Photosynthesis Flashcards
What is the chemical energy in sugar available for?
Respiration or the sugar can be converted into other substances, such as starch (storage) and cellulose (structural)
What are limiting factors of photosynthesis?
Carbon dioxide concentration
Light intensity
Temperature
What is photosynthesis?
A series of enzyme controlled reactions that builds up glucose from carbon dioxide and water
What four things are needed for photosynthesis?
Energy from sun
Carbon dioxide absorbed from air
Water absorbed from soil
Chlorophyll in leaves
Where does photosynthesis take place?
In plant cells, inside tiny structures called chloroplasts which are found inside leaf cells
How are tissues that build leaf cells formed?
Plant cells are stacked together.
What do chloroplasts contain?
Chlorophyll
Where in the chloroplast does light reactions take place?
The granum
Where in the chloroplast does carbon fixation take place?
The stroma
Describe the five steps of light reaction
Light energy is captured by chlorophyll
Light energy is converted to chemical energy, which is carried by ATP
Light energy is used to split water into hydrogen and oxygen (photolysis)
ATP and hydrogen pass to the second stage of photosynthesis and are used to make glucose
Oxygen diffuses out of the cell
Describe the two steps of carbon fixation
Carbon dioxide from the air is combined with hydrogen, using energy carried by ATP
The glucose molecule is produced
Why is carbon fixation temperature dependent?
It’s enzyme controlled
How does CO2 reach the chloroplasts?
By diffusion through tiny holes on the underside of leaves
It then diffuses from cell to cell inside the leaf
What are the holes on the underside of leaves called?
Stomata
How does oxygen move through a leaf?
Diffusion, exiting through stomata
What is ATP?
An energy transport molecule
How does water reach the chloroplasts?
Water enters the root from the soil and moves between cells to cross the root
It travels to tubes in the stem called xylem to reach the leaves
It then moves across the leaf to reach the chloroplasts in the leaf cells
What changes ADP into ATP?
Light energy
What is light energy changed into?
Chemical energy
What is the purpose of a control in an experiment?
Controls allow the experimenter to minimize the effects of factors other than the one being tested.
What are the three fates of products of photosynthesis?
Respiration
Storage
Structural
What can sugar be immediately used up in?
Respiration
What does starch act as?
An energy store- it stores sugar for use in respiration later
What can the products of photosynthesis be converted into?
All the chemicals that a plant needs
What do plants use cellulose to do?
Build cell walls
What is osmosis?
The movement of water from regions of high concentrations to regions of low concentrations
Why is starch a good storage molecule?
It’s insoluble so there are no osmotic effects
What can sugar be converted into?
Starch and cellulose
When do plants grow best?
There is enough light
There is enough carbon dioxide
There is an ideal temperature
Why do plants need light?
Light reaction
Why do plants need carbon dioxide?
Carbon fixation
Why do plants need an ideal temperature?
So it’s not too hot or cold, for enzymes involved in carbon fixation so they don’t denature
