Photosynthesis

Why do plants photosynthesize

To grow and survive

Where does photosynthesis take place

In the leaves, chloroplasts.

What does chlorophyll do

Absorbs light

What are the reactants of photosynthesis

Carbon dioxide and water

What powers photosynthesis

sunlight

What is the equation of photosynthesis

Carbon Dioxide + Water→ glucose+oxygen

What is the chemical equation of photosynthesis

What reaction is photosynthesis

Endothermic

Why is photosynthesis endothermic

Because it gets its energy from the sun (light)

How does Carbon dioxide get into the plant

diffuses into the leaves via the stomata

How does water get into the plant

Taken up through the soil by its roots and then transported to the leaves by the xylem

Why does plants use oxygen

For respiration

How can glucose be used for respiration

It breaks glucose molecules to release energy

How can glucose be used for cellulose

Glucose molecules can combine to form cellulose which is used for plants to strengthen their cell wall.

How can glucose be used for starch

Glucose molecules also combine to make starch

Why is starch a better form of glucose for long term storage

Compact=Can fit more
Insoluble= water will not draw into the cell

Why do plants keep a good amount of starch

To turn it into glucose when photosynthesis is not happening as much

How can glucose be used for amino acids

Glucose combines with nitrate ions and make amino acids, where they get protein

Where do nitrate ions come from

soil

How can glucose be used for oils and fats (lipids)

stored as energy sources for the future

What affects the rate of photosynthesis

Light intensity
Temperature
Carbon Dioxide concentration
Amount of Chlorophyll

What happens if a plant has less chlorophyll

The rate of photosynthesis decreases because less light energy is absorbed

Do all plants have the same amount of chlorophyll

No,

Why can chlorophyll levels vary within the same plant

Due to disease, environmental stress and lack of nutrients (eg.water)

How do disease, environmental stress and lack of nutrients affect photosynthesis

Damages the chloroplasts, reducing the amount of chlorophyll

What are the three main limiting factors for photosynthesis

Light intensity
Temperature
Carbon dioxide concentration

On a photosynthesis graph, which variable goes on the x-axis

The limiting factor being investigated (e.g. light intensity)

How does increasing light intensity affect the rate of photosynthesis

The rate increases until another factor becomes limiting

What does it mean when a photosynthesis graph plateaus

The rate has stopped increasing because another factor is limiting

What factors may limit photosynthesis when light is no longer limiting?

Carbon dioxide concentration or temperature

How does carbon dioxide concentration affect photosynthesis

Increasing CO₂ increases the rate of photosynthesis up to a plateau.

Why does the rate of photosynthesis increase as temperature rises (at first)?

Enzymes work faster and molecules move quickly

Why does photosynthesis decrease at high temperatures?

Enzymes become denatured

What happens to photosynthesis at around 45°C?

Enzymes are denatured and the rate of photosynthesis is at 0.

Why do farmers uses greenhouses in the colder climates

To trap heat from the sun and increase the rate of photosynthesis

How does artificial light help plants in greenhouses

Allows photosynthesis to workj day and night

How do farmers increase carbon dioxide levels in greenhouses?

By pumping in carbon dioxide or using parrafin heaters

What does a paraffin heater release

Carbon dioxide and heat

What is another advantage of greenhouses besides increased photosynthesis?

They prevent pests sand insects

Why do farmers use fertilisers in greenhouses?

To ensure plants recieve the necessary nutrients