| Define a tissue | A tissue is a group of cells with a similar structure and function |
| Define an organ | An organ is a group of tissues that works together to perform a specific function, such as the stomach with contains muscle tissue and glandular tissue that release enzymes |
| Define an organ system | A organ system contains a group of organs which work together to form organisms |
| What are the three main nutrients in food? | The three main nutrients in food are carbohydrates, proteins and lipids |
| State why food molecules need to be digested and describe the process of digestion | Carbohydrates, proteins and lipids are all large molecules, and are therefore too big to be absorbed into the bloodstream so they have to be digested.
During digestion large food molecules break down into small molecules by ensures and the small molecules can then be absorbed into the bloodstream |
| Describe the first five stages of digestion in the digestive system | Firstly, food is chewed in the mouth as enzymes in the saliva begun digesting the starch into smaller molecules
Then the food passed down the oesophagus and into the stomach where enzymes begin the digestion of proteins, with the help of the stomaches hydrochloric acid
The food spends several hours in the stomach and the churning action of the stomach muscle turns the food into a
fluid; which increases the surface area for enzymes to digest
the fluid now passes into the small intestine, at this point chemicals are related into the small intestine from the liver and the pancreas
Then the pancreases release enzymes which continue the digestion of starch and protein and they start the digestion of lipids |
| Describe the next four stages digestion in the digestive system | In the sixth stage of digestion the liver speeds up the digestion of lipids and uses bile from the stomach to neutralise the released acid
At this point the acid makes its way down the rest of the small intestine, the small intestines wall releases enzymes in continuance of the digestion of proteins and lipids
Now food molecules in the small intestine produced by digestion are absorbed into the bloodstream either by diffusion or active transport
The fluid travels to the large intestine where water is absorbed into the bloodstream, and finally faces are released from the body |
| What is the effect of a temperature increase on enzymes? | As the is temperature increased; the activity of the enzyme increased (reaction gets faster) because as the temperature increases the enzyme and substrate are moving faster causing more collision per droned between the substrate and the active site |
| Describe the optimum temperature of enzymes | At a certain temperature; the enzyme works at the fastest possible rate: the optimum temperature, and this point is the maximum frequency of successful collision between the substrate and the active site ( for most humans the enzymes optimum temperature is 37 degrees celcius) |
| What happens when the temperature of an enzyme is increased past the optimum temperature? | When the temperature is increased past the optimum temperature, the enzyme’s activity begins to rapidly decrease to zero, the enzyme stops working because at high temperatures the enzyme molecules vibrates which changes the shape of the active site, making the active site denatured so the enzyme can no longer catalyse the reaction |
| What is the effect of pH on enzymes? | Enzymes have an optimum pH where activity is at its maximum and when the pH is made more acidic or alkaline the activity drops to zero, and under these conditions the active site denatures
Each enzyme has a specific optimum pH, an example of this would be a protease enzyme in the stomach which functions best at an acidic pH, or an enzyme which is released from the pancreas into the small intensive, such as lipase, functions best at an alkaline pH |
| What are the first four steps of the effects of pH on enzymes practical? | The first four steps of the practical: effect of pH on enzymes are
First, place one drop of iodine solution into each well of a spotting tile
Next take 3 test tubes. In the first test tube out 2cm cubed of starch solution, in the second hit 2cm cubed of amylase solution and in the third put 2cm cubed of pH 5 buffer solution (buffer solution is used to control the pH in biology)
In the third step you place the test tubes in a water bath of 30 degrees Celsius and leave them for 10 minutes to allow the solution to reach the correct temperature
Now combine the three solutions into one test tube and mud with a stirring rod then immediately return the test tube to the water bath and start a stopwatch |
| What do you do after returning the rest tube to the water bath? | After returning the test tube to the water bath, wait 30 seconds then use the stirring rod to transfer one drop of solution to a well in the spotting tile which contains iodine
And the iodine should turn blue-black showing that starch is present
Take a sample every 30 seconds until the iodine remains orange - which shows that starch is no longer present in the solution and the reaction is completed. Then record the time it took for the iodine to remain orange
Finally repeat this reaction several times using different pH buffers for example pH 6, 7 and 8 |
| What are the problems with the effect of pH on enzymes practice? | The problems which the effect of pH on enzymes practice are that samples are only taken every 30 seconds, so there is only an approximate time for the reaction to complete, this problem could be addressed by taking samples every 10 seconds
Secondly the person carrying out the experiment is looking for the time it takes for the iodine to not go blue-black which may not always be obvious as the colour change tends to be gradual and some wells might have blue-black mixed with orange, this problem could be addressed by asking several opinions on wether the colour change has occurred for the reaction to be complete |
| Give two key facts about enzymes | Enzymes catalyse chemical reactions and they are large protein molecules that have an active site on their surface where the substrate attaches to |
| What does ‘enzyme specific’ mean/ describe lock and key theory? | ‘Enzyme specific’ refers to when the substrate fits to the active site and the enzyme breaks it down into products, however when the enzyme is denatured it will not fit and can’t be broken down, therefore enzymes are specific - lock and key theory |
| Describe the digestion of proteins | Proteins found in the stomach, pancreas and small intestine are broken down by protease enzymes and when digested protease enzymes convert protein to individual amino acids which are then absorbed into the bloodstream
When the same amino acids in proteins are absorbed into body cells; they’re joined in a different order in their chain to make human proteins |
| Describe the digestion of carbohydrates | Carbohydrates are broken down by carbohydrase enzymes and in the case of starch, amylase - which is found in saliva and pancreatic fluid, and simple sugars are produced when carbohydrates like starch are digested |
| Describe the digestion of lipids | Lipids contain glycerol molecules which are attached to three fatty acid molecules. Lipid molecules are digested using the enzyme lipase that is found in pancreatic fluid and the small intestine, which produces glycerol molecules and fatty acids |
| What are the three steps of a food test practice? | The three steps of a food test practice are:
Take the food sample and grind it with distilled water to make a paste
Now transfer the paste to a beaker and add more distilled water, stir so the chemicals in the food dissolve in the water
Then filter the solution to remove suspended food particles |
| How is the presence of glucose (sugars) tested? | The presence of the glucose is tested by placing (2cm cubed of) the food solution into a test tube and adding 10 drops of Benedict solution to it, which is a blue colour. After this place the test tube into a beaker and half fill the beaker with hot water, now leave it for 5 minutes.
If the presence of sugar is high the solution will turn brick-red, if it’s moderately present the solution will turn yellow and if the presence is low it will turn green |
| How is the presence of protein tested for? | Protein is tested for by placing (2cm cubed of) the food solution into a test tube, adding 2cm cubed of biuret solution which is a blue colour. If protein is present the solution will change from blue to pink/purple |
| How is the presence of lipids tested? | lipids are tested for by placing (2cm cubed of) the food solution into a test tube, adding a few drops of distilled water and a few drops of ethanol, then gently shake the solution and if a white, emulsion forms: lipids are present |
| How is the small intestine adapted for absorbing products of digestion? | The small intestine is adapted for absorbing products of digestion because: it is 5 meters long so it provides a large surface area for the absorption of molecules produced by digestion, its covered with millions of villi which increase the surface area for absorption and the microvilli further increase the surface area.
Villi also have good blood supply so the bloodstream rapidly removed the products of digestion which increase the concentration gradient, and they have a thin membrane which ensures a short diffusion path |
| What happens to molecules that aren’t absorbed by diffusion? | Any molecules that cant be absorbed by diffusion is absorbed by active transport |
| Describe the single circulatory system of a fish | Fishes have a single circulatory system, in which deoxygenated blood is pumped from the gills where it’s collected and becomes oxygenated, now the oxygenated blood is passed from the gills to the organs where the oxygen diffused out the blood into the body cells. Now the blood returns to the heart |
| What problems does the single circulatory system impose? | The single circulatory system of a fish is the blood loses a lot of pressure as it passed through the gills before reaching the organs therefore the blood travels to the organs slowly so it can’t deliver a lot of oxygen |
| Describe the double circulatory system of a human | Humans have double circulatory systems where deoxygenated blood is pumped from the heart to the lunges where it collects oxygen. Then this oxygenated blood truths to the heart that pumps it to the organs where the blood transfers it’s oxygen to the body cells |
| What benefits do the double circulatory system impose? | The benefits imposed by the double circulatory system are that blood can rapidly travel to the body cells providing the body cells the oxygen they need because the blood passes through the heart twice |
| What are the details of the structure of the heart? | The heart has four chambers: at the top is the right atrium and the left atrium, at the bottom is the right ventricle and the left ventricle
The atria are separated from the ventricles by valves
There are four main blood vessels entering and leaving the heart: the vena cava brings in deoxygenated blood from the body, the blood passes from the heart to the lungs in the pulmonary artery, in the lungs the blood collects oxygen and this oxygenated blood passes from the lungs to the heart in the pulmonary vein where the blood is then pumped from the heart to the body in the aorta |
| What pattern does blood flow take in the heart? | First the blood enters the left and right atrium, then the atria contracts do the blood is forced into the ventricles. The ventricles now contract and force blood out of the heart and valves stop the blood from flowing backwards into the atria when the ventricles contract. |
| Why does the left side of the heart have a thicker muscular wall? | The left side of the heart has a thicker muscular wall because the right side only pumps blood to the heart while the left side pumps blood around the entire body so it needs more force |
| What’s the heart rate controlled by? | The natural resting heart rate is controlled by the pacemaker, which can stop working correctly and if it does doctors can implant an artificial pacemaker - a small electrical device that correct irregularities in the heart |
| What do artistes do? | Arteries carry a high blood pressure form the heart to the organs in the body |
| Describe the structure of arteries | Arteries have a very thick muscular wall so they can withstand they a very high pressure of blood.
In arteries blood travels in surges every time the heart beats, which forms your pulse.
Arteries are adapted to withstand the surges by having elastic fibres that stretch when the surge of blood passes through and the elastic fibres also recoil in between surges which keeps blood moving |
| What diffuses from the blood as it passes through the capillaries? | When the blood passes through capillaries substances such as glucose and oxygen diffuse from the blood to the cells and carbon dioxide diffuses from the cells back to the blood |
| What are the uses of donated blood in medicine? | Donated blood is used to replace blood lost during injury, people are given platelets extracted from blood to help in clotting and proteins extracted from blood can be useful such as antibodies |
| What are cardiovascular diseases? | Cardiovascular diseases are diseases of the heart and blood vessels they are non-communicable and not infections such ad coronary heart disease |
| What’s the purpose of the coronary arteries? | The purpose of coronary arteries is to provide oxygen to the hearts muscle cells and this oxygen is used in respiration to provide energy for contraction |
| What happens in coronary heart disease? | In coronary heart disease layers of fatty material build up outside the coronary arteries so the arteries narrow and the blood flow is reduced in the coronary arteries which result in a lack of oxygen for the heart muscle
In extreme cases this lack of oxygen can result in a heart attack where the heart is starved of oxygen |
| What are the two most common treatments for coronary heart disease? | Statins are drugs which reduce the level of cholesterol in the blood, and this slows down the rate fatty materials build up in the arteries
In some people coronary heart disease can cause almost total blockage of a coronary artery in which case the treatment stents would be used. A stent is a tube that’s inserted into the coronary artery to keep it open |
| What are the advantages and disadvantages of stents? | An advantage of stents would be they allow blood to flow normally through the artery however their disadvantage is they will not prevent other regions of the coronary arteries from narrowing and they don’t treat the underlying cause of the diseases |
| What are the advantages and disadvantages of statins? | Advantages of Statins are that they have been divided to reduce the risk of coronary heart disease/ they are an effective treatment, however their disadvantage is they have unwanted side effects such as liver problems |
| Describe different types of cardiovascular diseases that are caused by the hearts valves | Cardiovascular disease that are causes by the hearts valves consist of the heart enlarging due to valves not opening fully so the heart has to pump extra hard to get the blood through, and valves can become leaky causing patients to feel weak and tired. |
| How are faulty heart valves treated? | When heart valves are faulty they can be replaced with a mechanical valve made of metal or an animal valve made of pig |
| What are the advantages and disadvantages of mechanical valves? | Mechanical valves can last a lifetime but they increase the risk of blood clots so patient have to take anti clotting drugs |
| What are the advantages and disadvantages of animal valves? | Animal valves do not last as long as mechanical valves and they may need to be replicated however they don’t require patients to take drugs |
| What is heart failure? | Heart failure is when a person with a cardiovascular disease’s heart is unable to pump enough blood around their body |
| How is heart failure treated? | The treatment for heart failure is a donated heart or a donated heart and lungs. Patients may also be given an artificial heart as a temporary solution while they wait for a heart transplant |
| What are the disadvantages of heart donations? | There are not enough donated hearts available to treat every patient and the patient must take drugs to avoid their immune system rejecting the new heart |
| What are the disadvantages of artificial hearts? | Disadvantages of artificial hearts are they increase the risk of blood clotting and are not a long-term solution to heart failure |
| How does gas exchange happen | Gas exchange happens when air passes into the lungs through a tube called the trachea, (which contains rings of cartilage that prevent the trachea from collapsing during inhalation.)
The trachea now split into two smaller tubes called the bronchi with one passing to each lung, further into the lunges the bronchi sub-divide into smaller tubes called bronchioles and the bronchioles end in tiny air sacs called alveoli |
| What is the role of the alveoli in gas exchange | The alveoli are where gasses diffuse in and out of the bloodstream - they are sites of gas exchange |
| What are the alveoli adapted for gas exchange | In alveoli, oxygen in the air diffuses into the bloodstream and carbon dioxide diffuses out of the bloodstream and back into the air.
Alveoli have several adaptations to make the rate of gas exchange as fast as possible:
The millions of alveoli in the lungs give them a huge surface area, secondly the alveoli have very thin walls so the diffusion path is short and alveoli have a very god blood supply |
| What effect does breathing have on the rate of diffusion? | Breathing increases the rate of diffusion as it brings fresh oxygen to the alveoli and removes carbon dioxide making the concentration gradient high for these gasses that increase the rate of diffusion |
| What is epidemiology? | Epidemiology is the study of disease patterns to determine risk factors |
| What are carcinogens?
And what substance contains carcinogens? | Carcinogens are chemicals that damage DNA and increase the risk factor of cancer and cigarette smoking contains carcinogens |
| How can bias be avoided in sampling? | Bias can be avoided in sampling by taking the largest and most random sample as possible, as sampling is often biased because it’s impossible to sample every person in a country or the world so scientists will sample a group of people and draw conclusions from their data. This is therefore often inaccurate as people in that area may participate in or be exposed to external factors that could effect test results |
| What are the risk factors for cardiovascular diseases? | The main risk factors for cardiovascular diseases are a diet high in fat and low in vegetables, which increases the level of certain types of cholesterol in the blood increasing the rate of fatty material build up in the artistries.
Secondly a diet high in fat can also increase blood pressure and therefore increase the risk of developing cardiovascular diseases.
Lastly cardiovascular diseases can be developed by smoking which also causes the disease emphysema
while cardiovascular diseases is often less common in people who regularly exercise |
| What are the effects of smoking when pregnant? | Smoking when pregnant increases the risk of a premature birth or a miscarriage, alongside it increasing the risk of the baby being born with a low-body mass |
| What are the effects of drinking alcohol when pregnant? | Drinking alcohol when pregnant can cause fetal alcohol syndrome, children born with fetal alcohol syndrome can have learning difficulties and other metal or physical problems |
| What are the generic effects of drink alcohol? | People who drink alcohol excessively increase their risk of liver cirrhosis and liver cancer while alcohol can also effect the brain leading to addiction and memory loss |
| What’s a risk factor for type 2 diabetes? | A risk factor for type 2 diabetes is obesity |
| Define transpiration | Transpiration is a process where water is constantly evaporating from the leaves surfaces. Transpiration begins with the evaporation of water from cells inside the leaf, The water vapour formed then defuses through the air spaces in spongy mesophyll and exits the leaf through the stomata
Now water passes from the xylem into the leaf to replace the water that’s been lost
Finally water is drawn into the root hair cells and up the xylem vessels to leaf |
| Why is the process of transpiration important? | Transpiration is important because it brings water to the leaf needed for photosynthesis, it transports dissolved mineral ions which play important roles in plants, and the evaporation of water from the leaves cool them down which is important in warm weather |
| What factors affect the rate of transpiration? | The rate transpiration is greater at higher temperatures because evaporation is faster
The rate of transpiration is faster in dry conditions, when the air is not humid, because evaporation happens faster in the dry conditions
The rate of transpiration increases under windy conditions because wind removes water vapour to allowing more water to evaporate
The rate of transpiration is also increased when the light intensity is increased because a high light intensity increases the rate of photosynthesis |
| Describe how stomata work | Stomata are surrounded by two guard cells that swell and change shape under a high light intensity, causing the stomata to open, so carbon dioxide can diffuse into the leaf and be used in photosynthesis. |
| How do stomata reduce water loss in hot conditions? | Under hot conditions plants close the stomata to reduce water loss by transpiration, however this means the plant is unable to photosynthesise |
| What are the characteristics of a begin tumour | The characterises of begins tumours are the are slow-growing and contained in one area, surrounded by a membrane so they can be easily moved, and begin tumours cannot spread and invade other parts of the body |
| What are the characteristics of a malignant tumour? | Malignant tumours are ca more dangerous cancerous type of tumour that can be spread around the body |
| What do malignant tumours in the body? | In the body, a part of the tumour breaks off and goes into the bloodstream and around the body, malignant tumours can also get into healthy cells |
