Biology End of Year Exam

Topic 1: BY1.1 Cells
1. Eukaryotic cells
  1. Eukaryotic cells have a nucleus. Examples of Eukaryotic cells are Plant, Animal and Fungal cells
  2. Eukaryotic cells contain genetic material (DNA) in their nucleus
2. Prokaryotic cells
  1. Prokaryotic cells don't have a nucleus. Examples of Prokaryotic cells are bacteria cells
  2. Prokaryotic cells don't contain DNA in the nucleus their DNA is free
  3. Bacteria are prokaryotes.
3. Plant and Animal Cells
  1. Plant cells
    1. Plant cells usually have all the bits Animal cells have, plus a few extra things that Animal cells don't have: 1. Rigid Cell wall - made from Cellulose. 2. Permanent Vacuole - Filled with cell sap and helps to keep cells turgid depending on the amount of water in cell. 3. Chloroplast - Contains chlorophyll - where photosynthesis happens
      1. The different types of a cell are called subcellular structures
  2. Animal Cells
    1. Most Animal cells have the following subcellular structures: 1. Nucleus - The control centre of the cell. contains genetic material. 2. Cell Membrane - Thin layer around the cell that controls everything that enters and leaves the cell. 3. Mitochondria - Place within cells where aerobic respiration takes place to release energy. 4. Ribosomes - An organelle in the cell in which protein synthesis takes place. 5. Cytoplasm - Material in a cell but not the material in the nucleus. Most chemical processes take place here.
    2. Specialised cells
      1. A cell that has a special shape and features that help it do it's job
        Examples of Specialised Animal cells
        Specialised cells differentiate.
      2. Examples of Specialised Plant cells are Palisade cells, Root hair cells, Phloem cells and Xylem cells
        Palisade cells. Function - To carry out photosynthesis and to help make plant food. Specialisations - Found at the top of the leaf. Packed with chloroplast to absorb sunlight
        Root hair cells. Function - Absorbs minerals and water from soil. Specialisations - Large surface area to absorb lots of water. Thin cell wall to allow water to pass through easily. Doesn't contain chloropast
        Phloem Cells. Function - Carries food around the plant. Specialisations - Mitochondria in companion cells to keep them alive, Special sieve plates that allow water with dissolved food to move through the plant
        Xylem cells. Function - Carries water and minerals and supports. Specialisation - long hollow tube that allows water and minerals to move. Spirals of lignin support the cell and makes it strong
    3. Examples of Specialised Cells for Animal cells: Sperm cells, Muscle cells, Nerve Cells, Ciliated Cells
      1. Sperm Cell. Function - To carry the father's genetic information (DNA) to the egg. Specialisations - Lots of Mitochondria/ - Has a long tail to swim to find an egg
      2. Muscle Cell. Function - Contracts and relax in pairs to move our bones. Specialisations - Special proteins to make fibres contract. - Lots of Mitochondria for respiration, stores glucose used in respiration
      3. Nerve Cells. Function To carry nerve impulses around your body. Specialisations - Extremley long cell. - Branches to connect to other nerve cells
      4. Ciliated cells. Function - Designed to Stop lung damage. Traps dust and bacteria back up the throat to be swallowed. Specialisations - They line all air passages down to the lungs. They have tiny hairs called cilia
4. Bacterial cells
  1. Bacteria cells have a : Cell membrane, cell wall, cytoplasm and don't have chloroplasts or mitochondria
  2. Bacteria cells don't have a nucleus instead they have a single circular strand of DNA that floats freely in the cytoplasm
Topic 2: BY1.2 Movement of substances
1. Diffusion
  1. Diffusion - The passive movement of particles from an area of high concentration to an area of low concentration
  2. Factors which effect the rate of diffusion: Surface Area, Temperature and Concentration Gradient
    1. Surface Area - The longer the surface area the higher the rate of diffusion
    2. Temperature - The higher the temperature the faster the movement of the particles
    3. Concentration Gradient - The bigger the difference the faster the movement
2. Osmosis
  1. The net movement of water molecules from a high concentration to a low concentration through a partially permeable membrane
3. Active Transport
  1. Active transport - it is the movement of substances against the concentration gradient using energy
  2. Active transport requires energy to work. Active transport uses special carrier proteins in the cell membrane. Active transport moves substances to areas of high concentration. Active transport occurs across a semi - permeable cell membrane.
Topic 3: BY2.1 Organs and systems (heart, lungs and plants)
1. The blood
  1. The function of Red Blood cells is to carry oxygen from the lungs to all the cells
  2. Four components of Blood: White blood cell, Platelets, Plasma and Red blood cells
    1. Red Blood cells carry oxygen. White blood cells defend against infection. Platelets help blood clot. Plasma is the liquid that carries everything in blood.
2. The blood vessels
  1. Arteries - These carry the blood away from the heart. Narrow lumen. Thick muscular walls. Elastic walls
    1. Vein - These carry the blood to the heart. Thin walls and thin layers of muscle. Wider lumen
      1. Capillary - These are involved in the exchange of materials at the tissues. Carry blood from the arteries to veins
  2. Structure of an artery - The heat pumps blood through the arteries at high blood pressure. Thick muscular walls protects arteries from bursting. Elastic walls allow arteries to stretch and expand with every heartbeat
    1. Structure of the vein - Muscles around veins squeeze veins pushing blood through. Valves stop the blood from going backwards.
      1. structure of the capillary - Substances need to easily diffuse from the blood into the surround tissue and back again so the walls need to be as thin as possible..
3. The heart
  1. Coronary artery - The coronary arteries supply the heart muscle with blood that it needs
  2. The heart is positioned at an angle on the left side of your body. The heart sends blood to two places at the same time. The lungs and the body
  3. The Structure of the Heart: First, deoxygenated blood goes into the right atrium via the vena cava . The blood then goes into the right ventricle. The right ventricle then pumps the blood out of the heart to the lungs. The oxygenated blood from the lungs goes into the left atrium vi the pulmonary vein. It then goes into the left ventricle. The left ventricle then pumps the blood out of the heart, to the lungs.
  4. Cardiovascular diseases
    1. Cardiovascular disease is a name to describe diseases that affect the blood vessels of the heart. Coronary heart disease (CHD) is a very common disease affecting the coronary arteries.
      1. The coronary arteries supply your heart muscle with oxygen - rich blood. This is needed for respiration. if they don't get oxygen - rich blood it can cause a heart - attack
      2. CHD can be treated by using statins, diet and exercise, bypass surgery a heart transplant
        Stent - a wire mesh that is put into an artery to keep coronary arteries open and reduce the chance of a heart attack
    2. Risk factors: Obesity, Family history, Smoking, Gender, Blood Pressure, Lack of exercise and Alcohol consumption
    3. If the heart doesn't get blood, it doesn't get oxygen or glucose, heart muscle cells can't release energy via respiration causing cells to die.
4. Breathing and gas exchange
  1. Gas Exchange - The exchange of gases via diffusion occurring at the lungs and at the respiring tissues
  2. Features that allow for efficient gas exchange:
    1. One cell think – short diffusion distance Large surface area - many alveoli and folded alveoli walls Large concentration gradient - efficient blood supply Moist lining – gases dissolve
  3. Breathing in : Rib cage moves up and out. Diaphragm contracts and moves down. Pressure in lungs decreases, and air comes rushing in
    1. Breathing out: Rib cage moves down and in. Diaphragm relaxes and moves up. Pressure in lungs increases, and air comes rushing out
5. Tissues and organs in plants
  1. Meristem - The meristem is a type of tissue found in plants. It consists of undifferentiated cells capable of cell division
  2. Xylem and Phloem are the transport tissues in plants
6. Transpiration
  1. Transpiration - The process by which water is carried through plants from roots to small pores on the underside of leaves, where it changes to vapour and is released to the atmosphere
    1. Transpiration is the loss of water from plants by evaporation by the process of osmosis. Air around the plant usually contains less water than the cell of the plant, so water evaporates into the air
      1. Factors affecting the rate of transpiration: Light intensity, Temperature, Humidity and Wind speed
  2. Translocation - movement of liquids from place to place
Topic 4 :BY2.2 Enzymes and digestion
1. Enzymes
  1. Enzyme - A protein molecule that acts as a biological catalyst.
  2. Enzymes are proteins. Enzymes are biological catalysts. A catalyst is a substance that speeds up a reaction by lowering the activation energy but is not used.
  3. Enzymes can either: Break things down from large, to smaller molecules. Build things up from smaller, to larger molecules. Alter molecules
  4. Active site: The enzyme is the lock, and the reactant is the key.
2. Factors affecting enzymes
  1. Denature - loss of shape of the active site of the enzyme
  2. Temperature AND pH
  3. Problems with enzymes denaturing
    1. The enzyme loses the shape of it's active site and can no longer bind to the substrate. Therefore cannot catalyse the reaction. And therefore cannot form products
3. Food groups and enzymes
  1. Enzyme specificity - Enzymes can only act upon their specific substrate their specific substrate that is specific in shape to their active site.
4. The effect of pH on enzyme function required practical
5. Tissues and organs in the digestive system
6. The digestive system
Topic 5: BY2.3 Non-communicable diseases

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