Cell and movement across membrane Flashcards
What is diffusion?
The movement of particles from a high area of concentration to a low area of concentration across a partially permeable membrane. Doesn’t require energy.
What 4 factors affect the rate of diffusion?
Temperature.
Decrease the distance of diffusion.
Increase S.A.
Increase rate of concentration gradient.
What is an example of diffusion in plant cells?
CO2 enters the stomata and oxygen moves out of cells by diffusion.
Define osmosis.
The movement of water through a partially permeable membrane from a higher water potential to a lower water potential. Doesn’t require energy.
Example of osmosis.
Reabsorption of water in the kidneys.
What does hypotonic mean?
More dilute solution outside the cell.
What does hypertonic mean?
More concentrated solution outside the cell.
How do you find the change in mass
(Final mass - Initial mass) / Initial mass x 100
Define active transport.
Allows cells to move substances from an area of low concentration to an area of high concentration. Energy is required.
Example of active transport.
Nutrients in the soil moves from low to high concentration into the hair cells.
Define mitosis.
A type of cell division which produces daughter cells identical to the parent.
What are the 3 stages of the cell cycle?
Interphase.
Mitosis.
Cytokinesis.
What is interphase?
The replication of the cell, ready for mitosis.
What is prophase?
Where the nucleus membrane breaks down.
What is metaphase?
When the chromosomes align across the centre of the cell.
What is anaphase?
When one copy of each chromosomes move to opposite ends of the cell.
What is telophase?
When the nuclear membrane forms.
What is cytokinesis?
When the cell membrane and cytoplasm divide into 2 daughter cells.
What are stem cells?
They are undifferentiated cells.
What are the 2 types of stem cells found in animals?
Embryonic and Adult stem cells.
Describe stem cells in plants
They are found in meristems.
They have thin walls, small vacuoles and no chloroplasts.
Describe embryonic stem cells.
They are found in embryos.
They are divided by mitosis and can differentiate into all cell types.
Describe adult stem cells
They can’t divide into many cell types.
They act as a repair mechanism for the body.
Suggest 2 reasons why some people may object to the use of embryonic stem cells.
They are found in embryos which could develop into a person.
There’s no guarantee of how successful the therapies will be.
What is a benefit of using stem cells.
They have also been used as a model cells to study how diseases develop or for drug testing.
What is the function of a sperm cell?
To transfer genetic material from the male to the ovum.
State and explain 2 adaptations of the sperm cell.
Acrosome stores digestive enzymes.
Flagellum propels sperm to ovum.
What is the function of a fat cell?
For insulation and protection.
To store fat.
State an adaptation of a fat cell?
They have a smaller layer of cytoplasm surrounding a fat reservoir.
What is the function of the red blood cell?
To transport oxygen around the body.
State and explain 2 adaptations of the RBC.
No nucleus so there’s more space for haemoglobin molecules.
Full of haemoglobin so protein binds to oxygen to form oxyhaemoglobin which is red.
What is the function of a ciliated cell?
The cilia sweeps mucus to the back of the throat to be swallowed.
What is the function of the palisade cell?
To carryout photosynthesis.
State and explain 2 adaptations of palisade cell.
Large S.A to absorb as much sunlight as possible.
Packed with chloroplast to absorb sunlight.
What is the function of the root hair cell?
Takes up water and nutrients for a plant.
State and explain 2 adaptations of the root hair cell.
Large S.A to absorb water.
Long and thin to penetrate between soil particles.
What is an egg cell?
A female sex cell that’s fertilised by a sperm cell to form an embryo.
State and explain 2 adaptations of an egg cell.
Cytoplasm provides nutrients for the embryo.
Large cell to store all the nutrients.
As the size of an organism increases, …
it’s S.A:V decreases.
What is the formula for S.A?
S.A = height x length x number of faces.
