(P2) CB6: Plants (INCOMPLETE DECK)) Flashcards
(46 cards)
Why are some leaves darker?
They have more chloroplasts. This is because they aren’t used to recieving as much light.
What are the signs that a leaf is recieving less light?
It is larger and darker.
What is the name of the chemical that makes leaves green and what can it be found in?
Chlorophyll. In chloroplasts.
What is the name of the pigment that makes some plants orange?
Carotenoids
Why do plants have different pigments?
To maximise their usage of the solar energy that they recieve
Is photosynthesis exothermic or endothermic?
Endothermic. It needs energy.
What is the word equation and the balanced symbol equation for photosynthesis?
6CO2 + 6H2O —-(sunlight and chlorophyll)—-> C6H12O6 + 6O2
carbon dioxide + water -> glucose + oxygen
How is energy stored in a plant?
starch
Why do plants photosynthesise?
to get energy, which is used up in respiration
What is Fick’s law?
Rate of diffusion is roughly equal to (surface area * conc diff)/thickness of membrane
Why are leaves thin?
So that gases can reach cells easily
Why are leaves veiny?
to carry water to the cells and carry glucose away
Where are the stomata?
the underside of the leaf
What do stomata do?
they move gas in and out
How are cacti adapted? (7 factors)
- Some are whiter because they have densely packed spikes. This means that they stay cool to stop their enzymes denaturing.
- Fat cacti lose less water because they have a lower SA to volume ratio
- Leaves evolved into spikes to reduce SA so that they don’t dry out as quickly
- Only the stem contains chlorophyll
- Stem is rounded to reduce SA
- Long roots to reach water deep down
- Stem stores water during droughts
How are insect-pollinated flowers adapted?
- Flowers are bright leaves. They attract insects.
- Flowers smell good to attract insects.
- Bees accidentally brush pollen from the anthers to the stigma
- Nectar is made at the bottom of the petals
- The pollen is spiky to stick to insects
How are wind-pollinated flowers adapted?
- Anthers hanging out of the flower so they allow the wind to carry the pollen away. It falls onto stigma eventually.
- The pollen is round so it is aerodynamic.
Limiting factors of photosynthesis
- Amount of chloroplasts (contain chlorophyll)
- Light intensity
- Moisture in the air
- CO2 concentration
- Temperature
How do you test leaves for starch?
Simplified:
1. Boil in water to break down the cell wall
2. Boil in ethanol to remove colour
3. Add iodine which changes colour and tests for starch
More detail:
1. Boil 200ml water over blue flame
2. Add the leaf and leave it for 2 mins
3. Turn off the bunsen burner. Pick up the leaf.
4. Add to a test tube with ethanol to remove the colour
5. Place it back in the water with the bunsen burner off for ~2 mins
6. Take out the leaf and put it on a white tile. Dunk in cold water if it’s brittle.
7. Add iodine. Turns black if starch is present.
How do you measure the rate of photosynthesis?
Use an elodea bubbler.
- Put some pondweed in water and baking soda. It will photosynthesise.
- Oxygen produced can be collected in a test tube.
- Rate can be measured by counting the bubbles
THIS IS A BAD EXPERIMENT THOUGH:
- innacurate - a gas syringe could be used to measure more precisely.
Translocation
movement of sugars and other chemicals (assimilate) made by plant cells along the phloem.
assimilate
a complex solution (eg: sap)
main assimilate
sucrose (a type of sugar)
xylem
transports water from the root to the leaf
