Biology - Topic 2 Cell Division and Stem Cells Flashcards
What is Diffusion?
Net movement of molecules from an area of higher concentration to an area of lower concentration.
What is the Cell Membrane
An envelope that surrounds the cell and lets substances in and out
What are Particles?
Everything is made of particles and in a liquid or a gas these are free to move around
What is a Solution?
Something can dissolve in a liquid to make a solution. For example sugar can dissolve in water to give a sugar solution
What is Oxygen used for?
This gas is needed by all living things for respiration. All cells need oxygen and oxygen is carried in the blood to all parts of the body
What is Carbon dioxide used for?
This is a waste product of respiration and needs to be removed from tissues in the body. It is removed by the blood and breathed out of the lungs
What is Blood Plasma?
The liquid part of the blood which contains water, sugar, salt and carbon dioxide
What is a Concentration Gradient?
The difference in concentration between two solutions
What is Surface area?
The area of the surface of something. E.g. The lungs have a very large surface area for gas exchange.
What is the Small Intestine used for?
An organ in the lower part of your abdomen that absorbs food and nutrients from your food
What are the Lungs used for?
Organs where oxygen diffuses into the blood and carbon dioxide diffuses out.
Whatndo fish use gills for?
Fish have gills which are the exchange surface for oxygen to diffuse into the blood and carbon dioxide to diffuse out
What is Osmosis?
The diffusion of water from a region of high water potential (dilute) to a lower water potential through a partially permeable membrane
What is a Dilite solution?
A solution which has a lot of water in it and not much solute. E.g. Dilute squash is very weak
What is a Concentrated solution?
A solution which doesn’t have very much water in it and a lot of solute. E.g. concentrated squash is very strong
What is a Partially Permeable Membrane?
A membrane that lets some things through and not others. E.g. it lets water through but not sugar or salt molecules
What is Active Transport?
The net movement of substances from a region of low concentration to a region of high concentration (against a concentration gradient). It requires input of energy.
What are Villi and Microvilli?
These coat the small intestine and allow food to diffuse into the blood by having thin walls, a good blood supply and a LARGE SURFACE AREA
What are Alveoli?
Tiny sacs in the lungs that have thin walls, a good blood supply and a large surface area for diffusion of oxygen in and carbon dioxide out
Describe what happens in the alveoli
CO2 moves from the blood into the alveolus
Factors which affect the rate of diffusion
- The difference in concentration
- temperature
-surface area of the membrane
Factors which increase the effectiveness of an exchange surface
- large surface area
- thin membrane for a short diffusion path
- efficient blood supply
- ventilation
How to calculate percentage change in mass of potatoes?
(Change in mass / by original mass) x 100%
Why is there no change in mass for some cylinders?
There is the same water potential both inside the cell and the surrounding solution.
What is a passive process?
Does not require the input of energy
What is an active process?
Requires energy in the form of ATP
