Biology

• hi guys is your science teacher here back with a another video this time i'm gonna try and go through the whole of paper one gcse biology which i know it sounds like a lot um but i'm gonna try and keep it as concise as possible if you do find any of the topics a little bit tricky or you're struggling to understand it please go into my playlist and watch my individual topic videos they go into the topics in a lot more depth but without further ado let's get started as i'm going to try and waste as little time as possible
• Cell structure


  The first topic in biology paper one
• Types of cells


  • Plant cells
  • Animal cells
• Plant cell


  • Cell wall makes it rigid and acts as a barrier
  • Cell membrane controls what goes in and out
  • Chloroplasts are the site of photosynthesis
  • Nucleus contains genetic information and controls the cell
  • Vacuole contains sugar and helps the cell stay in shape
  • Mitochondria are the site of respiration
  • Ribosomes are where proteins are synthesized
• Animal cell


  • Does not contain chloroplasts, vacuole, or cell wall
  • Contains nucleus, ribosomes, and mitochondria
  • Cytoplasm is the jelly-like substance where chemical reactions take place
• Microscopes


  • Used to see incredibly small things like cells
  • Light microscopes can be used to see live or dead samples, are cheap and portable
  • Scanning electron microscopes can only be used for dead samples, are expensive and large
• Magnification


  • Real size of an object = size of image / magnification
  • Magnification = objective lens x focusing lens
• Specialized animal cells


  • Red blood cells
  • White blood cells
  • Muscle cells
  • Sperm cells
• Red blood cells


  • Donut shape to carry more oxygen
  • No nucleus to free up space for oxygen
• White blood cells


  • Irregular shape to fit in blood vessels
  • Flexible to travel to sites of infection
• Muscle cells


  • Long and flexible to allow tensing
  • Packed with mitochondria for energy
• Sperm cells


  • Long tail to swim
  • Acrosome in head to penetrate egg
  • Packed with mitochondria for energy
• Specialized plant cells


  • Root hair cells
  • Xylem cells
  • Phloem cells
• Root hair cells


  • Large surface area to absorb water and minerals
  • Large vacuole to store sugar
  • Many mitochondria for active transport
• Xylem cells


  • Made of dead cells to transport water and minerals upwards
• Phloem cells


  • Living cells that transport glucose up and down the plant
  • Contain mitochondria to provide energy for transport
• Eukaryotic cells


  Cells that work together in multicellular organisms
• Prokaryotic cells


  • Cells that don't work together, like bacteria
  • Have a nucleoid instead of a nucleus
  • May have a flagellum, cell wall, and organelles like mitochondria and chloroplasts
• Diffusion


  1. Movement from high to low concentration

  2. Increases with higher temperature and concentration gradient
• Osmosis


  Movement of water across a partially permeable membrane
• Active transport


  Movement from low to high concentration, requires energy
• Mitosis


  1. Cell division to produce genetically identical daughter cells

  2. DNA is copied, then the cell splits into two
• Meiosis


  1. Cell division to produce gametes with half the normal number of chromosomes

  2. DNA is copied, then the cell divides twice to produce four genetically different daughter cells
• Stem cells


  • Unspecialized cells that can develop into different cell types
  • Found in embryos and bone marrow
  • Controversial due to ethical issues with using embryos
• Tissues


  Groups of cells working together
• Organs


  Groups of different tissues working together, e.g. the heart
• It's not accepted by many religious groups they don't believe um their embryonic stem cell research is right as it's come from a fertilized um egg and this could have developed into a person also many embryos are discarded and it doesn't have a 100 success rate
• But i am almost certain that there will be some more research into stem cells and looking at stem cells to cure a wide variety of different diseases whether them stem cells are acquired by bone marrow or embryo though is up for debate
• Cellular basis


  Humans are a lot more complicated than just cells, we have thousands of different types of cells that work together
• Tissue


  When cells work together
• Organ


  When many different tissues work together
• Plants also have organization, a plant organ is a leaf and it's made up of many different types of tissue
• Organ system


  When organs work together
• Organ systems we will look at


  • Digestive system
  • Circulatory system
• Organism


  When all organ systems work together, an example is a human being
• Digestive system


  1. Chewing in mouth

  2. Mixing with saliva

  3. Travelling down esophagus

  4. Stomach churning and acid breaking down food

  5. Enzymes from pancreas added

  6. Bile from liver emulsifies fats

  7. Small intestine absorption

  8. Large intestine disposal
• Lock and key mechanism


  Enzyme binds to substrate in active site, forms enzyme-substrate complex, then breaks it down into smaller products
• Nutrients broken down


  • Starch into glucose
  • Lipids into fatty acids and glycerol
  • Proteins into amino acids
  • Carbohydrates into glucose
• Enzymes


  • Amylase breaks down starch
  • Lipase breaks down lipids
  • Protease breaks down proteins
  • Carbohydrases break down carbohydrates
• As temperature increases


  Enzyme activity increases up to a point, then they denature