Cells Photosynthesis and what affects it Menstrual cycle ... · Photosynthesis is controlled by...

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Biology Booster Topics Paper 2 Cells Photosynthesis and what affects it Menstrual cycle Carbon/nitrogen cycle

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  • Biology Booster Topics

    Paper 2• Cells• Photosynthesis and what affects it • Menstrual cycle• Carbon/nitrogen cycle

  • Cells and microscope

    Combined Science

    Paper 1

  • Units

    Units Meters 10 ⁰= 1m

















  • Changes in microscope technology

    Light microscope

    • Can magnify images up to x1500

    • Uses lenses and light

    • Can magnify small organisms.

  • Labelling microscopes

  • Electron microscope

    • Can magnify up to

    x 2,000,000

    • Uses beams of electrons to build up image.

    • More resolution (clarity.)

    • Can see sub cellular structures (organelles) in cells.

    Same magnification but different resolution.

  • Which organelles are in animal or plant cells?


    Cell membrane

    Cytoplasm Cell wall




  • How are plant cells adapted?

  • A single bacterium

    cell wall

    loose genetic


    absent from animal cells




    present in animal cells

    Bacteria can be different shapes but this diagram can

    represent them.

  • Plant structures and function

    Combined Science

    Paper 2

  • What is photosynthesis?Plants make their own food( by photosynthesis using light energy.

    light energy

    ‘photo’ means ‘light’

    ‘synthesis’ means ‘putting together’

    Photosynthesis just means ‘putting together with light’.

    Photosynthetic organisms are main producers of food and therefore biomass.

  • Word and symbol reaction

    CO2 H2O C6H12O2 O2+ +6 6 6

    light energy


    carbon dioxide + water oxygen+glucose

    light energy


    Photosynthesis is a chemical reaction that takes place in the chloroplasts of green plant cells, where light energy is used to convert carbon dioxide and water into glucose and oxygen.

  • Rate of photosynthesis

    Like many reactions, photosynthesis requires enzymes.

    Photosynthesis is a chemical reaction and so has a rate.


    Factors affecting the rate of photosynthesis:

    carbon dioxide temperature

  • Factors affecting photosynthesis

    Light energy has to be absorbed by chlorophyll for photosynthesis to take place. More light energy means that photosynthesis will be faster.

    Carbon dioxide is one of the raw materials used by plants to make their food. More carbon dioxide means more photosynthesis, so plants make more food and grow more quickly.

    Photosynthesis is controlled by enzymes, which usually work best at warmer temperatures. If it gets too hot (above 40°C), the enzymes begin to break down and are destroyed or denatured. The rate of photosynthesis decreases or even stops completely.

  • What is the ideal combination of factors for the maximum rate of photosynthesis?

    What is a limiting factor?

    enough light

    How does restricting one of these facts affect the rate?

    If one of the factors is restricted, the rate of photosynthesis will be reduced.

    The restricted factor controls how quickly photosynthesis occurs and so limits the rate. It is called the limiting factor.

    enough carbon dioxide


    ideal temperature (not too hot or cold).

  • Limiting factors

    Photosynthesis is controlled by enzymes.

    If it gets above or below optimum temperature the

    enzymes begin to denatured. The rate of

    photosynthesis decreases.

    More light energy means that

    photosynthesis will be faster.

    More carbon dioxide means more

    photosynthesis, so plants make more

    food and grow more quickly.

  • Animal coordination, control and homeostasis

    Combined Science

    Paper 2

  • Cells in different parts of the body recognize the hormones and respond by making changes.



    Hormones are chemicals that act like messengers. They are secreted by glands and carried in the blood from organ to organ.


  • Glands and their hormonesMajor glands of the body:


    adrenal glands

    testes (males)

    pituitary gland


    ovaries (females)

  • Adrenal glands releases adrenalin

    adrenal glands

    This is to prepare the body for fight or flight; this includes:a. increased heart rateb. increased blood pressurec. increased blood flow to the musclesd. raised blood sugar levels by

    stimulating the liver to change glycogen into glucose

  • Thyroxine controls metabolic rate as anexample of negative feedback, including:a low levels of thyroxine stimulates production of TRH (thyrotropin releasing hormone) in hypothalamusb this causes release of TSH (thyroid stimulating hormone) from the pituitary glandc TSH acts on the thyroid to produce thyroxined when thyroxine levels are normal thyroxine inhibits the release of TRH and the production of TSH

    Thyroid gland releases thyroxine

    Thyroid glands

  • RECAP: The Female Reproductive System

  • Day 0-5 – menstruation occurs.

    The lining of the uterus wall breaks down.

    Day 0-5 – Hormones oestrogen and

    progesterone are at their minimum levels.

  • Day 5-13 – The levels of oestrogen rise, eggs

    develop(matures), inside the follicle.

    Day 5-13 – The increase in oestrogen causes the uterus lining to thicken with blood


  • Day 14- ovulation (egg is released)

    14- 28 – The levels of oestrogen fall and the

    levels of progesterone rise.

    Day 14-28 – Progesterone is produced by the empty follicle.

    This follicle is now yellow (corpus luteum) and is withering away.

    Day 14-28 – Progesterone stops the uterus wall breaking down and causes it to become more thick. The level drops near day


    This means the uterus wall can breakdown.

  • Day 0-5 – menstruation occurs. The lining of the uterus wall breaks down.

    Day 0-5 – Hormones oestrogen and

    progesterone are at their minimum levels.

  • Inside the ovaryWhat happens in the ovary during

    the menstrual cycle?

    Day 1-13:

    egg developing

    inside the

    growing follicle

    Day 14:

    ovulation – egg

    released from follicle

    Day 15-28:

    empty follicle turns

    into corpus luteum

    (yellow body)



  • Hormones involved in fertility

    The pituitary gland is a gland at the base of the brain. It releases many hormones and controls glands in the body.

    The pituitary gland produces two hormones involved in fertility:

    follicle stimulating hormone (FSH)

    luteinizing hormone (LH).

    pituitary gland

    In females, the ovaries produce the sex hormones oestrogen and progesterone.

  • Contraceptives

    Hormones to prevent pregnancy

    • Hormones that control the menstrual cycle.

    Barrier method

    • Puts a barrier between sperm and egg so they don’t meet.


    Diaphragms- dome shaped devices that cover the cervix.

    Things that prevent pregnancy. Two types

  • Hormonal contraception

  • Diabetes

  • Diabetes- when some people are unable to regulate their blood glucose levels because their pancreas doesn’t produce enough insulin.

    Symptoms of diabetes develop quickly and can be severe. Initial symptoms include:

    increased thirst, hunger and production of urine

    loss of weight, tiredness and nausea.

    Later symptoms include vomiting and abdominal pain. If untreated, diabetes can lead to coma and even death.

    The lack of insulin means that blood glucose levels can rise dangerously high after eating, which can cause cell damage.

    What is diabetes?

  • Controlling glucose levelsBlood glucose levels are monitored by the pancreas.


    If blood glucose levels are too high, the pancreas releases the hormone insulin. This tells the liver to convert glucose into glycogen, which is stored in the liver and muscles. If blood glucose levels are too low, the pancreas releases the hormone glucagon. This tells the liver to convert glycogen into glucose, and release it into the blood.

  • Type 1 Diabetes


    • The pancreas doesn’t make insulin.


    • Insulin therapy- means injecting insulin into the blood.

    • Reduce intake sugary food

    • Regular exercise

  • Type 2 Diabetes


    • When a person is resistant to insulin

    • This means their cells don't respond properly to the hormone.


    • Can be controlled by

    – Healthy eating

    – Regular exercise

    – Losing weight

    – Medication or insulin injections.

  • Nitrogen and Carbon Cycles

  • Nitrogen cycle

    Nitrogen is essential for growth because it is used by plants and animals to make proteins.

    Atmospheric nitrogen needs to be changed into a useable form.

    Nitrogen gas (N2) is unreactive and is not easily converted into other compounds.

    Most plants can only take up nitrogen in the form of ammonia or nitrate.

  • Nitrogen cycle

  • Nitrogen cycle role

    Into ammonia

    Into ammonia

  • Why is carbon important?

    What happens to the carbon in organisms when they die?

    The carbon from dead organisms can also form fossil fuels and sedimentary rocks such as limestone. These are long-term carbon stores.

    As dead matter decomposes, carbon is released back into the atmosphere in the form of carbon dioxide.

    Plants use carbon dioxide duringphotosynthesis to produce sugars. The carbon is then transferred to animals along food chains.

  • Carbon cycle