B3: Living Together Food and Ecosystems
- B3: Living Together: Food and Ecosystems
- OCR 21st Century
- Created by: Monoruvwe
- Created on: 17-02-19 14:48
View mindmap
- B3:Living Together (Food and Ecosystems)
- Transport in Plants + Prokaryotes
- Single celled organisms are only 1 cell big (which makes diffusion a lot easier)
- in multicellular organisms, some cells are deep inside an organism
- This makes diffusion difficult because it's a long way from them to the outside enviroment and so specialised exchange surfaces are needed.
- Plants
- Carbon dioxide and oxygen move in out of plant cells by diffusion
- Lower surface of leaf is full of tiny pores called stomata
- Stomata let carbon dioxide and oxygen diffuse in out
- Also allow water vapour to escape
- Roots hairs
- Plants take both water and ions in through their roots
- Cells on plant roots grow long 'hairs' which stick out into soil
- Diffusion, Osmosis and Active transport
- Diffusion
- The net movement of particles from an area of higher concentration to an area of lower concentration
- Happens in both liquids and gases
- Continues until concentration of diffusing particles are EVEN in BOTH areas
- Osmosis
- The net movement of water molecules across a partially permeable membrane form area of higher concentration to lower concentration
- Water Molecules actually pass through both ways
- Happens because water molecules are moving all the time
- Steady net flow of reigon with fewer water molecules
- Dilutes strong sugar
- Important because plant don't have skeletons
- This means that the cells being the right size and shape matter
- When plant cells take water, they stretch and bulge
- This means that the cells being the right size and shape matter
- Diffusion
- Photosynthesis
- What is it?
- A series of Chemical reactions in the cells of producer.
- Plants make their own food in the form of glucose
- Glucose= Made from Carbon dioxide and water by photosynthesis
- Equation Model
- Uses words to represent the reactants and products
- Carbon dioxide + Water ---> Glucose + Oxygen
- CO + H O -> C H C O + O
- 2 stage Model
- Can be summarised in two main stages
- Inside a Leaf Cell
- Contain organelles called chloroplasts
- Each chloroplast contains chlorophyll
- Chloroplasts contains enzymes needed for photosynthesis
- Energy
- Only happens in light
- Without the sun (or another light source)= NO PHOTOSYNTHESIS
- An endothermic process
- Endothermic= A process that transfers energy from its surroundings, make them cooler.
- Rate of Photosynthesis
- Temperature
- Too slow= Can't photosynthesise
- Untitled
- Too High= Enzymes become denatured
- Happens about 45 degrees Celsius
- Carbon Dioxide
- One of the substrates needed for Photosynthesis
- More Carbon dioxide= Increased rate of photosynthesis
- However after a certain pint, carbon dioxide is no longer a limiting factor.
- Light
- Light transfers energy needed for photosynthesis
- Increased light level= Increased rate of photo synthesis
- Distance of Light source and light intensity are INVERSELY proportional
- Distance increases= Light intensity decreases
- LI 1 divide by d
- Temperature
- What is it?
- Enzymes
- What are they?
- Biological Catalyst
- Speed up chemical reactions.
- Catalyse recations
- Break down larger molecules into smaller ones.
- Proteins
- Made up of a long chain of amino acids
- What is the use?
- Biological temperatures are from 0 to 50 degrees Celsius
- This WAY too slow to support life.
- Increasing Temperature helps. but it also damages cells
- Enzymes can increase rate of reaction by up to 10 billion times
- IMPOSSIBLE to live without
- Rate of reaction
- PH
- Too high/low = Interferes with bonds holding them together
- Changes shape of active site and denatures enzyme.
- All enzymes have an optimum PH (often 7, but not always)
- Temperature
- Higher temperature = Faster rate of reaction
- Enzymes and substrates have more energy meaning they move about more.
- Too Hot= Bonds will break and enzymes become denatured.
- Substrate Concentration
- Higher substrate concentration=Faster Reaction
- Due to Enzyme more likely to meet up and react with a substrate molecule
- Only true up until a point
- After all the active sights are full, there will be no increase.
- PH
- Lock and Key Model
- 1) An enzyme has an active sight
- 2) Only the correct substrate fits into the active site
- 3) The reaction takes place in the active site
- 4) The products molecules leave the active site.
- The enzymes is not permanently changed can be used again
- What are they?
- Xylem, Phloem and Stomata
- Xylem
- Plant tissue that transports water and dissolved minerals through a plant
- Made of dead cells joined together end to end
- Have a hole down the middle
- Thick side walls are made of cellulose
- Cells walls are also strengthened by lignin
- Take water and water up the stem from the root
- Pholem
- A plant tissue that transports sugar through the plant
- Made of columns of living cells called sieve tube elements
- Sieve tubes have no nucleus
- Pholem vessels transport food substances up and down the stem (translocation)
- Sugars enter through active transport
- Stomata
- Tiny holes in the outer surface of a leaf that enable a plant to exhange gases with its surrounding
- Open and close automatically
- surrounded by guard cells which change shape to control size
- Sensitive to light
- Xylem
- Transpiration
- The process of water movement through a plant and its evaporation from cells in the leaves
- Pulls water thrugh plant
- rate of water uptake
- Temperature
- Warmer = faster
- Light intensity
- Brighter= greater
- Air Movement
- More air= faster
- Temperature
- Transport in Plants + Prokaryotes
Comments
No comments have yet been made