Order the following from smallest to largest: Tissue, Organ, Organelle, System
Organelle, Tissue, Organ, System
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Give three characteristics of an animal cell (and explain what they do)
Nucleus (contains genetic material), Cell membrane (Controls substances going in and out), Cytoplasm (Where most chemical reactions occur)
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How is a red blood cell specialised?
Small biconcave shape to increase surface area, contain haemoglobin which reacts with oxygen to become oxyhaemoglobin, no nucleus to maximise space for carrying oxygen
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What is a tissue (in the body!)?
A collection of similar cells that work together to perform a particular function
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What is an organ?
A group of different tissues that work together to perform a function
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What are the main features of a plant?
Multicellular, have chloroplasts, have cellulose cell walls, store carbohydrates as sucrose or starch.
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What are the main features of an animal?
Multicellular, can move around, often store carbohydrate as glycogen
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What are the main features of Fungi?
Some are single celled (others have a body called a mycelium), can't photosynthesise, chitin cell walls, can store carbohydrate as glycogen.
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Give an example of a plant, animal, and fungus
Cereals & legumes etc. , Humans etc., Yeast
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What are the main features of protoctists? (Give an example)
single celled and microscopic, some have chloroplasts and are similar to plant cells, others are more like animal cells. (Amoeba)
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What are the main features of bacteria? (Give an example)
Single celled and microscopic, No nucleus, Circular chromosome of DNA, some can photosynthesise, most feed off other organisms. (Pneumococcus)
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What are the main features of viruses? (Give an example)
Particles rather than cells, can only reproduce inside living cells, Infect all lving organisms, No cellular structure, contain RNA. (Influenza virus)
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What are enzymes?
A catalyst substance which increases the speed of a reaction without being used up in the reaction. (note, enzymes only activate with a specific substrate)
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What affects enzymes?
Temperature and pH
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What is the optimum temperature for important human enzymes?
37C
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What is usually the optimum pH for enzymes? (What about pepsin?)
pH 7 (pH 2)
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What is diffusion?
The movement of particles from an area of high concentration to an area of low concentration (down the concentration gradient)
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What is osmosis?
Diffusion within water (The movement of particles from an area of high concentration to an area of low concentration (down the concentration gradient)) through a semi permeable membrane
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When a plant cell is plump and swollen with water, it is..., which makes for a well... plant
Turgid, supported
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If a plant cell contains no water, it is..., this causes the plant to...
Flaccid, Wilt
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What is active transport?
The movement of particles from a low concentration to a high concentration
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Active transport requires what?
Energy
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What are the three factors affecting the movement of substances? (which one does not affect active transport?)
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