Topic 6 - Plants Flashcards
What is the equation for photosynthesis?
Carbon dioxide + water —> glucose + oxygen
What does photosynthesis require?
Sunlight
Where does photosynthesis occur?
Chloroplasts
What is glucose used for?
1) Stored as starch
2) Used for respiration
3) Converted into cellulose
4) Used to make protein
What are photosynthetic organisms the main producers of?
Food and therefore biomass.
What type of reaction is photosynthesis?
Endothermic
Requires energy for it to occur.
What are limiting factors?
Definition
When a process depends on 2 or more factors, the rate of that process is limited by the factor which is in shortest supply.
What limiting factors is photosynthesis affected by?
• Light intensity
• Temperature
• Availability of carbon dioxide
• Availability of chlorophyll
• Availability of water
What are the interactions of limiting factors in limiting the rate of photosynthesis?
As a factor increases so will the rate of photosynthesis until it has no effect as the rate of photosynthesis is limited by availability of another factor.
What is the distance from the lamp and light intensity known as?
They are inversely proportional to each other - this means as the distance increases, the light intensity decreases.
What is the inverse square law?
Definition
Light intensity decreases in proportion to the square of the distance.
What is the equation for inverse square law?
1/ distance squared
If you halve the distance, the light intensity will be 4 times greater. If you double the distance the light intensity will be 4 times smaller.
What is the role of the root hair cell?
To absorb water and mineral ions.
Mineral ions are absorbed by active transport. Water is absorbed by osmosis.
What are features of root hair cells?
• Long projections that increases the surface area that the plant can use to absorb water an minerals.
• No chloroplasts because they are located underground.
What is transpiration?
The movement of water and mineral ions into the root, up the stem through the xylem vessels and evaporating out of the leaf. This is done by capillary action
What is the function of the stomata?
Controls water lost by transpiration
Controls gas exchange in the leaf
What is the structure of the stomata?
Surrounded by 2 guard cells. They control the opening and closing by filling with or loosing water.
Most stomata are underneath the leaf to limit evaporation.
What does the phloem transport and what’s the method called?
Sucrose
Translocation = Sugars distributed to all cells in the body of the plant.
What is the structure of the phloem?
Living
Not hollow
Sieve cells
Transports in both directions
Transports by active transport
Companion cells - filled with mitochondria to pump out sucrose.
What does the xylem transport?
Water and minerals
What is the structure of the xylem?
Dead
Hollow
Only one direction
Cell walls are strengthened with lignin
No end cells (continuous column)
Transports by osmosis
From roots to leaves
Moves the water by capillary action
Why is transpiration important?
Cools the plant
Pumping water and minerals to the leaves for photosynthesis.
What kind of factors will affect transpiration?
Any factor that reduces the number of water molecules outside the stomata to increase the gradient will affect the rate of transpiration.
What are the 4 factors affecting rate of transpiration?
1) Light - increase
2) Temperature - increase
3) Humidity - decrease
4) Wind - increase
