Plant Nutrition Flashcards
What are the word and symbol equations for photosynthesis?
- carbon dioxide + water –> glucose + oxygen
* 6CO₂ + 6H₂O –> C₆H₁₂O₆ + 6O₂
What things, in addition to the elements in the equations, are required for photosynthesis?
- Sunlight
* Chlorophyll
What absorbs light energy and where is it found?
Chlorophyll absorbs light energy, and is found in the chloroplasts of plant cells.
What is glucose in plants stored as and why?
- Glucose as stored as starch (a large molecule made of thousands of glucose molecules).
- Starch is insoluble, which means that it does not have an osmotic effect on the plant.
- Starch is also a large molecule and more compact so it takes up less space in the plant than glucose.
What substance tests the production of starch? What colour change will occur?
Iodine solution will go from brown to blue/black.
What are the stages of testing with iodine solution?
- Put the leaf in boiling water to kill it and prevent any further chemical reactions.
- Put the leaf in a boiling tube with ethanol and heat it in a water bath to remove any chlorophyll.
- Rinse the leaf in cold water and add iodine solution to test for the production of starch.
How to test for requirement of light for photosynthesis:
Cover a part of the leaf with foil/card - no starch should be produced in this area so it will remain brown when tested with iodine.
How to test for requirement of chlorophyll for photosynthesis:
Use variegated leaves which have no chlorophyll in the white areas - no starch should be produced in these areas and so they will remain brown when tested with iodine.
How to test for production of oxygen for photosynthesis:
Use a water plant such as Elodea - as photosynthesis takes place bubbles of gas become visible, which can be collected in a test tube (with a scale) and tested for oxygen by using a glowing splint.
How to test for requirement of carbon dioxide for photosynthesis:
By using soda lime to trap the carbon dioxide from the air, it is no longer available for photosynthesis - leaves cultured in the presence of soda lime should not turn blue/black when tested with iodine.
What does the waxy cuticle do?
It is waterproof, prevents water loss.
What does the upper epidermis do?
Protection for the leaf, lets light through for photosynthesis.
What do the palisade cells do?
They are tightly packed and have lots of chloroplasts, therefore there is a high rate of photosynthesis.
What do the spongy cells do?
They are loosely packed, have some chloroplasts and there is some photosynthesis.
What do the air spaces do?
Provide air channels through the lead for gas exchange.
What does the phloem do?
Carries dissolved sugar (sucrose) to the rest of the plant.
What does the xylem do?
Carries water and minerals from roots to leaf.
What do the guard cells do?
Control the opening and closing of the stomata.
What does the stoma(-ta) do?
- Controls gas exchange (carbon dioxide in, oxygen out).
* Controls transpiration (water out).
What is the use and what are the elements for glucose?
- Substrate for respiration.
* C, H, O.
What is the use and what are the elements for sucrose?
- Main sugar carried in phloem, also in nectar.
* C, H, O.
What is the use and what are the elements for starch?
- Storage carbohydrate.
* C, H, O.
What is the use and what are the elements for lipids?
- Components of cell membranes.
- Long-term energy store (seeds).
- C, H, O.
What is the use and what are the elements for cellulose?
- Component of cell walls.
* C, H, O.
What is the use and what are the elements for amino acids?
- Components of proteins.
* C, H, O, N.
What is the use and what are the elements for nucleotides?
- Components of DNA.
* C, H, O, N, P.
What is the use and what are the elements for chlorophyll?
- Absorption of light in photosynthesis.
* C, H, O, Mg.
What will happen to a plant lacking in nitrogen?
- Nitrogen is needed to make amino acids, proteins, ATP and DNA.
- The plant will have stunted growth and slightly yellow leaves.
What will happen to a plant lacking in magnesium?
- Magnesium is needed to make chlorophyll.
* The plant will have yellow leaves.
What will happen to a plant lacking in phosphorus?
- Phosphorus is needed to make ATP and DNA.
* The plant will have sounded growth and a purple tinge.
What do farmers do to increase plant growth and crop yield?
Farmers use fertiliser/manure which contains:
• Nitrate –> nitrogen.
• Phosphate –> phosphorus.
• Some magnesium.
What is the function of the petal?
Large and powerful to attract pollinators.
What is the function of the anther?
Contains pollen grains.
What is the function of the ovule?
Will become seeds when it is fertilised.
What is the function of the filament?
Hold the anthers in place.
What is the function of the ovary?
Where the ovules are.
What is the function of the receptacle?
Hold in place the main parts of the flower.
What is the function of the stigma?
A sticky surface for pollen to land on.
What is the function of the sepal?
Protected the flower when it was in bud.
What is the function of the style?
Provides a path from the stigma to the ovary for the pollen.
What is pollination?
The transfer of pollen from the anther to the stigma.
What is insect pollination?
Pollination by insects.
What is wind pollination?
Pollination by wind.
What is self pollination?
Pollination from flower onto flower on same plant.
What is cross pollination?
Pollination from flower onto flower on different plant.
How do the petals differ in a wind versus insect pollinated flower?
- Insect pollinated - usually large and brightly coloured.
* Wind pollinated - small and green.
How does the stamen differ in a wind versus insect pollinated flower?
- Insect pollinated - held within the flower.
* Wind pollinated - dangles out of the flower.
How does the scent differ in a wind versus insect pollinated flower?
- Insect pollinated - scent is present to attract pollinators.
- Wind pollinated - no scent present.
How do the anthers differ in a wind versus insect pollinated flower?
- Insect pollinated - positioned within the flower.
* Wind pollinated - held outside the flower so wind blows pollen away.
How do the flowers differ in a wind versus insect pollinated flower?
- Insect pollinated - in any position on plant.
* Wind pollinated - close to the top of the plant so pollen can be blown off.
How does the stigma differ in a wind versus insect pollinated flower?
- Insect pollinated - usually solid shape with 3-5 lobes.
* Wind pollinated - feathery to catch as much pollen as possible.
How does the pollen differ in a wind versus insect pollinated flower?
- Insect pollinated - small amount (as it is easily transferred to animal) and sticky.
- Wind pollinated - large amount (as much is lost in the wind) and light.
What is fertilisation?
The fusion of male and female gametes.
What happens during fertilisation of plants?
- The pollen grain lands on the stigma.
- The pollen grain develops a pollen tube which grows down the style and makes its way towards the ovary.
- The nucleus of the pollen grain travels down the pollen tube.
- The pollen nucleus reaches the ovary and fuses with the nucleus of the ovule.
- The fertilised ovule develops into seeds containing the plant embryos.
What happens to the ovary wall?
It sometimes develops into a fleshy fruit (e.g. tomato) or a hard covering (e.g. coconut) which surrounds the seeds.
What’s the role of the seed?
Embryo and food store.
What’s the role of the fruit?
Fruit helps with seed disposal (e.g. fruit is eaten by animals).
Why do the seeds need to be dispersed?
The new plants then have enough space, light and water.
What are the different seed dispersal by animal types?
- Hitch hikers - hooks which catch onto animal coats (e.g. cleavers).
- Take-aways - seeds get carried away and buried (e.g. nuts).
- Juicy fruits - get eaten and excreted (e.g. berries).
What are the different seed dispersal by wind types?
- Helicopters - wings hep seed fly away (e.g. sycamore).
* Parachutes - catch the wind (e.g. dandelion).
What is the seed dispersal by water type?
• Boats - light and waterproof (e.g. coconuts).
What are the different seed dispersal by the plant itself types?
- Pepperpods - shaken by wind so seeds fall out (e.g. poppy seeds).
- Exploders - pods dry and flick seeds out (e.g. bean pods).
What is germination?
The development of a plant from a dormant seed.
What happens during germination?
- Seed takes in water.
- Food store breaks down and is used for growth.
- First root and first leaves appear.
- Seedling starts to grow.
What conditions are necessary for germination?
• Water - rehydrates the seed.
• Temperature - allows enzymes to work better (the enzymes break down food store and are involved in respiration.
• Oxygen - allows respiration to occur (energy for growth).
(• light)
Why are there these conditions for germination?
When the food store is broken down and starch is converted into glucose - energy is released for plant growth, which is done through respiration.
What happens in a leaf when it is destarched?
- There is no starch in the leaf.
- One makes the leaf use up all the starch, by putting it in darkness - all the starch turns into glucose and is used up for respiration.
How does one remove the green pigment in leaf cells safely?
- Put it in boiling water for 30 seconds.
- Make sure there are no naked flames.
- Boil the ethanol in a water bath.
What happens to the stomata in the morning when the leaf is exposed to bright light.
The stomata open as they can then let oxygen out and carbon dioxide in so gas exchange can be done efficiently (function of stomata is gas exchange) - bright light in the morning is a good environment for photosynthesis.
What factors affect the rate of photosynthesis?
• Carbon dioxide concentration. • Water availability. • Light availability. • Temperature. =limiting factors
What happens to a plant when the temperature is increased?
- At first the rate of photosynthesis increases because there is more kinetic energy and therefore more substrate collisions.
- When the temperature gets too high (above around 40ºC) the rate of photosynthesis drops because the enzymes involved denature.
How can one tell from a picture of a lily whether a flower pollinates itself or not?
If the anther and stigma are not near each other - the plant will not self-pollinate.
What is are advantage and disadvantage of self-pollination compared with cross-pollination.
- Advantage - no vector needed, good chance of pollination.
* Disadvantage - less variation.
What stimulus makes the stem and leaves of a plant grow upwards?
Light.
What happens during the uptake of water into the roots?
- Water is taken up into root hair cells by osmosis.
- Minerals are taken up into root hair cells by active transport.
- Root hair cells have got many mitochondria to provide the energy for this.
- Water and ions then diffuse from root hair cells to the xylem vessels.
What happens during the transport of water by the xylem?
- Water rises from the roots to the leaves through the xylem vessels through capillary action.
- Water is drawn up through suction pressure.
What happens during the evaporation of water from the leaves?
- Water molecules leave xylem and enter leaf.
- Water molecules diffuse through spongy cell layer into air spaces.
- Water evaporates through stomata into surrounding air.
- Some water does not evaporate and is used for photosynthesis.
What is transpiration?
The evaporation of water through the stomata.
Advantages and disadvantages of transpiration.
- Advantage - drives water transport to leaves for photosythesis.
- Disadvantage - water loss.
What is the transpiration stream?
Uninterrupted stream of water which is taken up by the roots, transported via xylem to leaves, where it will evaporate.
How is transpiration controlled by the stomata?
- The stoma open when water moves into guard cell vacuoles by osmosis - if the plant senses an increase in levels of light/temperature/CO₂, it will send water to make guard cells turgid (filled with water) and open stomata.
- If the guard cells are flaccid (not filled with water), the stoma will be closed.
What is the principle of transpiration?
+ allow photosynthesis
- prevent water loss
How will an increase in light intensity affect transpiration?
Transpiration will increase, as more photosynthesis means that the stomata need to stay open.
What collective name is given to the male and female parts of a flower?
- Male - stamen (anther and filament).
* Female - carpel (stigma, style, ovary and ovule).
How will an increase in temperature affect transpiration?
Transpiration will increase, as evaporation increases - the stomata will stay closed if it’s too hot.
How will an increase in humidity affect transpiration?
Transpiration will decrease, as the concentration gradient is lower, less evaporation - stomata will open.
How will an increase in wind speed affect transpiration?
Transpiration will increase, as there is faster air movement which removes the water vapour - stomata will close.
How do plants prevent too much water loss?
- Closing of stomata.
- Waxy cuticle.
- Stomata only open on the bottom of the leaf (bottom side is cooler - less evaporation).
- Wilting - less water is sucked up.
How can transpiration be measured and what are the steps?
- Potometer.
- Set up a potometer with a freshly cut shoot in the open end of a tube.
- Seal two rubber bungs of either side of the tube with vaseline to prevent evaporation from the potometer.
- Water will move up the plant and evaporate via the stomata - air bubbles will move along the scale.
- The scale gives a measure of water absorbed by the plant over time - transpiration rate.
What is the name of the response of a plant to light?
Phototropism
What is the name of the response of a plant to gravity?
Geotropism
What is the name of the response of a plant to water?
Hydrotropism
What is the name of the response of a plant to touch?
Thigmotropism
How do the shoots and roots respond to light?
- Shoots grow away from the direction of gravity (positive phototropism).
- Roots mostly do not respond or grow away from light (negative phototropism).
How do the shoots and roots respond to gravity?
- Shoots grow away from gravity (positive geotropism).
* Roots grow towards direction of gravity (negative geotropism).
What is auxin and how does it control tropism?
- Auxin is a hormone in plants which is responsible for tropism.
- Produced in the tip of the shoot.
- Diffuses from the tip to the shoot.
- Destroyed by light.
- Accumulates on the shady side and causes cell elongation and the shoot bends towards the light.
What can be used to detect gravity as a stimulus for tropism?
Clinostat.
Why do people only show symptoms of hay fever at certain times of the year?
- Flowers appear/reproduce at different times.
* Flowers release pollen at different times.
How is the excretory product of photosynthesis removed from the leaf?
Oxygen diffuses across a concentration gradient out of the stomata.
Why do some plants lose their leaves in cooler months?
- To reduce water loss.
- There is less photosynthesis.
- To conserve energy.
- There is too little light.
What are the events which follow pollination and lead to seed formation?
- Pollen tube forms and the pollen grain grows down the style.
- The pollen grain enters the ovule.
- The pollen grain nucleus fuses with a female gamete (ovum).
- The ovule becomes a seed.
- The ovary wall forms the seed coat.
- The ovary forms a fruit.
What factors affect the rate of water loss on a leaf?
- Humidity.
- Light.
- Surface area / size of leaf.
- Thickness of leaf.
- The number of stomata on a leaf.
- The size of the stomata on a leaf.
- Wind.
- Light intensity.
- Temperature.
What are the disadvantages of a plant closing its stomata?
- Less carbon dioxide for photosynthesis.
- Less glucose/starch (from photosynthesis).
- Less cooling (transport of water/mineral ions).
What are the conditions to successfully grow large numbers of algae (microorganisms that can carry out photosynthesis).
- Sunlight.
- Carbon dioxide.
- Warm temperature for enzymes.
- Magnesium for chlorophyll.
- Nitrates for amino acids.
- Many other minerals/salts (e.g. phosphates).
What are the different colours that hydrogen-carbonate can be?
- Normal levels of carbon dioxide - orange.
- Increased levels of carbon dioxide - yellow.
- Decreased levels of carbon dioxide - purple.
Are there more stomata on the top or the bottom of a leaf?
Plants in general have fewer stomata on the top of their leaf - to reduce water loss by evaporation.
