Plants & Food Flashcards
Write a reason for this feature in plant leaf
Leaves have a large surface area
To absorb more light rays
Write a reason for this feature in plants leaves
Leaves have stomata and guard cells
Guard cells control opening and closing of stomata to allow gases to pass into and out of leaf
Write a reason for this feature in plants leaves
Leaves are thin
To allow gases to diffuse in and out easily
The upper epidermis is covered by a waxy cuticle Why?
To reduce the loss of water and prevent microbe entry
Palisade mesophyll cells are mainly on the upper side of the leaf
To increase the absorption of light, as this is where most light falls
There are air spaces between the mesophyll cells
They make it easy for gases (carbon dioxide, oxygen and water vapour) to diffuse to and from all the mesophyll cells.
The leaf contains transport tissues (xylem and phloem)
Xylem: brings water and minerals to leaf cells
Water is needed for photosynthesis
Mg ions are needed by the cells to make chlorophyll
Phloem: transports products of photosynthesis e.g. sugars, from the leaf
The upper epidermis is transparent
To allow light to reach photosynthesising cells beneath
Explain how the plant leaf are adapted to it’s function?
Leaves have lots of veins Why?
to carry water to the cells and carry sugars away.
label the following diagram
How is the leaf adapted for photosynthesis?
write the symbol equation of photosynthesis
Pathway of carbon dioxide from atmosphere to chloroplasts by ————-
A. Active Transport
B. Diffusion
Pathway of carbon dioxide from atmosphere to chloroplasts by diffusion.
The leaf is specifically adapted to maximise gas exchange. What are the key gases which we must consider?
- Carbon dioxide
- Oxygen
- Water vapour
Gases will always diffuse down a concentration gradient (from where there is a high concentration to where there is a low concentration)
True / False
True
Explain the adaptations of the whole leaf for gas exchange
Adaptations of leaves to maximise gas exchange:
- They are thin which gives a short diffusion distance
- They are flat which provides a large surface area to volume ratio
- They have many stomata which allow movement of gases in and out of the air spaces inside the leaf to maintain a steep concentration gradient.
Other adaptations of the internal leaf structure/tissues include:
- Air spaces to allow gas movement around the loosely packed mesophyll cells
- Many stomata in the lower epidermis open in sunlight to allow gas movement in and out of the leaf
- Thin cell walls allow gases to move into the cells easily
- Moist air which gases can dissolve into for easier movement into and out of cells
- The close contact between the cells and the air spaces allows efficient gas exchange for photosynthesis and respiration.
Stomata are spaces found on the ……………..
A.betweem cells
B.lower epidermis of the leaf
C. Upper epidermis of the leaf
B.lower epidermis of the leaf
Stomata tend to ——— when there is plenty of water and sunlight
Stomata tend to ———— to low water availability or low sunlight
Stomata tend to open when there is plenty of water and sunlight
Stomata tend to close due to low water availability or low sunlight
Write a paragraph explaining the funciton of Stomata
Stomata are spaces found between two guard cells predominantly on the lower epidermis of the leaf
The guard cells are responsible for the opening and closing of the stomatal pore which controls gas exchange and water loss
Stomata open when water moves (by osmosis) into the guard cells causing them to become turgid
This allows gases to diffuse in and out of the leaf through the stomatal pore
Stomata tend to open when there is plenty of water and sunlight
Stomata close when the guard cells lose water (by osmosis) to the neighbouring epidermal cells and they become flaccid
This prevents any diffusion into or out of the leaf
Stomata tend to close due to low water availability or low sunlight
Explain why a leaf is classed as an organ.
leaf is composed of more than one type of cell, therefore is an organ . A leaf also performs various functions (e.g. transpiration, photosynthesis
Transport of water to the cells of leaf
Xylem
in this experiment
what is the purpose of the bungs in the tubes?
what are the 2 control varialbles?
Suggest one source of inaccuracy
What is the dependent variable (DV)
- Suggest hypothesis for this invistigation .
Light intensity affects photosynthesis.
- what is the purpose of the bungs in the tubes?
to prevent CO2 from escaping the tube
-
what are the 2 control varialbles?
1) Size of the leaf 2) Volume of indicator - Suggest one source of inaccuracy
amount of hydrogen carbonate
- What is the dependent variable (DV)
the colour change of hydrogen carbonate indicator
- what is the independant variable (IV)? the thing that is being changed.
Light intensity ( light / dark / dim light )
Why tube 4 is left empty?
It acts as a control to show that it is the oresence of the leaf which effects the color of the indicator
the attached graph showing the effect of light intensity on the rate of photosynthesis.why the rate of phytosynthesis becomes constant at points
A to B?
The rate becomes constant regardless of how much light intensity increases as something else is limiting the rate, such as carbon dioxide or temperature.
In measuring the rate of photosynthesis experiment, what is the
Independent variable:
Dependent variable:
Control variables:
Independent variable: Light intensity ( it is what is being changed in the investigation)
Dependent variable: o_xygen bubbles produced ( what is being measured in the investigation)_
Control variables: The aquatic plant / Temperature / PH / carbon dioxide ( what is being controlled in the investigation)
What is the result you ovserve in the tube exposed to light?
and what is your explanation ?
Result
The tube exposed to light changed colour from orange to purple.
Explanation
In bright light, the rate of photosynthesis is greater than rate of respiration. So, leaf takes in CO2 from the air in the test tube. This reduces the CO2 inside the test tube and the colour of hydrogen-carbonate indicator solution changes from orange to purple as CO2 is taken away form the solution.
What is the result you ovserve in the tube covered (dark)?
and what is your explanation ?
Result
The test tube covered l changed colour from orange to yellow.
Explanation
Aluminium foil prevents light entering the test tube. The rate of respiration is greater than rate of photosynthesis (as light is needed for photosynthesis). So, leaf gives out CO2, which dissolves in the hydrogen-carbonate indicator solution to change its colour from orange to yellow
