Gcse B3 OCR Flashcards
What is a catalyst?
A substance that increases the speed of a reaction with out being used
What are enzymes
Biological catalysts
What is an active site
Where the molecule is changed in the reaction
What happens when you heat an enzyme
It increases until it reaches its optimum pH then decreases
What it is the photosynthesis equation
Carbon dioxide + water ->
glucose + oxygen
How is glucose stored in plants
As starch
What is diffusion
Diffusion is the Movement from high concentration to a low concentration
What is osmosis
The movement of water molecules across a partially permeable membrane
High water concentration to a low
It’s like diffusion but in water
What is active transport
Movement of particles across a membrane against the concentration gradient
Lower concentration to a higher
Requires energy
Describe phloem tubes
Columbs of living cells
Transports mostly sugars up and down the stem to growing and storage tissues
Describe xylem tubes
Make of dead cells
Think side walls made of cellulose
Carry water and nitrates up the stem to the leaves
