BIOLOGY - B4
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- Created by: vimal__
- Created on: 30-12-16 18:49
Name 4 similarities between animal and plant cells.
1) They both have a nucleus 2) They both have cell cytoplasm 3) They both have a cell membrane 4) They both have mitochondria
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Describe a nucleus.
Contains DNA, which has instructions for the production of different proteins.
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Describe cell cytoplasm.
Gel-like substance where proteins are made and where chemical reactions happen
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Describe a cell membrane.
Controls what goes in and out of the cell and holds it together
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Describe mitochondria.
Where aerobic respiration reactions take place.
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Name 3 differences between animal and plant cells.
1) Palisade cells have a rigid cell wall. 2) Plant cells have vacuoles. 3) Plant cells have chloroplasts.
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Describe a cell wall.
Made of cellulose, supports and strengthens the cell.
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Describe vacuoles.
Contain cell sap (a weak solution of sugars and salts)
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Describe chloroplasts.
Contains chlorophyll which allows the reactions of photosynthesis to take place.
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State the four main components of a bacterial cell
(Outermost wall is the cell wall, innermost wall is cell membrane, jelly-like substance inside the cell is cytoplasm and the squiggly structure is a 'circular DNA molecule')
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What do bacterial cells not have and how is this somewhat insignificant?
Bacterial cells don't have mitochondria. However, this is insignificant as they are still able to respire aerobically.
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What are enzymes?
Enzymes are proteins that speed up chemical reactions.
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The 'lock and key' model consists of two main things. What are these?
The 'lock and key' model consists of an enzyme and a substrate.
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What is a substrate?
A substrate is a molecule that is being changed in a reaction.
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Every enzyme has an active site. What is an active site?
An active site is the part where a substrate joins onto the enzyme.
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Describe the process of how enzymes speed up chemical reactions (in context to the 'lock and key' model)
1) Substrate molecules move towards an active site in an enzyme. 2) Substrate molecule fits in active site in enzyme. 3) The reaction occurs and products are made; the enzyme speeds up this reaction.
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Enzymes usually only speed up one type of reaction. Why is this?
This is due to the fact that substrates have to be exactly the correct shape to fit to the active site. (Different substrates have very different shapes)
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What effect does a higher temperature have on the rate of reaction (involving the enzyme)?
As temperature increases, the speed of the reaction increases.
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Enzymes can stop functioning if the temperature is too high and/or if the pH is too high/low. Explain how this is.
The bonds holding the enzymes together break. This changes the shape of the enzyme and so the substrate will not fit onto the active site. Therefore, the enzyme will not work. The enzyme is denatured.
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What is respiration?
Respiration is a series of chemical reactions that releases energy by breaking down large food molecules. This happens in every living cell.
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State the three things that energy (from respiration) is used for.
1) Movement 2) Active Transport 3) Synthesis of large molecules
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Describe these three things.
1) Movement - muscle contraction 2) Active transport - moving substances in and out of cells. 3) Synthesis of large molecules - joining small molecules to make larger ones. e.g. glucose --------> cellulose
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Which releases more energy (per glucose molecule): aerobic or anaerobic respiration?
Aerobic respiration releases more energy (per glucose molecule).
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State the word and symbol equation for aerobic respiration.
Glucose + Oxygen ----> Carbon dioxide + Water (+ ENERGY) C6H12O6 + 6O2 → 6CO2 + 6H2O
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State a scenario in which humans, plants and bacteria may respire anaerobically.
HUMANS: when doing vigorous exercise, there is a build up of lactic acid (a 'stitch') PLANTS: waterlogged soil mean that there is no oxygen for the plant, so they must respire anaerobically. BACTERIA: there is a lack of oxygen under the skin so the
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State the equation for anaerobic respiration.
Glucose -----> Lactic Acid (+ENERGY)
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State the equation of anaerobic respiration in plants and micro-organisms.
Glucose -----> Ethanol + Carbon Dioxide (+ENERGY)
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Anaerobic respiration in plants and micro-organisms is an example of fermentation. Define fermentation.
Fermentation is when micro-organisms break down sugars into other products as they respire anaerobically.
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Humans use fermentation to make things such as bread and alcohol. State how fermentation makes these things.
BREAD: yeast ferments carbohydrates and releases CO2 ALCOHOL: yeast ferments sugar to form ethanol (alcohol)
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What is photosynthesis?
Photosynthesis is a series of chemical reactions that uses energy from sunlight to produce glucose.
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Photosynthesis happens in the chlorophyll. Describe chlorophyll.
Green substance that absorbs sunlight and allows the energy to be used to convert CO2 and H20 into glucose.
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Plants use glucose for three main things. State these.
1) Respiration 2) Growth 3) Starch
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Describe how glucose is needed for these three things.
1) Respiration allows energy to be released from glucose. 2) Glucose + Nitrogen -----> Amino Acids (-----> Proteins) 3) Glucose -----> Starch (stored in the roots)
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Name the three factors that affect the rate of photosynthesis.
1) Light intensity 2) Amount of CO2 available 3) Temperature
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Comment on how light intensity affects the rate of photosynthesis.
Light provides the energy for photosynthesis. As light intensity increases, rate of photosynthesis increases to a certain point (and then plateaus)
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Comment on how inadequate carbon dioxide levels affect the rate of photosynthesis.
As carbon dioxide level increases, rate of photosynthesis increases to a certain point (and then plateaus)
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Comment on how temperature affects the rate of photosynthesis.
The temperature must be perfect. Photosynthesis enzymes work slowly at low temperatures. If the plants get too hot, the photosynthesis enzymes get denatured (this happens at around 45 degrees Celsius)
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What is diffusion?
The passive overall movement of particles from a region of their high concentration to a region of their low concentration.
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State an example of diffusion.
For example, carbon dioxide and oxygen move in and out of plants using diffusion.
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What is osmosis?
The overall movement of water from a dilute to a more concentrated solution through a semi-permeable membrane.
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Plants take in water by osmosis. Explain how and why this happens.
Concentration of water is higher in the soil than inside the plant. Therefore, water is drawn into the root by osmosis.
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What is active transport?
The overall movement of chemicals across a cell membrane from a region of lower concentration to higher concentration using energy released by respiration.
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Plants take in nitrates through the roots by active transport.
The concentration of nitrates in root cells is normally higher than in the soil around them. Active transport uses energy from respiration to move nitrates from the soil into the root cells.
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Other cards in this set
Card 2
Front
Describe a nucleus.
Back
Contains DNA, which has instructions for the production of different proteins.
Card 3
Front
Describe cell cytoplasm.
Back
Card 4
Front
Describe a cell membrane.
Back
Card 5
Front
Describe mitochondria.
Back
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