Biology- B8: Photosynthesis

What is the word equation for photosynthesis?

Carbon dioxide + water → Glucose + Oxygen

What is the symbol equation for photosynthesis?

6CO₂+6H₂ → C₆H₁₂O6+6O₂

Describe the process of photosynethsis

-Energy is transferred from the environment to the chloroplasts by light

-This energy is transferred to convert carbon dioxide and water into glucose

-Oxygen is produced as a byproduct

Why is photosynthesis so important in ecosystems?

Plants need to make glucose in order to respire

How has a leaf adapted for efficient photosynthesis?

-Broad so big surface area for light to fall on

-Thin so diffusion distance for gasses are short

-Have chlorophyll in chloroplasts to absorb light

-Veins which bring water into xylem and remove products of photosynthesis in phloem

-Air spaces to allow carbon dioxide to get to cells, oxygen to leave by diffusion

-Guard cells that open/close the stomata to regulate gas exchange

What are the three limiting factors for photosynthesis?

-Carbon dioxide concentration

-Light intensity

-Temperature

Describe the graph the CO₂ concentration and photosynthesis.

-As rate of carbon dioxide increases, photosynthesis rate increases

-It then plateaus

Describe the graph the of Light Intensity and photosynthesis.

-As light intensity increases, photosynthesis rate increases

-It then plateaus

Describe the graph the of Temperature and photosynthesis.

-As light temperature increases, photosynthesis rate increases

-When it gets to hot enzymes get denatured and stops rate of photosynthesis

Why might a plants level of photosynethis be limited by chlorophyll levels its leaves?

How can you carry out a fair test to measure the effect of light intensity on the rate of photosynthesis?

-Place a beaker with 20cm2 of water and a piece of pondweed inside

-Turn on lamp and place beaker 10cm away, leave for five minutes to equilibrate to the light intensity

-Start timer and count bubbles for a minute

-Repeat, moving the pondweed beaker back 10cm each time.

-Make sure the water temperature stays the same using a controlled water basin and an LED bulb

-Use same species/mass/surface area of pondweed every time

Why might the level of photosynthesis be limited by the levels of chlorophyll in the plant?

-Less chlorophyll = less light absorbed

-So it cant turn carbon dioxide into glucose

What is the formula for inverse square law?

y=k/x²

What are the main uses of glucose from photosynthesis?

-Respiration

-Converted into insoluble starch for storage

-Producing fat/oil for storage

-Producing cellulose to strengthen cell walls

-Combines with nitrates to form amino acids which produce proteins

Why are nitrate ions from the soil important for growth?

Produce amino acids for photosynthesis

How does the manipulation of potential limiting factors can maximise the rate of photosynthesis in greenhouses?

Change the conditions so nothing is a limiting factor so photosynthesis rate can be maximised

How do features of greenhouses help increase the biomass of crops grown?

Made of glass which traps suns heat and increase temperature to optimum which maximises photosynthesis

Paraffin heater which increases temperature and pumps carbon dioxide in

How might economic factors determine the extent to which manipulating limiting factors in greenhouses may be carried out?

-Expensive to get loads of carbon dioxide in if there is loads of light

-Energy costs