surface membrane - Outer membrane and a ring of 9 pairs of microtublues with a pair in the centre - Only in animal cells |
| Describe the function of flagellum | Microtubules contract to make the flagellum move - used like a motor to help the prokaryote swim |
| Describe the function of undulipodium | Microtubules contract to make the flagellum move - helps sperm to swim |
| Describe the structure of undulipodium | Similar structure to cilia, just a bit longer |
Created by:
r7milad
Popular Biology sets