Download - ocr biology b3
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Cholesterol
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LEARNING OUTCOMES
•Describe the effects of cholesterol on the body
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The good, the bad, and the even better
Saturated Mono-unsaturated Poly-unsaturated
the bad The good The even better
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Restoring the balanceSaturated fats (“bad fats”) increase cholesterol levels.
Mono-unsaturated fats and polyunsaturates may help reduce cholesterol and restore the balance between LDLs and HDLs.
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The problem with cholesterol
• Sometimes cholesterol in the blood sticks to the inside of artery walls.
• As it builds up it forms a plaque, this restricts the flow of blood.
• Sometimes, the cholesterol can break away and block the artery completely.
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Statins
• Statins are a group of chemicals which prevent all of the cholesterol being absorbed in to the blood stream
• This lowers peoples overall cholesterol – which can reduce health problems
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The Big Picture
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Mitosis v Meiosis
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LEARNING OUTCOMES
•Compare and contrast meiosis and mitosis
•Describe adaptations of a sperm cell
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The Big Picture
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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
MeiosisMeiosis
Mitosis
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Cell division – the differences
MITOSIS MEIOSISDiploid 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
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Sperm adaptations• Acrosome - contains
enzymes to digest the egg cell membrane
• Tail – many mitochondria in cells to release energy.
WHY
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ENZYMES
DIGESTS EGG MEMBRANE / PENETRATE / GET INSIDE THE EGG
RESPIRATION
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MITOSIS – DIPLOID CELLS (46 CHROMOSOMES)MEIOSIS – HAPLOID CELLS (23 CHROMOSOMES)
MITOSIS – IDENTICAL CELLSMEIOSIS – DIFFERENT CELLS
MITOSIS – 1 CELL DIVISIONSMEIOSIS – 2 CELL DIVISIONS
MITOSIS 2 DAUGHTER CELLSMEIOSIS 4 DAUGHTER CELLS
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The Big Picture
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Growth spurts
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LEARNING OUTCOMES
•Explain why gestation periods differ in different animals
•State that different parts of a foetus and baby grow at different rates
•Describe the main phases of human growth
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Human growth
• Put the stages of human growth in the correct order, starting with the earliest:– Adulthood (maturity)– Childhood– Infancy– Old age– Adolescence (puberty)
• What stage of growth are you in?
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The Big Picture
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Plant cells and growth
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LEARNING OUTCOMES
•Compare and contrast an animal and plant cell
•State how animals and plants grow differently
•Explain animal and plant growth in terms of cell growth
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ChloroplastsCell Wall
Vacuole
Cell Membrane
Nucleus
Cytoplasm
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Plant and animal cells
• Name three structures found in a plant cell but not in an animal cell
• Name three structures found in both a plant cell and an animal cell
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Growth
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Growth
• Plant• Most growth is due to
cells elongating (growing longer) not dividing
• Cell division only normally occurs at the tips of shoots and roots
• Many cells never lose the ability to differentiate
• Animal• Growth is due to cells
dividing• Cell division occurs all
over the body• Most animal cells lose the
ability to differentiate very early on
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LEARNING OUTCOMES
•Compare and contrast an animal and plant cell
•State how animals and plants grow differently
•Explain animal and plant growth in terms of cell growth