Cells And Control 🧫 Flashcards
What is diffusion?
Diffusion is the net movement of particles from an area of high concentration to an area of lower concentration.
What factors affect diffusion?
Temperature, concentration gradient, membrane surface area
How does membrane surface area affect diffusion?
The larger the surface area of the membrane that a substance is diffusing through (e.g. the membrane around a cell), the faster the rate of diffusion.
How does temperature affect diffusion?
The higher the temperature, the faster the rate of diffusion.
How does concentration gradient affect diffusion?
The bigger the difference in concentration between two areas, the greater the concentration gradient and the faster the rate of diffusion.
What is osmosis?
Osmosis is the diffusion of water across a partially permeable membrane from a dilute solution (high concentration of water) to a concentrated solution (low concentration of water).
What is an independent variable?
A variable which is controlled and is changed in the experiment
How do you calculate the percentage change in mass?
(final mass - initial mass)÷ initial mass x 100
What are the three main forms of transport in cells?
Osmosis, diffusion, active transport
What is active transport?
Active transport is the net movement of particles against a concentration gradient.
Energy is therefore required.
What is a dependant variable?
A dependent variable is what we measure in an experiment.
What a waste product is removed during diffusion at the lungs?
CO2
What are stem cells
Cells that have not yet undergone differentiation (unspecialised cells)
What happens when a cells differentiates
It becomes specialised
Give 3 examples of where stem cells are found in the body
Bone marrow
Muscle
Heart
Where does cell division in plants occur
In meristems
How do cells become differentiated in a meristem
As the shoot grows new cells are being produced continuously near the tip. These will eventually become differentiated and enlarge to form a vacuole
Why are stems cells useful to us
They have the potential to be transplanted into patients with a disease by replacing cells have been damaged or destroyed
What stem cells can be used for stem cell transplants
Embryonic stem cells (can differentiate into a wide range of cell types)
Adult stem cells ( can differentiate into a narrow range of cell types)
What are the ethical issues associated with embryonic stem cells used in medicine
At what stage of its development should an embryo be regarded as a person
Fear that embryos will come to be viewed as a commodity
What are the three main types of neurones
Sensory
Motor
Relay