Section 3 - Plant Nutrition and Transport Flashcards
Where does photosynthesis take place? (1)
Chloroplasts
What pigment do chloroplasts contain? (1)
Chlorophyll
What does chlorophyll do? (2)
- Absorbs sunlight
- Uses its energy for photosyenthesis
Word equation for photosynthesis? (2)
carbon dioxide + water —> glucose + oxygen
Symbol equation for photosynthesis? (2)
6CO2 + 6H20 —> C6H12O6 + 6O2
Label the parts {9)
1 - Waxy Cuticle
2 - Upper Epidermis
3 - Palisade
4 - Spongy Mesophyll
5 - Xylem
6 - Phloem
7 - Lower Epidermis
8 - Guard Cells
9 - Stoma
Why are leaves broad? (1)
- Large surface area exposed to light
Where are most chloroplasts found in a leaf and why? (3)
- Palisade layer
- So they are near the top of the leaf
- To get the most light
How is the upper epidermis adapted for efficent photosyenthesis (2)
- It is transparent
- So light can pass through it to the palisade layer
Why do leaves have a network of vascular bundles (4)
- These are the transport vessels xylem and phloem
- They deliver water and other nutriets to every part of the leaf
- They take away the glucose produced by photosyenthesis
- Help to support the leaf structure
What is the role of the waxy cuticle (1)
reduces water loss by evaporation
What are stomata and how do they make gas exchange/photosyenthesis more efficent (2)
- Stomata are little holes
- Let CO2 diffuse directly into the leaf
Name 3 factors affecting a plant’s rate of photosyenthesis (3)
- Light
- Amount of CO2
- Temperature of surrondings
Why does not enough light slow down the rate of photosyenthesis (3)
- Chlorophyll uses light energy to perform photosyenthesis
- It can only do it as quickly as the light energy is arriving
- If light intensity is increased, rate of photosyenthesis will steadily increase, up to a point
Why does too little carbon dioxide slow down photosyenthesis (2)
- Because it is a raw material needed for photosyenthesis
- Increasing conc of CO2 will increase rate of photosyenthesis up to a point
Why does this curve flatten out (2)
- Shows the amount of CO2 is not the limiting factor affecting photosyenthesis
- Limiting factor is temperature or light intensity or both
Describe the graph; how temperature affects rate of photosyenthesis (3)
- As the temperature increases, so does the rate of photosyenthesis, up to a point
- If the tempeature goes above roughly 45 degrees, enzymes will denature
- This means the rate of photosyenthesis rapidly decreases
Describe how to test a leaf for Starch? (5)
- Kill it by dunking it in boiling water (hold with tweezers)
- Put leaf in a boiling tube with ethanol
- Heat the tube in a water bath (gets rid of chlorophyll)
- Rinse the leaf in cold water and add a few drops of iodine
- If starch is present, leaf will go blue-black
Describe an experiement to show chlorophyll is needed for photosyenthesis (5)
- Use a variegated leaf that’s been exposed to light
- Record which parts are green and which aren’t (green parts contain chlorophyll)
- Test the leaf for starch (see other flashcard)
- Only the Green parts will turn blue-black
- Shows only parts that contained chlorophyll could photosyenthesise and produce starch
Describe an experiement to show CO2 is needed for photosyenthesis (5)
- Use a soda lime, sealed bell jar, plant and light source
- Soda lime will absorb CO2 out of the air in the jar
- Leave the plant for a day
- Test leaves for starch, won’t turn blue/black
- Shows no starch has been made in the leaf, means that CO2 is needed for photosyenthesis
Describe an experiement to show light is needed for photosyenthesis (4)
- Grow a plant without any light, e.g in a cupboard
- Cut a leaf and test for starch (see other flashcard)
- The leaf won’t turn blue/black, no starch present
- Shows light is needed for photosyenthesis, as no starch has been made
If a plant can’t photosyenthesise, it can’t produce ….. (1)
Starch
Describe an experiment to measure the effect of light intensity on the rate of photosyenthesis (7)
- Use canadian pondweed
- Faster it produces oxygen, faster the rate of photosyenthesis
- Source of white light is placed 30cm away from the pondweed
- Leave pondweed to photosyenthesise for 2 minutes
- Count no. of bubbles produced
- Control temperature, time
- Repeat with light source, 40cm, 50cm, 60cm and 70cm
If there aren’t enough mineral ions in the soil, plants suffer ………….. …………
deficiency symptoms
Name the 4 mineral ions plants need (4)
- Nitrates
- Phosphates
- Potassium
- Magnesium (small amounts)
Why do plants need nitrates and what happens if there is a deficency (3)
- Nitrates contain nitrogen for making amino acids and protein
- These are needed for cell growth
- If a plant can’t get enough; it will be stunted and will have yellow older leaves
Why do plants need magnesium and what happens if there is a deficency (3)
- Needed in small amounts
- Required for making chlorophyll, needed for photosyenthesis
- Plants without enough magnesium have yellow leaves
Name the two main transport systems in plants (2)
- Xylem
- Phloem
Why do plants and animals need transport systems to move substances around their bodies but unicellular don’t (4)
- Unicellular, substances can diffuse directly in and out across the cell membrane
- Diffusion rate is quick because of the short distances
- Multicellular, direct diffusion is too slow, large distances
- So multicellular need transport systems to move substances quickly
What is the xylem and what does it transport (3)
- Vascular tissue
- Carries water and mineral salts
- From the roots to the leaves in the transpiration stream
What is the phloem and what does it transport (4)
- Vascular tissue
- Transports amino acids, surcrose and other sugars
- From where they are made in the leaves to other parts of the plant
- By translocation
How are root hairs adapted to absorbing water from soil (3)
- Millions of microscropic hairs on each branch of a root
- Gives the plant a big surface area for absorbing water from the soil
- By osmomis
Draw a root hair cell and label it (5)
Outline 2 substances taken in by root hair cells (2)
- Minerals (by active transport)
- Water (by osmosis)
What is transpiration (2)
- Transpiration is the process of water movement through a plant
- Caued by evaporation and diffusion of water from a plant’s surface
Explain how transpiration helps a plant lose/obtain water (6)
- Transpiration is caused by the evaporation and diffusion of water from a plant’s surface
- Most transpiration happens at the leaves
- Water escaping from the leaves through the stomata by diffusion causes a slight shortage of water in the leaf
- More water is drawn up from the rest of the plant through the xylem to replace it
- Means more water is drawn up from the roots
- Constant transpiraton stream of water through the plant
What 4 factors affects the rate of transpiration (4)
- Light intensity
- Temperature
- Wind Speed
- Humidity
How does light intensity affect the rate of transpiration (2)
- Brighter the light, greater the transpiration rate
- Stomata begins to close as it gets darker, meaning very little water can escape
How does temperature affect the rate of transpiration (2)
- The warmer it is, the faster transpiration happens
- When it’s warm, water particles have more energy to evaporate and diffuse out of the stomata
How does wind speed affect the rate of transpiration (3)
- The higher the wind speed, the greater the transpiration rate
- If it’s windy, water vapour is swept away, maintating a low conc of water in the air outside the leaf
- Therefore diffusion happens faster, inreasing the transpiration rate
How does humidity affect the rate of transpiration (4)
- The drier the air around a leaf, the faster transpiration happens
- If the air is humid, diffusion happens slower
- This is because there’s a lot of water in the air, making less of a difference between the inside and outside of a leaf
- Diffusion (and therefore transpiration) happens faster with a high conc in one place, and a low conc in the other
Describe an experiment to measure transpiration (9)
- Use a potometer to estimate transpiration rate
- Cut a shoot underwater to prevent air from entering the xylem
- Cut it at a slant to increase surface area for water uptake
- Insert the shoot underwater, so no air can enter
- Remove apparatus from water, but keep the end of a capillary tube submerged in a beaker of water, watertight and airtight
- Dry the leaves, shut the tap
- Remove the end of the capillary tube from the beaker of water until one air bubble has formed, then put it back into water
- Start a stopwatch and measure distance moved by the bubble per hour
- Keep conditions constant, e.g temperature and humidity
-
Experiement to show how light intensity affects transpiration rate (3)
- Use previous experiment as a control, vary light intensity and compare results
- Use a lamp to increase the intensity of light that hits the plant; this should increase the transpiration rate
- To decrease the light intensity, put the potometer in a cupboard, decreasing transpiration rate
Experiement to show how temperature affects transpiration rate (2)
- Vary temperature by putting the potometer in a room that’s warmer or colder than the control experiement room
- An increase in temperature should increase rate of transpiration, a decrease should lower it.
Experiement to show how humdity affects transpiration rate (3)
- Increase humiditiy of air around the plant
- By spraying water in a clear plastic bag before sealing it around the plant
- Should decrease the rate of transpiration
Experiement to show how wind speed affects transpiration rate (3)
- Use a fan
- Increases wind speed
- Increase the transpiration rate
