P1-Topic 4- Bioenergetics Flashcards
What is photosynthesis?
2
process by which plants make glucose from sunlight
Light energy is converted into chemical
energy
Where does photosynthesis take place?2
Within chloroplasts in leaf palisade
cells.They contain chlorophyll, a pigment
which absorbs light energy.
State the equations for photosynthesis 2
Word: carbon dioxide + water → glucose + oxygen
Symbol:
6CO₂+ 6H₂O → C₆H₁₂O₆
+ 6O₂
why is photosynthesis endothermic
- energy is transferred from
the environment to chloroplasts by light.
How can you show that a plant gives off oxygen
during photosynthesis?3
Using a water plant (eg. Elodea),
collect gas bubbles produced during photosynthesis.
The gas will relight a glowing splint as it contains
oxygen.
Give examples of leaf adaptations which
maximise the rate of photosynthesis 4
Broad leaves - maximise surface area.
● Thin leaves - short diffusion distance.
● Chlorophyll present - trap light energy.
● Veins - transport water to leaves via xylem, remove photosynthesis products via phloem.
● Air spaces - allow CO2 to enter and O2 to leave.
● Guard cells - control opening of stomata for gaseous exchange and
prevent water loss.
What are the four main factors that affect the rate of photosynthesis?
● Temperature
● Light intensity
● Carbon dioxide concentration
● Amount of chlorophyll
How does temperature affect the rate of photosynthesis?2
Increasing the temperature increases the rate of
photosynthesis as the kinetic energy of particles
is increased.
The rate decreases past a certain temperature as enzymes become denatured.
How does light intensity affect the rate of photosynthesis?
Increasing the light intensity increases the rate of photosynthesis until another factor
becomes limiting
How does carbon dioxide concentration affect the rate of photosynthesis?2
Carbon dioxide is also needed to make glucose
As the concentration of carbon dioxide increases,
the rate of reaction increases.
(until another factor becomes limiting) a
How does the amount of chlorophyll
affect the rate of photosynthesis?
Decreasing the amount of chlorophyll (eg. due to
a lack of magnesium) decreases the rate of
photosynthesis as chlorophyll is required to
absorb light energy
What is a limiting factor?
An environmental factor which can
restrict the rate of photosynthesis eg.
light intensity
photosyntheris 27 spec4.4.1.2
