Test 23/9/21 Flashcards
cornea
A curved transparent disc at the front of the eye. Does most of the focussing.
pupil
A circular opening whose size is controlled by the Iris.
lens
It is soft, flexible and transparent. Its shape can be changed to fine tune the focussing of light onto the retina
ciliary muscles
A ring of muscle at the edge of the eye which circles the lens. When it relaxes, the lens gets thinner. When it contracts, the lens gets fatter.
suspensory ligament
Strong fibres which attach the lens to the ciliary muscle
retina
Contains light sensitive cells called rods and cones
optic nerve
Consists of many neurones which carry impulses from the retina to the brain
fovea
The region of the retina with the greatest number of cones
conjunctivia
A mucous membrane that covers the eye to prevent infection
Dim light eyes
Radial muscles contract
Circular muscles relax
Iris narrower
Pupil dilates
Bright light eye
Radial muscles relax
Circular muscles contract
Iris wider
Pupil constricts
Photosynthesis word and symbol equation
Carbon dioxide + water —> glucose + oxygen
6CO2 + 6H2O —> C6H12O6 + 6O2
How does carbon dioxide affect the rate of photosynthesis?
More carbon dioxide = faster reaction
As there are more molecules to collide with enzymes
However, it will reach a point when adding more carbon dioxide has no effect, there is a lack of energy
How does light intensity affect the rate of photosynthesis?
Brighter light = increased rate of photosynthesis
As there is more energy for the reaction to occur
This doesn’t last forever, as at high light intensities, a different factor is limiting and the graph levels off
How does temperature increase the rate of photosynthesis?
Increasing temperature = faster reaction
Enzymes and substrates have more kinetic energy and collide more often
However, at too high temperatures, photosynthesis decreases and the reaction stops
This is because the enzymes carrying out this stage of the photosynthesis have been denatured
