Unit 3: Plant Nutrition and Transport Flashcards
What is photosynthesis
Photosynthesis is the process of converting carbon dioxide and water into glucose and oxygen using sunlight
What is the word equation for photosynthesis
Carbon dioxide + Water —> Glucose + oxygen
Write the chemical equation for photosynthesis
6CO2 + 6H2O —> C6H12O6 + 6O2
Name all the oeganelles found in a plant cell
- Waxy cuticle
- upper epidermis
- palisade mesophyll layer
- spongy mesophyll layer
- vascular bundle
- lowe epidermis
- air space
- guard cells
- stoma
How are leaves adapted for Efficient photosynthesis
- Leaves are broad so they have a large surface area to absorb more light
- Most of the chloroplast is found in the palisade layer which is at the top, meaning they can absorb the most light
- The upper epidermis is transparent so that light can pass through it to the palisade layer
- Leaves have a xylem and phloem to deliver water and other nutrients to every part of the leaf and take away glucose produced by photosynthesis, they also help to support the leaf structure
- The waxy cuticle helps to reduce water loss by evaporation
- The lower surface contains stomata that lets CO2 diffuse directly into the leaf
What three things affect the rate of photosynthesis
- Light
- CO2
- Temperature
Describe an experiment to test a leaf for starch
- Dunk the leaf in boiling water (hold it with tweezers or forceps). This will denature the enzymes and stop any chemical reactions from happening inside the leaf
- Put the leaf in a boiling tube with some ethanol and heat it in an electric water bath until it boils, this will get rid of any chlorophyll and make the leaf a white-ish colour
- Rinse the leaf in cold water and add a few drops of iodine solution, if starch is present the leaf will turn blue black
What does the iodine in a starch test turning blue-black indicate
- If the iodine is blue-black then the leaf can photosynthesize
- If the iodine doesn’t change colour then the leaf can’t photosynthesize
What is the function of nitrogens in plants and what does a plant look like when it lacks nitrogen
- Nitrogen makes amino acids and proteins which are needed for cell growth
- If a plant lacks nitrogen the plant becomes stunted and the older leaves will turn yellow
What is the function of phosphates in plants and what does a plant look like when it lacks phosphate
- Phosphate makes DNA and cell membranes, they are also needed for respiration and growth
- Lack of phosphate have poor root growth and their older leaves turn purple
What is the function of potassium in plants and what does a plant look like when it lacks potassium
- Potassium helps the enzymes needed for photosynthesis and respiration
- Lack of potassium causes poor fruit growth and discoloured leaves
What are the two main transport systems in plants and what do they each transport
- Xylem: Carries water and mineral salts from the roots up the shoot to the leaves in the transpiration stream
- Phloem: Transports sugars like sucrose and amino acids from where they were made in the leaves to other parts of the plant
translocation: The movement of food substances across a plant
How are root hair cells adapted to take in water
- They have a large surface area to absorb water
- They have a lower concentration of water than the soil, allowing water to enter the root hair cells by osmosis
What is transpiration
The loss of water from a plant
How is transpiration caused
Transpiration is caused by the evaporation and diffusion of water from a plants surface
Where does transpiration occure most frequently
At the leaves
What do plants do to overcome transpiration
- The slight shortage of water due to transpiration causes more water to be drawn up through the xylem vessels to replace it
- This in turn causes more water to be drawn from the roots
This process isn known as a transpiration stream
What are the four main factors that affect transpiration rate
- Light intensity
- Temperature
- Wind speed
- Humidity
How does light intensity affect transpiration rate
- The brighter the light, the greater the transpiration rates
- When it is dark the stomata begins to close because photosynthesis cannot occure in the dark and the plant therefore doesn’t need CO2
- This causes less water to escape the closed stomata
How does temperature affect transpiration rate
- The warmer it is, the greater the rate of transpiration
- This is because water can evaporate faster
How does wind speed affect transpiration rate
- The greater the wind speed the greater the transpiration rate
- This is because when its more windy the water vapour is swept away, maintaining low concentration of water in the air outside the leaf
- This causes diffusion in the leaf to occure faster
How does humidity affect transpiration rate
- The drier the air around a leaf, the faster transpiration occurs
- This is because the drier the area the lower the concentration of water around the plant is
- This causes diffusion to happen faster
Describe an investigation to estimate transpiration rate
- A potometer would be used to estimate transpiration
- Cut a shoot underwater to prevent air from entering the xylem
- Assemble the potomenter in water aand insert the shoot under water so no air can enter
- Remove the apparatus from the water but keep the end of the capillary tube submerged into a beaker of water
- Check the apparatus is watertight and not airtight
- Dry the leaves, allow time for the shoot to acclimatise and then shut the tap
- Remove the end of the capillary tube from the beaker of water until one air bubble has formed, then put the end of the tube back into the water
- Record the starting position of the air bubble
- Start a stopwatch and record the distance moved by the bubble per unit time
- Keep the conditions constant thoughout the experiment
Cut the shoot in a slant to increase surface area
