Cells

• magnification = size of image ÷ size of real object
• Total Magnification = magnification of eyepiece x objective lens
• resolution is the ability to distinguish two objects that are close together, or two objects that are far apart
• electron microscope can magify up to 2 million times and can see sub-cellular structures
• plant cell, cellulose wall is the outer layer, rigid, keeps the wall in shape
• plant cell, large permanent vacuole, stores water, sugar and minerals, plant support
• plant cell, chloroplasts, contain green chemical chlorophyll, which absorbs light energy for photosynthesis
• Mitochondrion, found in cells cytoplasm that are the site of respiration, they release energy
• Nucleus, controls cell, contains chromosomes that carry genes that control characteristics
• Nuclear membrane, surrounds nucleus, contains pores to allow substances to move between nucleus and cytoplasm
• cell membrane, controls what enters and leaves the cell
• cytoplasm, jelly-like substance where most chemical reactions occur, keeps cell alive
• Bacteria Cells, capsule, for defence against invading viruses
• bacteria cells, non-cellulose cell wall, made from protein and carbohydrates
• bacteria cell, plasmid, additional loop of DNA
• bacteria cell, mesosome, for chemical reactions e.g. respiration
• specialised cells and differentiated to do different jobs
• Leaf palisade cell makes sugar, lots of them + cylindrical shape to pack tightly, on upper surface of leaves

  
• Root hair cell, absorbs water + minerals from soil, long to increase surface area to absorb easier, at tip of plant root

  
• sperm cell, male sex cell that fertilises egg, swims using flagellum, has many mitochondria to release energy for movement, half normal chromosomes, produced in testes

  
• red blood cells, carry oxygen and haemoglobin around the body, biconcave disc to increase surface area for gas diffusion, no nucleus to hold more oxygen

  
• nerve cell, carries nerve impulses, long nerve fibre to reach other cells, covered in myelin to speed up transmission of impulses, found in all parts of the body

  
• ciliated epithelial cell, cells that line the bronchioles, use cilia to move mucus upwards towards the trachea

  
• digestive system is the process of breaking down food into smaller molecules for absorption, mouth, stomach, intestines
• respiratory system is the exchange of gases between the body and the environment, oxygen exchanges with CO2, trachea, bronchi, lungs
• circulatory system is the transportation of materials around the body by the blood, heat and protection, heart, blood vessels
• skeletal system is for support, protection and movement, ribs, backbone
• excretory system is getting rid of toxic waste, liver, kidneys, bladder
• reproductive system is the production of gametes and fertilisation, testes, ovaries
• sensory system is touch, taste, smell, hearing, and vision, skin tongue nose ears eyes
• nervous system is the response to stimuli and coordination, brain, spinal cord, nerves
• tissue is a similar group of cells
• organs are different tissues working together to do a particular job
• organ systems are a collection of organs working together
• an organism is a collection of organ systems that can carry out all characteristics of life
• unicellular organisms exchange through the cell-surface membrane
• multicellular organisms have cells that are not in direct contact with the surrounding enviornment
• multicellular organisms have specialised exchange surfaces, have more complex transport system links
• rate of exchange depends on organisms surface area that is in contact with the surroundings
• As an organism increases in size the surface area to volume ratio decreases