Chapter 6: Plant nutrition Flashcards
Define ‘photosynthesis’
The process by which plants synthesise carbohydrates from raw materials using energy from light
What is the word equation for photosynthesis?
Carbon dioxide + water → oxygen + glucose
What is the chemical equation for photosynthesis?
6CO2 + 6H2O → C6H12O6 + 6O2
What is the use of sucrose?
Transport in the phloem
What is the use of nectar?
Attracts insects for pollination
What is the importance of nitrate ions for making amino acids?
Primary source of nitrogen for plants, which is essential for amino acid synthesis, through the process of nitrogen assimilation
What is the importance of magnesium ions for making chlorophyll?
Central component of chlorophyll, deficiency leads to reduced chlorophyll production which leads to slower photosynthesis
How do you investigate the importance of chlorophyll in photosynthesis?
Use a variegated leaf, test it with iodine solution and the white parts with no chlorophyll will stay brown, while the green parts will turn blue-black
How do you investigate the importance of light in photosynthesis?
Destarch a leaf, cover part of it with aluminium foil, and put it in sunlight for 24 hours, then test it with iodine solution. The part covered by the foil will stay brown, and the part that was uncovered will turn blue-black
How do you investigate the importance of carbon dioxide in photosynthesis?
Cover 2 destarched plants in airtight plastic bags, place sodium hydroxide into one to absorb carbon dioxide and water into the other, leave them for 24 hours and use iodine solution to test for starch. The plant with carbon dioxide will remain brown, and the plant with water will turn blue-black
How do you investigate the effects of varying light intensity on the rate of photosynthesis?
Attach a paperclip to a piece of aquatic plant and place it in a beaker of water. Place a lamp as close as possible to the beaker and count how many bubbles are released in a minute. Repeat this by moving the lamp further away to compare the rates. As the lamp moves further away, the number of bubble released will decrease
How do you investigate the effects of carbon dioxide concentration on the rate of photosynthesis?
Immerse an aquatic plant in increasingly concentrated sodium hydrogencarbonate solution for 3 minutes and count the number of oxygen bubbles that are released. As the concentration increases, so does the number of bubbles produced
How do you investigate the effects of temperature on the rate of photosynthesis?
Place 5 aquatic plants in 5 beakers on hot plates, and set the temperatures at 0, 10, 20, 30, 40, and 50 degrees Celsius. Count the number of bubbles that are released in 3 minutes. As the temperature increases, so does the number of bubbles released until about 30 degrees, where the number slows down as the temperature gets too high.
Investigate the effect of light and dark conditions on gas exchange in an aquatic plant using hydrogencarbonate indicator solution
Prepare four test tubes with equal volumes of hydrogencarbonate indicator solution.
Label the tubes as follows:
Tube A: Control (no plant)
Tube B: Contains a leaf from the aquatic plant, exposed to light
Tube C: Contains a leaf wrapped in aluminium foil (no light)
Leave the tubes for 30 minutes and observe the results
Describe the effect of light and dark conditions on gas exchange in an aquatic plant using hydrogencarbonate indicator
Tube A (Control): The hydrogencarbonate indicator remains orange/red, no net gas exchange occurs; CO₂ levels are at atmospheric levels.
Tube B (Light Condition): The hydrogencarbonate indicator changes to purple, the rate of photosynthesis exceeds the rate of respiration, resulting in a net uptake of CO₂. The decrease in CO₂ concentration leads to an increase in pH, causing the colour change to purple.
Tube C (Dark Condition): The hydrogencarbonate indicator turns yellow, in the absence of light, photosynthesis does not occur, but respiration continues. This results in an accumulation of CO₂, which lowers the pH and causes the indicator to change colour to yellow.
What are the 3 limiting factors of photosynthesis?
Temperature, carbon dioxide concentration, light intensity
What adapted features do leaves have for photosynthesis?
Have a large surface area: allows large amounts of sunlight to fall onto the leaf, and increases rate at which carbon dioxide can diffuse into the leaf
Thin: allows sunlight to pass right through, allows many cells to photosynthesise, and helps carbon dioxide reach all cells quicker through diffusion
