Plant Nutrition Flashcards
(11 cards)
Function of chloroplasts
Contain green pigment called chlorophyll which absorbs sunlight and uses energy to convert carbon dioxide and water into glucose. Oxygen also produced.
How are leaves adapted for efficient photosynthesis? (6 reasons)
- broad —-> large surface area exposed to light
- most chloroplasts in palisade layer —> near top of leaf (most light)
- transparent upper epidermis (light can pass through to palisade layer)
- have vascular bundles which deliver water and nutrients to every part of leave and remove glucose - also help support structure
- waxy cuticle - helps reduce water loss by evaporation
- stomata allow CO2 to diffuse directly into leaf
Why are nitrates required for plant growth?
- contain nitrogen for making amino acids and protein
- needed for cell growth
- lack = stunted and yellow older leaves
Why are phosphates required for plant growth?
- contain phosphorus for making DNA and cell membranes
- needed for respiration and growth
- lack = poor root growth and yellow older leaves
Why is potassium needed for plant growth?
- helps enzymes needed for photosynthesis and respiration
- lack = poor flower and root growth / discoloured leaves
Why is magnesium required (in small amounts) for plant growth?
- making chlorophyll for photosynthesis
- lack = yellow leaves
Experiment for rate of photosynthesis
- place source of white light at specific distance from pondweed and repeat experiment with different distances
- leave to photosynthesize for SET AMOUNT OF TIME and oxygen released collects in capillary tube
- at end, use syringe to draw gas bubble in tube alongside a ruler and measure length of bubble (proportional to O2 produced)
- control temp and time
Alterations for temp and CO2:
- put test tube in beaker of water and set temp, bubble CO2 through, repeat with different water temp/ CO2 concentrations
Test for starch
- boil leaf (stops chemical reactions happening-kills leaf)
- put in boiling tube with ethanol and put tube in heated water bath (removes chlorophyll- should be left pale / white)
KEEP ETHANOL AWAY FROM BUNSEN - rinse leaf in cold water (removes ethanol)
- put on Petri dish and add few drops of iodine (if present - blue/black)
Experiment to show chlorophyll requirement
- use variegated leaves (only green contains chlorophyll)
- take leaf from plant briefly exposed to light (record green and white areas)
- test leaf for starch (only green bits blue/ black)
Experiment for CO2 requirement
- plant in jar with light source and soda lime in Petri Dish
- soda like absorbs CO2 out of air
- leave plant in jar then test leaf for starch (won’t turn blue / black)
- shows no starch made in leaf (meaning CO2 needed for photosynthesis)
Experiment to show requirement of light
- grow plant in dark cupboard
- cut leaf from plant –> test for starch (leaf won’t turn blue/ black)
- no starch made (shows light needed)
