Diffusion, Osmosis, and Active Transport Flashcards
Describe the process of Diffusion.
The particles are separate when first put together
-They slowly start to mix due to their random motion
-The particles are now nearly fully diffused
-The particles are fully diffused, and they will carry on moving.
What is the link between the concentration gradient and the rate of diffusion?
The bigger the difference in concentration between two separate environments, the faster the rate.
What about if the concentration gradient is around equal?
Then there will be equal distribution, between the two separate environments.
Name an example of diffusion in the body
During gas exchange of Oxygen and Carbon Dioxide in the Alveoli.
Apart from concentration gradient, what other factors affect the rate of diffusion and how?
Distance- Particles will diffuse quicker if they don’t have that far to travel.
Surface Area- The greater the surface area, the faster the rate of diffusion and MORE diffusion will occur
Temperature- The hotter the temperature, the faster the particles will diffuse as they have more Kinetic Energy
What is Osmosis?
Osmosis is the diffusion (a net movement) of water molecules across a partially permeable membrane from a dilute (Hypotonic) solution to a concentrated (Hypertonic) solution.
How is the cell membrane PARTIALLY permeable?
The cell membrane has very small holes in it. This enables small molecules to pass through but larger ones cant and so it is partially or selectively permeable as not every particle can go through.
If a membrane is not partially permeable, Osmosis will NOT take place.
What can be used to demonstrate Osmosis?
Osmosis can be demonstrated using Visking Tubing filled with a solution + placed in a beaker of pure water.
What is a Hypotonic solution?
A Hypotonic solution is a solution of a lower concentration than inside the cell (the solute)
What is a Hypertonic solution?
A Hypertonic solution is a solution of a higher concentration than inside the cell (solute).
What is an Isotonic solution?
An Isotonic solution is a solution with the same concentration as inside the cell.
Describe animal cells in a Hypotonic solution:
Animal cells in a Hypotonic solution have more sugar molecules inside them than the solution they are in. This means that the water will move from where it’s in higher concentration (outside) to where it’s in lower concentration (inside). This causes the animal cell to SWELL UP and INCREASE in size. This continues until it bursts (LYSIS).
Describe animal cells in a Hypertonic solution:
Animal Cells in a Hypertonic solution have less sugar molecules inside them than the solution that they are in. This means that water will move from where it is in higher concentration (inside) to where it is in lower concentration (outside). This causes the animal cell to SHRIVEL and DECREASE in size, leading to crenation.
Describe Plant cells in a Hypotonic solution:
There is more sugar inside the plant cell than outside. Water moves from where it’s in higher concentration (outside) to low concentration (inside). This causes the cell membrane to push against the cell wall but it does NOT burst. It become TURGID or swollen as it could lose water from the surface of the leaf due to evaporation.
Describe Plant cells in a Hypertonic solution?
There is more sugar outside the plant cell than inside. Water moves from where it is in high concentration (inside) to low concentration (outside). This causes the cell membrane to move away from the cell wall and the cell is flaccid (floppy but not dead). If this continues, the cell membrane pulls away totally and collapses. This is because the pressure of the water inside pushes the cell membrane to the cell wall. Without this water, it will start to move away and collapse.
What is Active Transport?
Active Transport is the movement of dissolved molecules into or out of a cell through a cell membrane, from a region of lower concentration to a region of higher concentration. The particles move against the
concentration gradient
, requiring energy from the cell, released during respiration, from the mitochondria, producing ATP.
Name three examples of Active Transport.
Root Hair cells take in mineral ions from the soil, absorbing water, even when the concentration is higher outside of the cell.
-Phloem- how plants pump sugar in
-In the Small Intestine
How are protein carriers linked to Active Transport?
During Active Transport, protein carriers in the cell membrane ‘pick up’ particles + move them AGAINST the concentration gradient. The protein molecules change shape (in the membrane) to allow molecules in. This takes energy, and taking Glucose in can help repay this lost energy.
What is ATP?
ATP is how we store energy around the body. ATP is our energy currency, holding energy for us. It is released during Respiration, in a chemical process where ATP = ADP +P + Energy.
How are root hair cells adapted to Active Transport?
While oxygen is necessary for cellular respiration to produce ATP, root hair cells have alternative energy sources, like stored glucose, transported from the leaves, which can be broken down anaerobically to generate ATP for active transport.
-having a large surface area to facilitate mineral ion absorption -numerous mitochondria to provide the energy required for this process.
-They also have a thin cell wall that allows for easier entry of water and dissolved substances.
What two things are required for Active Transport?
Oxygen and Glucose (so Respiration) is required for Active Transport to take place. Oxygen is indirectly needed to power the process of cellular respiration, which provides the energy (ATP) that Active Transport requires. And Glucose is what is broken down during respiration.
How does the Root Hair Cell utilise both Active Transport and Osmosis?
The Root Hair Cell needs water, and so, using up energy, utilises Active Transport to bring in the mineral (magnesium) ions. This is so that there would be more water outside (Hypotonic), and Osmosis can take place to bring the water from where it is high in concentration to low (inside the cell).
Mineral Ions are taken up by the root hair cells of plants.
Name the type of vessel that transports these mineral ions through plant.
The Xylem, a specialised cell in Plants transports these mineral ions through the plant.
Why does Osmosis require a partially permeable membrane?
Osmosis requires a partially permeable membrane to allow water molecules through but not larger solute molecules eg sugar. This is to ensure that water moves DOWN it’s concentration gradient, from an area of high water concentration (low solute) to an area of low water concentration (high solute).
