ocr biology b3

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key points from a few lessons linked to mock exam

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ocr biology b3

  1. 2. Cholesterol
  2. 3. LEARNING OUTCOMES <ul><li>Describe the effects of cholesterol on the body </li></ul>
  3. 4. The good, the bad, and the even better Saturated Mono-unsaturated Poly-unsaturated the bad The good The even better
  4. 5. Restoring the balance Saturated fats (“bad fats”) increase cholesterol levels. Mono-unsaturated fats and polyunsaturates may help reduce cholesterol and restore the balance between LDLs and HDLs.
  5. 6. The problem with cholesterol <ul><li>Sometimes cholesterol in the blood sticks to the inside of artery walls. </li></ul><ul><li>As it builds up it forms a plaque, this restricts the flow of blood. </li></ul><ul><li>Sometimes, the cholesterol can break away and block the artery completely . </li></ul>
  6. 8. Statins <ul><li>Statins are a group of chemicals which prevent all of the cholesterol being absorbed in to the blood stream </li></ul><ul><li>This lowers peoples overall cholesterol – which can reduce health problems </li></ul>
  7. 9. The Big Picture
  8. 10. Mitosis v Meiosis
  9. 11. LEARNING OUTCOMES <ul><li>Compare and contrast meiosis and mitosis </li></ul><ul><li>Describe adaptations of a sperm cell </li></ul>
  10. 12. The Big Picture
  11. 13. Egg Haploid 23 chromosomes Sperm Haploid 23 chromosomes Zygote (fertilised egg) Diploid 46 chromosomes Cell in ovary Diploid 46 chromosomes Cell in testes Diploid 46 chromosomes Fertilisation Meiosis Meiosis Mitosis
  12. 14. Cell division – the differences MITOSIS MEIOSIS Diploid cells / 2n Haploid cells / n (1) Produces identical cells Produces different cells Involves 1 cell division 2 cell divisions Makes 2 daughter cells Makes 4 daughter cells
  13. 15. Sperm adaptations <ul><li>Acrosome - contains enzymes to digest the egg cell membrane </li></ul><ul><li>Tail – many mitochondria in cells to release energy. </li></ul><ul><li>WHY </li></ul>
  14. 16. ENZYMES DIGESTS EGG MEMBRANE / PENETRATE / GET INSIDE THE EGG RESPIRATION
  15. 17. MITOSIS – DIPLOID CELLS (46 CHROMOSOMES) MEIOSIS – HAPLOID CELLS (23 CHROMOSOMES) MITOSIS – IDENTICAL CELLS MEIOSIS – DIFFERENT CELLS MITOSIS – 1 CELL DIVISIONS MEIOSIS – 2 CELL DIVISIONS MITOSIS 2 DAUGHTER CELLS MEIOSIS 4 DAUGHTER CELLS
  16. 18. The Big Picture
  17. 19. Growth spurts
  18. 20. LEARNING OUTCOMES <ul><li>Explain why gestation periods differ in different animals </li></ul><ul><li>State that different parts of a foetus and baby grow at different rates </li></ul><ul><li>Describe the main phases of human growth </li></ul>
  19. 21. Human growth <ul><li>Put the stages of human growth in the correct order, starting with the earliest: </li></ul><ul><ul><li>Adulthood (maturity) </li></ul></ul><ul><ul><li>Childhood </li></ul></ul><ul><ul><li>Infancy </li></ul></ul><ul><ul><li>Old age </li></ul></ul><ul><ul><li>Adolescence (puberty) </li></ul></ul><ul><li>What stage of growth are you in? </li></ul>
  20. 22. The Big Picture
  21. 23. Plant cells and growth
  22. 24. LEARNING OUTCOMES <ul><li>Compare and contrast an animal and plant cell </li></ul><ul><li>State how animals and plants grow differently </li></ul><ul><li>Explain animal and plant growth in terms of cell growth </li></ul>
  23. 25. Chloroplasts Cell Wall Vacuole Cell Membrane Nucleus Cytoplasm
  24. 26. Plant and animal cells <ul><li>Name three structures found in a plant cell but not in an animal cell </li></ul><ul><li>Name three structures found in both a plant cell and an animal cell </li></ul>
  25. 27. Growth
  26. 28. Growth <ul><li>Plant </li></ul><ul><li>Most growth is due to cells elongating (growing longer) not dividing </li></ul><ul><li>Cell division only normally occurs at the tips of shoots and roots </li></ul><ul><li>Many cells never lose the ability to differentiate </li></ul><ul><li>Animal </li></ul><ul><li>Growth is due to cells dividing </li></ul><ul><li>Cell division occurs all over the body </li></ul><ul><li>Most animal cells lose the ability to differentiate very early on </li></ul>
  27. 29. LEARNING OUTCOMES <ul><li>Compare and contrast an animal and plant cell </li></ul><ul><li>State how animals and plants grow differently </li></ul><ul><li>Explain animal and plant growth in terms of cell growth </li></ul>

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