levels of organisation

• cell - the smallest units of life
• tissue - a collection of differentiated cells that have a specialised function
• organ - a collection of tissues that are adapted to perform a particular function
• organ system - made up of a number of organs working together to carry out a function
• organism - a living system that functions as an individual entity
• eryhtrocytes - RBC biconcave shape increase SA:V. role to transport oxygen. No nuclei +++ space for haemoglobin + flexible to fit through capillaries
• Sperm cell - mitochondria +++, tail, acrosome digestive enzymes etc
• Neutrophils - WBC multi lobed nucleus so can squeeze through small gaps. Cytoplasm contains lysosomes to attack pathogens
• Thin/elastic outer wall - it bulges outwards;

  Thick/less elastic inner wall - it curves to open the stomata/straightens to close the stomata; Has chloroplasts. Osmotically active. Pairs are thicker on one side so don’t change shape symmetrically
• Palisade - shape closely packed to form continuous layer. Thin cell walls +++ diffusion, packed with chloroplasts, large vacuole to maintain turgor pressure
• Root hair cells - increase SA maximum uptake
• nervous tissue - adapted to support transmission of electrical impulses
• epithelial tissue - to cover body surfaces and as a layer of protection
• muscle tissue - to contract and aid movement
• connective tissue - as a transport medium or to hold tissues together
• 1. prophase
  2. metaphase
  3. anaphase
  4. telophase
  5. cytokinesis