B4 - photosynthesis part 2

B4 ocr gateway b part 2 of photosynthesis notes including osmosis, diffusion, sctive transport, transpiration, guard cells and minerals. 

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What is diffusion?
the movement of gas or liquid from an area of high to low concentration. It is a passive movement.
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What 3 things influence the rate of diffusion?
1. shorter distance 2. greater surface area 3.greater concentration gradient
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What is osmosis?
The NET movement of water molecules from an area of high to low concentration. Molecules move across a partially permeable membrane.
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What is a hypotonic solution?
When the concentration is more dilute on the outside - therefore water moves inwards
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What is an isotonic solution?
similar concentration so is balanced movement
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What is a hypertonic solution?
When the concentration is dilute on the inside so the water moves outwards
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In what processes is osmosis important?
- cooling - photosynthesis - support - mineral movement
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Why do root hairs have a large surface area?
So more water can be taken up by osmosis
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What is turgor pressure?
when water acts against the inelastic cell wall. Plants are supported by it.
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Describe what happens to guard cells in the day.
They photosynthesise to produce sugar (increases sugar concentration) - osmosis takes water to cells making it turgid so opens stomata.
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What happens to guard cells in the night?
Doesn't photosynthesise so sugar is used in respiration or transported elsewhere (decrease concentration) - net outflow of water by osmosis so loses turgor pressure = closed stomata.
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Define flaccid.
Lost water so cytoplasm doesn't push on cell wall outward.
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what is turgid?
Plenty of water so pushes out on cytoplasm
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Define plasmolysis.
Shrinking of cytoplasm so cell membrane tears away from wall due to lack of water
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Define crenation.
Cytoplasm shrinks because hypertonic solution outside causes movement out of cell
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Define cytolysis
The bursting of cells e.g red Blood Cells as they have no cell walls in a hypotonic environment.
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What increases the rate of transpiration?
1. Dry air humidity (less water outside) 2. Warm temperature (more energy) 3. windy air movement (water swept away) 4. Brighter light intensity (stomata open)
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What is active transport?
the movement of a substance (dissolved minerals) from an area of low to high concentration against a concentration gradient.
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Give an example of a place where active transport happens.
Root hairs as there are more minerals in the root than soil.
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What is the principle function of phloem?
They are for food transport (sugars). Translocation movement.
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What are the principle function and characteristics of the xylem?
For water transport (and minerals). Very strong dead cells.
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Why do plants need Nitrates and what happens if there is a deficiency?
Need them to manufacture amino acids and proteins (cell growth). If they dont have enough plants have poor growth and are yellow.
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Why do plants need Phosphates and what happens if there is a deficiency?
Need them for respiration and growth - phosphates help make DNA. if they dont have enough plants have poor root growth and discoloured purple leaves
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Why do plants need Potassium and what happens if there is a deficiency?
Need for enzymes for photo. and reps.. If they dont have enough plants have poor flower and fruit growth
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What is magnesium needed for?
Used in chlorophyll and photosynthesis.
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Other cards in this set

Card 2

Front

What 3 things influence the rate of diffusion?

Back

1. shorter distance 2. greater surface area 3.greater concentration gradient

Card 3

Front

What is osmosis?

Back

Preview of the front of card 3

Card 4

Front

What is a hypotonic solution?

Back

Preview of the front of card 4

Card 5

Front

What is an isotonic solution?

Back

Preview of the front of card 5
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This set of revision cards is useful for learning  GCSE Gateway Science Biology Module B4 It’s A Green World Unit-Item B4d Diffusion and osmosis. Students need to check their specification and entry level carefully as some of the terms used are only needed for the Higher paper.  Students of other specifications would also find this useful as it contains cards on key terms in biology such as active transport, diffusion and osmosis.

Try summarising the key information on a mind map with pictures, diagrams and sketch graphs.

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