Plants Flashcards
Function of waxy cuticle
Water resistant- decreases water loss from evaporation and water glides off
Function of upper epidermis
Thin, protective and transparent to allow free passage of light
Function of palisade layer
Compact cell, layer full of chloroplasts, dense packing allows the maximum amount of light energy absorbed
Function of spongy mesophyll
Gaps allow fast diffusion of gases
Function of the vein
Xylem Carrie’s minerals and water from the roots
Phloem Carrie’s nutrients (sucrose) from the leaves
Function of guard cell
Controls stomata opening and closing
Function of stoma
A gap that allows gases through CO2 and H2O and O2
Stomata control
Water entering the guard cells by osmosis causes the cells to become turgid. This results in the pushing away and there by opening the stoma. In low water conditions, the water in the guard cells leave by osmosis. Guard cells become flaccid and close the stoma.
Requirements for photosynthesis
- the availability of light
- the presence of a pigment to absorb the light
- a supply of carbon dioxide and water
- a temperature suitable for enzyme activity
Why do plants need nitrate
Plants need nitrate to be able to join with glucose to produce amino acids that are then used to form proteins . A shortage of nitrate, the plant will reduce it rate of photosynthesis because it will need fewer sugars to make amino acids. Stunted growth, yellowing leaves, poor seed development
Testing for starch
- Collect leaf samples: A) has been covered with black paper
B) has been left exposed - Dip the leaves in boiling water - kills the cells to stop metabolic activity- soften up the leaf
- Dip the boiled leaves in ethanol- chlorophyll is soluble in ethanol so it leaves the leaf - will look brown
- Dip the leaves in water again
- Add iodine to the leaf
Hypothesis- A) covered leaf: negative ( iodine remains brown)
B) exposed leaf: positive ( iodine turns starch black/ blue)
What is the use of the availability of light
Light provides the energy that drives photosynthesis by splitting water molecules
Light energy absorbed by a plant depends on what
- the intensity of the light source
-v the wavelength of the light - the length of time that the light is available
What is the use of cholorophyll
Chlorophyll is essential for the absorption of light energy. The synthesis of chlorophyll requires magnesium ions, which must be supplied from the soil
What is the use of carbon dioxide
Carbon dioxide concentration has a major influence on the rate of photosynthesis because it is the substrate that is in shortest supply there is almost always enough water
What does temperature affect
Temperature affects the rate of enzyme activity. A 10C rise in temperature can cause a doubling in the rate of enzyme activity, higher temperatures cause denaturation. This is important both on leaves, enzymes involved directly in photosynthesis and in roots involved in active transport of mineral ions
Equation of photosynthesis
6CO2 + 6H2O ——-> 6O2 + C6H12O6
Factors of photosynthesis
- temperature
- light intensity
- CO2 concentration
- surface areas of leaves
- stomatal density
Factor of temperature on photosynthesis
Overall kinetic energy increases so substrates and enzymes meet and react more often. The limit of reaction increase is around 50C since enzymes denature
how to measure the rate of photosynthesis
A) Underwater set up with pondweed
B) Potometer
How do you use the method of underwater set up with pondweed
bubbles/time = rate
volume of O2/ time = rate
how to use the method of potometer
Δd/t = rate
measure how far the bubble moves in given amount of time
why is transpiration rate related to photosynthesis rate
water is needed for photosynthesis which is brought by the transipiration stream. Photosynthesis also needs CO2 which is obtained from stomata. Open stomata causes loss of water vapour which speeds up the transpiration rate
what are the indicator for photosynthesis experiments
- hydrogen carbonate indicator
- lime water indicator
what is the hydrogen carbonate indicator
- normally a pink hue
- in acidic conditions turns yellow
-in more alkali environment it turns violet/ purple
what is the limewater indicator
-normally transparent/ colourless
- with CO2 turns milky white/ opaque
what are the result when the leaf is exposed to light
photosynthesis takes the CO2 thereby reducing acidity
CO2 + H2O —–> carbonic acid
hat are the results when the leaf is in darkness
respiration and no photosynthesis increases CO2 concentration more acidic
all nutrients in plants
carbon
nitrogen
phosphorus
potassium
magnesium
what does the carbon nutrient do
it is used to make glucose into starch and is also used for all organic molecules
what does the nitrogen nutrient do
it is converted in soil into ammonia and then nitrates. Nitrates used to make amino acids and nucleotides for DNA & RNA
what does the phosphorous nutrient do
in phosphate form to make nucleotides
what does the potassium nutrient do
for protein production
what does the magnesium nutrient do
used for chlorophyll production
examples of natural fertilizers
manure and compost
Pros and Cons of natural fertilizers
Pros- sustainable, no harmful chemicals involved
Cons- odor, time needed, nutrient/ mineral component not consistent
Pros and Cons of chemical fertilizers
pros- easily and readily accessible, know exactly how much of each nutrient/ mineral you are adding to you fild/ crop
cons- easy to over use, top layer gets washed away, run off causes algal bloom( eutrification), more expensive
whats good about greenhouses
are transparent to allow light through and light energy is absorbed and released as thermal energy which heats up the greenhouse
hat are paraffin lamps
you install paraffin lamps in greenhouses to release CO2 and increase the concentration beyond atmosphere concentrations
what is the compensation point
when the rate of photosynthesis is equal to the rate of respiration
what should be controlled in greenhouses
intensity- higher intensity leads to more photosynthesis until some other limiting factors intervenes
quality- photosynthesis is most efficient at red and blue wavelengths: white light contains some wavelengths (green) which are not useful
duration- if fruit is desired product, the plant must flower: flowering is controlled by day length (the duration of light in a 24- hour period)
- artificial lighting systems are more controllable
explain why temperature has effect on the rate of photosynthesis
temperature increase leads to an increase of kinetic energy in substrates allowing for them to have successful collisions more often. However, when the temperature increases too much, the enzymes denature causing the plant to die
discuss the advantages of growing crops in glasshouses
- light goes through which plants need + heat gets trapped
- can protect from pests
- can control carbon dioxide concentration (parassin lamps)
- can control temperature regardless of the season (heaters)
- can control water supply and minerals, nutrients
- hydroponides (when you grow plants in water)
Describe how the palisade layer is adapted to maximize photosynthesis
The palisade layer is compact, it has a high chloroplast concentration, it is located near the surface and therefore has access to light and its large central vacuoles, presses chlorplasts on the edge, all of which help maximize photosynthesis
Describe the function of stomata
they are gaps in leafs located next guard cells that allow gases to enter and exit the cell (gas exchange). They open depending on the plants needs and close when in dry conditions to limit water loss and prevent wilting
./explain the effects of nitrate ion deficiency on plant growth
stunted growth, yellowing leaves, reduced seed and production and poor root developement which makes plants susceptible to disease
