hello and welcome to Noel for GCSE in this video we will be looking at every single exam question for organization which is a second topic of the GCSE biology spec now in this video you'll find at least three exam questions on each subtopic in organization I've compiled a massive document and we'll be going through the answers you can find the document itself in the description and in the comments pinned at the top where you can download it for free and answer along with the video so we're going to begin with the first subtopic principles of organization each of the subtopics will be time stamped and each of these resources have come from all of the papers from the specimen papers to 2018 to 2022 along with textbooks so this is the only exam question resource you will need for your exams so the first question describe the relationship between cells genes DNA and chromosomes so this is definitely a question where you're going to have to use your knowledge and mainly your knowledge there's not much understanding to it you just need to know the hierarchical structure so let's look at the answer cell contains a nucleus the nucleus contains chromosomes and chromosomes are made up of coiled strands of DNA a gene is a section of DNA that codes for a protein so in that you've discussed the relation going from the biggest thing the nucleus which contains chromosomes chromosomes are made of DNA and a gene is a part of the DNA okay the next subtopic is the digestive system but there's also some questions about stem cells which is the B1 topic so this question is explain the enzymes needed in digestion now because this is four marks you might have to talk about what the what each enzyme does as well so in this case oh I'm so sorry this is supposed to say explain why enzymes are needed um my apologies for that you'll probably see the change in the document so explain why enzymes are needed in digestion so enzymes are biological catalysts they break down large insoluble molecules into small soluble molecules that can be absorbed by the blood so they're basically making big food bits into small bits so that our body can actually use all of the minerals from them so biological catalysts break down of large insoluble molecules to small soluble ones that can then be absorbed by the blood explain how the release of bile into the small intestine increases the rate of fat breakdown this is a three marker so in this question you need to use your knowledge of bile in and its role in the digestive system where it comes from so the role of bile it contains two roles firstly to neutralize the acid because the bile itself is alkaline and then it hence helps to maintain the optimum pH for lipase enzymes because as you know fats which are being asked about in this question are known as lipids and the things that break down these lipids are lipase enzymes and therefore by making it the optimum pH by neutralizing the acid you're helping the lipase enzymes and the second role of the bile is to emulsify fats now what emulsifying means is basically cutting it down from Big molecules into smaller molecules and this helps to increase the surface area to volume ratio and therefore that because there are more surfaces to for the enzyme to act on it can be broken down much more quicker the next question explain why protease Works more effectively in the stomach this is again a three markup so in this question you have to use your knowledge of again conditions rates of enzymes now enzymes tends to come up a lot in exam papers so make sure you're really familiar with these questions so the answer is the stomach contains acid acid has a low ph and this then provides Optimum conditions for the enzyme proteased work now this next question is a specialized question that's why there's a start it's more difficult and it's relating to a specific context so in a person with cystic fibrosis cells lining the lungs and the digestive system create too much mucus explain why children with cystic fibrosis grow more slowly than children without cystic fibrosis now this was actually a question found in paper two however I thought it was relevant in terms of the enzymes and that portion of it so if you're only strictly revising just organization you do not have to answer this topic but if you are revising the whole of biology then I recommend you look at this or it just gives you a great understanding so it's kind of connecting together all of the biology knowledge you've got what happens in the pancreas so the pancreas um there's fewer digestive enzymes which enter the small intestine so enzymes break down less food because remember enzymes there's pancreatic juices which are the different enzymes so because there's so much mucus it prevents it lessens the amount of enzymes that can enter the small intestine and therefore there's less absorption of nutrients there's fewer amino acids and so on and going into paper two content foreign I'll show you the answers if you did want to answer them however they're not strictly relevant to paper one so let's go on to so moving on to the next subtopic which is all about the food tests required practical so as I said in my previous video for all the required practicals I've written you six Mark responses and if you put every bullet point that is listed on there you will no doubtedly get four marks in any question about it so what I want you to do is just mind map everything you can remember about the food tests and I'm going to reveal the answers now okay let me just make sure there's some on the other page as well okay so let's go through the food tests required practical so firstly what you're going to do and this is part of it's contradictory whether it's part of the a level do you need to mention this or not but I would say mention it to be safe so use a pesto and mortar to break up the food into small particles that is the a level GCSE bit but if you do include it I guess the examiner will only be impressed add this crushed food into a test tube with water and mention a specific volume shake to get these chemicals to dissolve if testing for fats use ethanol instead of water because why fats do not dissolve in water then you're going to remove any undissolved solid material through filtration and then you've got the following tests so for the tests you've got starch which is you using iodine solution and if starch is present it will turn dark blue or black protein which you use buret solution and it should turn violet and for tests for fats and sugars so for fats it's a sudan regiment test and you get a red layer at the top and for sugar you do the Benedict solution test and sugar and you would put it in hot water make always make sure when you're talking about the sugar test of Benedict's solution you must mention otherwise you won't get the mark that you need to put it into hot water and then it should turn orange okay moving on to the next subtopic which is about the rates of enzymes so similarly to what we were just discussing so the first question is the effect of p h is on enzymes required practical so this is the second required practical that's closely related so let's look at the answer for this so the buffer solution you're going to have a buffer solution and the purpose of this buffer solution is just to contain a constant pH value often it's ph5 you're going to put one drop of iodine into each spotting tile you're going to take three test tubes and put two centimeters cubed of starch two centimeters cubed of amylase so amylase is the enzyme that breaks down starch and two centimeters cubed of the pH five buffer solution and that's to ensure that there's a constant pH you're going to put all three test tubes in a water bath at 30 degrees so again that is a variable that you want to keep the same and you're going to do that for 10 minutes you're going to transfer one drop of solution into a spotting tile or well every 30 seconds until the iodine remains Orange so what you're doing is you're seeing how long it takes for the starch to be fully broken down by the amylase because the iodine will remain orange when it detects no more starch because it's been broken down I hope that makes sense to you if not I would recommend going to watch free science lessons video on that topic it's really helpful so the next question describe the effect protease would have on baby food now protease in case you didn't remember it's a protein that breaks is the enzyme that breaks down proteins so let's see the answer so just think in this context a lot of students got this question wrong because it came in an exam paper think about what's being asked if you're unsure what to answer think about the context given baby food now obviously babies can't have really crunchy material but to eat because of their lack of development in teeth so they need soft and runny food and what does protease do protease breaks down the food specifically the proteins into amino acids and remember proteins are long chains and amino acids are slightly shorter chains and therefore by making it shorter you're making it softer and runnier and easier for the baby so that's the thinking outside of the box type of question okay your next question describe how ribosomes and mitochondria help to make enzymes this is a three marker so the ribosomes synth the size which means to make so ribosomes make proteins and enzymes using the amino acids and then the mitochondria releases energy for the process if you're ever asked how does mitochondria help in any process it's always along the lines of the mitochondria undergoes respiration in order to release energy for work to be done the next question explain the look and key theory of enzyme action so this question comes up a lot each year and just in different forms so here's one answer you could say the enzymes active site binds to the substrate because they are complementary so keywords that the examiner will be looking for enzyme active site substrate and complementary hence the substrate is broken down into products and the products are then released and the enzyme itself is not changed now sometimes this particular Clause at the end the examiners will say that that's a very important Clause you cannot get the third Mark unless you mention that the enzyme has not changed just the product has changed the substrate has changed okay so here is a again in a more context question and you can see the different questions here so instead of going through this I'm just going to leave the answers up on the screen so that you can just pause the video and use them at your leisure but they're not necessarily in Need Just for understanding the topic so the next question is explain why amylase does not work at 5 degrees Celsius and 80 degrees Celsius so this is a five marker so you've got to think quite methodically when answering this question you're given a temperature but really a low temperature and a really high temperature now normally this would be accompanied with a graph but if you know enough about enzymes you wouldn't need the graph because you know that five degrees is too cold for the enzyme to work it needs it's it needs to meet its minimum activation energy and 80 degrees will mean that the enzyme will denature now you've just got to put this your ideas into a form that will achieve five marks so let's look at that at 5 degrees Celsius amylase has a low kinetic energy and therefore fewer enzyme substrate collisions and hence fewer if it works less and does not break down as much food at 80 degrees the amylase enzyme denatures and its active site changes and if you wanted to go specifically into that the reason why the active site changes is because the bonds holding together the shape of the active site change and break the next question what is an enzyme so hopefully you would have answered this question long enough to know an enzyme is a chemical which catalyzes reactions in living organisms this is only one mark So a simple answer like this would be fine but if it was a multi-mark question then I would definitely recommend going into more about how enzymes work and the final question for this topic explain how pancreatic cancer may cause a person to lose weight now cancer is a topic that comes a bit later in biology but it's still worth going through this because it talks about digestion food is not fully digested and less glucose absorbed into the bloodstream so because of remember we said if there's any problem with the pancreas you know that there's going to be problems metabolic issues because the pancreas produces all of the enzymes and because there's pancreatic cancer you're not releasing enough enzymes and therefore your food is not digesting enough and therefore you've got less glucose When there's less glucose available that means that you can you less respiration has to occur because respiration gives energy from glucose and therefore you will use more fat instead now there will be fewer amino acids absorbed into the blood and therefore fewer acids making protein for growth and repair and let's just finish that answer therefore there are fewer fatty acids absorbed so less fat is actually stored in the body okay moving on to the next subtopic which is the heart the blood and blood vessels so the first one is a six marker describe the levels of organization in the human circulatory system so take a deep think about this think about how it's a double circulatory system so how would both paths work and I'm now going to reveal the answer so muscle cells can contract and respiration occurs in the muscle cells the muscle cardiac tissue then work together to contract and respire and as a muscle as a cardiac muscle does not fatigue the heart which is the organ the muscle Valves and the blood vessels all put the blood under pressure and the circulatory system is made up of the heart the blood the blood vessels all working together to pump blood around the body now that is a different method of attempting this question a lot of students thought let's discuss both circulatory system and in this case it is a really tricky way to tell hopefully you don't get a really vague question like this where you're unsure which path to go the next question explain why the left side of the heart is thicker now do note that in future exams they won't ask this question again but they will mask this question under another situation so be very careful and remember that the left side is thicker and the exact reason why let's read it so the left ventricle pumps oxygen around the entire body but the right ventricle only needs to pump blood to the lungs in order to go and get oxygen so if you've got one thing pumping to the whole body and one only to the lungs then the left ventricle needs to generate a much greater force of contraction and therefore they need thicker walls to withstand this greater pressure okay let's move on to the next question compare the structure of an artery with the structure of the vein so this is a loss of your knowledge and comparison techniques so arteries have a thicker layer of muscle than veins and arteries have a narrower Lumen so a lumen is practically just the whole and that allows blood to go through so arteries are much more narrower whereas veins are thinner and wider veins also have valves but arteries do not have valves and arteries have more or thicker elastic tissue the next question Define the term double circulatory system this is only one Mark so you do not need to put too much attention into this so a double seculatory system is when there's blood that's being pumped to the lungs on one side of the heart and to the blood and body sorry to the body by the other now six marker explain how the human circulatory system is adapted to supply oxygen to the tissues and remove waste product from the tissues so this is asking you to be specific in terms of the adaptations into how is it adapted so that it can get a lot of oxygen around the body and also remove the waste products Okay so we've got quite a hearty answer here so the double circulatory system allows for higher blood pressure and greater flow of blood because imagine if there's one path there will be a lot of people on that one path so it'll be more congested but if there were two parts this would make it much easier to move around and therefore it would allow a greater flow of people or a greater flow of blood to be supplied to the tissues another adaptation is that the pulmonary artery carries a deoxygenated blood to the alveoli and the alveoli is where it absorbs oxygen and it's got a thin wall elastic tissue discuss all of that this is carried back to the heart in the pulmonary vein before being pumped to tissues by the heart through the aorta oxygen is carried by red blood cells which contain no nucleus and the whole point of blood cells containing no nucleus is so that it can hold more hemoglobin for oxygen transport and remember hemoglobin binds to oxygen to create oxyhemoglobin which is the thing that makes the red blood cells red the capillaries carry blood into the tissues they have thin walls to allow for Optimum diffusion of oxygen out and waste products in it also has a higher surface area of capillaries for Optimum diffusion and the blood goes back to the heart in the veins with the valves to prevent backflow so we've discussed numerous adaptations you definitely do not need to talk about all of them in a single six marker but the more you talk about the stronger your chance and ability of getting to upgrade is okay the next question and the last question of this subtopic explain why having only one ventricle makes a circulatory system less efficient than having two ventricles so what you need to think about here is what is the function of ventricles and therefore how would not having one prohibit your and limit the body so in the mark scheme it detailed oxygenated and deoxygenated blood would mix if there was one ventricle and if it would mix that means that there's actually less oxygen that reaches the body cells because if you're thinking about diffusion or transport of gases you need to know that it needs to maintain a steep concentration gradient which just means that there's a difference there's an area of high oxygen and then there's an area of low oxygen so that it can diffuse quickly however if it's all mixed up together then it will not really have a concentration gradient so oxygen would not move across the next subtopic is ventilation and gas exchange this is a little smaller one yet it still is a six marker so explain how the human lungs are adapted for efficient exchanges of gas via diffusion so if you want some tips it will be talking about alveoli bronchi the rings of cartilage Etc so there's many alveolar which is the increases of surface area to volume ratio the capillaries mean that there's a short diffusion path for oxygen the breathing mechanism and the diaphragm moves air in and out subconsciously which allows you to bring in fresh oxygen and remove all that waste product of carbon dioxide and also talking again about the capillaries there's a large capillary Network which means that there's a good blood supply to rapidly bring in oxygen and to rapidly move out carbon dioxide on to the next subtopic explain why a stent prevents a heart attack from happening so remember you have statins and you have stents so let's see how this works so this is three marks and what's mentioned in the mark scheme a stent keeps the coronary heart open because remember it's that mesh coil so it keeps the coronary heart open so that blood flow can carry all those needed um things in the body so with all that needed glucose and oxygen and therefore glucose and oxygen is needed for respiration okay the next subtopic non-communicable diseases list to the risk factors of coronary heart disease so remember risk factors are things that can lead to whatever disease you're talking about so what things can lead to you having heart problems well lack of exercise obesity smoking stress alcohol consumption because that reduces the capacity and abilities of things like your your lungs and your liver your diet and your sugar this next one is a six marker so this is evaluating the use of cholesterol blockers versus statins for a person with high cholesterol now I remember specifically in this question you were actually given some context about cholesterol blockers so it's unfair for you to just be expected to know it now so I'm just going to give you the answer here and you can check this in your own leisure although you should know about statins because that's in the syllabus now what condition may be treated using an artificial pacemaker now through this question it's testing do you know what a pacemaker does and hence what condition is there which is caused by you not having a good one let's look at the answer now this is a irregular heartbeat all known as chorusif Mia now the pacemaker controls the heartbeat and I think it's found in the right ventricle and it has these small electrical impulses that cause your whole heart to contract and that's known as your heartbeat so that's why you need an artificial pacemaker to treat something like if you had an irregular one this next question is comparing mechanical valves to biological valves so firstly make sure you know what valves are and mention them and then talk about mechanical versus biological so mechanical valves are more durable and longer lasting than biological so an example of a biological valve could be a valve from a pig for example and hence it's less durable than a mechanical one but mechanical valves can also cause blood clots to the brain which could be really dangerous and this means that you the patients need to take anti-clotting medicine in order to prevent that from happening and medication can lead to excessive bleeding after the injury however there is still a higher survival rate with mechanical and you'll be told that in the context with biological there is no additional medical requirements however there could be some ethical issues because it's an animal you're taking it from and the valve may be harder you're more likely to need a replacement valve with biological valves and it's more likely to be rejected because your body only rejects things in your lab entered your body that are living for example a virus it wouldn't project a mechanical valve because that's made of metal which is not living next question explain why a person with a leaking heart valve has difficulty exercising so again use your knowledge on what valves are what their function is to prevent the backflow of blood and how would that then mean that if there was an issue would it how would it cause you to have difficulty in exercising so this is again a methodological one where you have to go from one step to another so because backflow of blood can occur this means that less blood is pumped around the body efficiently so that means less oxygen is applied to the muscles therefore less aerobic respiration takes place less energy is released less efficient muscle contraction and also your body has to rely therefore on anaerobic respiration so respiration without the need of oxygen but this causes an oxygen debt which eventually needs to be paid and also muscle tension because of the lactic acid the next subtopic the effect of Lifestyle on non-communical diseases so this sixth marker is to asks to explain the risks of a pregnant woman smoking and drinking so here in the mark scheme they've discussed both topics separately so for smoking they've said that there's carcinogens which increase the risk of cancer carbon monoxide is a toxic gas and carbon monoxide is really bad because it reduces the amount of oxygen that your red blood cells can hold and this means that it can cause fatigue and you're you're less likely to create energy and muscle fatigue and for the fetus this means that because it can't get enough oxygen it could actually suffocate this increases the risk of having miscarriages being premature and SIDS as well alcohol in the first three months having alcohol can actually increase the risk of having a child that's premature or having a miscarriage and heavy drinking that's sustained can actually lead to FAS which is fetal alcohol syndrome the next question describe the effects of liver failure on the human body so for this question think about what the purpose of liver is what does it do and therefore what would its absence do to the body so the liver one of the functions of the liver is to produce biles so if there was liver failure it wouldn't produce bile and therefore the fats and the lipids would not emulsify and the pH of the small intestine would not be neutralized which means that the enzymes like lipase would not work effectively the food would not be digested properly this means that a person may lose weight lactic acid may not be properly broken down or oxidized the accumulation of lactic acid is toxic and it could actually cause body poisoning proteins such as amino acids won't be broken down so there would be no deamination and therefore ammonia would form which again is toxic and glycogen stores were not also be formed now this is kind of a mix-up of paper 2 content as well so do forgive yourself if you didn't get all of those marks there and make sure that you remember its paper 2 content as well so the next question is explain how diabetes can cause the body to lose more water so when someone has diabetes it actually means that the blood is more concentrated than the solution within the body cells therefore water moves out of the cells via osmosis through a partially permeable membrane and because more water is moving out you're more likely to have more water being wasted and lost suggest two reasons why data isn't considered valid and it's just one factor that might reduce the validity this is just practical questions that might I thought might be helpful for added at the bottom so a large number in the survey or a well-controlled survey and an under or over instrument of alcohol consumption people's Lifestyles may change over time so the next subtopic is cancer compare the similarities and differences between benign and malignant tumors um so similarities include that both are uncontrollable growths both are formed from a person's own cells however differences start now benign tumors are enclosed and in a barrier by a membrane so it can't leave the membrane and therefore because it can't leave it doesn't invade nearby tissue so that's good for humans because if a tumor is not allowed to go and invade the rest of your body that means it's just limited to that one area whereas with malignant tumors these are not enclosed and they are therefore cancerous they can spread and invade and form secondary tumors around your body name some risk factors of cancer so we already discussed what is a risk factor anything that causes something to happen so a HPV linked the carcinogens in smoking alcohol intake UV radiation diet all of these things have linking links to the ability to get cancer smoking can cause diseases such as cancer now explain why cancer is not a communicable disease which just means a disease that can spread so you need to realize that cancers caused by smoking cannot be passed from person to person and the cancer itself is not caused by a pathogen communicable diseases tend to be caused by pathogens and other living organisms whereas cancers tend to be caused by a person's own body cells now Helio back to pylori or acid tolerant bacteria can damage the human mucous lining suggest how an infection might result in a stomach ulcer developing so bacteria are not killed by the hydrochloric acid because they are acid tolerant and then that means that they can damage the mucous lining and therefore the hydrochloric acid would cause an ulcer because it's therefore getting into contact with other things that is behind the mucous lining and finally describe how a person infected with heliobacter pylori could also develop liver cancer and you would say that if the cancer is malignant which means it spreads that means that they can spread to other organs and they move by the blood forming secondary tumors okay let's move on to the next subtopic which is the leaf structure so the changes in the mean width of the stomata in normal conditions are an advantage to the plant so what they're asking you here is to talk about how does the plant itself how is it able to change the size of this tomato and how is this a benefit to the plant so let's look at the answer here the stomata are closed at night because there is less or very little photosynthesis because remember it has to occur in sunlight closing this stomata reduces and prevents water loss stomata then opens wide at midday as maximum light intensity for the photosynthesis occurs and the stomata opening wide to taking more carbon dioxide also does this for photosynthesis this tomato yeah moving on to the next subtopic which is all about transpiration and translocation mode and forgetting this far we are drawing to a close in this video so define and explain the process of transpiration so transpiration is the movement of water and mineral ions don't forget that from the roots to the leaves via xylem tissue evaporation in the leaf of water from inside the cells it diffuses through the air spaces and out through the stomata water passes from the xylem to the leaf to replace that lost water water is then drawn from the root hair cells to the xylem cells and that's how the transpiration works the next exam question is to compare the process of transpiration to translocation so in transpiration there's use it uses the xylem tissue and this transports water from Roots to the leaves it's a one-directional flow the movement of water leaving in evaporation causes a transpirational pull drawing out more and more water from the roots whereas in translocation the phloem tissue transports dissolved sugars from the leaves to the rest of the plant so it's a multi-directional flow and it also has sieve plates which help to control the flow the phloem tissue is not dead unlike xylem and both are essential for the plant to survive and grow now the next question describe three reasons why transpiration is important and this is the final question you guys almost made it now the three reasons are firstly it transports dissolved mineral ions which are key for plant growth secondly water is required for photosynthesis to work and therefore all of the reaction to make food and energy and finally the evaporation of the water helps to cool down the Plant especially in warm conditions well done forgetting all the way through the video and I hope you found this video helpful I'll be releasing these videos for biology chemistry and physics that will be coming soon again thank you so much for watching and see you soon