P1P2B1 - Key concepts Flashcards
What is Osmosis?
The movement of water molecules from an area of high concentration to an area of low concentration across a partially permeable membrane.
What is Active transport?
The movement of molecules from an area of low concentration to an area of high concentration against a concentration gradient, using energy from respiration.
What is Diffusion?
The movement of molecules from an area of high concentration to an area of low concentration, down a concentration gradient.
What are Prokaryotic cells? Example?
Cells without a nucleus. EG - Bacteria
What are Eukaryotic cells? Example?
Cells with a nucleus. EG - Animal cell, fungi
How large can Prokaryotic cells be?
0.1 - 5.0 Micrometres (μm)
How large can Eukaryotic cells be?
10 - 100 Micrometres (μm)
What are key features of Prokaryotic cells?
- Prokaryotic cells may have one or more small rings of DNA, which are called plasmids which can replicate and move between cells so that genetic information is shared.
- Single DNA loop (Stored in Cytoplasm)
- No mitochondria or chloroplasts
What are key features of Eukaryotic cells?
NA
What 5 sub-cellular structures are found in an animal cell? Functions?
- Nucleus = Stores DNA, controls the cell.
- Mitochondria = Aerobic Respiration.
- Cytoplasm = Jelly like substance, where most chemical reactions take place.
- Cell membrane = Controls what enters and exits, partially permeable.
- Ribosomes = Protein Synthesis
What are 3 extra sub-cellular structures found in plants but not animal cells? Functions?
- Permanent vacuole = Keeps cell firm and rigid, stores cell sap and water.
- Chloroplasts = Contains chlorophyll, site of Photosynthesis.
- Cell wall = Protects and supports the cell, made of cellulose.
What are Plasmids?
Small rings/loops of DNA.
What are some structural components of a bacterial cell?
- Single DNA loops
- Plasmids
- Flagella
What are the 3 digestive enzymes?
- Amylase
- Lipase
- Protease
What is an enzyme?
A biological catalyst that speeds up the rate of reactions.
Equation for magnification?
Size of image / Size of real object
How does a LIGHT microscope work?
A light microscope passes light through a specimen and creates a magnified image using lenses.
What was discovered using a light microscope, what was its limitation?
Light microscopes allowed bacteria to be seen for the first time.
However, we still could not tell lots of sub-cellular (within the cell) structures apart.
How does an ELECTRON microscope work?
Electrons are passed through the specimen, creating a magnified image using lenses.
What was discovered using an electron microscope?
Electron microscopes allowed scientists to see sub-cellular structures more clearly.
They also allowed scientists to study how structures such as mitochondria, chloroplasts and ribosomes function.
In what year was the electron microscope first used?
1933
Describe a light microscope experiment
Put a thin sample of tissue (e.g. onion epidermis) onto a microscope slide.
Add a few drops of a suitable stain/dye (e.g. iodine).
Place a coverslip on top of the tissue and place the slide onto the microscope stage.
Use the objective lens with the lowest magnification, and focus on the sample.
Increase the magnification and refocus to see different features of the cell.
How do you find the optimal pH for amylase?
- Add amylase to starch solution.
- Every 30 seconds, take a drop of the mixture and add a drop of iodine solution.
- Record the total time taken for the iodine solution to stop turning blue when added
- Repeat this experiment using starch solutions with different pHs.
- The shorter the time taken for the iodine to stop changing colour, the faster the amylase has broken down the starch and the closer this pH is to amylase’s optimal pH.
What does amylase break down? Into what?
Starch that breaks down into smaller sugars (Maltose and glucose)
