Movement of Particles Flashcards
How to increase SA : vol ratio
- flatter and wider
- give it villi or folds + gaps to increase surface area (like an amoeba)
Why is having a large cell with a small SA : vol ration problematic?
It doesn’t get enough oxygen to supply its large amount of respiration so it dies
Diffusion
The movement of molecules from an area of high concentration to an area of low concentration, down the concentration gradient
Why do molecules diffuse from an area of high concentration?
All of the molecules are moving due to kinetic energy, so more molecules = more collisions. The molecules change direction after each collision, eventually dispersing them evenly throughout the solution
Net Movement
The overall movement of molecules during diffusion. No concentration gradient = not net movement as movement of molecules is in all directions equally
Why are molecules moving?
Kinetic energy + collisions
Surface area in diffusion
Larger surface area = faster rate of diffusion
Concentration gradient in diffusion
Higher concentration gradient = faster rate of diffusion
Diffusion distance in diffusion
Shorter diffusion distance = faster rate of diffusion
Temperature in diffusion
Higher temperature = faster rate of diffusion
How is an amoeba adapted for efficient intake of oxygen in low oxygen environments?
It has an irregular shape with many projections (bits that stick out) which increase the surface area to volume ratio. This allows efficient diffusion of oxygen into the amoeba
What is the cell membrane made of?
Phospholipids stacked against each other like a sandwich, with soluble phosphate heads on the outside, and the insoluble lipid tails inside. Proteins in the membrane form small channels for solutes to diffuse through
Can larger molecules diffuse through the phospholipid bilayer?
No. They are carried across by active transport which requires energy
How do you increase the active uptake in a cell?
Increase the proteins needed for active transport by adding more ribosomes, ER, and Golgi
Experiment for supplying cells
Indijelly experiment
Osmosis
The net movement of water molecules across a semi-permeable membrane, from high water potential to low water potential
Low water potential =
high concentration
High water potential =
low concentration
Turgid
Firm (plant cells only)
Flaccid
Floppy (plant cells only)
Active Transport
The movement of large molecules across a membrane using energy from respiration
Plants wilt when grown in soil with little nutrients
There aren’t enough nutrients to take in to lower the water potential. Water cannot move into the root hair cell
Waterlogged soil will suffocate the plants
The water fills the air pockets in the soil so the plant can’t take in oxygen
How does active transport affect water potential?
It increases the concentration of nutrients, decreasing the water potential
