organisation

• bacteria are organisms that are single celled. Other organisms can be made of millions or billions of cells. Complex multicellular organisms have many different types of cells
• a tissue is a group of cells with a similar structure and function working together to carry out a particular function e.g. muscle cells form muscle tissue or epidermal tissue to make the epidermis
• an organ is a group of tissues that perform a specific function e.g. muscle tissues form the heat or epidermis tissue form a leaf
• an enzyme is a biological catalyst that speeds up a chemical reaction without being used up e.g. digestive enzymes help to break down large food molecules into smaller, soluble ones
• enzymes work best at an optimum temperature and ph level if the temp is below this the reaction will be slower, if the temp is to high the enzymes will denature
• Different enzymes have different optimum pHs and temperatures. e.g. digestive enzymes work best in acidic environments in the stomach
• the lock and key theory is the idea that only a particular shaped enzyme can fit into a particular shape of substrate
• Carbohydrases are a group of enzymes that break down carbohydrates into simple sugars e.g. Amylase, lipase or protease
• carbohydrase

  Amylase helps to break down the carbohydrate starch into simple sugars.Proteases are enzymes that help break down proteins into amino acids.

  Lipases are enzymes that help break down lipids (fats) into fatty acids and glycerol.
• Amylase is made in the salivary glands, the pancreas and the small intestine.

  Proteases are made in the pancreas, the stomach and the small intestine.

  Lipases are made in the pancreas and the small intestine.
• bile is made in the liver and digests fats by emulsifying them, this means it breaks down the fat into small droplets with a high surface area making it easier to digest
• The gall bladder stores the bile and then releases it into the small intestine after a meal. The bile is alkaline and neutralises the hydrochloric acid from the stomach. The high surface area and alkalinity increase the rate at which lipase can break down fats.
• calculation for rate of reaction

  
• calculation for volume of product

  
• the heart is a double circulatory system this is because the blood flows in two circuits. one carries oxygenated blood around the body and the other carries deoxygenated blood to the lungs to pick up more oxygen
• the heart is a muscle so it needs its own blood supply. the coronary arteries supply the heart with its own source of oxygenated blood and glucose
• deoxygenated blood enters the heart through the vena cava and the right atrium, then the right ventricle pumps the blood to the lungs through the pulmonary artery
• oxygenated blood enters the heart through the pulmonary vein and passes through the left atrium, then the left ventricle pumps the blood through the aorta to the rest of the body
• A group of cells in the right atrium controls the natural resting heart rate. These cells act as a natural pacemaker. People with an irregular heart beat can be fitted with an artificial pacemaker. Artificial pacemakers produce electrical pulses to make the heart beat.
• when you breath air travels from your trachea into the bronchi, these are tubes leading to your lungs (bronchus) the end of each pipe has millions of alveoli (alveolus)
• Each alveolus is surrounded by tiny blood vessels called capillaries.

  The capillaries maintain a high concentration gradient for a faster rate of diffusion. The blood arriving in the capillaries is deoxygenated.

  As a result, there is more oxygen in the alveoli than in the blood.

  This causes oxygen to move into the blood by diffusion.
• • Arteries carry blood away from the heart and t hey have thick, elastic walls to cope with the high pressure of the blood.
  • Veins carry blood back to the heart and this blood is at a lower pressure, so veins are wide to help the blood to flow. they contain valves to keep the blood flowing in the right direction.
  • Capillaries are tiny vessels that carry blood close to every cell in the body. A thin wall allows substances such as oxygen and nutrients to move in and out of the blood.
• the rate of blood flow

  
• communicable diseases - can be transferred between people
• Non-communicable diseases - cant be transferred between people
• pathogens are microorganisms that cause communicable disease ( viruses, bacteria, fungi, protist )
• Coronary heart disease is a non-communicable disease.

  This means that it can't spread between people. Coronary heart disease causes the heart to receive less oxygen than normal and can lead to heart attacks or heart failure.
• Coronary heart disease is treated with stents and statins.

  • Statins are drugs that reduce the cholesterol in the blood. As a result, less fatty material builds up in the coronary arteries. One disadvantage of statins is that they may cause side effects.
  • Stents are tubes used to hold the coronary arteries open. Stents are a long term solution as they last a long tine. a disadvantage is that the operation sometimes has complications
• Valves make sure the blood flows the right way around the heart. sometimes heart valves don't open properly others may fail to close and leak. Heart valves can be replaced with artificial (mechanical) valves. They can also be replaced by biological valves ( donor or animal
• If a patient has heart failure, the heart can be replaced with a donor heart. This is known as a transplant operation. There can be long waiting lists for donor hearts. An artificial (mechanical) heart can help to keep patients alive until a donor heart is available.
• When scientists study lifestyle and disease, the bigger the sample size the better. Because of this, individuals are chosen at random. Scientists also take into account other factors that could affect their results such as the participants lifestyle choices ( if they are a smoker or not )
• Tumours are unwanted balls of cells that grow in the body.

  Tumors can be benign or malignant. Benign tumours are found in one place in the body and are normally contained within a membrane. Benign tumours don't invade other parts of the body. A malignant tumour is also known as a cancer. Malignant tumours can invade nearby tissues and enter the bloodstream.
• risks of cancer include:

  • large alcohol consumption (liver)
  • high sun exposure (skin)
  • genetics
• Plants have specialised cells that are adapted to perform different functions. e.g. palisade mesophyll cells are specialised for photosynthesis because they have lots of chloroplasts.
• Meristem tissue contains special cells that can turn into any type of plant cell. The growing tips of roots and shoots contain meristem tissue. Meristem allows the plant to grow.
• Different tissues join together to make an organ. For example, palisade mesophyll tissue joins with other tissues to form a leaf.
• Different organs work together to form an organ system. The roots, stems and leaves work together in an organ system. This system transports substances around the plant.
• The epidermal tissue is the outer layer of tissue in the leaf.

  It has a waxy cuticle that protects against water loss.

  Epidermal tissue is also thin and transparent to allow sunlight through.
• leafs contain xylem and phloem

  • xylem transports water up the plant
  • phloem transports sugar up and down the plant
• A leaf has pores called stomata.

  They help carbon dioxide and oxygen to diffuse in and out of the leaf.

  Each stoma is surrounded by guard cells. When the guard cells are filled with water they swell. This makes the stomata open, and allows gas exchange to happen. When there is a shortage of water, the guard cells shrink. This closes the stomata, so less water vapour is lost through the pores.