Plants Flashcards
What is the equation for photosynthesis?
6CO2 + 6H2O ——> C6H12O6 + 6O2
What type of reaction is photosynthesis?
Endothermic
Name 3 limiting factors on the rate of photosynthesis
- Temperature
- Light intensity
- CO2 concentration
Compare the relationship between the rate of photosynthesis and light intensity
They are directly proportional
Compare the relationship between the rate of photosynthesis and distance away from light
They are inversely proportional
Photosynthetic organisms are the main producers of ____ and therefore _______
Food, biomass
Name 3 ways a plant is adapted to maximise photosynthesis
- Large surface area to maximise light absorption
- Thin for gases to reach cells easily
- Have stomata for gas exchange
What are xerophytes?
Plants adapted to live in extreme environments
Describe some adaptations of a xerophyte
Cacti:
- Have spines with small surface area and very thick waxy cuticle to reduce water loss
- Less stomata to reduce water loss by transpiration
- Spines also for protection
What is the waxy cuticle?
Waterproof layer of the plant
What is the epidermis?
The protective layer of the plant
What is the palisade layer of a plant?
Where light is absorbed
What is the spongy mesophyll for?
Taking in CO2 and releasing oxygen
What are stomata and guard cells for?
For allowing gas exchange and controlling water loss
Explain how the stomata open and close
- Guard cells take in water by osmosis and become turgid, causing the stoma to open
- When it is dark guard cells lose water and become flaccid, closing the stoma
The light intensity 20cm from a lamp is 600 lux, calculate the the light intensity 40cm away using inverse square law
Calculate how much further away the distance is
40/20 = 2 Therefore x2 further away
Then find the inverse of that and square it
2-1 = 1/2
(1/2)2 = 1/4
Lastly, multiply by the original amount
600 x 1/4 = 150 lux
Describe the effect of light intensity on the rate of photosynthesis
As the light intensity increases, the rate if photosynthesis increases this happens until a limiting factor causes the rate to stop increasing
Describe the effect of rate of CO2 concentration on the rate of photosynthesis
As the CO2 concentration increases, the rate if photosynthesis increases this happens until a limiting factor causes the rate to stop increasing
Describe the effect of temperature on the rate of photosynthesis
As the temperature increases, the rate if photosynthesis increases, this will happen until the optimum temperature is reached and the enzymes involved will denature
How are root hair cells adapted to better absorb water and mineral ions?
- Has a large surface area to increase rate of absorption
- Has lots of mitochondria to gain more energy through aerobic respiration for active transport in translocation
What is transpiration?
Movement of water and minerals up the xylem vessel
What is translocation?
Movements of dissolved sugars up and down the phloem
What happens in transpiration?
- Water in the soil passes into the root hair cells by osmosis
- The water then passes into the xylem vessel by osmosis
- The water is transported to the leaves
- The water evaporates through the stoma
What are the factors that affect the rate of transpiration?
- Temperature
- Humidity
- Wind speed
- Light intensity
