6 - Plants Flashcards
1
Q
What is photosynthesis?
A
- The process by which plants make their own food from raw materials, using energy from light
- Biomass will increase as a result
2
Q
Why is photosynthesis described as an endothermic reaction?
A
Energy is taken in from the surroundings in the form of light
3
Q
What is the equation for photosynthesis?
A
- Carbon Dioxide + Water = Glucose + Oxygen
- 6CO2 + 6H2O = C6H12O6 + 6O2
4
Q
How does temperature affect the rate of photosynthesis?
A
- Affects the enzymes
- If temp is too low it becomes the limiting factor - enzymes work slower at lower temps
- Enzymes denatured if too hot (around 45c)
5
Q
How does light affect the rate of photosynthesis?
A
- Light transfers energy needed for photosynthesis
- If the light level is raised, the rate increases until a certain point
- Beyond that the CO2 and temperature become the limiting factors
6
Q
How does carbon dioxide affect the rate of photosynthesis?
A
- CO2 is one of the raw materials needed for photosynthesis
- Increasing the CO2 concentration increases the rate until a certain point
- Beyond that, temperature and light become the limiting factors
7
Q
How is the structure of root hair cells adapted to absorb water and mineral ions?
A
- The cells in a plant grow into hairs which stick out into the soil
- This gives the plant a larger surface area to help absorb mineral ions and water from the soil
- Minerals are absorbed by active transport, water is absorbed by osmosis
8
Q
What is the function of the Phloem?
A
- To transport food (mainly sucrose) made in the leaves to the rest of the plant for use or storage
- Transport goes in both directions (up and down plant)
- Phloem tubes are made of columns of cells with small pores in the walls
9
Q
What is the function of the Xylem?
A
- To transport water and mineral ions from the roots to the stem and leaves
- This stream is called the transpiration stream
- Xylem tubes are made of dead cells joined together with a hole down the middle
10
Q
What is transpiration?
A
- The loss of water through a plant
- Caused by the evaporation and diffusion of water from a plant’s surface
- Mostly happens at the leaves
11
Q
What happens during transpiration?
A
- The loss of water creates a shortage of water in the leaf, so more water is drawn up to replace it
- This means more water is drawn up from the roots, causing a constant transpiration stream
- The stream also carries mineral ions dissolved in the water
12
Q
What is the structure of the stomata?
A
- They are tiny pores on the surface of a plant
- Mostly found on lower surface of leaves
13
Q
What is the function of the stomata?
A
- To allow CO2 and Oxygen to diffuse directly in and out of a leaf and allow water vapour to escape during transpiration
14
Q
What is the function of guard cells in the stomata?
A
- They surround the stomata and can change shape to control the size of the pore
- When they are turgid (swollen with water) the stomata is open
- When they are flaccid (low on water) the stomata is closed
15
Q
What affects the rate of transpiration?
A
- Light
- Air flow (wind)
- Temperature
- Humidity
