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Biology B3

Movement of molecules in and out of cells
1. When the body exercises, glucose is used to release energy. Water and ions are lost via sweating-If these ions aren't replaced, the body will not function efficiently
2. Certain organ systems are specialised to aid the exchange of materials. The villi in the small intestine provides a large surface area for exchange to take place. They have an extensive network of blood capillaries to maximise absorption of the products of digestion. The walls of the capillaries are very thin, providing a short diffusion path
  1. The trachea (windpipe) has cartilage to prevent it from collapsing
    1. The bronchus (branch of trachea)
      1. The Ribs protect the contents of the thorax
        The intercostal muscles raise and lower the ribs
        The Diaphragm divides the thorax and abdomen
        The alveoli is where gas exchange takes place
        The Bronchiole is one of the many branches of the bronchi
4. The alveoli in the lungs are tiny air sacs where the exchange of oxygen and carbon dioxide takes place, this is maximised by the millions of alveoli in each lung creating a large surface area. The great blood supply. The walls of the capillaries supplying the blood are very thin.
Inspiration
1. Ribcage moves outwards and upwards due to intercostal muscles contracting
  1. Diaphragm becomes flatter
    1. Increases the space in the thorax, decreasing pressure. Air is drawn in
2. Expiration
  1. Ribcage moves in and down as intercostal muscles relax
    1. The diaphragm relaxes and moves upwards
      1. Decreases the space in the thorax, increasing the pressure so the air is forced out.
LEAVES have the stomata to allow carbon dioxide in and oxygen out (by diffusion). This does however lead to loss of water vapour in a process called transpiration
1. The size of the plant is controlled by a pair of guard cells, these adjust the amount of water released and CO2 taken in
Transport Systems in Plants and Animals
2. The upper chambers of the heart are the atria, the lower chambers are the ventricles
  1. The blood flowers into the atria via the veins, the atria contracts forcing the blood out of the heart. Blood flows from the heart to the organs through the arteries
  2. Arteries have thick walls containing muscle and elastic fibres to withstand blood at high pressure
    1. Veins have thin walls and have valves to prevent blood from flowing backwards
      1. Blood flows through thin walled blood vessels called capillaries in organs. Substances pass out of the blood in these
3. There area 2 separate circulatory systems. One carries blood from the heart to the lungs and then back to the heart. The other caries blood from the heart to all other organs of the body
4. Sometimes arteries become narrow and blood flow becomes restricted. A stent is used to keep it open
  1. Blood is composed of four components, Plasma (Transports CO2, Glucose and waste), Red blood cells (lots of haemoglobin), White blood cells (defence system against microbes) and platelets (Help to clot wounds)
  2. Plants have 2 transport systems
    1. Xylem tissue transports water and mineral ions from the roots to the stem and leaves. The movement is called transpiration stream
    2. Phloem tissue transports sugars produced in the leaves to the rest of the plants
Homeostasis
1. Humans need to remove waste products-Two of these waste products are CO2 and urea (Left over from respiration and produced in the liver to break down excess amino acids.
  1. A dialysis machine is where a person blood flows between partially permable membrances. As the blood lfows, it is seperated from the dialysis fluid by these partially permeable membranes. These membranes allow all urea, excess substances etc to pass from the blood to the dialysis fluid, restoring concentrations to normal levels. Dialysis fluid contains the same concentration of useful substanced as blood, ensuring that glucose and minerals aren't lost through diffusion.
    1. Kidney transplants are an alternate to dialysis machines however, antigens may be produced, rejecting this new kidney. Donor kidneys with a tissue type similar to that of the recipient is useful to stop rejection. The recipient can also be treated with drugs that suppress the immune response.
    2. Body temperature is controlled by the nervous system. Monitoring is performed in the brain which has receptors that are sensistive to the temperature of blood. There are also temperature receptors in the skin that send impulses to the thermoregulatory centre.
2. Humans need to maintain their temperature at 37 degress (increased by shivering and narrowing blood vessels and decreased by sweating and widening blood vessels)
  1. Their water content (gained by drinking, lost by breathing-excess water is lost in the urine)
    1. Ion content (Gained by eating and drinking, lost by sweating)
      1. Blood sugar (glucose is gained by eating and drinkin and provides cells with energy-Glucose is removed from the blood and stored as glycogen)
        Urine is produced when blood is filtered and water and small molecules pass into the kidney tubules. Sugars in the tubules are reabsorbed back into the blood, dissolved ions are reabsorbed and some water is reabsorbed. Urea, excess ions and water form urine in the tubule
        People that suffer from kidney failure are treated by a kidney dialysis machine
        The blood sugar concentration is managed in the pancrea. THe pancreas produces insulin which allows glucose to move from the blood into the clels. Type 1 diabetes is a disease where the blood glucose may rise to a level that the pancreas does not produce enough insulin
Humans and their environment
1. The earth is suffering from over population due to developments in science and medicine, this is causing a lack of non-renewable materials such a copper or coal, a higher production of domestic and industrial waste meaning more landfill sites are needed, improper handling of waste causing an increase in environmental pollution, more land is taken up by farms to grow crops and keep animals, and cities are expanding which means there is less land.
2. Human activities are starting to pollute water, air and land
3. Water is being polluted by toxic chemicals and sewage.
  1. Air is being polluted by carbon dioxide, sulfur dioxide and oxides of nitrogen-causing acid rain.
    1. Land is being polluted by toxic chemicals such as pesticides and herbicides which may be washed from the land to the water.
      1. Deforestation is also a growing problem, it involves large scale cutting down of trees for timber, deforestation has increased the amount of carbon dioxide released into the atmosphere due to the burning of wood and lack of tree respiration, it also reduces biodiversity and results in the loss of organisms that could be of future use.
        Along with forests being destroyed, peat bogs are also being destroyed. These are areas of wetland where over thousands of years, decaying plants have been formed into peat, peat is used as a compost to grow plants. It can also be burnt as fuel. In many countries, vast areas of peat bogs are cleared, drained and burnt. Destruction of peat bogs releases large amounts of carbon dioxide into the atmosphere, to preserve peat bogs, the use of peat free composts is becoming more important
        The greenhouse effect is where methane and carbon dioxide "insulates" the earth, stopping energy from escaping from the earths surface to space. Without this, the earth would be frozen over, however the level of these gases is rising along with the temperature of the planet.
        Global warming can cause the following things, climate change, a rise in sea level, reduced biodiversity, changes to migration patterns in birds, changes in the distribution of species
        Biofuels are liquid fuels made from any living thing (biomass). They are normally made by fermentation of fast growing crops such as corn or sugarcane. Gasohol is a biofuel that is a mixture of alcohol (ethanol) and petrol, used to make cheaper and cleaner fuel for cars.
      2. There are multiple reasons for deforestation: some land is deforested to grow crops for which biofuels can be made. Some land is deforested to grow more food. Some land is deforested and turned into cattle ranches. Some are deforested for land and resources.
        Biogas is made of mostly methane, it can be produced by anaerobic fermentation using a wide range of organic or waste material containing carbohydrates.
        Many different organisms are involved in the digestion of waste material. Waste from sugar or sewage factories can be used to provide large amounts of biogas-Biogas generators can supply the energy needs of individual families or farms.
        Mycoprotein is a meat-free, high quality protein suitable for vegetarians. It is produced by the fungus "fusarium" which is grown on glucose syrup in aerobic conditions. The biomass is then harvested and purified
        Every stage in a food chain loses energy and is contained in the biomass of the organisms. Since the loss of energy and biomass is due to heat loss, waste and movement, we can improve the efficiency of food production by reducing the number of stages in a chain.
        You can input more energy into an animal by restricting the amount of which it can move, meaning less energy is lost
        Fish stocks in the ocean are declining, this is due to overfishing in order to meet increasing demands for food. It is important that we maintain fish stocks at a level where breeding can continue, failure to do this can lead to certain species disappearing

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Biology B3

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	Created by James Burns over 9 years ago