1.Photosynthesis, Respiration, Movement Of Water and Minerals In Plants Flashcards
4.11 State the equation for photosynthesis in words
- Photosynthesis is the process of turning co2 and water using light energy/Chlorophyll into glucose (fuel)
- This is unique to plants
- Takes place in the Chloroplasts
Carbon dioxide + water + (chlorophyll + light energy) = glucose + oxygen + water
4.11 State the equation for respiration in words
- Opposite of Photosynthesis
- Glucose and oxygen are turned into Co2 and water with the release of energy
- Energy used to create chemical compounds
- Not unique to plants
- Takes place in the Mitochondria
Glucose + oxygen → Carbon dioxide + water + (Energy)
4.12 List the three environmental factors that affect the rate of photosynthesis
- Temperature
- Light (intensity/quality/duration)
- Carbon dioxide
- Water
- Mineral nutrients
4.13 Describe the’Law of Limiting Factors’ in relation to optimising the conditions for photosynthesis
- Correct levels of light, CO2 and temperature are needed
- ‘Law of Limiting Factors’ : states that the factor in least supply will limit the rate of photosynthesis.
- The rate can only be increased by increasing the lowest of these factors, increasing the others will have no effect.
4.13a Describe how the environmental factor temperature can affect the rate of photosynthesis and how growers can optimise the conditions for photosynthesis
- Temperature needs to be adjusted for each plant
- Higher temperatures can inhibit photosynthesis and as low temperatures can
- Different temperatures maybe required for different stage of growth
Grower Optimisation:
- Growing plants under protection in glass houses / poly-tunnels with a heat source
- Insulation/plastic sheeting may be used on a small scale.
- Shading to reduce the solar gain
- Ventilation and damping down to prevent high levels of humidity
4.13b Describe how the environmental factor light can affect the rate of photosynthesis and how growers can optimise the conditions for photosynthesis
- Light energy fuels the reactions tacking place in photosynthesis
- The amount/quality/duration of light energy available is important in determining the rate of photosynthesis
- Generally the more light supplied to the plant, the faster photosynthesis can take place
- Beyond the optimum level the rate of photosynthesis levels off as the chloroplasts are fully engaged. This is called the saturation point and varies from species to species
Grower Optimisation:
- Care must be taken to ensure glass is clean / and condensation is avoided as these would reduce light transmition.
- Lighting can be increased by using artificial light to boost light levels particularly in winter when light is the rate-limiting factor in temperate climates
4.13e Describe how the environmental factor Carbon Dioxide can affect the rate of photosynthesis and how growers can optimise the conditions for photosynthesis
- CO2 level immediately around plants can fall if planting is very dense
- CO2 Level call fall if plants have been photosynthesising very rapidly in an enclosed space such as an unventilated greenhouse
- Once saturation point it reached efficient can not rise
Grower Optimisation:
- Atmosphere in protected environments can be enriched by supplying CO2 at levels above that found naturally in the atmosphere
- Ensure plants are well spaced and not overly crowded
4.21 State the equation for aerobic respiration
- Aerobic respiration is the process by which the products of photosynthesis are broken down in a controlled way
- To release energy for use in the plant
- Respiration takes place in the mitochondria of cells
Aerobic respiration: Glucose+ oxygen → water + carbon dioxide + high yield of energy
4.21 State the equation for anaerobic respiration in words
- Anaerobic respiration takes place in the absence of oxygen
- It is comparatively inefficient
- Takes place in the cytoplasm of the cells
- High levels of ethanol a waste product are produced
- Over time this can prove toxic and cause root death
- Anaerobic conditions can be temporarily advantageous, allows plants to survive periodic water logging
Anaerobic respiration: Glucose → ethanol + carbon dioxide + low yield of energy
4.13f Describe how the environmental factor water can affect the rate of photosynthesis and how growers can optimise the conditions for photosynthesis
- Water is required for photosynthesis reactions
- Needed for Transpiration
- A constant water supply up the xylem to the leaves is needed to maintain leaf tugidity (ie keeping leaf surface area optimised for photosynthesis).
- Similarly constant water supply is needed to keep stomata open thereby enabling CO2 uptake.
- Excessive soil water, known as ‘water-logging’ leads to anerobic conditions around the roots of plants which may cause root tissue to decompose and can lead to death
Grower Optimisation:
- Electronically controlled irrigation systems
- Air humidifying systems
- Watering can and manual pressure sprayer for smaller scale
- Excessive water levels can be mitigated by improving drainage though digging open ditches
- The use of containers to raise plants
4.22 List the two factors that affect the rate of respiration
- Oxygen
- Temperature
- Water
- Mineral nutrients
4.23 Describe how oxygen and temperature affect the rate of respiration
- Oxygen must be present for the complete break down of carbohydrate and to maximise energy release
- The increase in temperature enhances the rate of cellular respiration
- When temperature decreases, in order to conserve energy, cellular processes slow
4.13a Distinguish between diffusion, osmosis and active transport:
Diffusion
- Molecules of a liquid or gas move from an area of high concentration to an area of lower concentration of the diffusing substance
- Equally diffusing the molecules
- Moving along the concentration gradient
Osmosis
- Movement of water from a high water concentration to a lower water concentration across a semi-permeable membrane
- Allows Turgidity
- Moving along the concentration gradient
Active transport
- When these processes happen against the concentration gradient
4.13b Identify examples of diffusion in plants to include transpiration and gaseous exchange
- Movement of water vapour during transpiration
- Movement of carbon dioxide into the leaf during photosynthesis
- Movement of oxygen out of the leaf during photosynthesis
4.32a Describe the pathway of water movement from the soil through the plant into the atmosphere
- Roots: Initially water crosses the epidermis predominantly entering the root hair cells by osmosis
- Endodermis: Water passes through the endodermis and pericycle to the xylem
- Xylem: transports the water and solutes up to the stem and leaves above.
- Leaf: It first enters the mesophyll in the leaf
- Stoma: and is transported into the stoma where it is released into the atmosphere
