science at school podcast

Aims of this Episode: Explain how to draw a professional graph, Explain how to draw a line of best fit, Explain how to use a graph to answer questions, Understand methods for using equations in exams, Understand how to use command words in exams. Graph Drawing Checklist: Draw the axes with a pencil and ruler, Label the axes in this format – Name (units) or Name / units Mark out the values on each axis in equal intervals (for example, 1, 2, 3… rather than 1, 5, 12…) Plot  the points with a SMALL dot or cross, Sit back and try to see if the data shows a straight line or curve, (If you’ve been asked to) draw a line of best fit. If you need to use a graph to answer a question, identify some evidence on your graph and quote this in your written answer. Remember to PEE on your work! (Point, Evidence, Explanation) Equation Question Checklist: Highlight the information in the question that you need (basically highlight all the numbers); Write down the equation (without the numbers in it) that you think you should use, You might want to rearrange the equation now if needed or wait until you’ve put the numbers in, Put the correct numbers into the equation, Calculate the answer and write it clearly. There’s no easy way to memorize equations, but the best thing to do is test yourself little and often. Start as far ahead of the exam as possible. Write the equations on flashcards and test yourself. Do this everyday or a couple of times each day – to begin with it’ll be pretty depressing because you’ll get most of them wrong, but if you stick at it you’ll know them all. Don’t forget to keep using practice questions to help prepare for how you’ll use the equations that you’ve memorized. Here’s a great link to help understand what each command words means.

Aims of this Episode: Describe the structure of the nervous system, Explain the function of the different parts of the nervous system, Explain how Nerve Agents can affect the nervous system. Nervous System This is an organ system, just like the circulatory system or the digestive system. The nervous system is made up of the brain and nerves. It detects changes in your environment and coordinates the body’s response. There are three different types of nerve in the body: Sensory Neuron – the nerves that detect changes; Relay Neuron – nerves that transfer messages around the body; Motor Neuron – nerves that cause your body to do something. You don’t have one continuous nerve moving through your body. Instead messages travel as small electrical impulses down the nerves and pass from one to another across a synapse. At the synapse the electrical message is turned into a chemical signal; when the chemicals arrive at the synapse of the next nerve they are converted back into electrical impulses to continue their journey. Click here to learn more about neurons. Most major movements in your body are caused by signals sent from your brain to the muscles that cause the movement. However, in an emergency your brain is left out of the loop. For example, when you put your hand on something hot the sensory neurons in your skin cause a message saying that something is too hot, this message travels to your spinal column where the immediate response is sent back along a motor neuron causing you to pull your hand away. Without having to send a message to the brain your body can respond a lot faster and therefore less damage is caused to you. This is called a reflex response. Nerve Agents Nerve Agents are a type of chemical weapon that affect the nervous system. It is illegal to use chemical weapons in a war because of the damage they caused during World War One. Most nerve agents attack the synapses between neurons. Many recreational drugs (like alcohol) cause changes in behaviour by affecting the same area of the nervous system. However, whilst recreational drugs only cause temporary changes, the damage caused by nerve agents is severe and can cause death. Basically what happens is the nerve agent blocks the transmitting or receiving parts of the neuron. This means that you enter paralysis (you can’t move) because the messages can’t travel around your body. If the nerve agent continues to work eventually the messages from your brain telling your lungs to breath will stop and you will die. Watch this video about how drugs affect the body and see if you can see similarities between them and nerve agents.

Aims of this Episode Define producer, primary and secondary consumer, predator and prey; Describe the cause and effect of bio-accumulation, Describe the structure of a food chain or food web, Explain to role of different animals in a food chain or food web. Food chains and food webs are simply ways of seeing what animals eat and how energy is transferred from the sun to the very top predator. The producers are often the plants at the very bottom and predators are the animals towards the top. Click here for a great video explaining food chains and food webs. Key definitions Producer – the organism at the very bottom of the food chain. On land they are usually plants, whilst in the sea they are plankton. Either way, they get their energy from the sun and store it in a chemical form. Consumer – these are animals that eat plants or other animals (basically anything that’s not a producer). You can find primary consumers that eat the producers and secondary consumers that eat plants and/or other animals (also known as Carnivores and Omnivores). Predator – animals that eat other animals; these can also be classed as secondary consumers. Prey – animals that get eaten by other animals. Most of the time predators are also prey to another animal. Both primary and secondary consumers can be prey. If an animal is not prey to anything else then it is called an Apex Predator. Bio-accumulation When toxins are released into the environment they might be spread out, so animals aren’t initially harmed by them. Producers will absorb some of the toxins and when they are eaten by primary consumers they pass the toxins on. Since the primary consumers eat many producers they will have a lot more of the toxin in their body than the producers did. As predators eat these primary consumers the concentration of the toxin will increase. Eventually, usually near the top of the food chain, the toxin levels are so high that it can kill the predators or seriously harm their babies. This effect is call bio-accumulation because the toxin is accumulating as it goes up the food chain. Click here for a video helping to explain it. Finally, here’s the pictures of the Baboons on the front of the car…

Aims of this Episode: Describe the pH scale, Explain why certain substances have certain pH values, Describe and explain a neutralisation reaction involving an acid and a base, Interpret basic reactions and name the products. The pH Scale pH is a measure of how acidic or alkali a substance is. Simply, it can help us to decide if a substance is dangerous or not. Like many things in science, it’s best if we can measure pH accurately. To do this we use the pH scale; this scale runs from one to 14, but also has colours: One (Highly Acidic), Seven (Neutral), 14 (Highly Alkali). But what does highly acidic actually mean? Well, a substance is classified as an acid if it has Hydrogen Ions (H+) in it; the more Hydrogen Ions there are in a certain amount, the more acidic the substance is, so it will have a lower pH number. Alkalies work in a similar way except instead of H+ ions, they are called alkalies because of the Hydroxide Ions (OH-) in the substance. The more of these there is, the higher the pH. Acids will cancel out alkalies, so if you mix an acid and an alkali in the correct amounts, you will get a neutral substance (pH 7). There are a couple of different ways to measure pH, some give you a colour (which you can then convert to a number) whilst others measure the pH number itself: Universal Indicator – this chemical changes colour depending on the pH. Litmus Paper – like UI (above) Litmus Paper changes colour. Red Cabbage Juice – basically a homemade version of UI. pH Meter – a device that gives a very accurate pH number. Neutralisation Reaction Most of the time you will see acids and alkalis in liquid form. As well as the normal liquids there is something called a Base. A Base is a solid (usually a powder) that dissolves (is soluble) to form an alkali. This is the start of a major practical in GCSE Chemistry: Dissolve a base in water to form an alkali, Add Universal Indicator (this should turn purple), Gradually add acid until the UI turns green, Stir in some charcoal to remove the UI, Pour the mixture through some filter paper to remove the charcoal, Leave the substance overnight to evaporate the water – you will be left with a salt. In this reaction the acid reacts with the alkali to form water and a salt. Often you will be asked to name the salt that is produced. This is simply a case of using the name of the metal oxide used in the reaction and the name of the acid. Nitric Acid will form a Nitrate salt etc. Click here for a great video explaining this reaction.

Aims of this Episode: Compare and contrast Longitudinal and Transverse waves, Describe uses of the different parts of the EM Spectrum, Explain the Doppler Effect, Explain Redshift as one example of The Doppler Effect. What is the EM Spectrum? Light. But not just visible light. EM stands for ‘Electro-Magnetic’; the EM Spectrum is a type of wave formed by electric and magnetic fields. The wave ranges from very long (10 km between one wave and the next) to very short (less than the width of a hair between two waves) and everything in between. As you move along the spectrum the properties of the wave change, so it is useful for different things. The wavelength and frequency are constantly changing along the wave. Scientists have broken the spectrum down into different ‘chunks’ based on their wavelength and frequency. At GCSE you need to know the details of each ‘chunk’. Click here for all the info. The Doppler Effect Waves are affected by movement (either of the source or the receiver). If the source is moving towards you (or you are moving towards the source) the wave squashes up and the wavelength gets shorter. If the source is moving away from you (or you are moving away from the source) the wave stretches out and the wavelength gets longer. With sound this is heard as a change in pitch. With light, the entire spectrum shifts either to the blue end or the red end. When observing distant stars it was seen that the entire spectrum of each star had shifted towards the red end of the spectrum (longer wavelength) – this meant that the stars were moving away from us and hence, provided evidence for the theory of the Big Bang. Click here for a great video explaining The Doppler Effect. Also, click here for some more information about Longitudinal and Transverse waves.

Aims of this Episode: Describe the structure of the Periodic Table, Identify properties of elements based on their location in the Periodic Table. Groups of Elements The main way in which the Periodic Table is organised is in vertical Groups. Elements in the same Group have similar properties. These similarities come from the fact that elements in the same Group have the same number of electrons in their outer shell. (Click here if you need to know more about electron shells.) Helpfully, the Group number is the number of electrons in the outer most shell. (Lithium is in Group 1, so it has one electron in its outer shell.) The Groups of the Periodic Table. One thing that doesn’t fit this pattern of Groups are the Transition Metals. They don’t have a specific group, so don’t fall into the trap of thinking that these have the same number of electrons in their outer shell. Periods of Elements If you look across the Periodic Table, there are also similarities between the elements. This time, the elements in each Period will have the same number of electron shells. Once again, the Period number is the number of shells. For example, Lithium is in Period 2, so we know it has two shells in total. The Periods of the Periodic Table. Metals and Non-metals Finally, the elements can be classed as Metals or Non-metals. Metals and Non-metals. What does the Periodic Table tell us? With very little knowledge of the individual elements, you can steal a lot of information from the Periodic Table. Let’s take our example of Lithium: From its Group, we know it has only one electron in its outer shell; From its Period, we know it has two electron shells; Being on the left of the dividing line, we know its a metal. Taking the information above one step further we can draw the electron shell diagram extremely quickly – it has two shells and the second shell will only have one electron. The only other fact we need to remember is that the first shell can only have two electrons in it: Electron Shell Diagram of Lithium.

Aims of this Episode: Define Homeostasis, Describe how your body maintains water content, temperature and blood sugar; Compare the two types of Diabetes. What is Homeostasis? Simply put, Homeostasis is the group of processes that maintain your body’s conditions. Think Homeo (human) and Stasis (status) – Human Status. There is a great number of things that need to be kept constant in the body. Three of the most important are Water Content, Temperature and Blood Sugar. Water Content Around 60% of your body is made up of water, so keeping that level constant is really important. The main organ responsible for this is the Kidneys; they filter excess water out of the blood and release this as Urine. You also lose water through sweating. Temperature Controlling temperature is the process you’re most likely to see yourself. Your body can lose heat by dilating the blood vessels in the surface of the skin (making you blush) and making you sweat. In reverse, the body can keep the heat in by constricting the blood vessels (making you look pale) and lifting the hairs on your body to reduce the amount of heat lost to the air. In addition, when you shiver your body is trying to generate heat by moving your muscles. Blood Sugar The amount of Glucose (sugar) in the blood is controlled by a hormone called Insulin, which is produced in the Pancreas. Insulin removes Glucose from the blood and stores it in the Liver, ready for when it is next needed. Diabetes is a condition that means your body is unable to control the amount of sugar in the blood by itself. Some people will have to inject enough Insulin, whilst others will be able to control their blood sugar levels by not eating too much sugary food. What now? There’s a lot of information that links to Homeostasis. Here are a couple of links to help you explore these areas further: Endocrine System: Video & Revision Page Kidney Structure: Video & Bitesize Page

Aims of this Episode: Describe the process of Nuclear Fission; Describe the function of different components of a Nuclear Reactor; Explain the difference between Nuclear Fission and Nuclear Fusion. Nuclear Fission Nuclear Fission is currently the only way that humans can generate electricity from a nuclear reaction. It is the splitting of a heavy nuclei [middle of an atom, not including the electrons] caused by absorbing a neutron. The heavy nuclei is either Uranium or Plutonium, since they are already pretty unstable. When they split, a large amount of energy is given off (in a thermal form), along with two waste nuclei (highly radioactive) and three more neutrons. These neutrons then go on to complete more fission reactions (a chain reaction)… and so on. In a Nuclear Power Station there are a number of components that you need to be familiar with: Fuel Rods – These contain the Uranium or Plutonium fuel and so this is where the reactions occur. Control Rods – As their name suggests these control the reaction by absorbing some of the neutrons created during a fission reaction. If we just let each reaction create three more then the process would get out of control, so we absorb some of the neutrons to maintain the reaction at a desired level. To increase the reaction, the control rods are removed and to reduce the reaction they are inserted further into the Reactor. Moderator – This is a solid or liquid that is used the slow the neutrons down. If the neutrons (created during each reaction) were not slowed down then they would be too fast to successfully cause more reactions, so the Chain Reaction would stop. Nuclear Fusion Nuclear Fusion is the fusing of two nuclei to produce energy. At present the only places that Nuclear Fusion successfully produces energy are in stars like the Sun. This process uses lighter elements such as Hydrogen. The Hydrogen nuclei fuse together to produce Helium nuclei and a lot of energy. The waste products of this reaction are not as dangerous as those of Nuclear Fission. To find out more about Nuclear Fission and Fusion, watch this video. Chernobyl The Chernobyl disaster occurred when a reactor in a Nuclear Fission Power Station overheated. This led to an explosion and fire that spread radioactive waste across Europe. Once you’ve got your head around the different parts of a Fission Power Station (above) check out this video. PS: We don’t think Dr Chekov (mentioned in the podcast) actually existed and the dramatisation is meant as a scientific explanation, not a re-enactment of history (basically we made the events up, if you hadn’t already guessed).

Aims of this Episode: Describe some examples of forces in the world around us; Explain the effect that forces can have on objects; Define speed and acceleration; Explain how forces can alter speed and cause acceleration. What is Speed? Simply put, speed is a measure of how quickly you travel a certain distance. 30 mph means that in one hour, you will travel 30 miles; 10 m/s means 10 metres every second and so on… The faster you travel, the more distance you will cover in a certain time or the less time it takes you to travel a set distance. How do Forces affect Speed? Unless you are in deep space there are always forces acting on you. Sometimes these forces balance out (up cancels out down, left cancels right etc.). When the forces cancel out your speed will not change – if you’re stationary, you will remain stationary; if you’re travelling at 30 mph, you will stay at 30 mph. A simple example would be a bike travelling along the road. As you ride the bike at a steady speed, you know that all the forces are balanced. If you apply the brakes then the force acting backwards increases – there is an overall force (resultant force) – this means that you slow down. What is Acceleration? Acceleration means a change in speed*. Normally we say something accelerates if it gets faster, but weirdly something slowing down is also said to accelerate (in a negative direction). In order for something to accelerate it needs a resultant force (the forces not to balance out). *On a slightly more advanced note acceleration is not only a change in speed, it can also be a change in direction. Therefore, a resultant force can cause a change in speed or direction.

New episodes of the Science At School Podcast coming out to you fortnightly on 17th September!

Aims of this Episode: Describe the process of Photosynthesis; Describe the function of Glucose within a plant; Explain how Active Transport is used in Photosynthesis; Describe the different cells within a leaf. The back garden of Buckingham Palace. What is Photosynthesis? Photosynthesis is the process whereby a plant turns the energy from the sun into a usable form – glucose. In order to do this the plant needs Carbon Dioxide and water as well as the sun light. As Photosynthesis takes place Oxygen is generated as a waste product. Light, Carbon Dioxide and water are in limited supply in some areas, so there is an element of competition. You can see this in the picture below – small plants don’t grow too close to the larger trees as the sun light is limited and the larger trees have a larger root system to get the water out of the soil. The Glucose that is created during Photosynthesis is stored in the plant as starch. This is because starch does not dissolve in water, so it cannot be lost through evaporation. Active Transport Some of the Glucose is combined with Nitrates from the soil to form Proteins. These Nitrates are pulled into the plant by Active Transport. What’s the job of the leaf? The leaves on a plant are responsible for gathering the sun light and the Carbon Dioxide. The Carbon Dioxide enters the base of the leaf, through small holes called Stomata. The opening and closing of these holes is controlled by the Guard Cells. The waste product of Photosynthesis, Oxygen, also comes out through the Stomata. At the top of the lead are cells that contain a large amount of Chloroplasts – small packets of Chlorophyll, the light absorbing pigment that looks green in colour.

Aims of this Episode: Describe Reflection; Describe Refraction; Describe Diffraction; Identify different types of lens; Explain how lenses focus light in the eye and the camera. Reflection, Refraction & Diffraction Reflection occurs when a wave bounces off a surface – echoes are examples of reflection. Refraction is the process whereby a wave changes its speed and therefore its direction when it goes from one medium (substance) into another medium (of a different density). Diffraction is when waves spread out as they pass through a gap. The width of the gap needs to be similar to the wavelength of the wave for this to happen. Lenses Convex lenses have a cross-section that looks like an oval. These lenses cause the light to converge onto a particular point. Concave lenses cause light to diverge from a particular point. These have a cross-section that looks a little bit like two caves back-to-back. Inside your eye and a camera there is a convex lens, which focuses the light onto your retina or the film. In your eye the lens can change shape to focus on things at different distances, whereas in the camera the lens moves backwards and forwards to achieve this focusing.

Aims of this Episode: Describe the process of Electrolysis; Identify the charge on the two different electrodes; Explain the reactions that occur on each electrode; Identify simple examples of Electrolysis. What is needed for Electrolysis? In order for Electrolysis to happen you need an ionic substance and two electrodes. The ionic substance is known as the electrolyte. This is either molten (melted soil) or something dissolved as a solution. The electrolyte contains charged particles called ions – these can be positively charged (an atom with too few electrons) or negatively charged (an atom with too many electrons). The electrodes are two pieces of metal connected to an electrical circuit. One will be positive (called the Anode) and one will be negative (called the Cathode). An easy way to remember this is PANIC: Positive Anode, Negative Is Cathode. What happens during the reaction? Once the electrical circuit is switched on the positive ions are attracted to the negative cathode and the negative ions are attracted to the positive anode. When the positive ions arrive at the cathode, they gain some electrons – this is called Reduction. When the negative ions arrive at the anode, they lose some electrons – the is called Oxidation. A way to remember this is OIL RIG: Oxidation Is Loss, Reduction Is Gain (of electrons). Reactivity Series In the cases that the electrolyte is a solution (not molten), the reactivity series is an important consideration. If the metal in the solution is above Hydrogen in the reactivity series then instead of this metal being deposited at the cathode, Hydrogen gas is produced. If the metal is below Hydrogen then the metal is deposited as expected. In addition to these basic principles of electrolysis, you need to be aware of the electrolysis of Aluminium and Brine. Click here for the BBC Bitesize pages. Here is a video for Aluminium and here is one for Brine.

Aims of the episode: Describe the structure of DNA; State what the process of DNA fingerprinting is used for; Explain how DNA controls your characteristics; Identify the uses of Punnett Squares. What is DNA? DNA is contained within the Nucleus of a cell and it makes up your Chromosomes. Its shape is described as a Double Helix – click here to see a video about the discovery of the Double Helix. Each long strand of DNA can be broken down into different sections, called Genes. Each Gene is further made up of bases – scientists are still discovering what each Gene is for. There are Genes to control everything from your hair colour to whether you are susceptible to certain diseases or not. For every Gene there are different forms of the Gene (Alleles) – for example, options for the hair colour Gene are the blonde hair Allele, brown hair Allele etc. DNA Fingerprinting DNA is pretty unique (but not as unique as your actual fingerprints). This means it can be used to identify someone who may have been at a crime scene. During the process of DNA fingerprinting the DNA strand is broken down into different sections – each section will move through a gel at different speeds, leaving a trail that looks like a bar code. Bar codes can be compared to find a match. In some cases the bar codes may be similar, but not identical, which may suggest a link to a relative; you will share some aspects of your DNA with your blood relatives. Inheritance Some Alleles are considered dominant, whilst some are recessive. If an Allele is dominant, you will see its effect even if that Allele has only come from one parent. An example would be brown eyes, if one of your parents passes the brown eye Allele to you then you will have brown eyes. Recessive Alleles need to be passed on from both parents in order for you to see the effect. The Allele for blue eyes is recessive, meaning both you mother and father need to pass on the blue eye Allele for you to have blue eyes. Punnett Squares are a useful tool to predict the likelihood of an offspring having certain characteristics. An example of a Punnett Square is shown below. Click here to see a video explaining how to figure out the likelihood of certain characteristics being passed on.

Aims of this Episode: Define the basic key terms: Charge, Current, Potential Difference and Resistance; Describe the differences between Series and Parallel circuits; Describe the differences between Direct and Alternating Current. Charge Charge is simply the thing that carries energy around a circuit. In a metal wire the charge is electrons (free electrons or valence electrons). These are put into groups called coulombs. One coulomb contains 16,000,000,000,000,000,000 electrons! Think “Herd of Sheep = Coulomb of Electrons”. Current “The rate of flow of charge.” This is a measure of how many coulombs pass a particular point in a circuit in one second. A current of 5 Amps means that five coulombs pass a point in one second. Potential Difference “Energy transferred per unit charge (coulomb).” As the coulombs of electrons pass through a bulb for example, they pass some energy onto the bulb. Therefore there will be a difference between the amount of energy per coulomb before the bulb and the amount of energy per coulomb after the bulb – this is the potential difference. Resistance Resistance is a measure of how difficult it is for coulombs of electrons to pass through the component (bulb or resistor for example). If the component has a higher resistance then the coulombs will either use more energy (higher potential difference) or move slower (lower current). Series & Parallel Series In a series circuit the components are arranged one after the other (much like the episodes in a TV series come one after another). The current is the same throughout a series circuit, whilst the potential difference is shared between all of the components. This makes sense, since the coulombs will move at the same rate, but will have to share their energy between all of the components because they have to pass through them all before returning to the battery. This is how you calculate the total resistance of a series circuit: Parallel In this type of circuit the components are arranged in loops, so there are multiple branches to each circuit. Because of these branches, the current splits and is shared out between each branch. However, each coulomb no longer has to share its energy with all of the components, so the potential difference is the same in each branch. The total resistance is calculated using this equation: Alternating & Direct Current Direct Current The coulombs in a circuit using direct current all flow in the same direction (from positive to negative), this is sometimes called conventional current. Your phone battery uses direct current. Alternating Current This type of current is found in mains electricity (the plugs in your wall at home). The coulombs move backwards and forwards (weird, I know), passing their energy a bit like a human chain passing buckets of water to put out a fire. In the UK, the mains electricity has a potential difference of 230V and changes direction 50 times per second, so it is said to have a frequency of 50Hz.

Aims of this episode: Identify sources of background radiation; Describe the three main types of radiation; Explain how your location can affect the level of background radiation; Explain how avalanches are formed. Radiation Firstly, you need to understand that radiation is all around us. Right now, as you sit wherever reading this, tiny particles or waves of radiation are hitting you, some stop inside your body and damage the DNA in a cell whilst some pass straight through you and keep going. This ‘background radiation‘ does not cause you any lasting harm – we receive it in such small doses that it can’t do any lasting harm. The background radiation comes from a variety of sources, these include the rocks around you and under your feet (Radon Gas), space (Cosmic Radiation), food, other humans, medical sources and finally (making up less than 1% of your background dose of radiation) nuclear experimentation (bombs and the like). There are three main types of radiation: Alpha This is made of 2 protons and 2 neutrons (the more observant among you will recognise this as the nucleus of a Helium atom). This is a pretty big particle and moves relatively slowly, meaning it is easily stopped. When a particle of radiation is stopped it ionises another atom, so Alpha is highly ionising. Alpha is weakly penetrating – it won’t pass through much: 2 cm of air, some card or the first layer of your skin are enough to stop it. This means that from outside your body Alpha is the least dangerous, but if the material giving off Alpha Radiation gets inside your body… well let’s just say it never ends well. Click here for more. Beta This is just 1 lonely electron. Being much smaller and faster, Beta has an average ionising power and will require 50 cm of air or 5 mm of Aluminium to stop it. This is the most dangerous form of radiation if directed at you from outside your body since the thickness of the human body is usually enough to stop it. Gamma Gamma Radiation is a wave, so has no mass and moves at the speed of light since it is light (part of the EM Spectrum). Therefore, Gamma is weakly ionising and will pass through a lot of material (up to 30 cm of Lead) before coming to a stop, meaning it is highly penetrating. This is a good thing for us as most of it will pass straight through your body without damaging it. If you want to learn more about background radiation and the danger to humans, here’s our favourite radiation video. Avalanches Well, who knew you should be afraid of snow? Check this out.

Aims of this Episode: Identify the different parts of the Circulatory System; Describe the differences between each blood vessel; Identify the function of the different parts of the blood. The Heart Human hearts beat twice in each cycle, meaning our Circulatory System is known as a ‘double circulatory system’. Firstly, the blood is received from the body through the Vena Cava and pumped to the lungs via the Pulmonary Artery, so that gas exchange can happen. The now oxygen rich blood re-enters the heart via the Pulmonary Vein and is then pumped at high pressure around the rest of the body, via the Aorta. Not all organisms have a double circulatory system. Smaller animals, like fish, don’t need the high blood pressures seen in double circulatory systems, so their hearts only beat once per cycle. If you ever get chance to dissect a heart, take some time to notice how one side is more muscular than the other. The Blood Vessels Artery – The arteries usually carry oxygenated blood away from the heart and towards the cells and tissues around the body. They have a very thick muscular wall to cope with the high pressure. They also deform to allow the surges of blood to pass through. It is this deformation that you can feel when you take your pulse. Vein – The veins usually carry de-oxygenated blood towards the heart and away from the cells and tissues. They don’t have a very thick wall because the pressure is much lower. However, veins have valves to prevent the blood from flowing the wrong way down the body. Capillary – The capillaries are tiny blood vessels between the main arteries and veins. Imagine them as the small roads around your house that you travel on after you have come off the motorway. They have a very thin wall (one cell thick in some cases), which allows diffusion of the important compounds to happen very quickly – it creates a short diffusion pathway. The Blood Plasma – The plasma is the liquid, which carries all of the other parts of the blood around the body. Red Blood Cells – The most popular type of blood cell, the Red Blood Cell carries the oxygen and carbon dioxide around the body. They are red because of the haemoglobin, which the oxygen and carbon dioxide attach to. Red Blood Cells also have a dip in the middle of the cell, which increases the surface area and allows diffusion to happen quicker. White Blood Cells – These are much bigger than the Red Blood Cells and their job is to target an destroy any diseases or germs in the body. They do this by consuming the germ cell into themselves and destroying them. Platelets – Platelets are key for clotting blood (binding the cells together to stop bleeding). When they arrive at a cut they form a spaghetti like mesh, which holds the blood cells together. This is more commonly known as a scab.

Aims of this episode: Identify the main pollutants from fossil fuel burning; Describe the effects of pollutants on the environment; Understand the causes and effects of global warming. Types of Pollutants There are more pollutants than just Carbon Dioxide. When fossil fuels are burnt, many different chemicals are given off and most of these either contribute to global warming or are toxic to humans and animals. Click here to read about some of the less well known pollutants. Global Warming Global Warming is the gradual increase in global temperatures caused by the Sun’s heat getting trapped in the atmosphere by the pollutants given off primarily due to human activity. 2016 was an important year for global warming – click here to find out why. Whilst it is called ‘global warming’ the effects are more varied, so we use the term ‘climate change’ to describe what we see. Here is a map showing you how the climate is changing around the world. We found a video that explains a bit more about how global warming works – click here. So, what can you do? Sky News produced a quick video to give you some ideas.

Aims of this episode: Understand what defines an area as a desert; Explain how radiation and convection currents mean that the Sahara Desert is very cold at night; Explain how Specific Heat Capacity means that most desert animals are nocturnal. Click here for the Planet Earth 2 homepage. Deserts are just sand… right? Actually, the definition of a desert only mentions how much rain it receives in a year (25 cm). It doesn’t mention temperature or how many plants or animals there are. Therefore, some parts of Antarctica (one of the coldest places on Earth) are classed as deserts because of their lack of rain (or snow). However, even the ‘hottest’ deserts can be very cold. The Sahara Desert in Africa can reach temperatures of 50 degrees Centigrade during the day, but at night these can fall to below zero! This is because all of the energy that has beaten down on the desert during the day radiates off at night. Since there is no cloud cover at night, there is nothing to reflect this energy back towards the ground, therefore the temperature falls. In addition to radiation, there are convection currents in the air. The air particles at the surface gain energy from the ground. The particles spread out – reducing the density of the air – which then rises up. This is replaced by cool air, so gradually the energy is taken from the surface of the desert. This rising air can cause problems for aircraft flying overhead and is known as turbulence. Now, 50 degrees Centigrade is extremely hot when it comes to living things. Therefore animals find it extremely difficult to live in hot deserts during the day. However, at night the temperature becomes a lot more bearable. Therefore, most animals burrow into the sand during the day. The high temperatures don’t reach very far below the surface because the sand will be able to hold a lot of energy without its temperature rising too much.

Aims of this episode: Understand the extent of competition in jungles; Understand that we know very little about jungles – even in 2016. Click here for the Planet Earth 2 homepage. Jungles or Rainforests? Jungles are described as areas of over grown vegetation. Rainforests include this defintion, but in addition they have an overhead canopy of trees. Therefore, all rainforests are jungles, but not all jungles are rainforests. There’s so much in jungles and here’s a link to a National Geographic website, which will tell you more. Aside from that, we’ll let Sir David Attenborough do the talking.