B1

• prokaryotic cells - single celled living organism - no nucleus, beacterial cells, cell wall, cell membrane, cytoplasm, bacterial DNA loop, plasmid
• eukaryotic cells - animal/plant cells - cell membrane, cytoplasm, nucleus
• bacterial DNA - loop of DNA not found in the nucleus
• plasmid - small ring of DNA which stores extra genes
• pili - attatches to structures
• flagella - tail like structure which allows the cell to swim
• slime capsule - protects the bacteria rom drying out and poisonous substances
• cell wall - made of cellulose and provides support and structure to the cell
• chloroplast - contains chlorophyll which absorbs sunlight to make food through photosynthesis
• vacuole - filled with cell sap to help keep the cell turgid
• mitochondria - most of the reactions for aerobic respiration takes place here. respiration transfers energy the cell needs to work
• cytoplasm - chemical reactions take place, controlled by enzymes
• cell membrane - barrier to the cell, controls what goes in and out of the cell
• nucleus - contains genetic material, controls the activities of the cell
• ribosomes - protein synthesis happens here
• isotonic solution - same concentration outside the cell as the solution in the cell
• hypotonic solution - less concentrated (more dilute) solution outside than in the cell
• hypertonic solution - more concentrated solution outside than in the cells
• xylem cells - to carry water and mineral in plants

  • form tubes of dead tubes
  • cell walls layered with lignin
  • everything flows in one direction
  • no structure
• phloem cells - carry glucose around the plant

  • tubes made of living tissues
  • cells have end plates with holes in them
  • two way flow
• muscle cells - contract and relax to allow movement

  • mitochondria to release energy for movement
  • long so that there is enough space to contract
• nerve cell - to carry out electrical signals

  • long to carry signals from a distance
  • branched at either end to attach to other nerve cells
  • dendrites
  • myelin sheath insulates the axon to increase the speed of electrical impulses
• root hair cell - to absorb water and minerals from the soil

  • hairs to increase surface area
  • no chloroplast, it is underground
  • lots of mitochondria - to release energy for active transport
• sperm cell - to fertilise the egg

  • long tail to swim
  • enzymes in the head to digest the cell membrane of the egg
  • mitochondria to release energy
• paliade cell - enables photosynthesis in the leaf

  • lots of chloroplasts to absorb light energy
  • located at the top surface of leaf where it can absorb the most light energy
• red blood cells - transports oxygen around the body

  • no nucleus - more oxygen can be carried around
  • contains red pigment that binds to oxygen molecules - haemoglobin
  • flat bi-concave disc shape to increase surface area:volume
• osmosis - movement of water particles from a high concentration to a low concentration through a partially-permeable membrane - depends on conentration gradient and temperature
• active transport - movement of substances from low to high concentration using energy provided by respiration
• osmosis in plants

  water moves by osmosis from a dilute solution in the soil to a concentrated solution in the soil to a concentrated solution in the root hair cell
• active transport in humans

  allows sugar molecules to be absorbed from the small intestine when the sugar concentration is higher in the blood than in the small intestine
• active transport in plants

  used to absorb mineral ions into the root hair cells from more dilute solutions in the soil
• diffusion - the net movement of substances from an area of high concentration to an area of low concentration.
• factors which affects diffusion

  1. concentration gradient - when bigger, diffusion rate is faster
  2. the temperature - higher, faster diffusion
  3. surface area of cell membrane - larger, faster diffusion
• diffusion in humans

  • nutrients in the small intestine diffuse into capillaries through the villi
  • oxygen diffuses from the air in the alveoli into the blood in the capillaries. Carbon dioxide diffuses from the blood in the capillaries into the air in the alveoli
  • urea diffuses from cells into the blood for excretion in the kidney
• diffusion in plants

  • CO2 used for photosynthesis diffuses into leaves by stomata
  • O2 produced during photosynthesis diffuses out of the leaves through the stomata
• magnification = image size/actual size
• light microscope:

  • uses lgiht to form images
  • living samples can be viewed
  • low magnification
  • low resolution
• electron microscope:

  • uses a beam of electrons to form an image
  • samples cannot be living
  • expensive
  • high magnification
  • high resolution
  • allows you to see sub-cellular structures e.g. ribosomes