Biology End of years

• Cells are the basic building blocks of life and are the smallest unit of structure that can perform all the functions of life
• A typical prokaryotic cell contains -

  plasmids, ribosomes, a cell wall, a cell membrane , capsule, DNA

  , cytoplasm and flagellum
• A typical eukaryotic animal cell contains-

  A cell membrane, cytoplasm,ribosomes,mitochondria, and a nucleus
• A typical eukaryotic plant cell contains-

  a vacuole, cell membrane,cell wall,chloroplasts,cytoplasm,ribosomes,mitochondria and a nucleus
• Plants and animal cells are multicellular
• multicellular


  they contain many different cells
• Animal cells differentiate at an early stage, whereas plant cells differentiate throughout their life
• Red blood cells


  transport oxygen, high surface area,bi-concave disc and contain haemoglobin,they also have no nuclei
• Nerve Cells


  Send electrical messages around the body, they have a mylen sheath and have branches a the end of them to other nerve cells
• Sperm Cells


  they have acrosomes (enzymes to help the cell penetrate through the egg),flagellum(to help the cell swim to the egg), mitochondria (releases energy) and is required for fertilisation
• White blood cells


  they fight pathogens,engulf pathogens and make antibodies
• Root hair cell


  they have a large surface area to increase the rate of absorption
• Cells start as stem cells and then they specialise into specialised cells
• stem cells->progenitor cells->specialised cells
• Stem cells are special human cells
• Stem cells musty replicate, they do this to make more stem cells
• Stem cells can become any other type of cell
• Others can become only one type of cells
• Stem cell Division

  
• Embryonic stem cells can become any cell type


  embryo
• Adult stem cells in bone marrow can be used to treat blood disorders
• Embryonic stem cells are theorised to be able to treat paralysis
• Uses for embryo's for stem cells

  For

  cure diseases that have no cure

  research

  the embryo's technically haven't been born yet

  help people in pain

  save endangered species

  
  

  Against

  kills embryos's which could've potentially led to life

  leads to physical pain

  cause overpopulation
• Mitosis is the process of cell division, in which one cell divides into two genetically identical daughter cells.
• Mitosis(cell cycle)

  
• Diffusion is the movement of particles from an area of high concentration to an area of low concentration
• Active transport is the movement of particles against the concentration gradient from a region of low concentration to a region of high concentration
• Osmosis is the net movement of water across a partially permeable membrane, from an area of lower solute to an area of higher solute
• Rate of diffusion is the number of particles that pass a given area per unit time.
• These factors increase the rate of diffusion-

  1.More surface area(More space/area for diffusion)

  2.Temperature(More kinetic energy=faster moving particles)

  3.Concentration(Larger the gradient,faster the rate)

  4.Distance of diffusion(Shorter distance=quicker)
• Enzymes have optimum conditions (condition in which they work best at), they are made out of proteins and can denature(change shape).
• Lock and key theory

  
• Rate of reaction=change of 'x'

  ---------------

  change of time
• Increase temp increases enzyme activity because it gives more kinetic energy so molecules move faster and collide with enzymes more often.
• The heart is a muscular organ that pumps blood around the body.

  
• Right side->deoxygentaed blood

  Left side->oxygenated blood
• veins carry blood to the heart, whereas, arteries carry blood away from the heart
• pulmonary artery carries deoxygenated blood to the lungs

  pulmonary vein carries oxygenated blood to the rest of the body
• Arteries are thicker due to high pressure andhave strong thick walls which contain a thick muscular layer which contracts to increase pressure.They have a lumen-empty space where blood flows
• veins have valves but arteries don't to prevent backflow