B1 - Cells And Organisation Flashcards
Can a solid diffuse?
No
Can a liquid diffuse?
Yes
Can a gas diffuse?
Yes
Whats the definition of diffusion?
The net movements of particles from an area of high concentration to an area of low concentration. Due to the random movement of particles. A passive process which means that no energy is needed.
Whats a difference in concentration between two areas?
Concentration gradient
List some factors that affect diffusion
Concentration gradient
Temperature
Large surface area
There is faster diffusion when there is…
Large concentration gradient
Higher temperature
Larger surface area
Surface Area to Volume Ratio means that…
The surface area to volume ratio falls as the object gets bigger.
What does dilute mean?
Weak
What does concentrated mean?
Strong
Definition of osmosis:
Osmosis is the movement of water molecules from a region of higher water concentration to a region of lower water concentration across a partially permeable membrane
Definition of isotonic:
If the concentration of the solutes in the solution outside the cell is the same as the internal concentration, the solution is isotonic to the cell.
Definition of hypertonic
If the concentration of the solutes in the solution outside the cell is higher than the internal concentration, the solution is hyertonic to the cell.
Definition of hypotonic
If the concentration of solutes in the solution oustside the cell is lower than the internal concentration, the solution is hypotonic to the cell.
What is the function of the cell membrane?
Controls what enters and leaves the cell
What are eukaryotes?
They are cells that are complex and include all animal and plant cells
What are Prokaryotic cells?
Prokaryotic cells are single-celled organisms and are much smaller and simpler ( e.g. bacteria)
What are plasmids?
Small rings of DNA
What is the function of a ribosome?
It is where all the protiens are made in the cell and it is the place where protein synthesis happens
What is the function of the mitochondria?
It is the site of aerobic respiration ( release of energy from food )
What is the function of a cytoplasm?
It is the place where chemical reactions take place in the cell
What is the function of the nucleus?
- controls the cell
- contains the genetic information called DNA
What is the function of the cellulose and the cell wall?
The cell wall is made of cellulose and it supports the cell and strengthens it
What is the formula for magnification?
Magnification x real size
How do you prepare a slide for the microscopy practical?
1) add a drop of water to the middle of a clean slide
2) cut up an onion and use tweezers to peel of some tissue and put it into the water of the slide
3) Add a drop of iodine solution
4) Place a cover slip on top of the iodine and onion and try to not get any airbubbles
How do you use the light microscope in the microscopy practical?
1) clip in the prepared slide onto the stage
2) select the lowest power objective lens first
3) look down the eyepiece lens
4) Turn the coarse adjustment knob to move the stage upwards and get the slide roughly in focus
5) Turn the fine adjustment knob to get a clear image of whats on the slide
6) Select the medium power objective lens and repeat steps 3 and 4
How do you calculate percentage change?
Percentage change = final value - original value x100
Original value
How do you do the osmosis practical?
1) You cut up a potatoe into identical cylinders and get some beakers with different sugar solutions in them ( 1 should be with water and another with a very concentrated sugar solution )
2) You measure the mass of the cylinders and then leave one cylinder in each beaker for 24h
3) Later, you take them out and dry them with a paper towel and measure their masses again
4) If the cylinders have drawn in water by osmosis, they’ll have increased in mass. If the water has been drawn out then they will have decreased in mass.
What are root hair cells specialised to do?
They are specialised to have a higher surface area therefore water and minerals could be absorbed easyer
What is active transport?
Active transport is the movement of dissolved molecules into or out of a cell through the cell membrane, from a region of lower concentration to a region of higher concentration. The molecules move against the concentration gradient , using energy released during respiration.
What do you do to get from mm to um to nm
mm x1000 um x1000 nm
What is the function of a Vacuole?
Stores cell sap
What do chloroplasts do?
They contain chlorophyll which absorbs light needed for photosynthesis and is the place where photosynthesis happens which makes food for the plant.
