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biology edexcel igcse/gcse
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Lecture notes of 33 pages for the course Edexcel at Edexcel (.)
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Living organisms characteristics: (MRS C GREN)- Movement
- Respiration
- Sensitivity
- Control
- Growth
- Reproduction
- Excretion
- Nutrition
● Organisms that dont carry out all these life processes are dead or nonliving
● Example is VIRUS
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5 kingdoms
- Animal
- Plant
- Fungi
- Protoctists
- Prokaryotes
Eukaryotic: are organism that CONTAIN a nucleus and membrane bound organelles
- Plants
- Animal
- Fungi
- Protoctists
Prokaryotes: are single celled organisms that LACK a nucleus or membrane bound organelles.
- Bacteria
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Types of organelles:
Nucleus: is a cell organelle that controls the activities of the cell
Cell membrane: thin surface layer around cytoplasm of a cell that forms a partially permeable barrier to control entry
and exit of substances into the cell
Cell wall: made out of cellulose it protects and supports the cell
Cytoplasms: jelly like material where chemical reactions take place
Mitochondria: organelle that carries out aerobic respiration to release energy
Ribosomes: organelles that are the site of protein synthesis
Vacuole: filled with cell sap, which helps to maintain the structure of the cell
Chloroplasts: Organelles that are the site of the reaction of photosynthesis
,Animals:
● Multicellular organisms
● Carbohydrates is stored as glycogen
Fungi:
● Multicellular: Mushrooms, toadstools, molds, mucor
● Unicellular: yeasts
● Chitin cell wall
● NO chloroplast
● Carbohydrate is stored as glycogen
Hyphae: thread like filaments
Mycelium: a network of hyphae
Saprotrophic nutrition: extracellular enzymes are secreted onto the food/ dead matter which breaks it into smaller
pieces that can be absorbed.
- Cattle Ringworm
- Athletes foot
- Black sigatoka
Protoctists:
● Most are microscopic single-celled organisms
● Some are animal like: Protozoa
Amoeba
● Some are plant like: algae
Seaweeds (multicellular)
chlorella
● Some are pathogens
Plasmodium which causes malaria
- P. infestans causes potato blight
Pathogens: are organisms that causes disease in other organisms
,Bacteria:
● Single celled organisms
● Shapes: spheres rods and spirals
● Cell wall made of peptidoglycan
● plasmids
● Capsule (slimy layer) that gives extra protection
● Flagellum
● Does Not contain nucleus instead contains circular chromosomes of DNA
Some carry out photosynthesis
Both fungi and bacteria are decomposers
- Lactobacillus bulgaricus (rod-shaped bacterium used for yoghurt production)
Pneumococcus (spherical bacterium (pathogen) causing pneumonia)
- M. tuberculosis causes tuberculosis (TB) in humans
- N. meningitidis causes bacterial meningitis in humans
Viruses:
- The tobacco mosaic virus (TMV) causes discolouration of the leaves on tobacco plants by preventing the
formation of chloroplasts
- The HIV virus causes AIDS
- The influenza virus causes the ‘flu’
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Cell: group of organelles that are working together to form the same function.
Tissue: group of cells that are working together to form the same function.
Organ: group of tissues that are working together to form the same function
Organ system: group of organs that are working together to form same function
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Biological molecules
● Carbohydrate: Carbon, Oxygen, Hydrogen
● Protein: Carbon, Oxygen, Hydrogen, Nitrogen
● Lipids: Carbon, Oxygen, Hydrogen
, Carbohydrate
● Monosaccharide: simple sugar
- Glucose
- Fructose
● Disaccharide: made up of 2 monosaccharides joined together
- Glucose + Glucose = Maltose
- Glucose + Fructose = Sucrose
● Polysaccharide: made up of many monosaccharides joined together
- Insoluble, they are used as storage molecules
- Strach
- Glycogen
- Cellulose
Lipids
● Fats are made up of triglycerides
● 1 glycerol molecule + 3 fatty acids
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Tests for biological molecules
- Break food using pestle and mortar
- Add to test tube and add distilled water
- Mix by stirring with glass rod
- Filter the mixture using a funnel and filter paper, collecting the solution
● Sugars (glucose) → Benedicts
● Starch → iodine
● Lipid → ethanol
● Protein → biuret
BENEDICT'S and GLUCOSE:
● Add benedict's solution to the test tube
● Heat in boiling water bath for 5 minutes
● Take test tube out of water bath and observe color change
● POSITIVE: Blue to orange/brick red
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