Biology

• Mitochondria are responsible for producing energy through aerobic respiration.
• Ribosomes are sites of protein synthesis.
• The nucleus is the control centre of the cell, containing genetic material (DNA) that controls all activities within the cell.
• Chloroplasts contain chlorophyll and are involved in photosynthesis.
• Vacuoles store water, waste products, pigments, and enzymes.
• Cell membranes regulate what enters and exits the cell.
• A communicable disease is a disease cause by a pathogen when can be passed from one person to another
• Infectious diseases can be treated with antibiotics which kill bacteria
• a pathogen is a disease causing microorganism e.g bacteria
• Bacteria cause disease as once they are inside the body, they divide rapidly by binary fission. They kill cells and produce harmful toxins.
• viruses cause disease as they invade and reproduce inside living cells, leading to cell damage.
• Three ways pathogens can be spread is by:

  By air- droplet infection

  By water

  by direct contact
• Four ways in which the spread of pathogens cause be reduced is by improving hygiene such as handwashing and disinfectant. Another way is by reducing contact with infected individuals. Another way is by vaccination, and last is by removing vectors.
• Is it especially important to prevent the spread of viral diseases because scientists have not yet developed cures for many viral diseases.
• bacterial cells have a cell wall, cell membrane, cytoplasm and a single circular strand of dna and plasmids.
• sperm cells are specialised for reproduction and have a long tail and streamlined head to help them swim. They also have many mitochondria which supply the energy to allow the cell to move.
• mitochondria produce energy through respiration
• Nerve cells have a long axon to enable the impulses to be carried along long distances. They also have many mitochondria which supply the energy to make special transmitter chemicals called neurotransmitters.
• muscle cells are specialised for contraction and movement, they have lots of mitochondria to provide energy from respiration for contraction.
• root hair cells have a large surface area due to root hairs, meaning more water can move in. they also contain mitochondria to provide energy from respirion for the active transport of mineral ions into the root hair cell.
• Carbohydrases convert carbohydrates into simple sugars.
• proteases convert proteins into amino acids
• lipases convert lipids into fatty acids and glycerol
• bile is produced in the liver and stored in the gallbladder. it is then released into the small intestine.
• rate= change/time
• the heart is a organ in the circulatory system. The circulatory system carries oxygen and nutrients to every cell in the body and removes the waste products.
• deoxygenated blood flows into the right atrium and then into the right ventricle which pumps it to the lungs. oxygenated blood flows into the left atrium and then into the left ventricle which pumps oxygenated blood around the body.
• The structure of the heart has musclar walls to provide a strong heartbeat. The muscular wall of the left ventricle is thicker because blood needs to be pumped all around the body rather than just to the lung like the right ventricle. It has 4 chambers that separate the oxygenated blood from the deoxygenated blood. It has valves that prevent the backflow of blood.
• The natural resting heart rate is around 70 beats per minute and is controlled by a group of cells found in the right atrium that act as a pacemaker, they provide stimulation through small electrical impulses which pass as a wave across the heart muscle, causing it to contract. An artificial pacemaker can be used if the individual as an irregular heartbeat.
• Capillaries allow blood flow very close to cells to enable substances to move between them. They have one cell thick walls to create short diffusion pathway. they have permeable walls so substances can move across them.
• The gas exchange system is made up of the trachea, intercostal muscles bronchi, bronchioles, alveoli and diaphragm.
• in ventilation, the ribcage moves up and out and the diaphragm down causing the volume of the chest to increase. The increased volume results in lower pressure. Air is draw into the chest as air moves from areas of high pressure to areas of low pressure. the opposite happens when exhaling.
• In gas exchange, upon inhalation the alveoli fill with oxygen. The blood in the capillaries surrounding the alveoli is deoxygenated, it has lots of carbon dioxide as this is a product of respiration. oxygen diffuses down its concentration gradient into the capillary bloodstream, which has a low concentration of oxygen. carbon dioxide diffuses down its concentration gradient from the blood to the alveoli.
• alveoli are adapted to gas exchange as the walls of alveoli are very thin, meaning there is a short diffusion pathway. they are very small and arranged in clusters, creating a large surface area for diffusion to take place over.
• breathing rate = number of breaths / number of minutes
• plasma is the liquid that carries the components in the blood. such as red blood cells, white blood cells, platelets, glucose, animo acids, carbon dioxide, urea, hormones.
• red blood cells carry oxygen molecules from the lungs to all the cells in the body.
• platelets help to clot blood to form at the site of a wound, the clot dries and hardens to form a scab, which allows new skin to grow underneath while preventing microorganisms from entering.
• solutions of coronary heart disease is stents. this keeps the arteries open to allow blood to flow through. They are effective in lowering the risk of a heart attack and the recovery time from surgery is quick. however there is a risk of a heart attack or infection during the procedure.
• other problems with hearts is faulty valves. this is where the valves don’t close properly leading to leaks. You can replace it with a biological valve from pigs or cattle which works very well however they only last 12-15 years. You can also replace it with a mechanical valve which lasts a long time however you need to take constant medication to stop blood from clotting around the valve.