LEAVES AND PHOTOSYNTHESIS

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Where does photosynthesis mostly occur?
The Leaves.
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How are leaves adapted for photosynthesis?
Contains the pigment chlorophyll in chloroplasts, are broad and flat, has a network of vascular bundles for support, has a thin structure and has stomata to allow exchange of gases.
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What happens during photosynthesis in terms of gases?
Carbon Dioxide diffuses in through the stomata and oxygen diffuses out through the stomata.
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What are the four distinct layers of a leaf?
Upper epidermis, the palisade layer, the spongy mesophyll and lower epidermis.
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What colour is the upper epidermis and why?
it is transparent to allow sunlight to the layer below.
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Why is the palisade layer near the top of the leaf?
Because the cells are packed with chloroplasts.
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Why does the spongy mesophyll contain lots of air spaces?
For efficient gas exchange.
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What different pigments is 'chlorophyll' made up of?
Chlorophyll a, chlorophyll b, xanthophylls and carotene.
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Why do plants tend to be green?
Because red and violet ends of the light spectrum are absorbed more whereas greener colours tend to be reflected.
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What is diffusion?
Diffusion is the movement of a substance from an area of high concentration to an area of low concentration.
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What is osmosis?
Osmosis is the movement of water from a high concentration (dilute solution) to a low concentration (Concentrated solution)
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What is active transport?
The movement of substances from a low concentration against a concentration gradient to an area of high concentration. This used energy from respiration.
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How does diffusion of gasses differ inside plants during the day and night?
During the day the concentration of CO2 in side the leaves is low, because it is used in photosynthesis. Carbon dioxide diffuses into the plant via the stomata, and oxygen diffuses out via the stomata.
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What process occurs in plants during the day and night?
The plants respire. Meaning that oxygen diffuses into the leaf cells and carbon dioxide diffuses out of the leaf cells.
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Why do the stomata open and close?
They open to help increase the rate of diffusion and close to prevent water loss in drought conditions.
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Why do plant cells have inelastic cell walls?
Prevents cells from bursting due to high water pressure and contributes to rigidity.
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What is the pressure of the water pushing against the cell wall called?
Turgor Pressure
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Describe what happens when water moves in and out of the cell via osmosis in terms or turgidity, flaccidity ans plasmolysis,
Cells will become turgid. The plant will be fully upright. If water is in short supply, cells will start to lose water, they will become flaccid and wilt. When a lot of water is lost the inside of the cell contacts. This is called Plasmolysis.
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What is the Xylem?
A tube from root to leaf that transports mineral salts via transpiration. (Made of dead plant cells with hollow lumen)
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What is the phloem?
A tube that allows the movement of food substances (sugars) around the plant by translocation. (Made of long columns of living cells.)
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What is transpiration?
The diffusion and evaporation of water from inside a leaf. It causes water to be moved up the xylem vessels and provides plants with water for cooling, photosynthesis and support as well as bringing minerals to the plant.
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What can the rate of transpiration be affected by?
High Light intensity, increased air movement, high temperature and high humidity.
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How does water move up the Xylem?
By water passing from the xylem to the leaf via osmosis, which causes the water to move up slightly. Water from the root hair cells replaces the water that has been lost.
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How can transpiration be measured in a leafy shoot?
Mass Potometer
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Which two adaptations reduce the rate of water loss in leaves?
A waxy cuticle and the majority of the stomata being on the lower surface of the leaf.
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Describe what happens to the guard cells during photosynthesis.
The guard cells become turgid and the stomata are fully open. But when there is a lack of water, the guard cells become flaccid and the stomata close to prevent unnecessary water loss.
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What minerals do plants need?
Nitrates, Potassium Compounds, Phosphates and Magnesium.
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What are nitrates used for in plants and what happens without them?
To make amino acids that form proteins. Yellow leaves and poor growth.
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What are potassium compounds used for in plants and what happens without them?
Used to help the enzymes in respiration and photosynthesis. Poor flower and fruit growth, discolored leaves.
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What are phosphates used for in plants and what happens without them?
Used to make DNA and Cell membranes. Poor root growth and discoloured leaves.
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What is magnesium used for in plants and what happens without it?
Is used to make chlorophyll for photosynthesis. Yellow Leaves.
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Why do farmers use fertilizers?
Because the necessary minerals only occur in small concentrations.
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Other cards in this set

Card 2

Front

How are leaves adapted for photosynthesis?

Back

Contains the pigment chlorophyll in chloroplasts, are broad and flat, has a network of vascular bundles for support, has a thin structure and has stomata to allow exchange of gases.

Card 3

Front

What happens during photosynthesis in terms of gases?

Back

Preview of the front of card 3

Card 4

Front

What are the four distinct layers of a leaf?

Back

Preview of the front of card 4

Card 5

Front

What colour is the upper epidermis and why?

Back

Preview of the front of card 5
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Comments

Lorran payne

This is a very good set of cards. Useful for my mocks i have and other exams x

Swallowtail

This is a good set of cards as the answers contain the expected key words that examiners would look for. They would be useful in most specifications as this topic is universal. Try linking these cards with a set of notes that contains diagrams of root and leaf structure so that you can learn the names and positions of the key tissues and their functions.

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