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Miss Ventress' Work

What is the relative W.P in a hypotonic solution? The W.P is higher, so water diffuses out of the cell.
What is the relative W.P in a hypertonic solution? The W.P is lower, so water diffuses into the cell.
What is an isotonic solution? A solution of the same W.P, so there is no movement of water.
What is meant by the term water potential? The tendency of a solution to gain or lose water.
What unit of measurement is used for water potential? Pascales.
What is osmosis? The net movement water particles from an area of low water concentration to an area of high water concentration.
What 4 factors affect the rate of diffusion? Length of the diffusion pathway, concentration gradient, surface area, and temperature.
How are diffusion gradients maintained for exchange surfaces? By movement of air (ventilation) or blood flow.
What is the relationship between size and SA:Vol? As size increases, SA:Vol increases.
What do insects use to control water loss and gas exchange? Spiracles.
In insects, what do spiracles do? Open and close to control water loss and gas exchange.
In insects, how does water in tracheoles slow oxygen uptake? Oxygen diffusion is slower in water than in air.
How do fish maintain a high oxygen concentration gradient? The countercurrent of the blood and the water means there will always be a higher concentration of oxygen in the water than in the blood.
When would diffusion stop? When molecules are equally distributed and equilibrium is reached. (The molecules would still move)
Diffusion is proportional to: (Surface area x diffusion concentration) / length of the diffusion pathway
Which particles can diffuse directly through the phospholipid bilayer? Lipid soluble molecules and very small molecules.
What is facilitated diffusion? When a membrane protein helps (facilitates) movement through the phospholipid bilayer.
Give three characteristics of a channel protein. Always open, lined with hydrophilic amino acids, allows hydrophilic molecules through the membrane.
What are carrier proteins? A protein that transports specific molecules across the membrane.
How do carrier proteins transfer molecules? Specific molecules bind to the protein, causing it to change shape and release the molecule on the other side of the membrane.
What is Co-Transport? When two substances are simultaneously transported across a membrane by one protein without the use of ATP.
Why and how is the concentration gradient maintained for Na+ ions in co-transport? A sodium pump gets rid of sodium from the epithelial cells into the lumen, where it can be carried away by circulation. This means sodium can diffuse into the cell and bring in glucose via co-transport without the use of ATP.
What are glycoproteins used for? Cell recognition e.g. antigens.
What are glycolipids used for? They are used as an energy store as they can be hydrolysed to produce energy.
What is meant by the term fluid mosaic? The components fit together but are not fixed in place, so they can move to an extent.
What is the function of cholesterol in the cell membrane? Stability. It makes sure the components of the cell membrane are not moving too much and makes it less permeable.
Where is the thoracic cavity? The chest.
What is the diaphragm's role in breathing? The diaphragm contracts and moves down, which increases the volume, which decreases the pressure and draws in air.
What is pulmonary ventilation? The total volume of air moved into the lungs.
(Equation) Pulmonary ventilation= Tidal volume x ventilation rate.
What is tidal volume? The volume of air per breath at rest.
What is the ventilation rate? The no. of breaths per minute.
What is meant by the term 'lumen'? The inside space of a tubular structure (e.g. intestine)
What is meant by epithelium? A membranous tissue that covers an internal or external surface.
Give five factors that make Alveoli efficient. Narrow capillaries, good blood supply, thin walls, large SA, ventilation.
What happens to the W.P when the stoma are open / turgid? Potassium ions are actively transported into the guard cells, causing the water potential to fall.
What happens to the W.P when the stoma are closed / flaccid? Potassium ions diffuse out of guard cells, causing the water potential to rise.
What effect does increased humidity have on transpiration in plants? The transpiration would decreased because there would be a higher concentration of water in the air than in the plant, so the rate of osmosis would decrease.
What effect does windy weather have on transpiration in plants? The wind would move the water vapour away from the top of the leaf, so cohesion would mean the rate of osmosis would increase.
What effect would warmer weather have on transpiration in plants? The water molecules would have more kinetic energy and would move/ diffuse faster.
What effect would a light surrounding have of transpiration in plants? The stomata would open to allow photosynthesis, so the rate would increase.
What are xerophytes? Plants with adaptations to reduce water loss.
Created by: 11BricknellH