Paper 1 Cell 4 Flashcards
Define a strong solution
A low concentration of water
What’s a hypotonic solution?
Distilled water
In an animal cell, if the surrounding solution is too dilute what would happened?
- the solution is hypotonic to the cell
- water will enter the cell and cause it to burst
- because there’s less water in the cell so due to osmosis the water from the surroundings goes into the cell
What’s a hypertonic solution?
A strong solution
Hyper lots of sugar
If the solution is more concentrated then the animal cell what would happen?
If the solution is too concentrated, we say it’s hypertonic to the cell
Water will leave the cells, causing them to shrivel up
If the surrounding solution is the same concentration as the animal cell, what will happen to the animal cell?
- if the solution is the same concentration as the cell, it’s called isotonic
- under these conditions, there’s no net movement of water so the cells will remain the same size
What’s an isotonic solution?
When the concentration outside the cell is equal to concentration in the cell, so there’s no net movement
(It’s what kidneys try to do)
What happens to plant cells, if water enters the cell?
- if water enters a plant cell, the vacuole swells and pushes the cytoplasm against the cell wall
- But the wall pushes preventing the cell from bursting
- the ce,k becomes swollen and ‘turgid’ which is important in maintaining the rigid shape of the plant
What happens when a plant is dehydrated?
The solution outside the cell become too concentrated, so water leaves the cell and loses its rigid form which is called plasmolysed
This causes the plant to wilt
Why and how does active transport work?
- to control reactions in cells, it’s often necessary to build a higher concentration of molecules on 1 side of a membrane than another
- active transport uses energy for the membrane proteins to pump molecules against their concentration gradient
Explain why active transports happens in plant root hair cells?
-plant root hair cells use active transport to carry the low concentration of mineral salts from the soil into the cells
Explain why active transports happens in the small intestine?
- after eating, the high concentration of molecules in the gut allows them to pass through to blood by diffusion at first
- as the concentration decreases, active transport by the cells lining the intestine move the remaining molecules across against their concentration gradients
What do cells contain to carry out active transports?
- cells that carry out active transport have lots of mitochondria to carry out reparation
- they also require a large supply of oxygen to enable aerobic respiration to provide all of the energy needed to do active transport
Define active transport
- the process in which dissolved molecules move across a cell membrane from a lower concentration to a higher concentration
- particles move across the concentration gradient, therefore require an input of energy from the cell
Define breathing
Define respiration
- breathing-Moving air in and out of the lungs
- respiration-the release of energy from glucose
Where is osmosis used in living things (2 examples)
- it’s used in plant cells it inflates the cell and makes it rigid
- absorbing water in the large intestine (through its wall)
name the action of water vapour being lost from a leaf?
Transpiration
Name 2 food molecules absorbed by epithelial cells by active transport?
Amino acids
Glucose
What are epithelial cells?
They form the lining of your small intestine
but also parts of the body
Give a substance plants absorb by active transport
Mineral ions
What word is used to describe plant cells surrounded by a hypotonic solution?
Turgid
What word is used to describe plant cells placed in a hypertonic solution?
Plasmolysed
What type of solutions are High energy drinks used in sports?
Isotonic
How are fish gills adapted for exchanging materials?
- water enters the mouth, oxygen diffuses from the water into the blood in the gills & CO2 diffuses from the blood into the water
- the gills have gill filaments, which have tiny lamellae which increase the surface area for the exchange of gases
- lamellae have lots of blood capillaries (speed up diffusion) & have a thin layer of cells to minimise the distance gases have to diffuse
- blood and water flow in opposite directions in the lamellae which keeps a large concentration gradient between water and blood
- the concentration of oxygen in the water is always higher then that in the blood so as much oxygen as possible diffuses from the water into the blood
Give 2 examples if substances transported in and out of cells by diffusion?
- oxygen and carbon dioxide (gas exchange)
- waste product urea from cells into the blood plasma for excretion in the kidney
What’s the advantage if single-celled organism having a large surface area to volume ratio?
It allows sufficient transport of molecules into and out of the cell to meet the demands of the organism
Explain how exchange surfaces are adapted to maximise effectiveness?
- they have a thin membrane, so substances only have a short distance to diffuse
- a large surface area so lots of substances can diffuse at once
- exchange surfaces in animals have lots of blood vessels, so it gets stuff in and out of the blood efficiently and quickly
- gas exchange surfaces in animals (alveoli) are ventilated
