B2 Flashcards
How do particles in a gas or solution behave?
- They are constantly moving, movement can be random so particles can move in all directions
What is the defenition for diffusion?
Diffusio in the net movement of particles from an area of high concentration to an area of low concentration. Moving down a conc gradient
When does diffusion continue until?
- Concentration gradient is zero, conc of particles same everywhere
Is energy transferred during diffusion?
- No its a passive process as it is the ordinary motion of particles
Where does diffusion occur in the body?
- Glucose and blood for respiration is transported by blood and diffuses into cells
- Some chemical reaction waste products are toxic, eg, CO2, it diffuses out respiring cells
What are 3 factors affecting rate of diffusion?
- Distance
- Conc gradient
- Surface area
How does distance affect rate of diffusion?
To increase rate of diffusion
- Decrease distance particles need to move, less time shorter distance. E.g Capillaries 1 cell thick increases rate of diffusion gasses in and out blood
How does conc graident affect rate of diffusion?
- Steeper conc gradient, greter net movement of particles. E.g. Plants use CO2 in photosynthesis, CO2 conc in plants drop increasig rate ofdiffusion CO2 into cells
How does surface are affect rate of diffusion?
- Allows more space for diffusion, more patricles move in a period of time. E.g. Small intestine wall folde to increase surface area in cnotact with blood, increasing rate of diffusion of molecules
What is defenition of Osmosis?
Osmosis is net movement of water particles across a semi permeable memebrane from an are of high water potential to low water potential
How does water potential work?
- Pure water highest water potential, all molecules free to move
- Conc solution, lower water potential
What is a semi/partially permeable membrane?
- Memebrane with small holes, only tiny molecules like water can pass through
Do water particles move both ways in osmosis?
- Yes, as water molecules move randomly all the time
BUT net movement high water potential to low water potential
What happens to a plant cell if surroundings are more or less concentrated than cell contents?
- Surroundings lower water potential, cell loses water by osmosis - turgor pressure falls, cells becomes flaccid - after cell wall colapses Cell is known as plasmolyed cell
- Surroundings higher water potenial, cell takes water by Osmsis, turgor pressure increases, cell becomes firm and rigid
What happens to an animal cell if surroundings are more or less concentrated than cell contents?
- Surroundings lower water potential, cell loses water by osmosis, becomes crenated(crinkles)
- Surroundings higher water potential, cell takes up water, swells and may burst, lysis
Why is watering a plant extremly important (in terms of osmosis)?
- Watering plant increases water potential of soil around it - plant cells draw in water by osmosis til they’re turgid - contents of cell push cell wall,turgor pressure, this supports plant
- If no water in soil, cells become flaccid, plant starts to droop - but not comlete;y
Whats defenition of active transport?
Active transport is the movement of particles across a membrane against a concentration gradient using ATP released during respiration
What are 3 key features of active transport?
- Particles transported agaisnt a conc gradietn
- ATP is required - that comes from respiration
- Process makes use of carrier proteins in cell memebrane
Why do cells that carry out a lot of active transport have high amounts of mitochondira?
- So they can respire rapidly producing large amounts of ATP, rate at which actove transport occurs depends on rate of respiration to produce ATP
What are carrier proteins?
- Special proteins that span the width of a memebrane
How do carrier protiens work in active transport?
- Particular molecule cell requires binds to sppecific carrier protein
- Energy transferred from energy to store to protein so it can chage shape or rotate
- Carrier protein transports molecule to cell
How is active transport used during digestion?
- In small intestine, carbs broken down to glucose
- Glucose actively transported into bloodstream through villi
- Blood takes glucose to where it is needed in body
How is active transport used in nerve cells?
- Carrier protein pumps sodium ions out cell, same time potassium ions pumped back in
- Sodium potassium pump plays big role in creating nerve impulses
How is active transport used in plants?
To take minerals from soil
- Plants need nitrate ions forgrowth, soil water usually has lower conc of nitrate ions compared to plant
- Root hair cels use active transport to move the ions across cell membrane into root cell
