Transport in out and of cells Flashcards
Diffusion is ?
the movement of particles of any substance in solution or particles of gas down the concentration gradient from an area of higher concentration to an area of lower concentration, until equilibrium is reached
What 3 factors increase the diffusion rate?
-Bigger concentration gradient: the faster the rate of diffusion because the net movement from one side is greater
-Higher temperature: make diffusion rate faster because particles have more energy, so move around faster
-Larger surface area: faster rate of diffusion because more particles can pass through at once
What size of molecules can diffuse through a cell membrane
Small molecules (oxygen, glucose, amino acids, water, glycerol)
Not big molecules(starch, proteins)
What is osmosis?
Movement of water molecules from an area of higher water potential to one on lower water potential down the water potential gradient across a partially permeable membrane
Name the dependent variables of the potato practical.
length and mass of potato chips
Name the independent variable of the potato practical.
concentration of sugar solution
Name two control variables for the potato practical.
- cut all chips from the same potato
- keep both at the same temperature.
Name three things you can do to prevent error in the potato practical.
- make sure the scale is set to 0 before weighing the chips
- use a vernier caliper to measure the potato chips or use a cork borer to cut them.
- make sure potato cylinders are fully dried, so the excess water will not give a higher ending mass
What is the formula for percentage change?
Percentage change= final value-original value/ original value x100
What is active transport?
the movement of molecules from an area of lower concentration to an area of higher concentration against the concentration gradient, using ATP or energy
Name two places where active transport occurs.
The gut taking in nutrients(glucose, amino acids) from the blood, root hair cells taking in nutrients(water, mineral ions)
Why is active transport used in the gut
- there is a lower concentration of nutrient in the gut but a higher concentration of nutrients in the blood
- when there’s a higher concert ration of glucose and amino acids in the gut they diffuse naturally into the blood
- BUT, sometimes there’s a lower concentration of nutrients in the gut than in the blood, so the process of active transport is used.
Why is active transport needed in root hair cells
The concentration of mineral is usually higher in the root hair cell than in the soil around them, so active transport is needed because diffusion cant be used to since the concentration area is already higher in the cell.
What is a hypertonic solution?
- a solution with a higher concentration of solute dissolve in it.
- Therefore it has a lower water potential.
What is a hypotonic solution?
- a solution with a lower concentration of solute dissolved in it.
- Therefore it is has higher water potential
Volume=
length x width x height
surface area (for a cube)=
length x width x number of sides
What is the surface area to volume ratio of a cube which is 1 cm on all sides?
6:1
Having a larger surface area to volume means …
More substances can be exchanged more efficiently
Do unicellular (single-celled) organisms, gases and dissolved substances diffuse directly into or out of the cell, or do they need exchange surfaces adapted to make them more efficient.
- unicellular cells, gases and dissolved substances diffuse directly into or out of the cell across the cell membrane
- because they have a larger surface area compared to their volume, so enough substances can be exchanged across the membrane to supply the volume of the cell
Why cant multicellular organisms not take in their substances via diffusion?
they have too small a surface area compared to their volume
- not enough substance can diffuse from the outside surface to supply their entire volume
- need a special exchange surface for efficient diffusion
How are exchange surfaces adapted to maximise effectiveness?
- being thin: substances will have a shorter diffusion distance to travel
- large surface area: lots of substances can diffuse at once
- good blood supply in animals: creates a steep concentration gradient
- ventilation in gas exchange systems in animals: The moving blood and ventilated surfaces mean that a steep concentration gradient can be maintained
How are alveoli adapted to maximise efficiency?
-made up of tiny air sacs: gives lungs enormous surface area
-moist lining for dissolving gases(but doesn’t affect rate of diffusion)
-very thin walls: wall of alveolus is only 1 cell thick. Walls of capillaries also 1 cell thick
-good blood supply: wall off alveoli are covered in capillaries
What happens to plant cells in hypertonic solution
- water potential is higher on the inside than on the outside
-water moves out of the cell down the water potential gradient
-sap vacuole shrinks. Cell is not longer form
-cell becomes flaccid, becoming plasmolysed
What happens to plant cells in hypotonic solution
-cells have lower water potential than the solution
- net movement of water into the cell
- cytoplasm and vacuole push against the cell wall
-cell swells, becomes turgid
What happens to plant cells in isotonic solution
- -water potential is equal between cell and solution
- -no net movement
- -normal cell
What happens to animal cells in hypertonic solution
- water moves out of red blood cell by osmosis
- red blood cell have higher water potential than solution
-net movement of water out of the cell
-shrivelled cells
Summarise the different types of transport and their differences.
Diffusion:
* -movement of particles from an area of higher concentration to an area of lower concentration
* -doesn’t require energy
Osmosis:
* -movement of water molecules across a partially permeable membrane from a region of higher water concentration to an area of lower water concentration.
* -doesn’t require energy
Active Transport:
* -movement of particles against a concentration gradient
* - requires energy
How are villi adapted to maximise absorption?
- nutrients e.g. glucose and amino arise, are absorbed into the bloodstream from the small intestines
- to aid absorption the inside of the small intestines are covered with millions of tiny projection called villi
- villi create a large surface area (due to larger surface area to volume) so lots of digested food is absorbed much more quickly into the blood
-They also have:
- a single layer of surface cells (shorter diffusion distance)
- a very good blood supply to assist quick absorption
Where are the villi found?
The inside of the small intestines
What gas is needed for photosynthesis?
Carbon dioxide
How is the structure of a leaf adapted for the the dissuasion of gases in and out of it? Name 5
- underneath of leaf is an exchange surface, it’s covered by little holes called stomata
- oxygen (produced in photosynthesis) and water vapour can also diffuse out of the stomata (water vapour is actually lost from all over the leaf, but mostly through the stomata)
- size of stomata is controlled by guard cells: these close of the plant is losing water faster than it is being replaced by the roots. Without guard cells the plant would soon wilt
- flattened shape of leaf increases the surface area of exchange surface so it’s more effective
- wall of the cells inside the leaf form another exchange surface. Air spaces inside leaf increase the area of this surface so there’s more chance for carbon dioxide to enter the cells.
Now do the gills work as a gas exchange surface?
- Water containing oxygen enters the fish’s mouth and passes out through the gills
- As this happened, oxygen diffuses from the water into the blood in the gills and carbon dioxide diffuse out of the blood into the water.
- Each gill is made up of lots of thin plates called gill filaments: give large surface area(increase rate of diffusion)
4.Gill filaments are covered in lots of tiny structure called lamellae
5.Lamellae have lots of blood capillaries to speed up diffusion between water and blood
6.Lamellae also have thin surface layer of cells to minimise the distance the gases have to diffuse. - Blood flows through the lamellae in one direction and water flower over in the opposite direction. This maintains a large concentration gradient between the water and the blood
- Concentration of oxygen in the water is always higher than that in the blood so as much uxygen as possible diffuses from the water into the blood
How does temperature affect the rate of diffusion?
- increase temperature on environment —> increases kinetic energy of the molecules
- molecules move and mix faster
- increased rate of diffusion
5 ways the small intestines are adapted to make the absorption of nutrients more efficient
- thin lining - reduce diffusion distance
- many capillaries - increase blood supply + maintains steep concentration gradient
- walls form villi - increase SA
- contains lacteals - for absorption of fatty acids + glycerol
- layer of muscle - allow peristalsis to occur to move digested food through small intestine
how are fish gills adapted for exchange f oxygen + carbon dioxode
- many gill filaments - larger SA
- thin gills - short diffusion distance
- good blood supply - maintain steep concentration gradient
- water continuously flows over gills - maintain steep concentration gradient
how are leaves adapted for the exchange of oxygen and carbon dioxide for photosynthesis
- broad + flat plant leaves - larger SA
- thin leaves - shorter diffusion distance
funtion of stomata and guard cell
- allow gas exchange between atmosphere and air spaces
- water vapour diffuses out stomata
