Plants Flashcards
Geotropism experiment
Can be demonstrated using clinostate- holds the plant
Rotates in a verticals plane
Hormone accumulates where the plant bends
Geotropisms
Gravity always acts downwards not he plant
Auxin levels appear to be part of the response
Phototropisms
Due to a water-soluble chemical that is produced in the growing tip
Called auxins
Auxin
Build up on the dark side of the root
The more auxins the more the plant cells grow
The shoot bends due to the side with the most auxins grows more
Tropisms
Directional response by plants to stimuli from the environment
Towards or away from stimuli
Phototropism
Responses of plants to light coming from one direction
Geotropisms
Responses of plants to the force of gravity which always act downwards
Plant movement
Move in response to stimuli (the world around them)
Don’t have a CNS
Positive phototropism /negative geotropism
Stems
Negative phototropism /positive geotropism
Roots
Rate of transpiration
Controlled by the stomata
Stomata
Open and close to allow gas exchange and to control the rate of water loss
Transpiration
Water leaves the leaf as water vapour thought the stomata
It evaporates from the surface of the cells in the menophyll
Water from xylem to menophyll by
Osmosis
Water moved closer to the xylem by
Osmosis
Water moved up the xylem
By being ‘pulled’ all the way from the roots by osmosis
Transpiration stream
The continuous flow of water
To measure transpiration
Use a potometer
Change light intensity, air flow, temperature
Uptake of water
Roots are covered in hairs
Concentration of mineral ions in the soil water is lower than in the root cells cytoplasm
Why are roots covered in hairs
To increase the surface area
How does water enter the roots to the xylem
By osmosis
Across root cells to the xylem
Along a concentration gradient
Uptake of minerals
Moved into the root hair cells against a concentration gradient
Done by active transport
Minerals from roots to the xylem
Move along by diffusion and enter the xylem
Diffusion
The movement of solute molecules down a concentration gradient
(High to low concentration)
Osmosis
Diffusion through a partially permeable membrane
Movement of water down a concentration gradient
Plant cell bathed in pure water
Water will move into the cell until it is turgid
Plant cells placed in a more concentrated solution
Water moves out of the cell
Plasmolysed
Excessive loss of water
Cytoplasm no longer pushes against the cell wall
Wilting
Plasmolysed cells can no longer support the plant
Plant wilts so that it doesn’t lose anymore water
Osmosis is used for
Moving water in and out of living cells
Transpiration affected by
Humidity, wind speed, temperature, light intensity
Xylem
Made of dead cell walls
Transports water and mineral ions up from the roots to the rest of the plant
Phloem
Made of living cells
Transports sucrose (sugars) for energy
And amino acids for cell building all around the plant
Turgid
In dilute solution
Absorbs water by osmosis
Flaccid
In concentrated solution
Loses water by osmosis
Nitrates
For amino acids (built up into proteins)
Magnesium
To make chlorophyll
Adaptations of the leaf
Thin and flat
Chloroplasts
Large surface area
Why is the leaf thin and flat
So as much light can be absorbed as possible
The distance that the gases need to diffuse are short
Why does the leaf have a large surface area
For gas diffusion to allow gas exchange between leaf and air
Test: photosynthesis, produces starch
Boil the leaf to kill it
Boil in ethanol
Test for starch using iodine solution
Test: photosynthesis, due to oxygen
Use an aquatic plant in bright light
capture the gas produced
Analyse to find the raised oxygen levels
Test: photosynthesis, chlorophyll is needed
Green/white leaf must be used
Test: photosynthesis, carbon dioxide
Remove carbon dioxide from the air using soda lime
Test: photosynthesis, light
Cover part of the leaf
Show starch wasn’t made there
Leaves make
Glucose from carbon dioxide and water
Photosynthesis requires
Light and chlorophyll
The energy from photosynthesis is captured by
Chlorophyll in chloroplasts
Light Energy converted how (photosynthesis)
To chemical energy in the glucose
Waste product of photosynthesis
Oxygen
Glucose converted to what (photosynthesis)
Sucrose starch Cellulose Proteins DNA lipids Chlorophyll
Glucose
Converted into sucrose
Transported round the plant
Starch
To be stored
Cellulose
For cell walls
Lipids
As an energy store in seeds
What type of energy is light energy
Chemical
Equation for photosynthesis
Carbon dioxide + water —light/chlorophyll—> glucose + oxygen
Short equation for photosynthesis
6CO2 + 6H2O ——> C6 H12 06 + 6O2
Photosynthesis affected by
Carbon dioxide concentration
Light intensity
Temperature
Mineral ions
For growth
Nitrate ions
Make amino acids, build proteins
Magnesium
To make chlorophyll