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Science Revision HW - Week 4 (Digestion (Liver (Produces bile), Gall…
Science Revision HW - Week 4
Cell Organisation
Animal Cell Organisation
Cells form tissues, that form organs, that form organ systems
Stem cells are unspecialised, then become specialised by differentiation
Plant Cell Organisation
Tissues
Epidermal tissue
Palisade mesophyll tissue
Spongy mesophyll tissue
Xylem and Phloem
Meristem tissue
Leaves contain epidermal, mesophyll, xylem and phloem
waxy cuticle preserves water
upper epidermis is transparent to let light through
palisade cells have lots of chloroplasts for photosynthesis
xylem and phloem transport food and water.
Adapted for gas exchange
Made of organs like stem, roots and leaves
Xylem and Phloem
Transpiration
Evaporation and diffusion of water
One way, from roots to leaves
Translocation
goes in both directions
Allow cell sap (made of food substances) to flow through
Digestion
Liver
Produces bile
Gall Bladder
Where bile is stored
Stomach
Pummels food in muscular walls, produces protease, has acid to break down food and kill bacteria
Pancreas
Produces lipase, protease and amylase which is released into small intestine
Gullet
Oesophagus. Connects to stomach
Small Intestine
Completes digestion and absorbs nutrients into the bloodstream
Salivary glands
Produce amylase enzyme
Large Intestine
Excess water is absorbed
Rectum
Where faeces are stored until they come out of the anus
Enzymes
Proteases convert protein into amino acids
Lipase breaks down glycerol into fatty acids
Carbohydrases break down carbs into sugars
Bile neutralises stomach acids and emulsifies fats
Enzymes are effected by pH and temperature
Food Tests
Sudan III Test
Test for lipids
Prepare sample, add Sudan III, if lipids are present they will float to the top, and go red.
Biuret Test
Test for protein
Prepare sample, add biurets solution, will go from blue to purple/pink if protein is present
Iodine
Test for starch
Make food sample, add iodine, will go from orange to black
Benedicts Test
Tests for sugars
Prepare food sample, place in 75c bath, and benedicts solution, leave for 5 mins, will go from blue to green, yellow or red depending on sugar content