organisation

• a tissue is a group of similar cells that work together to carry out a particular function
• main examples of tissues in mammals (e.g humans)


  1)epithelial tissue - which covers some parts of the body (e.g the inside of the guy) 2)muscular tissue - which contracts to move whatever its attached to. 3)glandular tissue - which makes and secrets chemicals like enzymes and hormones
• an organ is a group of different tissues that work together to perform a specific function.
• the stomach is an organ made up of muscular tissue (which moves the stomach wall to churn up the food), glandular tissue (which makes digestive juices to digest food), epithelial tissues (which covers the outside and inside of the stomach)
• an organ system is a group of different organs working together to perform a particular function
• the cardiovascular system is considered an organ system because it consists of a group of organs working together to perform a particular function of transporting substances around our body. the blood contains the substances that need to be transported, the blood vessels contain the blood, and the heart provides the force to pump the blood around the body.
• what are the levels of organisation in organisms from least complex to most complex?

  organelles, cell, tissue, organ, organ system, organism.
• examples of organ systems 


  respiratory system, nervous system, cardiovascular system, skeletal system, muscular system, endocrine system, lymphatic system, digestive system, urinary system, reproductive system
• organisms need enzymes because most chemical reactions are naturally very slow so enzymes speed up the reaction, without being changed or used up
• the rate of chemical reactions increases with temperature. why don't we just increase the temperature of our cells to increase the rate of chemical reactions?

  1)heating our cells would require a lot of energy. 2)higher temperatures could damage our cells. 3)higher temperatures would speed up non-useful reactions
• our body temperature is at 37 degrees Celsius, which is higher than the environment.
• an enzyme is a biological catalyst, made by living organisms. enzymes are large proteins, made up of chains of amino acids.
• the active site is the special region that binds to the substrate.

  
• the lock and key model was the first model that scientist proposed. they thought that in order for an enzyme to catalyse a reaction, the substance had to fit perfectly into the active site (like a key to a lock)

  
• in the induced fit model, the enzyme's active site slightly changes shape as it binds to the substate in order for the enzyme to catalyse the reaction.
• what are the two main factors that affect enzyme activity?

  temperature and pH
• enzymes work best within their optimum range. if the conditions change outside this range then the rate of reaction will decrease.
• optimum temperature - the highest temperature where the enzyme works fastest. above this temperature the enzyme denatures and loses its shape so cannot function properly.
• denaturation - when the enzyme loses its shape due to high temperatures or extreme pH levels.
• the optimum temperature of an enzyme in the human body is 37 degrees celsius
• ph is a measure of acidity or alkalinity of a solution
• high or low ph can cause an enzyme to denature (change shape) because too high or too low ph can break the bonds holding the enzyme together, which causes the enzyme and its active site to change shape. this means the enzyme's active site will no longer be complementary to the substrate. and it can no longer form an enzyme-substrate complex.
• 4 biological molecules do we need to consume in large quantities

  water , carbohydrates , proteins , lipids
• if you were mine you would not get the same. if you were mine you would top everything. suicide in the drop, switching lanes. and that thing so fire, baby no propane
• we get the majority of the energy we need each day from carbohydrates. however lipids are also used for energy, and even proteins can be broken down for energy when necessary.
• 3 factors that affect how much energy a person requires each day

  1)activity level - the more active you are, the more energy you need. 2)age - teenagers often need a lot of energy because they are still growing, whereas elderly people need less. 3)pregnancy - pregnant women need more energy because the baby inside them requires a lot of energy.
• lipids


  lipids refer to both fats and oils. if a lipid is solid at room temperature=a fat. if a lipid is liquid at room temperature=oil. lipids can be found in oily fish, nuts, seeds, avocados and dairy products. lipids provide energy or they act as long term stores of energy.
• the main use of carbohydrates are to provide energy for chemical reactions.
• main uses of lipids:

  1)to provide energy for chemical reactions. 2)to insulate us from the warm or cold. 3)act as long term stores of energy. 4)protect our organs
• proteins provide the material for building things; such as organelles and cells. this means proteins are important for development, growth and repair.
• main similarities and differences between vitamins and minerals


  similarities=vitamins and minerals are both essential for healthy growth, and are both required in small quantities. differences=vitamins are organic compounds produced by living organisms and made from carbon atoms. whilst mineral ions are simple charged particles and are not made by living organisms.
• carbohydrates


  carbohydrates are found in starchy foods like bread, pasta, potatoes, fruits and vegetables. we need carbohydrates as an energy source as they provide us with most of the energy for chemical reactions.
• proteins 


  proteins are found in nuts and seeds, meat and fish and legumes (lentils and beans). proteins can be thought of as building blocks; we need them to grow, repair damaged tissues and they can be used for energy if we don't have enough carbohydrates or lipids.
• vitamin a


  vitamin a can be gained from liver or leafy vegetables. they are needed for good vision or healthy hair and skin.
• vitamin c


  vitamin c can be gained from citrus fruits (oranges), strawberries or vegetables. they are needed to prevent yourself from getting the disease scurvy.
• a lack of vitamin c can lead to the disease scurvy, which can lead to bleeding gums, loosened teeth and bleeding under your skin.
• vitamin d


  your body can make vitamin d using sunlight but you can also gain it from eggs and oily fish. vitamin d helps you absorb calcium.
• calcium 


  calcium is a mineral and can be found in dairy products, leafy vegetables. they are needed for strong bones. if you don't eat enough calcium (or you can absorb it because you don't have enough vitamin d) it can lead to the disease rickets (your bones are deformed)
• rickets causes your bones to be deformed
• iron


  iron is a mineral that can be found in red meat, spinach and beans. iron is an important component of haemoglobin (haemoglobin helps red blood cells transport oxygen.) a lack of iron leads to anaemia, which is when your red blood cells can't transport as much oxygen to your tissues