Half Term Exam PDF - Science Past Paper

# 7A DOCTORS PAST AND PRESENT For thousands of years people have gone to see doctors when they feel unwell. Some of the ways in which doctors examine patients have not changed! For example, 3000 years ago, Ancient Egyptian doctors knew that if a person's heart was not beating as well as usual th...

# 7A DOCTORS PAST AND PRESENT For thousands of years people have gone to see doctors when they feel unwell. Some of the ways in which doctors examine patients have not changed! For example, 3000 years ago, Ancient Egyptian doctors knew that if a person's heart was not beating as well as usual that person could be ill. Today, doctors still find out how well your heart is beating. They may also measure temperature and do blood and urine tests to see if there are changes in your body compared to normal. These changes are called symptoms. Different problems cause different symptoms. The symptoms of a cold include a sore throat and runny nose. ## Examining Patients Doctors have written instructions for how to treat problems for thousands of years. This Ancient Egyptian carving records the range of instruments and medicines that a doctor used to treat patients. Many of the instruments still look familiar! ## Modern Equipment Modern equipment can see organs inside our bodies. Scientists have used this technology on Egyptian mummies and found that many had heart problems. ## Matching Symptoms A doctor sees if there is a match between a patient's symptoms and a known problem. If there is a match, the symptoms are evidence that the person has a certain illness. Luckily, if you need a **medicine** today it will not contain a favourite ingredient of Ancient Egyptian medicine - animal dung! *** ## Questions 1. A patient has a high temperature, a headache and a stuffy nose. Which word in bold on this page best describes these findings? 2. Suggest what illness the patient has. 3. A doctor tells a patient that they have acne. Suggest what evidence the doctor has found to make them think this. ## The Heart 1. Which of the following best describes the heart: * A) an organ * B) a cell * C) a tissue * D) a system? 2. State one job that the heart does. *** # 7A LIFE PROCESSES ## What Do All Living Things Do? The Ancient Egyptians believed they had cures for death, including one made from onions. It is doubtful that this worked! When they died, the bodies of important people were treated to stop them rotting - they were mummified. This was done because Ancient Egyptians believed that living things contained a 'life force' called ka, which needed somewhere to live. Today, we have different ideas about what it means to be alive. We look at what things do. If something can do the following life processes, it is a 'living thing' or organism: * move * reproduce * sense things * grow * respire * need nutrition. * excrete waste ## Organism or Not an Organism Copy and complete the table below with the items in the list. | Organism | Not an organism | | :-------- | :---------------- | | car, chair, coal, cow, | daffodil, goldfish, | | mouse, octopus, robot, | rock, snake, Sun | ## Movement All living things can either move from place to place or move parts of themselves. ## Reproduction Organisms can make more living things like themselves. We say that they can reproduce. ## Questions 1. A | The mummies of some of the most important Ancient Egyptian rulers (the pharaohs) were placed inside huge stone pyramids. A mnemonic is a word or phrase that helps you remember a list. It is usually made using the first letters of the words in a list. What mnemonic is spelled out by the first letters of the life processes? 2. B | Arctic poppies move parts of themselves. Their flowers turn to follow the Sun during the day. Suggest one difference between how most animals move and how most plants move. 3. C | Offspring are the result of reproduction. Suggest one thing that many plants do to reproduce but animals do not do. *** # 7A SENSITIVITY, GROWTH, RESPIRATION, EXCRETION, NUTRITION ## Sensitivity Organisms sense and react to things around them. ## Growth Living things increase in size. We say that they grow. ## Respiration Living things use a process called respiration to release energy for them to use. ## Excretion Organisms produce waste materials. When they get rid of these waste materials we say that they excrete them. ## Nutrition Living things require various substances to help carry out other life processes. We say that they need nutrition. ## Questions 1. Describe two ways in which you show sensitivity. 2. Suggest one difference between how trees grow and how humans grow. 3. Suggest one difference between how fish and humans get their oxygen. 4. a) In what ways is a car like an organism? b) Why is a car not an organism? *** # 7A ORGANS ## What Do Organs Do? In Ancient Egypt, the heart was thought to be the most important part of a person. When people were mummified, the organs in their bodies were removed but the heart was left in place. The stomach, intestines, lungs and liver were thought to be useful on the person's journey in the afterlife and these organs were preserved. They did not think the brain was important and so it was often thrown away. ## Human Organs The heart, stomach, intestines, lungs and liver are organs. Every organ has an important function (job). We now know that the brain is also an organ and has the very important function of controlling the body! Your body's biggest organ is on the outside. It's your skin. Skin is used for protection and sensing things. ## Questions 1. Draw a table to show the functions of five different organs in your body. 2. Which organ gets bigger as it fills with air? 3. List the organs that help to get nutrition into the body. 4. List the organs that excrete waste materials. 5. List two organs that store solid or liquid wastes. *** # 7A PLANT ORGANS ## Photo D shows some of the main organs in plants. * **Leaf:** traps sunlight to make food for the plant * **Stem:** carries substances around the plant and supports the leaves and flowers * **Root:** holds the plant in place. Roots also take water and small amounts of other substances from the soil. ## Photosynthesis Plants make their own food using a process called photosynthesis. This process occurs in the leaves when there is light. Photosynthesis needs carbon dioxide from the air, and water. Some plants also have storage organs, which they use to store some of the food that they make. Potatoes and carrots are storage organs. ## Questions 1. Which organ is the main organ of nutrition in a plant? 2. a) What process produces the food stored in plant storage organs? b) Why won't a potato grow if the potato plant does not get much light? 3. Which human organ is most similar to a leaf? Explain your reasoning. *** # 7A MEDICAL DOCTORS ## How Do Medical Doctors Use STEM Skills? STEM stands for science, technology, engineering and maths. There are many interesting jobs open to people with skills in these subjects. These include careers in communications, farming, fashion, films, finance, health, sport and video gaming. All STEM subjects are linked: * similar skills are needed for each one * changes or advances in one subject may change the way the others are done. ## STEM Skills An important STEM skill is problem-solving. This is often done by thinking up ideas and then testing them. Results from the tests are used as evidence (information used to decide if an idea is correct or incorrect). A decision made using evidence is called a conclusion. Doctors think up ideas about what might be wrong with a patient. They then perform tests. They use the test results and their knowledge of the human body to make a conclusion (called a 'medical diagnosis'). ## Questions 1. List the STEM subjects. *** # 7A ORGAN TRANSPLANTS ## What Is an Organ Transplant? Doctors today know a lot about cells, tissues and organs. They also have microscopes and other tools to help investigate problems with our bodies. If a doctor thinks there is something wrong with an organ, a biopsy (piece of tissue) might be taken from the organ and examined. This can help to identify the problem and a doctor can plan a treatment. ## Organ Transplantation Sometimes an organ cannot be treated and doctors may consider doing an organ transplant. This is when an unhealthy organ is replaced with a healthy organ (usually from a person who has recently died). ## What Does A Donor Carry? Some people want their organs to be used for transplants if they die. They may carry a card to show this. *** # 7A MIXTURES ## What Kinds of Mixtures are There? Water that carries waste materials needs to be treated in a water treatment plant so that it does not harm people or the environment. Waste water is not a single substance - it is not a pure substance. It is a mixture of water and solid substances. ## Grouping Mixtures Mixtures are grouped depending on whether the substances in them are solids, liquids or gases, and on how the substances can be separated. * **A solution** is a mixture in which the solid dissolves in the liquid. This makes the mixture clear or transparent. * **A suspension** is a mixture of two substances that separate if the mixture is not stirred. These two substances are often a solid and a liquid. When they are mixed, we say that one substance is suspended in the other. An example is sand mixed with water. * **In a colloid,** one substance is dispersed in another substance and the two substances will not separate easily. Either substance may be a solid, liquid or gas. A colloid is cloudy or opaque, so it is easy to see that it is a mixture. Milk is a colloid of different milk solids dispersed in water. ## Questions 1. Why is waste water an example of a mixture? 2. a) Suggest what is removed from waste water during the first stage of water treatment. b) Describe how this is removed. 3. Describe one difference between a suspension and a solution. 4. What kind of mixture is the waste water that enters a water treatment plant? Explain your reasoning. *** # 7A FORENSIC SCIENCE ## How Does a Forensic Scientist Prepare Evidence for a Court? Forensic scientists collect materials from crime scenes. They may collect soil, burnt or broken materials, hairs and body fluids. The scientists then examine and test the materials in a lab. Their results can be used as evidence in a court of law. For example, the evidence could be used to show whether a person or vehicle was in a certain place. ## Using Knowledge of Chemistry Most forensic scientists have a university degree in forensic science, or other science followed by forensic science training. A forensic scientist needs a good understanding of the techniques used to separate and identify small amounts of substances (samples). ## Questions 1. Write down what you think forensic science means. 2. Give a reason why a forensic scientist needs to know how to separate the different substances in a sample. 3. Explain why filtration could help analyse where a soil sample originally came from. *** # 7A CLEAR COMMUNICATION ## Important part of a method Forensic scientists need to explain clearly what they have done. An important part of this is their method, which is a set of written instructions showing how an experiment is carried out. The method may also include a diagram of the apparatus. A clear method lets other scientists repeat an experiment exactly, to check the results. It also allows people in a court to understand easily what a forensic scientist has done. ## Method of Filtering The Method on the right can be used to filter a sand (or soil) sample using the apparatus in diagram C. It is clear because: * it is done in steps, which each have a letter * each step describes only one action * each step begins with a command word (also called an imperative verb). This keeps the sentence simple. ## Questions * Why is it important for forensic scientists to describe their methods clearly? * 'Open' in step C is a command word because it tells you to do something. Identify three other command words in this Method. Explain your choices. * Suggest a part of this Method that could be made clearer by using a diagram rather than words. * Write a method to explain to someone how to set up the apparatus in diagram D. Use all the rules for writing a good method. Compare your method with one written by another student to see if your method could be improved to make it clearer. *** # 7A MICROSCOPES ## How is a Light Microscope Used to Examine a Specimen? To find out what is wrong with an organ, doctors do tests. Some tests involve taking a small piece of tissue (a biopsy) from an organ and looking at it under a light microscope. Microscopes make things appear bigger; they magnify things. The Method below shows how to use a light microscope. ## Method * **A:** Place the smallest objective lens (the lowest magnification) over the hole in the stage. Turn the coarse focusing wheel to make the gap between the objective lens and the stage as small as possible. * **B:** Place the slide under the clips on the stage. The slide contains the specimen (the thing you want to look at). Then adjust the light source so that light goes up through the hole. * **C:** Look through the eyepiece lens. Turn the coarse focusing wheel slowly until what you see is in focus (clear and sharp). * **D:** To see a bigger image, place the next largest objective lens over your specimen. * **E:** Use the fine focusing wheel too get your image in focus again. Do not use the coarse focusing wheel since you can break the slide and damage the objective lens. If you cannot see your specimen clearly, go back to a lower magnification. ## Important Information Never point a microscope mirror at the Sun. This can permanently damage your eyesight. ## Questions * How many types of lenses are found in a light microscope? * Write down some rules of your own for: * using a microscope safely * taking care of a microscope. * What part of a microscope makes the image clearer? * What is a specimen? *** # 7A TISSUES ## Why Are Tissues Important? Many good detective stories have a 'pathologist', who inspects a dead body to look for evidence to help to solve a murder. Pathologists have a long history; dead bodies were examined in Ancient Egypt, Ancient Greece and in Roman times. Pathologists are fully trained doctors. Some pathologists examine dead bodies to try to work out causes of death. Others examine small pieces taken from living people to try to identify diseases. ## Microscopes and Magnification Pathologists use microscopes, which magnify things. This allows pieces taken from a body to be examined in great detail. ## Questions * What does a microscope do? * Look at photo B. Describe what a heart looks like. *** # 7A PLANT AND ANIMAL CELLS ## How Are Plant and Animal Cells Similar and Different? Mummification preserves tissues. In 1825, Dr Augustus Granville tried to work out how a 2500-year-old Egyptian 'mummy' had died. His study included using a microscope to examine tissues. His conclusion was 'cancer'. Technology has now advanced and another examination of the same mummy in 2009 concluded that the person died from a lung disease called tuberculosis (TB). ## Cells Robert Hooke was the first person too study tissues with a microscope. In 1665, he examined the bark of a cork oak tree and saw little box shapes. He thought that they looked like the cells (small rooms ) in a monastery and so that's what he called them. Today we know that cells are the basic units from which all tissues and all living things are made. A tissue is a group of cells of the same type working together. ## Questions * What is a cell? * Granville was able to see much more in the mummy tissues than Hooke saw in the cork tissue. Why was this? * What do organisms always have that things that have never been alive do not? *** # 7A ORGAN SYSTEMS ## How Do Cells, Tissues and Organs Work Together? When cells of the same type are grouped together they form a tissue. Different tissues are found grouped together in an organ. ## Questions 1. Name three tissues found in the heart. *** # 7A MIXTURES AND SEPARATION ## What Kinds of Mixtures are There? Water that carries waste materials needs to be treated in a water treatment plant so that it does not harm people or the environment. Waste water is not a single substance - it is not a pure substance. It is a mixture of water and solid substances. ## Grouping Mixtures Mixtures are grouped depending on whether the substances in them are solids, liquids or gases, and on how the substances can be separated. * **A solution** is a mixture in which the solid dissolves in the liquid. This makes the mixture clear or transparent. * **A suspension** is a mixture of two substances that separate if the mixture is not stirred. These two substances are often a solid and a liquid. When they are mixed, we say that one substance is suspended in the other. An example is sand mixed with water. * **In a colloid,** one substance is dispersed in another substance and the two substances will not separate easily. Either substance may be a solid, liquid or gas. A colloid is cloudy or opaque, so it is easy to see that it is a mixture. Milk is a colloid of different milk solids dispersed in water. ## Questions 1. Why is waste water an example of a mixture? 2. a) Suggest what is removed from waste water during the first stage of water treatment. b) Describe how this is removed. 3. Describe one difference between a suspension and a solution. 4. What kind of mixture is the waste water that enters a water treatment plant? Explain your reasoning. *** # 7A SOLUTIONS ## Why Do Some People Use Filters for Tap Water? Tap water has been filtered and treated to make it safe for drinking but it does not contain only water. It is still a mixture, with many other substances dissolved in the water. ## Dissolving to Make Solutions Some substances dissolve in a liquid to make a solution. In a solution, the dissolved substance breaks up into pieces so small that light passes straight through the mixture. Because of this, solutions are transparent. A solution may be coloured or colourless, depending on the substances in it. ## Questions 1. What is meant when we say tap water is a solution? 2. Write down the names of two solids and one gas that dissolve in water. 3. Suggest two ways you could tell that a liquid was a solution. *** # 7A CHROMATOGRAPHY ## How Can You Separate Solutes for Identification? After water has been cleaned at the treatment works, it must be tested before it can be used as drinking water . Tests for many different substances are carried out to make sure the water is safe. ## Chromatography Chromatography is one technique used in water analysis. Chromatography separates substances dissolved in a mixture. This makes it easier to identify and analyse each substance. ## Types of Chromatography There are many different kinds of chromatography. Paper chromatography is the simplest method. It can be used to find out which colours are mixed together in different paints, dyes and inks. A concentrated dot of the mixture is placed near the bottom of special chromatography paper. The bottom of the paper is dipped into a solvent. The solvent carries the coloured substances in the ink or paint up the paper to form a pattern called a **chromatogram**. ## Chromatography Basics The basic process of chromatography is the same, whether it is done with paper or by machine. Different substances in a mixture are carried by a gas or liquid solvent. The substances are carried at different speeds, which separates them out from each other. ## Questions 1. What is chromatography? 2. Look at diagram B. Which of the two substances had the higher concentration in the original sample? Explain your answer. 3. Look at photo C. Describe how this experiment was set up. *** # 7A ENERGY AND CHANGES ## Energy is Needed for Many Things There are a lot of things happening in a theme park. Almost everything that happens involves energy in some way. For example, your body needs energy to stay alive, and to allow you to move around. Energy is needed to make all the rides in the theme park work. The energy needed is stored in food and in fuels, such as petrol. ## Questions 1. Which of the rides shown in photo A needs the most energy and which the least energy? Explain your answers. 2. a) Write down five different things that are happening in photos A and B that need energy. b) How is energy provided for these things to happen? 3. a) Write down five things you did yesterday that needed energy. b) Which of these things do you think needed the most energy, and which needed the least energy? How do you know? *** # 7A ENERGY FROM FOOD ## How Do Our Bodies Use Energy? Humans and other animals need energy to live. We need energy to help us to grow and repair our bodies, and to move and keep warm . Our bodies use food a source of energy. ## Joules and Kilojoules The unit for measuring energy is the joule (J ). The amount of energy needed to lift an apple from the floor onto a table is about 1 J. Most foods contain a lot more energy than this, so we usually measure the energy in foods using kilojoules (kJ). 1 kJ = 1000 J. ## Questions 1. Why does your body need food? 2. a) How much energy does 100 g of falafel burger contain? Give your answer in kilojoules. b) Mark eats two burgers (each burger is one falafel burger in a bun). How much energy is in the food he eats? *** # 7A ENERGY TRANSFERS AND STORES ## Energy can be Stored Energy can be stored. For example, energy is stored in the chemical substances in food, petrol and cells (batteries). We call this chemical energy. Things happen when energy moves from a store. We say that the energy is transferred. ## Ways Energy is Transferred This can happen by: * heating * light * sound * electricity * forces. ## Questions 1. Write down three things that: * a) transfer energy by heating or light * b) transfer energy by sound * c) use energy transferred by electricity. ## Kinetic Energy Many machines allow energy stores to be transferred into energy stored in other ways. For example, moving objects store energy. We call this kinetic energy. ## The Law of Conservation of Energy When energy is transferred, it is not used up . Energy cannot be created or destroyed; it can only be transferred and stored in different ways. This is called the law of conservation of energy. ## Questions 1. Diesel fuel is a store of energy in chemicals. Write down three other things that store energy in chemicals. *** # 7A EVAPORATION ## How Do You Get Solids Out of a Solution? During evaporation of a solution, the liquid turns into a gas which escapes into the air. The evaporating liquid leaves behind the solids that were dissolved in it. Evaporation can happen at any temperature, even when it is cold. However, the rate of evaporation increases as temperature increases. ## Questions 1. Look at photo C. The sea water is left in the ponds for a week or more. * a) Describe what happens to the water. * b) Explain why the salt is left behind in the ponds . 2. Would the rate of evaporation of water be greater in the cold cave in photo A or the warm salt ponds in photo C? Explain your answer. 3. Draw flow charts to show the two ways in which table salt is produced. *** # 7A FAIR COMPARISONS AND RATIOS ## How Can You Compare the Energy Stored in Different Foods? You can compare the amount of energy stored in different foods by burning them. Photo B shows the kind of apparatus you need. The energy released by the burning food heats the water in the boiling tube. The higher the temperature of the water, the more energy the food released when it was burnt. ## Method * **A:** Find the mass of a piece of food. * **B:** Carefully put the food on a pin (which has its other end in a piece of cork). * **C:** Put 10 cm³ of water into a boiling tube. Record its temperature. * **D:** Light the food using a Bunsen burner, and hold the burning food under the boiling tube. Make sure the flame is touching the boiling tube. * **E:** When the food has finished burning, record the temperature of the water again. * **F:** Let the food cool down, then carefully push what is left off the pin and find its mass. If there is no food left on the pin, write down 0 g for its mass. * **G:** Repeat steps A to F for other foods. ## Important Information Wear eye protection. Do not eat any of the foods. Do not use nuts. ## Questions 1. a) Look at tables C and D. Write down the foods in order of the temperature rise, starting with the lowest (bread). b) Now write down the foods in order of the temperature rise per gram of food. c) Which list is the best comparison of the amounts of energy stored in the different foods? Explain you answer. 2. The student also tested diet crispbreads in the investigation. The temperature rise per gram was 1.0°C. What is the ratio of the temperature rise caused by the crispbreads compared with: * a) the bread * b) the cheese? 3. A student says, "I would get the same energy from eating 50 g of bread or 25 g of cheese." Is the student correct? Explain your answer. 4. Pears store 175 kJ of energy per 100 g of fruit, and bananas store 350 kJ per 100 g. Calculate the ratio of the energy stored in the two kinds of fruit. *** # 7A CELLS ## How Are Plant and Animal Cells Similar and Different? Mummification preserves tissues. In 1825, Dr Augustus Granville tried to work out how a 2500-year-old Egyptian 'mummy' had died. His study included using a microscope to examine tissues. His conclusion was 'cancer'. Technology has now advanced and another examination of the same mummy in 2009 concluded that the person died from a lung disease called tuberculosis (TB). ## Cells Robert Hooke was the first person too study tissues with a microscope. In 1665, he examined the bark of a cork oak tree and saw little box shapes. He thought that they looked like the cells (small rooms ) in a monastery and so that's what he called them. Today we know that cells are the basic units from which all tissues and all living things are made. A tissue is a group of cells of the same type working together. ## Questions * What is a cell? * Granville was able to see much more in the mummy tissues than Hooke saw in the cork tissue. Why was this? * What do organisms always have that things that have never been alive do not? ***