Topic 6 Flashcards
What does photosynthesis occur in
Plants and algae
What is photosynthesis
Process that plants and algae use to make their own food
What energy transfer is photosynthesis
Light to chemical
Where is the energy stored in plants
In sugars produced
How is light energy absorbed
By chlorophyll in chloroplasts
What type of reaction is photosynthesis and why
Endothermic
Absorbs energy from surroundings
What are the limiting factors of photosynthesis
Temperature
Light intensity
CO2 concentration
What is an independent variable
Something you change
What is a dependant variable
What you record
What is the control variable
What stays the same
What is the practical for photosynthesis
Pondweed
How to work out light intensity
1/d^2
Unit for light intensity
Arbitrary units
Examples of root hair cell adaptations
Long extensions stretch into soil to increase surface area
Therefore - osmosis and diffusion of nutrients
Adaptations of xylem cells
Without cytoplasm or cell contents
Therefore more space for water and minerals to go through
Adaptations of phloem cell
Use energy for active transport of sucrose around the plant within phloem sieve tubes
Transpiration
Loss of water by evaporation from leaves
Transpiration stream definition
Movement of water from roots to leaves
Transpiration stream description
Water enters through osmosis
Up stem through xylem
Draws water out of xylem
Vapour evaporates through stomata
Translocation
Transport of sucrose around plant in phloem
Translocation description
Sucrose produced
Needed for growth
Carried in phloem
Dissolved sugars convert to starch in storage organs (eg potato)
2 reasons for a leaf to adapt
Photosynthesis and gas exchange
Examples of leaf adaptations
- epidermis cells and waxy cuticle transparent
- flat large surface area
- xylem brings water and phloem removes sugar
- stomata
- Internal air spaces for increase surface area
Why do stomata close at night
Light is limiting factor
Therefore need to reduce water loss
Three environmental factors affecting transpiration
Light intensity
Air movement
Temperature
Practical for rate of transpiration with explanataion
Potometer
1) note position of bubble
2) note position after no of mins
3) distance moved/time
Plant adaptation in dry
Cactus
Spikes (lose less water)
Thick fleshy body store water
Large root system
Plant adaptation for tropical
Large leaves
Climbing plants
Drop tips
Phototropism
Plant bends towards light
Gravotropism
Due to gravity
Auxins
Make cells elongate on shaded part of plant
Cause phototropism
Selective weed killers
Put on crops and weeds, weeds grow too fast and die so less competition for crops
Rooting powder
Contains auxins
Dip cutting of plant into it so it grows more quickly
Gibberelins
Decrease seeds
Increase size of flower or fruit
Stem elongation
Seedless fruit
Gibberellins
Spray on fruit for less seeds and more yield
What are unripe tomatoes picked
Less damage
Why is Ethene put on fruit
Ripen them
