Organisation

• As a cell differentiates, It may change shape or may develop different subcellular structures to carry out tasks.
• Tissues are made up of cells.
• Tissues are a group of cells that work together to do a job.
• Organs are made up of tissues.
• Organs systems are made up of organs that perform a certain role.
• The digestive system has multiple organs that work together to digest foods.
• Enzymes are biological catalysts that increase the rate of reaction.
• Enzymes are large proteins. Within the protein molecules, their is a space called the active site.
• Enzymes work best at a specific temperature and pH known as the optimum
• There is a model that is used to explain how catalysts work: the chemical that reacts is called the substrate and fits into the enzyme's active site. This theory is the lock and key theory.
• Enzymes can change shape due to high temperature and extremes of pH. This is called denaturing. Enzymes can no longer work when denatured.
• The 3 types of digestive enzyme are protease, lipase and carbohydrase. These digest proteins, lipids (fats and oils) and carbohydrates.
• Bile is a liquid made in the liver and stored in the gall bladder. It is alkaline to neutralise hydrochloric acid from the stomach.
• Amylase is produced in the salivary glands and the pancreas.
• Blood is a tissue made of a liquid called plasma.
• Plasma is made of red blood cells, white blood cells and platelets.
• Red blood cells contain haemoglobin, which binds to oxygen to transport it from the lungs to the tissues and cells.
• The heart pumps blood around the body in a double circulatory system.
• The four chambers in the heart are the left and right atria, which receive blood from the veins, and the left and right ventricles which pump blood into the arteries.
• The natural resting heart rate is controlled by a group of cells located in the right atrium, which act as a pacemaker.
• The heart sends blood to the lungs through the pulmonary artery.
• Air obtained by breathing reaches the lungs through the trachea.
• The trachea divides into the bronchi.
• The bronchi divide into bronchioles
• The blood is taken to the heart through the pulmonary vein.
• Health is a state of physical and mental wellbeing.
• There are two main types of disease: communicable and non-communicable.
• Communicable diseases can be spread between organisms whereas non-communicable diseases cannot.
• The risk factor is the likelihood of developing a disease due to a number of factors that could affect the person e.g. lifestyle or environment.
• Scientists look for a casual mechanism in order to prove that there is a risk factor involved in the likelihood of getting a disease. This is because some risk factors do not necessarily cause disease.
• In coronary heart disease, layers of fatty material build up inside the coronary arteries of the heart and narrow them.
• Treatments for this include: stents to keep the coronary arteries open and statins to slow down the rate at which fatty materials build up.
• Cancer is a non communicable disease. It is caused by uncontrolled cell division which forms masses of cells known as tumours.
• Benign tumours do not spread around the body. Malignant tumours spread in the blood to different parts of the body where they form secondary tumours.
• In the leaves, most of the water will evaporate and diffuse out of the stomata (small pores).
• The loss of water from leaves is called transpiration. Humidity can affect the rate of this.
• The movement of food through phloem tissue is called translocation.
• The stomata closes at night because carbon dioxide is not needed for photosynthesis, so closing the stomata reduces water loss.