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Summary Unit 1 - Principles and Applications of Science
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This document contains detailed notes on all the biology side of Unit 1 - Principles and Applications of Science with labelled diagrams.
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MICROSCOPY:
A microscope is an instrument which is used to magnify objects which are too
small to see with the naked eye.
LIGHT MICROSCOPE:
Visible light and magnifying lenses to observe small objects.
1. Specimen is placed on a slide.
2. Specimen should be thin, so that light can pass through
3. Stains are used to help see different features of specimen
ADVANTAGES:
. Can observe sub-cellular structures e.g. organelles
. Cheaper than an electron microscope
. Can examine living and non-living
DISADVANTAGES:
. Lower magnification (x500) and resolution (x200nm)
ELECTRON MICROSCOPE:
A beam of electrons are fired at the specimen, electrons are detected, and an image is
produced.
ADVANTAGES:
. Greater magnification (x 500,000)
. Able to see smaller structures inside cells
DISADVANTAGES:
. Very expensive
. Can only examine non-living (specimen must be dead)
, ANIMAL
CELLS:
mmm
PROKARYOTES – single celled organisms that do not have a nucleus or membrane bound
organelles.
EUKARYOTES – multicellular organism eg. Plant and animal cells. Complex cells with a nucleus and
membrane bound organelles.
FUNCTION OF ORGANELLES:
PLASMA MEMBRANE – regulates the transports of materials into and out of the cell.
CYTOPLASM – liquid that fills the cell to maintain its shape.
NUCLEUS – regulates cellular activity and houses genetic material in the cell.
NUCLEOLUS – produces ribosomes.
RIBOSOMES – protein synthesis takes place (80s in eukaryotes and 70s in prokaryotes)
ROUGH ER – membrane bound flattened sacs that produces proteins.
SMOOTH ER – membrane bound flattened sacs that produce lipids.
VESICLES – storing and transporting substances in the cell.
GOLGI APPARATUS – modifies proteins and packages them in vesicles for transport.
LYOSOMES – break down waste material eg. old organelles + pathogens
CENTRIOLES – two hollow tubes that form spindle fibres during cell division.
MITOCHONDRIA – where respiration takes place.
, PLANT
#
CELLS:
Plant cells have all the cellular components that animal cells have EXCEPT FOR CENTRIOLES.
Plants cell’s main function is to produce carbohydrates during photosynthesis.
FUNCTION OF ORGANELLES:
CHLOROPLASTS – contain chlorophyll and site of photosynthesis
VACUOLE – stores water + other substances to ensure a rigid framework in the cell.
CELL WALL – protects + supports cell and plant.
TONOPLASTS – membrane of vacuole; selectively permeable to allow substances to pass through
AMYLOPLASTS – responsible for the synthesis + storage of starch.
MIDDLE LAMELLA – sticks cells together.
PLASMODESMATA – allow transport + communication between individual plant cells.
PITS – allows water to enter + leave xylem vessels.
PROKARYOTIC CELL COMPONENTS:
NUCLEOID – single circular in shape + DNA is folded inside (generic information)
CAPSULE – protects the cell + prevents desiccation (drying out)
PLASMID – carry genes that may benefit the survival of the organism.
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