B2 Flashcards
What is diffusion?
The net movement of particles from a region of high concentration to a region of low concentration down the concentration gradient.
What type of process is diffusion?
A passive process
What factors affect the rate of diffusion?
The distance that the particles need to move
The size of the surface area
The concentration gradient
How does the distance the particles need to move help diffusion?
The less distance, the faster the rate of diffusion
What does increasing the concentration gradient do in diffusion?
Increases the rate of diffusion
What does the size of the surface area have to do with diffusion?
Increase of surface area increases the rate of diffusion
What is osmosis?
The diffusion of water molecules across a semi permeable membrane from a high water potential to a low water potential, down the concentration gradient.
How does water potential help osmosis?
The greater the difference in water potential, the greater the rate of osmosis
What happens if the surroundings of a plant have a higher water potential?
The plant will take up water and the pressure of the cell increases, called turgor pressure. The cell becomes firm or turgid.
Wha happens if the surrounding of a pant has the same water potential?
Nothing happens as there is no net movement of water
What happens if the plant cell has a higher water potential than its surroundings?
It loses water and the turgor pressure falls causing the cell to become flaccid. Eventually, the cell contents collapse away from the cell wall.
What is a plasmolysed cell.
When the cell contents collapse away from the cell wall.
What happens in an animal cell if the surroundings have a higher water potential?
The cell will take up water, swell and it might burst which is called lysis.
What happens if an animal cell has a higher water potential than its surrounding?
The cell loses water by osmosis and it becomes crenated (it crinkles).
What is active transport?
It allows cells to move from an area of low concentration to an area of high concentration, against the concentration gradient.
What are the 3 main features of active transport?
Particles are transported against the concentration gradient
ATP is required
This process makes use of carrier proteins in the cell membrane
What are carrier proteins?
They are special proteins that stretch across the width of the cell membrane.
What does a carrier protein do?
A particular molecule that the cells requires binds to a specific carrier protein. Energy is transferred from an energy store to the protein so that it can change shape or rotate. The carrier protein transports the molecule into the cell
What does the graph look like of rate of respiration to rate of active transport?
A curve gradually increasing
What is mitosis?
Mitosis is the process by which body cells divide. Each cell divides to produce two identical daughter cells which are genetically identical to the parent cell.
What is the order of the cell cycle?
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
What is the abbreviation for the order of mitosis?
PMAT
What is the interphase?
The predatory phase, DNA replication occurs
What happens during the prophase?
DNA condenses to from chromosomes, nuclear envelope breaks down
What happens during the metaphase?
The chromosomes align in the centre of the cell called the equatorial phase and the centrioles move to opposite poles and spindle fibres form.
What happens during the telophase?
Chromosomes fully move to opposite ends, nuclear envelope forms around the new nucleus
What is cytokinesis?
Cell membrane pinches inward to separate nuclei and forms 2 daughter cell
What is a stem cell?
They are undifferentiated cells that divide by mitosis
When are stem cells used in the body?
During development, growth and repair
What can stem cells form?
All types of tissues and organs
What are the two types of stem cells?
Embryonic and adult stem cells
Where are embryonic stem cells found?
In embryos
What do embryonic stem cells do?
Divide by mitosis to produce all the cells needed to make an organism and they have the ability to differentiate into all cell types
Where are adult stem cells found?
Various body tissues such as the brain, bone marrow, skin and liver
What do adult stem cells do?
Differentiate into some different types of cells, but not as many as embryonic stem cells
What particular part of plant grow where their stem cells are?
Meristems and include shoot tips, and root tips