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biology paper 1 - Coggle Diagram
biology paper 1
animal tissues, organs and organ systems
cells are the basic building blocks that make up all living organisms and specialised cells carry out a particular function.
the process by which cells become specialised for a particular job is called differentiation and this happens during the development of a multicellular organism
these specialised cells form tissues, which form organs, which form organ systems
large multicellular organisms e.g. squirrels, have different systems inside them for exchanging and transporting materials
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cell division
most cells in your body have a nucleus. the nucleus contains your genetic material in the form of chromosomes
chromosomes are coiled up lengths of DNA molecules and each chromosome carries a large number of genes. different genes control the development of different characteristics e.g. hair colour
body cells normally have two copies of each chromosome - one from the organism's 'mother' and one from its 'father' and there are 23 pairs of chromosome in a regular human body cell
the cell cycle makes new cells for growth, development and repair
body cells in multicellular organisms divide to produce new cells as part of a series of stages called the cell cycle
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the end of the cell cycle results in two new cells identical to the original cell, with the same number of chromosomes
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stem cells
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as cells change they develop different subcellular structures and turn into different types of cells allowing them to carry out specific functions
most differentiation occurs as an organism develops and in most animal cells, the ability to differentiate is then lost at an early stage, after they become specialised. However, lots of plant cells don't ever lose this ability.
the cells that differentiate in mature animals are mainly used for repairing and replacing cells such as skin or blood cells.- some cells are undifferentiated cells - they're called stem cells.
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photosynthesis
carbon dioxide + water --> glucose + oxygen is the equation and the symbol equation is 6CO(2) + 6H(2)O --> C(6)H(12)O(6) + 6O(2)
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enzymes and digestion
starch, proteins and fats are big molecules and therefore too big to pass through the walls of the digestive system. So digestive enzymes break these big molecules down into smaller ones like sugar (e.g. glucose and maltose), amino acids, glycerol and fatty acids
And these smaller, soluble molecules can pass easily through the walls of the digestive system allowing them to be absorbed into the bloodstream
carbohydrases convert carbohydrates into simpler sugars - amylase is an example of a carbohydrase and it breaks down starch - amylase is made in the salivary glands, the pancreas and the small intestine
proteases convert proteins into amino acids - proteases are made in three places, being the stomach, the pancreas and the small intestine
required practicals
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test for carbohydrates, lipids and proteins with qualitative reagents
there are several qualitative tests for food chemicals and these can be used to detect the presence of food chemicals, but not how much is present
the test for sugar is Benedict's test and this is when you add benedict's solution to food and heat it in a water bath - then after heating it goes through some stages - green, yellow, orange, red or brown depending on how much glucose is present
the test for starch is where you add iodine solution to the food and foods containing starch will turn a blue-black colour
the test for proteins is the biuret test - you add 1cm3 of biuret solution A to the food solution, mix the liquids, then add 1cm3 of biuret solution B and shake - a purple colour indicates protein is present and a purple ring between the layers also means protein is present
the test for fats is called the Sudan III - equal amounts of food and water are added to a test tube, then drops of Sudan III is added and the test tube is shaken - the result is that a red stained layer forms on the surface of the water
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