Biology Topic 6 Plants Flashcards
upper epidermis adaptions and how this feature helps the leaf
- waxy cuticle- reduces water loss
- No chloroplasts/transparent - lets lots of light through to palisade mesophyll
palisade mesophyl adaptions and how this feature helps the leaf
- lots of chloroplasts- absorbs light and carry’s out photosynthesis
spongy mesophyl adaptions and how this feature helps the leaf
- Air spaces- speeds up gas exchange
- xylem tissue- supplies water and minerals to the leaf
- phloem tissue- Supplies dissolved sugars to the leaf
lower epidermis adaptions and how this feature helps the leaf
- guard cells-can shut stomata to reduce water loss
- Stomata allows co2 to diffuse
xylem tissue adaptions and how this feature helps the leaf
- No end wall- allows water and mineral ions to flow from cell to cell
- Lignin in cell wall- strengthens the cell wall
- Dead and hollow cell- allows water to flow through cell easily
phloem tissue adaptions and how this feature helps the leaf
- very little cytoplasm-allows dissolved sugars to flow through cell easily
- Pores(holes) in end walls-Allows dissolved sugars to flow from one cell to another
photosynthesis equation
carbon dioxide + water →light above arrow glucose + oxygen
The glucose produced in photosynthesis may be:
used for respiration
converted into insoluble starch for storage
used to produce fat or oil for storage
used to produce cellulose, which strengthens the cell wall
used to produce amino acids for protein synthesis. To produce proteins, plants also use nitrate ions that are absorbed from the soil.
Describe photosynthesis
an endothermic reaction in which energy is transferred from the environment to the chloroplasts by light.
vascular bundle is
the xylem and phloem
CO2, H2O, O2
C6H12O6 .
carbon dioxide
hydrogen
oxygen
glucose
food tests to identify sugars
Method
Take a sample of the food/biological material to be tested and grind up
Then..
Dissolve the ground up food in a test tube of water
Add a few drops of Benedict’s solution
Heat (in a beaker of boiling water)
Positive result (if the substance is present)
Colour changes from blue to green / orange / red (increasing quantities of sugar present)
food tests to identify starch
Method
Take a sample of the food/biological material to be tested and grind up
Then..
Dissolve the ground up food in a test tube of water
Add a few drops of iodine solution
Colour changes from yellow/orange to blue/black
food test for Protein
Method
Take a sample of the food/biological material to be tested and grind up
Then..
Dissolve the ground up food in a test tube of water
Add a few drops of biuret solution (a mixture of sodium hydroxide and copper sulphate)
Colour changes from blue to purple
Fat food test
Method
Take a sample of the food/biological material to be tested and grind up
Then..
Dissolve the ground up food in a test tube of ethanol
Pour the ethanol into a test tube of water
Water changes colour from colourless to white emulsion
Photosynthesis experiment method
Simple method (method writing guide)
Fill a boiling tube 2/3rds full of sodium hydrogen carbonate solution
Place boiling tube in a beaker of water (room temperature water bath)
Cut a 7cm piece of pondweed (Elodea) and place cut side up in your boiling tube
Turn off all lights in the room
Place the beaker 10cm from a lamp and leave for 5 minutes
Then count the number of bubbles of oxygen produced in 1 minute and record.
Repeat at 20cm, 30cm, 40cm and 50cm
Independent variable
Dependent variable
Control variables
Distance from the lamp (affects light intensity)
Number of bubbles of oxygen
Brightness of lamp
Colour of the light
Concentration of sodium hydrogen carbonate
Temperature
Length of pondweed
Type / species of pondweed
Why did we turn off all the other lights in the room?
To reduce background light that could affect rate of photosynthesis in the plant
How did we control the temperature?
Place the tube containing the pondweed into a beaker of water (room temperature water bath)
What was the purpose of the sodium hydrogen carbonate?
Dissolves to release CO2, which can be used by the pondweed for photosynthesis
Suggest an experimental control
Set up the same experiment with no light
Describe the main sources of error
Miscounting the bubbles (dependent variable)
Bubbles may be different sizes (dependent variable)
Distances may not be measured accurately (independent variable)
Describe how to improve the accuracy of the experiment
Repeat and calculate an mean
Video the experiment and play back at a slower speed to make counting bubbles easier
Collect the gas in a gas syringe instead of counting bubbles
Suggest an uncontrolled variable
Background light in the room if the room is not in complete black out
Describe how to improve the validity of the experiment
Black out the room fully
Explain the effect of light intensity on the rate of photosynthesis
the most obvious factor effecting the rate of photosynthesis is light intensity.
If there is lots of light than plenty of photosynthesis can take place.If there is very little or no light then photosynthesis will stop. Whatever the other conditions are around the plant . For most plants the brighter the light the faster the rate of photosynthesis.
Plant tissues include:
epidermal tissues
palisade mesophyll
spongy mesophyll
xylem and phloem
meristem tissue found at the growing tips of shoots and roots- dont need to know for this test
The leaf is a plant organ. Knowledge limited to:
epidermis
palisade and spongy mesophyll
xylem and phloem
guard cells surrounding stomata
light intensity equation=
1/distance squared
enzymes?
explain the effect of temperature on photosynthesis
temperature effects all chemical reactions including photosynthesis. As temperature rises the rate of photosynthesis increases as the reaction speeds up .However photosynthesis is controlled by enzymes . Most enzymes are denatured once the temperature rises to around 40-50 degrees. If the temperature gets too high than the enzymes controlling photosynthesis are denatured and the rate of photosynthesis will fall.
explain the effect of carbon dioxide on photosynthesis
Carbon dioxide concentration
Plants need carbon dioxide to make glucose. The atmosphere is only about 0.04% carbon dioxide. This means carbon dioxide often limits the rate of photosynthesis. Increasing the carbon dioxide concentration will increase the rate of photosynthesis (Figure 4).
On a sunny day, carbon dioxide concentration is the most common limiting factor for plants. The carbon dioxide concentrations around a plant tend to rise at night, because in the dark a plant respires but doesn’t photosynthesise. As light intensity and temperature increase in the morning, most of the carbon dioxide around the plant gets used up.
In a science lab or a greenhouse the levels of carbon dioxide can be increased artificially. This means that carbon dioxide is no longer the limiting factor. Then the rate of photosynthesis increases with the rise in carbon dioxide concentration.
In a garden, woodland or field (rather than a lab or greenhouse, where conditions can be controlled), light intensity, temperature, and carbon dioxide concentrations interact, and any one of them might be the factor that limits photosynthesis.
explain the effect of chlorophyll levels on photosynthesis
Chlorophyll levels in the leaf
If the amount of chlorophyll in a leaf is limited in any way, less photosynthesis will take place. The leaves of some ornamental plants have white, chlorophyll-free areas. These plants grow less vigorously than plants with all green leaves. If they are permanently in dim light, variegated leaves often turn completely green. If a plant does not have enough minerals, especially magnesium, it cannot make chlorophyll. The rate of photosynthesis drops and eventually the plant may die.
Why do plants carry out photosynthesis?
The energy conversion that occurs as a result of photosynthesis is light energy (usually from the sun) to chemical energy (stored in sugars).
Which factor controls the reactions of photosynthesis reactions?
All the reactions of photosynthesis are controlled by enzymes.
Explain how the structure of root hair cells and xylem are adapted to their functions.
Root hair cells are adapted to increase surface area for the efficient uptake of water by osmosis and mineral ions by active transport. Xylem transports water/mineral ions from roots to stems and leaves. It is composed of hollow tubes strengthened by lignin adapted for transport of water in the transpiration stream.
how do the root hair cells form a system in the transpiration stream :
on the surface of roots are specialised cells called root hair cells
water moves from the soil into these cells by osmosis
mineral ions are pumped into these cells by active transport
both then move into xylem tissue
how does the stem form a system in the transpiration stream :
- water is pulled up the stem from the roots to the leaves
water travels up tubes known as xylem tissue
mineral ions (like nitrate ions and magnesium ions) are dissolved in the water
how does the leaf
form a system in the transpiration leaf :
water evaporates out of the stomata found on the underside of the leaf.
Guard cells can shut the stomata to reduce water loss
what is its function?
Translocation: Explain how phloem is adapted for its function.
Phloem tissue transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage. Phloem is composed of tubes of elongated cells. Cell sap can move from one phloem cell to the next through pores in the end walls (sieve plates).Translocation: Explain how phloem is adapted for its function.
volume of a cylinder
se 𝜋r2h to calculate volume of water taken up.
Factors affecting transpiration
temperature
humidity
air movement
light intensity
temperatures affect on transpiration
Temperature Increase Increases molecular movement so that more water molecules evaporate from cell surfaces. The rate of diffusion of water molecules from the leaf is increased
humiditys affect on transpiration
When the relative humidity is high, the atmosphere contains more moisture. This lowers the driving force for transpiration. Lower relative humidity levels correspond to less moisture in the atmosphere and thus a higher driving factor for transpiration.
airmovement affect on transpiration
Air movement Increase Removes water vapour from leaf surfaces. More water diffuses from the leaf.
light intensity affect on transpiration
higher light intensity levels will generally result in greater transpiration rates. This is because plants open their stomata in response to light, allowing water vapour to escape from the leaves.
translocation definition
transport of dissolved sugars from the plants leaves to other places in the plant
transpiration
the evaporation and movement of water away from the plant’s leaves from the inside of the plant. Transpiration occurs as water diffuses through the plant from the roots and evaporates from the leaves through the stomata openings
translocation in the leafs
sugars ( glucose) are made in a chemical reaction called photosynthesis . SUgar move into the phloem tissue in the leaf by diffusion
translocation in the stems
dissolved sugars (called cell sap) travel both up and down phloem tissue in the stem to other parts of the plant
transpiration stream
transport of water and mineral ions through a plant
translocation
transport of dissolved sugars from the leaves to other places in a plant
transpiration
Transpiration is the evaporation and movement of water away from the plant’s leaves from the inside of the plant. Transpiration occurs as water diffuses through the plant from the roots and evaporates from the leaves through the stomata openings (more on this later).
meristem tissue location and adaptations
this is found at the growing tips of shoots and roots and is able to differentiate into lots of different types of plant cell, allowing the plant to grow
The role of stomata and guard cells are to
control gas exchange and water loss
cylinder volume formula:
π r 2 h
Describe how you could change the photosynthesis experiment to investigate something different
Change the colour of the light (using coloured filters) but keep the distance from the lamp the same
Change the temperature (using water baths) but keep the distance from the light the same
Change the concentration of the hydrogen carbonate solution but keep the distance from the lamp the same
Change the species of pondweed but keep the distance from the light the same
Photosynthesis Experiment
Hazards:
Risks:
Precautions:
Hazard Risk
Lamp Hot bulb could
burn you
Could break and
Glassware cut you
Pondweed Could pass on
pathogens
Precaution
Don’t touch the bulb
Don’t leave near the edge of tables where it can be knocked off.
Wash hands with soap after handling
