6) Plant Structure & Function Flashcards
Where does photosynthesis take place?
In chloroplasts
What type of reaction is photosynthesis?
Endothermic (needs energy)
What is the energy source of photosynthesis?
Sunlight
What traps sunlight in chloroplasts?
The chemical chlorophyll
What is sunlight used to make?
Carbohydrates
What is the balanced chemical equation for photosynthesis?
6CO2 + 6H20 –> C6H12O6 + 6O2
What factors affect the rate of photosynthesis?
Carbon dioxide concentration
Chlorophyll concentration
Light intensity
Temperature
What happens in photosynthesis when light intensity increases above a certain threshold?
Rate no longer increases
What happens in photosynthesis when carbon dioxide concentration increases above a certain threshold?
Rate no longer increases
Why does increased temperature increase the rate of photosynthesis?
More energy is provided
What happens to photosynthesis when temperatrue increases above 45 degrees C?
Enzymes denature and rate of reaction sharply drops and stops
What is the temperature plant enzymes denature above?
45 degrees C
What is the limiting factor of photosynthesis in winter?
Temperature
What is the limiting factor of photosynthesis at night?
Light intensity
What is the limiting factor of photosynthesis in mineral deficient soil?
Chlorophyll concentration
How can you test the effect of light intensity on the rate of photosynthesis?
Change distance between lamp and pondweed and count oxygen bubbles produced
What are the gas bubbles pondweed produce?
Oxygen bubbles
What is the independent variable when investigating light intensity?
Light intensity
What is the dependent variable when investigating light intensity?
Number of bubbles
What is the inverse square law?
Light intensity = 1 / distance^2
What is accuracy?
How close a measured value is to its true value
What is reliability?
The ability of an experiment to produce consistent results
What is validity?
How appropriate an experimental method is at achieving the aim of an experiment
What do root hair cells do?
Take in the minerals plants need to survive
How are root hair cells specialised?
Long projections
No chloroplasts
Why do root hair cells have long projections?
To increase the surface area for absorbing water and minerals
WHy don’t root hair cells have chloroplasts?
They are located underground and do not receive sunlight
What do xylem cells transport?
Water up the stem into the leaves
What direction do xylem cells transport water?
Up the plant
Stem to leaves
What are xylem vesslels made from?
A series of connected dead xylem cells
Why can water move through dead xylem cells?
The end walls are broken (open-ended)
What substance strengthens the cell walls of xylem cells?
Lignin
What cells open and close the stomata?
Guard cells
What are stomata?
Gaps in the lower epidermis of leaves
Where are stomata found?
The lower epidermis of leaves
What do stomata do?
Facilitate the diffusion of gases (evaporatd water) in and out of leaves
How do guard cells open the stomata?
They take up lots of water causing them to swell
How do guard cells close the stomata?
They lose water and return to a limp state
What balance do stomata reach?
Allowing gases for photosynthesis into leaves and conserving water
What happens to the stomata when water is abundant?
Stomata opens to allow gases for photosynthesis to move freely in and out of the leaf
What happens to stomata when water is scarce?
Stomata close to prevent further water loss
What is the state of stomata at night and why?
Closed as no carbon dioxide is needed for photosynthesis as there is no sunlight
