Biology

Biology

Section 9- Use of biological resources
1. Making Yoghurt
  1. 1. sterilise equipment and pasteurise milk (72°C for 15seconds)
    1. 2. lactobacillus bacteria added and incubated at 40°C in a fermentor
      1. 3. bacteria ferment lactose sugar→lactic acid
        4. lactic acid causes milk to clot and solidify into yoghurt
        5. flavours and colours added
2. Making Beer
  1. 1. sugar removed from grain- barley grain is malted, mashed up, added with water making a sugary solution and sieved to remove bits
    1. malted= allowed to germinate so starch→sugar but then dried in a kiln
    2. 2. yeast added and mixture is incubated, yeast ferments sugar→alcohol, rising concentration of alcohol (due to anaerobic respiration) kills yeast eventually, fermentation slows
      1. 3. beer drawn off through a tap, chemicals called 'clarifying agents' added to remove particles to make it clearer
        4. beer is pasteurised to kill any yeast left
3. Genetic engineering
  1. vector=something that's used to transfer DNA into a cell (plasmids or viruses)
Section 8- Ecology and the Environment
1. Ecosystem= all the organisms living in a particular area and all the non-living (abiotic) conditions e.g. temperature, climate, soil-type
2. The Nitrogen cycle
  1. Nitrogen-fixing bacteria= turns atmospheric nitrogen into nitrates
  2. Nitrifying bacteria= turns ammonia into nitrates
  3. Denitrifying bacteria= make nitrates in the soil act as an energy source and turn them into atmospheric nitrogen
  4. Decomposers= break down proteins and urea into ammonia
3. water pollution and deforestation
  1. Eutrophication= when a lake or river becomes enriched with nutrients e.g. from fertilisers applied to fields, excess plant growth is followed by decay. Microorganisms use up oxygen from the water so that other organisms can no longer survive and an algae layer builds up blocking sunlight so underwater plants can't photosynthesise
  2. Leaching= when trees are cut down so that nutrients are washed away and then don't get replaced because there aren't any trees, leaving infertile soils
Section7- Reproduction and Inheritance
1. Genes
  1. Chromosome= long length of DNA coiled up
  2. Gene= a short section of DNA which is an instruction of how to put part of an organism together
  3. A and T join
    1. (adenine and thymine)
  4. C and G join
    1. (cytosine and guanine)
  5. DNA is a double helix (two spirals)
2. Reproduction
  1. MEIOSIS produces four haploid cells whose chromosomes are NOT identical
  2. the CARPEL on a flower is the female reproductive part
3. The Menstrual Cycle
  1. oestrogen- causes lining of uterus to thicken and grow, stimulates production of LH
  2. progesterone- maintains lining of uterus, when level of progesterone falls, lining breaks down (regulates menstrual cycle)
  3. LH- stimulates ovum release
  4. FSH- stimulates egg development and oestrogen secretion in females (sperm production on males)
Section 6- Coordination and Response
1. The eye
  1. Focusing on long distance objects
    1. cillary muscles relax
      1. suspensory muscles pull tight
        lens is thin
2. hormones
  1. Insulin is made in the pancreas
    1. it stimulates the liver to turn glucose into glycogen for storage, helping to control blood sugar level
3. Homeostasis= the maintaining of a constant internal environment
Section 5- Blood and Organs
1. The blood
  1. plasma carries everything that needs transporting around the body in the blood
    1. urea
    2. hormones
    3. heat energy
    4. CO₂
    5. O₂
    6. digested food products e.g. glucose and amino acids
  2. platelets clot the blood
2. vaccination
  1. inject dead or inactive pathogens into body
    1. lymphocytes produce antibodies (memory cells)
3. The Heart
  1. left side
    1. aorta
    2. pulmonary vein
  2. right side
    1. pulmonary artery
    2. vena cava
  3. tricuspid valve- atrium to ventricle
  4. semi-lunar valve- ventricle to blood vessel
  5. pulmonary= lungs
  6. renal= kidney
  7. hepatic= liver
4. Kidney
  1. removes urea from blood
    1. urea is produced in the liver from excess amino acids
    2. ultrafiltration in glomerulus
      1. into Browman's capsule
        all glucose is reabsorbed in the tubules
        water reabsorbed in the collecting ducts, controlled by ADH hormone
        ADH causes collecting ducts to be more permeable
        (sufficient salt and water are reabsorbed)
        remaining substances (urine- salt, water + urea) are released through the ureter to the bladder (where it's stored) before being released via the urethra
    3. osmoregulation (balancing the water content of the body)
      1. OUT: sweating, breathing, urinating
      2. IN: food and drink
Section 4- Respiration and Gas Exchange
1. RESPIRATION= the process of releasing energy from glucose, which happens in every living cell
  1. anaerobic
    1. animals
      1. glucose → lactic acid (+energy)
    2. plants
      1. glucose → ethanol + carbon dioxide (+energy)
  2. aerobic
    1. C₆H₁₂O₆ + 6O₂ → 6H₂O + 6CO₂ (+ energy)
      1. glucose + oxygen → water + carbon dioxide (+ energy)
2. leaf adaptations for efficient gas exchange
  1. air spaces
  2. stomata, close to leaf surface
  3. large surface area
  4. thin
3. experimenting with gas exchange
  1. hydrogen-carbonate indicator
    1. orange normally
      1. yellow if CO₂
      2. purple if CO₂ decreases
4. Lungs
  1. Breathing in...
    1. intercostal muscles and diaphragm contract
      1. thorax volume increases
        decreased pressure so air drawn in
  2. alveoli are specialised for gas exchange
    1. large surface area
    2. moist lining
    3. thin walls (1 cell thick)
    4. surrounded by capillary network so great blood supply (high concentration gradient)
    5. permeable walls (good for diffusion)
  3. problems from smoking
    1. tar damages cilia (little hairs)
      1. chest infections more likely
    2. alveoli covered in tar so reduced surface area meaning gas exchange less effective
      1. could lead to emphysema
    3. tar irritates bronchi, causing more mucus to be produced
      1. causes smoker's cough and chronic bronchitis
    4. CO in cigarette smoke reduces oxygen the blood can carry
      1. heart rate will increase
        increased blood pressure
    5. tobacco smoke contains carcinogens
      1. can lead to lung cancer
Section 3- Plant nutrition and Transport
1. Photosynthesis
  1. 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
    1. carbon dioxide + water → glucose + oxygen
      1. sunlight chlorophyll
  2. leaf adaptations for photosynthesis
    1. broad (wide surface exposed to light)
    2. most chloroplasts are found in the palisade layer (near the top of the leaf where there's the most light)
    3. upper epidermis is transparent
    4. network of vascular bundles to transport the glucose to other parts of the plant when it is made
    5. waxy cuticle reduces water loss through evaporation (water needed for photosynthesis)
    6. adaptations for gas exchange also help
  3. Limiting factors
    1. level of CO₂
    2. temperature
    3. sunlight
  4. experiment
    1. testing a leaf for starch
      1. kill leaf (put it in boiling water)
        put in boiling tube with ethanol and heat in a water bath (to remove chlorophyll, leaf should be pale white colour)
        rinse leaf in cold water
        add a few drops of iodine solution
        if starch present: orange to blue-black
      2. show light is needed
    2. show chlorophyll is needed for photosynthesis using variegated leaves
    3. show CO₂ needed using soda lime and a sealed bell jar
    4. O₂ production shows rate (distance from light source, gas syringe)
2. minerals for healthy growth
  1. nitrates
    1. making protein and amino acids, needed for cell growth
      1. yellow older leaves
  2. phosphates
    1. making DNA and cell membranes, needed for respiration and growth
      1. purple younger leaves
  3. potassium
    1. help enzymes needed for photosynthesis and respiration
      1. discoloured leaves
  4. (magnesium)
    1. needed form making chlorophyll, needed for photosynthesis
      1. yellow leaves
3. transport
  1. phloem
    1. transport water and minerals
    2. transpiration
      1. affected by...
        light intensity
        temperature
        wind speed
        humidity
      2. = the loss of water from a plant
      3. measuring
        use a potometer
  2. xylem
    1. transport sugars e.g. sucrose and amino acids
    2. translocation
  3. root hairs
    1. water in through osmosis
    2. minerals in through active transport
Section 2- Human nutrition
1. see 'a balanced diet' sheet
2. Structure of nutrients
  1. Carbohydrates
    1. carbon, hydrogen and oxygen
    2. e.g. starch, glycogen
  2. Lipids
    1. (fats and oils) built from fatty acids and glycerol
    2. carbon, hydrogen and oxygen
  3. Proteins
    1. made up of amino acids
    2. carbon, hydrogen, oxygen and nitrogen
3. test for glucose
  1. Benedict's reagent
  2. heat
  3. blue solution to orange precipitate
4. test for starch
  1. add iodine solution
    1. browny-orange- blue-black
5. things that affect energy requirements
  1. Activity level
  2. Age
  3. Pregnancy
6. Energy from food
  1. energy in food (J)= mass of water (g) x temperature change of water (°C) x 4.2
  2. energy per gram of food (J/g)= energy in food (J) ÷ mass of food (g)
7. Enzymes and digestion
  1. starch → maltose
    1. amylase enzyme
    2. maltose → glucose
      1. maltase enzyme
  2. protein → amino acids
    1. protease enzyme
  3. lipids → glycerol and fatty acids
    1. lipase enzyme
  4. bile neutralises the stomach acid and emulsifies fats
8. the alimentary canal
  1. Mouth
    1. oesophagus
      1. stomach
        liver
        bile produced here
        gall bladder
        bile stored here
        pancreas
        produces protease, amylase and lipase enzymes, releases them into small intestine
        small intestine
        protease, amylase and lipase enzymes produced, nutrients are absorbed out of the alimentary canal into the body
        large intestine
        anus
        faeces leaves the body
        excess water is absorbed from food
        muscluar walls pummel food, produses protease enzyme pepsin, produces HCl (to kill bacteria and give pH2 for protease
    2. food broken down mechanically and chemically (amylase secreted by salivary glands)
  2. peristalsis
    1. process through which food is moved through the gut
9. the digestive process
  1. 1. ingestion
    1. 2. digestion
      1. 3. absorption
        4. assimilation
        5. egestion
        villi in the small intestine help
        large surface area for absorption
        have microvilli
        network of blood capillaries
        cell wall 1 cell thick
        permeable layer of surface cells
Section 1- Structures and Functions in Living Organisms
1. 8 characteristics found in all living organisms
  1. need nutrition
  2. respire
  3. grow
  4. excrete
  5. reproduce
  6. respond to surroundings
  7. move
  8. control internal conditions
2. Fungi
  1. e.g. yeast + mucor
  2. can't photosynthesise
  3. feed by saprotrophic nutrition
3. protoctists
  1. amoeba, chlorella
4. bacteria
  1. lactobactillus
5. viruses
  1. HIV and influenza virus
6. pathogens
  1. = organisms that cause disease
7. Enzyme= biological catalyst
  1. investigate effect of temperature (use water bath, hydrogen peroxide solution and source of catalase e.g. potato)
8. movement
  1. osmosis
    1. net movement of water molecules across a partially permeable membrane from an area of high water concentration to an area of low water concentration
    2. turgid and flaccid cells
    3. investigate in living system (potato cylinders, sugar solution) or non-living system (e.g. visking tubing containing sugar solution)
  2. active transport
    1. AGAINST concentration gradient
    2. movement of particles against a concentration gradient using energy released during respiration
      1. low concentration to high concentration
  3. diffusion
    1. investigate in a non-living system, e.g. agar cubes and HCl
    2. net movement of particles from an area of higher concentration to an area of lower concentration
  4. things that affect it
    1. surface area to volume ratio
      1. larger surface area to volume ratio means substances move in and out quicker
    2. temperature
    3. concentration gradient
      1. bigger concentration gradient means faster movement (in osmosis and diffusion)

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