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GCSE Biology Revision

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Glucose or reducing sugar add Benedict's solution and boil turns brick red ... When we breathe in the intercostal muscles contract and the ribs move up and out. ... – PowerPoint PPT presentation

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Title: GCSE Biology Revision


1
GCSE Biology Revision
  • 2006-2007

2
Life Processes
  • Movement
  • Respiration
  • Sensitivity
  • Growth
  • Reproduction
  • Excretion
  • Nutrition

Mrs Gren or many naughty rabbits eat green
rhubarb stems
3
Plant and Animal Cells
(cellulose)
mitochondria
4
Cell specialisation
5
Cell organisation
system
organism
6
Transport In and Out of Cells
  • Diffusion from a high to a low concentration
    until they are evenly spread
  • Osmosis from a region of high water
    concentration to a region of low (weak to a
    strong solution) through a semi permeable
    membrane
  • Active transport from a low to a high
    concentration across a cell membrane

7
Digestion
8
Balanced Diets
  • Carbohydrates
  • Protein
  • Lipids / Fats
  • Vitamins
  • Minerals
  • Fibre
  • Water

9
The Duodenum
10
The Ileum
11
Absorption and Assimilation
Glucose and amino acids are absorbed into the
blood Fatty acids and glycerol are absorbed into
the lacteal
12
Assimilation
  • All digested glucose and amino acids pass into
    the liver in the Hepatic Portal Vein.
  • Fats enter the lymphatic system which enters the
    blood and returns them to the liver.
  • The food is used for growth, repair, respiration.
  • Excess food is mostly stored as fat.

13
Food Testing
  • Starch add iodine turns black
  • Glucose or reducing sugar add Benedict's
    solution and boil turns brick red
  • Protein Biuret test add NaOH or KOH and then
    1 copper sulphate a violet colouration

14
Aerobic Respiration
  • With oxygen
  • C6H12O6 6O2 6H2O 6CO2 energy

15
Anaerobic Respiration
  • Animals
  • Glucose Lactic acid
  • Plants
  • Glucose Ethanol and carbon dioxide
  • Oxygen debt the amount of oxygen needed to
    breakdown the lactic accumulated

16
Structure of Thorax
17
The Thorax
18
Breathing in
  • Is controlled by the intercostal muscles and the
    diaphragm.
  • When we breathe in the intercostal muscles
    contract and the ribs move up and out. The
    diaphragm contracts and moves down.
  • This increases the space inside the chest and air
    rushes into the lungs.

19
Breathing out
  • The intercostal muscles and the diaphragm relax.
  • The ribcage drops down and the diaphragm moves
    upwards.
  • This reduces the space inside the chest and
    pushes air out of the lungs.

20
Breathing Rate and Depth
  • Rate - how many breaths per minute
  • Depth how much air is being taken in, normally
    ½ litre per breath
  • Measured with a spirometer

21
of different gases in inhaled and exhaled air
22
Gaseous exchange
23
What makes the lung good at gaseous exchange?
  • Large surface area greater volume of gases
    exchanged
  • Good blood supply O2 and CO2 exchanged more
    quickly
  • Thin membranes allows diffusion
  • Moist lining for the gases to dissolve

24
Keeping the Lungs Clean
  • Dust, bacteria and other particles stick to the
    mucus secreted by cells lining the airways
  • Cilia attached to these cells waft the mucus and
    dirt out of the lungs and it is swallowed.
  • Acid in the stomach kills the bacteria

25
Effects of Smoking
  • Tar causes cancer
  • Nicotine is addictive
  • Smoking removes the hairs that keep the lungs
    clean

26
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27
Photosynthesis
  • lightcarbon dioxidewater
    glucoseoxygen chlorophyll
  • 6H2O 6CO2 C6H12O6
    6O2

28
Leaf Structure
29
  • The leaf has a waxy cuticle to stop it losing
    water.
  • The epidermis is a protective layer of cells and
    contains no chloroplasts.
  • The palisade layer contains the most chloroplasts
    as it is near the top of the leaf. The
    chloroplasts contain the pigment chlorophyll. It
    is here that photosynthesis takes place.
  • The palisade cells are arranged upright. This
    means the light has to pass through the cell
    lengthways and so increases the amount of light
    absorbed.

30
Stomata
Guard cells
stoma
Water moves into the guard cells by osmosis and
the stoma opens
31
Day
During the daytime the rate of photosynthesis is
greater than the rate of respiration
32
Night
During both the day and night respiration occurs
in plants.
33
Limiting Factors
  • Photosynthesis is a chemical reaction, its rate
    depends upon temperature, how much CO2 is
    available, light intensity, amount of chlorophyll
    or water.
  • Without enough light a plant cannot
    photosynthesise very fast, even if there is
    plenty of water and carbon dioxide. Increasing
    the light intensity will make photosynthesis
    faster.

34
  • Sometimes photosynthesis is limited by the level
    of carbon dioxide. Even if there is plenty of
    light a plant cannot photosynthesise if it has
    run out of carbon dioxide.
  • Temperature can be a limiting factor too. If it
    gets too cold the rate of photosynthesis will
    slow right down equally, plants cease to be able
    to photosynthesise if it gets too hot.

35
  • If you plot the rate of photosynthesis against
    the levels of these three limiting factors you
    get graphs like the ones below.

36
Maximising growth
  • Understanding the factors that limit
    photosynthesis enables greenhouse farmers to
    maximise the conditions for plant growth. They
    often use paraffin lamps inside the greenhouse
    because burning paraffin produces carbon dioxide
    as well as heat, and so makes photosynthesis
    proceed faster. They may also use artificial
    light to enable photosynthesis to continue beyond
    daylight hours.

37
Uses of Glucose
  • Turned into starch for storage
  • Converted into lipid/fat for storage energy
    rich
  • Nitrogen can be added and turned into protein
  • Stored in fruit
  • Used in respiration

38
Mineral Requirements
Magnesium for chlorophyll Nitrogen for
growth Phosphorus for cell membranes and DNA
Remember how to test leaves for starch
39
The Heart
40
The Heart
  • Pumps blood around the body
  • Pumps blood to the lungs
  • To pick up oxygen
  • Remove carbon dioxide

41
Double Circulation
Heart Lungs Heart Body Heart
Greater pressure, better oxygenation, faster flow
42
Arteries Veins and Capillaries
Thin walls, deoxygenated blood, to the heart,
valves
Thick walls, oxygenated blood, away from heart
Link arteries to veins, site of exchange of
metabolites and waste
43
Blood
Red blood cells, transport oxygen, biconcave, no
nucleus,
White blood cells, defence, engulf bacteria,
produce antibodies
44
Platelets
  • Used in the clotting of blood
  • Damage cause them to clump and they begin the
    conversion of soluble fibrinogen (blood protein)
    into insoluble fibrin which meshes over the wound
    and traps red cells. They dry and form a scab

45
Blood Cells
46
Tissue exchange
Glucose
Waste
PLASMA
47
The lymphatic system
  • Transports excess fluid from the tissues
  • Transports digested fat
  • Contains white blood cells that fight infection

48
William Harvey
  • 1578-1657
  • Observed blood flow around the body
  • Noticed existence of valves in veins
  • Concluded blood pumped via veins round body
  • Major medical breakthrough!

49
Galen
  • Lived 1,000 years before Harvey
  • Did not use the scientific method
  • Observation and experimentation
  • Thought blood went from side to side
  • Did not realise transport existed round body
    through capillaries

50
Transport in Plants
51
The Plant Transport System
A plant's transport system is made up of two
types of tubes - strong, thick pipes called xylem
vessels, and thinner tubes called phloem vessels.
The cells of these vessels are modified to make
them suited to performing their special
functions                                         
               Together xylem and phloem form
the vascular tissue, often also referred to as
the vascular bundle.
52
  • Xylem consists of dead cells with no end walls,
    which contain lignin to form stiff tubes. They
    are impermeable.

53
Phloem consists of living cells lined with
cytoplasm, with walls made of cellulose and
perforated end walls. They are permeable, and are
surrounded by companion cells.
54
                                                  
                
Water is taken up the plant from the roots to the
leaves (for photosynthesis and transpiration) -
in xylem vessels . Minerals dissolved in the
water are taken up the plant to the shoots and
leaves - in xylem vessels. Food (the product of
photosynthesis) is taken from the leaves and
moved up and down the plant to any part which
needs it (for growth or for storage) - in phloem
vessels.
55
Transpiration
  • Temperature
  • Humidity
  • Air movement
  • Light

56
Ecology Competition and Adaptation
Keeping cool
Keeping warm
57
Plant adaptations
Not being eaten Reducing water loss
58
Predators, Prey and Co-operation
Snowshoe hare
Arctic fox
59
Food Chains
60
Woodland Food Web
61
Pyramid of Numbers
Remember not always pyramid shape
62
Pyramid of biomass
fox
rabbit
grass
Biomass is dry weight water has been removed
63
Decomposition
Decomposers are bacteria and fungi
Organic matter- ammonium compounds-nitrite-nitrate
64
The Carbon Cycle
Plants and animals die and decay
65
Nitrogen Cycle
66
Food Production and farming methods
  • Monoculture
  • Hedgerow removal
  • Biological pest control
  • Pesticides and herbicides and insecticides

67
Energy and Waste
  • Burning fossil fuels such as coal, oil or gas
  • Greenhouse effect
  • Sulphur dioxide and nitrous oxides are formed
    which dissolve in water to form acid rain
  • Reduce the demand for energy so it reaches a
    sustainable level- will not use up the resources
    or pollute the planet

68
Global Warming and Acid Rain
69
Conservation
To prevent habitats and organisms from
disappearing
Limit or ban hunting. Gene banks of frozen eggs,
sperm or embryos. Zoos and captive breeding
programmes. Preserve habitats
70
The Nervous System
Stimulus
Response
Receptor
Effector
Sensory Neuron
Motor neuron
Central nervous system
71
Motor neuron
72
The Eye
73
Accommodation
Long distance lens long and thin, ciliary
muscle relaxed, suspensory ligaments taut Near
lens short and fat ciliary muscle contacted,
suspensory ligaments loose
74
Nerves Synapses and Drugs
Some drugs stimulate synapses like a
neurotransmitter, LSD and nicotine Others block
the enzyme that normally breaks down the
neurotransmitter Alcohol depresses synaptic
activity in the brain and acts as a depressant.
So do solvents
75
The CNS and Reflex Actions
76
Hormones
  • Proteins that are chemical messengers in the body
  • Carried in the blood to target cells
  • Response is slower
  • May last for hours
  • Can stimulate more than one target

77
Controlling glucose,
  • After eating a lot of carbohydrate blood sugar
    level rises.
  • Islets of Langerhans in the pancreas release
    insulin, the glucose is stored as glycogen in the
    liver.
  • The blood sugar level drops .
  • When blood sugar levels are low the insulin
    production stops.
  • Glucagon is produced by the pancreas allowing
    glucose release from the liver and muscles.

78
Uses of Hormones
  • Controlling fertility the contraceptive pill,
    may contain oestrogen and progesterone and
    controls the release of pituitary hormones and
    ovulation
  • Mini pill, progesterone allows ovulation but
    makes the vagina and uterus unsuitable for sperm
  • Anabolic steroids build muscle reduce the
    production of testosterone

79
Uses of plant hormones
  • Auxins allow plants to respond to the environment
    tropic responses
  • Auxin (IAA) causes -
  • They stimulate shoots to grow rapidly
  • Stops side shoots growing
  • Stimulates growth of roots from the base of stems
    or leaves
  • Auxin from seeds cause fruit to swell

80
Plant responses and Auxins
Hormone rooting powder causes roots to grow from
cut stems Seedless fruits grapes, cucumbers,
bananas. (parthenocarpy) Selective weedkillers
2-4-D causes weeds to grow too fast and results
in death, grass doesnt take it up well
Q 3,4,5 page 102 for Wednesday
81
Homeostasis
  • Temperature Control
  • Water Control
  • Salt Balance
  • Sugar control
  • Carbon Dioxide Control
  • Urea

82
Temperature Control
  • Thermoregulation keeps the body at constant
    temperature (37oC).
  • Enzymes work best.
  • Temperature is regulated by the hypothalamus.

83
Temperature Control
  • Heat is made in most cells but in particular
    muscle and liver.
  • Heat is lost by convection, conduction and
    radiation.
  • Evaporation of water from a surface removes heat.

84
Keeping Cool
  • Vasodilation, more blood flows nearer the skin
    and heat is lost.
  • Sweating, evaporation causes heat loss.
  • Hairs lie flat allowing more heat out.

85
Keeping Warm
  • Vasoconstriction - less blood flows to the skins
    surface, keeping heat in. You may look pale!!
  • Decrease in sweat.
  • Shivering generates heat (respiration).
  • Hairs stand up and trap insulating air.

86
Carbon dioxide
  • Excess carbon dioxide results in a drop in the
    bodys pH (acidic).
  • Breathing out removes this excess.
  • The rate and depth of breathing will alter to
    suit the amount of CO2.

87
The Kidney
88
Urea
  • Urea is produced when proteins and amino acids
    are broken down in the liver.
  • It is poisonous.
  • The kidneys remove it but so does sweating !!

89
The kidney
90
  • The kidneys have four functions
  • Regulation of blood water levels
  • Reabsorption of useful substances into the blood
  • Adjustment of the levels of salts and ions in the
    blood
  • Excretion of urea and other metabolic wastes

91
Kidneys how they work
92
Kidney transplant
  • This is when the diseased kidney is surgically
    removed and replaced by a fully functioning
    kidney from a deceased or a live donor.
  • It is only possible after a satisfactory
    tissue-match. Even after a successful
    tissue-match the recipient's immune system has to
    be drugged or suppressed to stop it from
    rejecting the new kidney.

93
Kidney failure
  • In the event of kidney failure due to infection
    or disease, the kidney can no longer remove
    metabolic waste products from the body. Excretion
    of metabolic waste is a vital function and their
    accumulation will result in eventual death.
  • There are two solutions to the problem of kidney
    malfunction or failure
  • Kidney transplant
  • Kidney dialysis

94
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95
Kidney dialysis
  • In the absence of a suitable donor kidney, the
    alternative solution is for the patient to be
    hooked-up to a dialysis machine every 2 - 3 days.
  • A dialysis machine mimics the functioning of the
    kidney. Blood from an artery in the patient's arm
    is pumped into the kidney machine which removes
    urea and excess salts from it.
  • The blood is checked for air bubbles before being
    returned to a vein in the arm.

96
Osmoregulation
  • Is keeping the water and salt levels constant in
    the blood.
  • They are regulated by the hypothalamus.
  • Water moves into the cells by osmosis and could
    cause them to burst.

97
Blood concentration too high
  • The hypothalamus senses too little water in the
    blood.
  • A message is sent to the pituitary gland to
    release anti-diuretic hormone.
  • This stops the kidneys removing water and going
    to the loo!!

98
Blood concentration too low.
  • Too much water in the blood stops the
    hypothalamus signalling the pituitary.
  • Water is removed by the kidneys.
  • Large amounts of dilute urine produced.

99
Cell Division - Mitosis
100
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101
DNA
DNA structure discovered by Crick and Watson
102
Genetic and Environmental causes of Variation
  • Variation is inherited
  • Genetic skin colour
  • Environmental hair length
  • Both height, weight, intelligence

103
Asexual reproduction
  • Produces identical copies called clones onions,
    strawberries, potatoes, greenfly
  • This type of cell division is mitosis
  • Cuttings and grafting in plants
  • Micropropogation used by growers

104
Mutations
  • Change in the DNA of an organism caused by an
    error when it is copied
  • Radiation and certain chemicals such as cigarette
    smoke can cause mutations
  • Most are harmful and leads to illness or death
  • Useful ones are rare but have a dramatic impact
    on a species and its evolution

105
Harmful mutations
  • Downs syndrome an extra chromosome number 21
  • Cystic fibrosis is caused by a mutation in the
    DNA. It is a recessive allele which affects 1 in
    2000 children.
  • It causes sticky mucus which blocks the lungs and
    pancreas

106
Genetic Engineering
  • Is the ability to alter DNA
  • A gene from one organism can be transferred into
    the DNA of a completely different organism
  • In some cases the all the DNA is removed from a
    cell and replaced with the DNA from another
    organism
  • Dolly the sheep was the first example of genetic
    cloning

107
Selective Breeding
  • In animals dogs, cows, sheep, cats and so on.
    To produce certain traits
  • In plants for taste, texture, shelf life
  • Is done by choosing parents with the required
    traits. These are then bred to produce offspring.
  • Sexual reproduction will ensure variation

108
Mendel
Studied peas and concluded that characteristics
were passed on from one generation to another.
Law of segregation the 2 alleles separate when
gametes are formed, one allele into one gamete
and the other into another Law of independent
assortment any gamete of the father can
fertilise any gamete of the mother
109
Genetic Crosses
110
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111
Evolution
  • Most organisms overproduce
  • Population numbers remain constant
  • Sexual reproduction ensures that all offspring
    exhibit variation
  • These variations are inherited from the parents
  • From these Darwin produced his theory of evolution

112
Darwin
  • Evidence for evolution
  • Fossils
  • Homologous structures bats wing, forearm,
    horses leg.

113
New Species Survival of the Fittest
  • The peppered moth
  • Pale ones no longer camouflaged during the
    Industrial Revolution were no longer
    camouflaged
  • Darker ones survived to reproduce and some of
    their offspring were even darker
  • This is survival of the fittest
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