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| Question | Answer |
| How are carbohydrates and fats used by the human body? | Carbohydrates and fats are used by the human body to release energy. |
| How are proteins used by the human body? | Proteins are used by the human body to build cells. |
| How are mineral ions and vitamins used by the human body? | Mineral ions and vitamins are needed in small amounts for healthy functioning of the body. |
| What is meant when a person is malnourished? | A person is malnourished is they have an unbalanced diet. |
| What can happen if a person is malnourished? | If a person is malnourished, they can become overweight or underweight. They may also develop deficiency diseases or conditions such as Type 2 diabetes. |
| What happens to a person’s body mass if they take in less energy from their food than their body needs? | If a person takes in less energy from their food than their body needs, their body mass will decrease. |
| How does exercise affect the amount of energy that the body needs? | Exercise increases the amount of energy that the body needs? |
| What is meant by a person’s metabolic rate. | The metabolic rate is the rate of all the chemical reactions in the cells in the body. |
| How is a person’s metabolic rate affected by the amount of muscle that they have? | Muscle tissue has a higher metabolic rate than fat tissue. So a more muscular person will have a higher metabolic rate than a less muscular person. |
| How is our body affected by inherited factors? | Inherited factors affect our metabolic rate (some people have a genetically high metabolic rate). Inherited factors can also affect our cholesterol level |
| What is the effect of exercise on our health? | People who exercise are usually healthier than people who take little exercise. |
| What did Semmelweis discover about preventing disease? | Semmelweis worked at a hospital where women gave birth. Many women died of infections. Semmelweis realised that doctors often handled dead bodies before treating patients and were spreading infection. He suggested that they regularly wash their hands. This reduced the number of infections. |
| What is meant by the word pathogen? Give two examples. | Pathogens are microorganisms that cause infectious disease. Examples are bacteria and viruses. |
| What is the key difference between bacteria and viruses in how they reproduce? | Bacteria can reproduce on their own. Viruses can only reproduce when they are inside living cells. |
| How do bacteria and viruses make us ill? | Bacteria and viruses can make us ill by releasing toxins. Viruses can also make us ill by damaging the cells in which they reproduce. |
| State three ways in which white blood cells defend us against pathogens. | White blood cells defend against pathogens by: • Ingesting pathogens (taking them in and destroying them). • Producing antibodies which destroy specific pathogens. • Producing antitoxins which prevent toxins from harming us. |
| Which three diseases does the MMR vaccine protect us against? | The MMR vaccine protects us from measles, mumps and rubella. |
| How does vaccination protect us from disease? | Vaccines contain small amounts of dead, or inactive forms of a pathogen. They trigger the body to produce antibodies. If the person is infected by the pathogen in the future, the body can now make antibodies more rapidly and protect us from infection. |
| How can the use of vaccines protect people who have not been vaccinated. | If enough people have been vaccinated, then the spread of a pathogen is reduced. This helps protect people who have not been vaccinated. |
| What do medicines such as painkillers do? | Medicines such as painkillers can help to relieve the symptoms of a disease but do not kill pathogens. |
| What do antibiotics such as penicillin do? | Antibiotics are medicines which kill bacteria. THEY DO NOT KILL VIRUSES. |
| Why do antibiotics not kill viruses? | Antibiotics cannot kill viruses because viruses live and reproduce inside cells. |
| How are bacteria becoming resistant to antibiotics? | Bacteria sometimes mutate and become resistant. If we overuse antibiotics (or use them when they cannot work e.g. for viruses), then these resistant bacteria have an advantage and resistance spreads. This is called natural selection. |
| How can we prevent resistant bacteria (such as MRSA) from developing? | To prevent resistant bacteria (such as MRSA) from developing we must: • Only use antibiotics when necessary and use the correct antibiotic to kill a specific bacterium. • Never use antibiotics against viruses as antibiotics do not kill viruses. |
| Why is mutation of pathogens a problem? | When a pathogen mutates, existing antibiotics and vaccinations may not work against the new strain. This can allow the new strain to spread. |
| Describe how natural selection leads to resistant strains of pathogens developing when antibiotics are used? (HIGHER TIER). | • Mutation leads to a resistant strain developing. • Antibiotics kill non-resistant pathogens. • Resistant pathogens survive and reproduce so the population of the resistant strain increases. |
| Why do we need to develop new antibiotics? | As bacteria become resistant to current antibiotics, we need to develop new antibiotics to treat bacterial diseases. |
| Describe the stages of culturing a microorganism (very common question). | • Sterilise petri dishes and culture growth medium • Sterilise inoculating loops by passing through a flame. • Tape the lid of Petri dishes shut to prevent microorganisms from the air contaminating the culture. |
| Why is it important that schools and colleges do not culture microorganisms at temperatures higher than 25C? | If we culture microorganisms at 25C or lower then this reduces the chance of culturing pathogens that may be harmful to humans. |
| Why are microorganisms used in industry cultured at temperatures higher than 25C? | In industry, we want to grow microorganisms rapidly so we use temperatures higher than 25C. |
| What do scientists call changes in the environment that we sense e.g. light, sound etc. | Changes in the environment that we sense are called stimuli. |
| What do we call cells that detect stimuli? Give examples. | Cells that detect stimuli are called receptors. Examples include: • eye - detect light • ears - detect sound • tongue and nose detect chemicals for taste and smell. • skin - detect touch, pressure, pain and temperature |
| What is meant by a reflex? What is the advantage of reflexes? | Reflexes are rapid, involuntary reactions. The benefit is that they can protect us from danger. |
| State the stages in a reflex. | • The stimulus is detected by a receptor. • Electrical impulses pass along a sensory neurone. • The impulse passes across a synapse (a chemical is released) to a relay neurone. • The impulse passes across a synapse to a motor neurone. • The impulse reaches the effector (eg a muscle or gland) and the response happens. |
| What is meant by an effector. State two examples? | An effector brings about a response • Muscles contract • Glands secrete chemicals |
| State three ways that water can leave the body. | Water can leave the body by: • the lungs in breathing out • the skin in sweating to keep cool • the kidneys producing urine |
| State two ways that ions e.g. the sodium ion are released from the body. | Ions are released by: • The skin in sweating • The kidneys when urine is produced |
| Why is it important that the body temperature is controlled? | The body temperature must be controlled so that it is at the temperature that enzymes work best. |
| What are hormones? | Hormones are chemicals released by glands. They are transported in the blood to the organs that they control (the target organs). |
| Why must the blood sugar levels be controlled? | Blood sugar levels must be controlled to provide cells with a constant supply of energy. |
| State two glands which release hormones controlling a woman’s menstrual cycle. | Hormones controlling a woman’s menstrual cycle are released by the ovaries and the pituitary gland. |
| Describe the stages of the menstrual cycle. | • Follicle stimulating hormone (FSH) released by the pituitary gland causes an egg to mature in the ovaries and triggers the ovaries to release oestrogen. • Luteinising hormone (LH) triggers the release of the mature egg. • Oestrogen from the ovaries inhibits the further production of FSH from the pituitary gland. |
| Describe how hormones can be used as an oral contraceptive. | Oral contraceptives can contain oestrogen and progesterone. This prevents eggs from being matured in the ovaries. |
| Describe the problems with early contraceptive pills and how these were solved in modern versions. | Early contraceptive pills contained high doses of oestrogen and caused side-effects. Modern pills contain much lower doses of oestrogen or progesterone only. These have fewer side effects. |
| Describe how hormones can be used as fertility drugs. | FSH and LH are used to stimulate eggs to mature in a woman. The eggs are collected and fertilised with sperm from the father. The embryos are inserted into the mother’s uterus (womb) to develop |
| Describe how plant shoots are sensitive to light and gravity. | Plant shoots grow towards light (positive phototropism) and away from gravity (negative gravitropism). |
| What is the name given to the plant hormones that control growth towards light and gravity? | Plant hormones are called auxins. |
| Describe how plant roots are sensitive to moisture and gravity. | Plant roots grow towards moisture and towards gravity. |
| What is meant by the words “phototropism” and “gravitropism”? | Phototropism means growth in response to light (eg shoots grow towards light). Gravitropism means growth in response to gravity (eg shoots grow away from gravity). |
| Describe how auxins are used in shoots to grow towards light. | In shoots, auxins trigger cell division. There is a higher level of auxin on the darker side of a shoot, so this side grows faster than the light side. This causes the shoot to grow towards light. |
| Describe how auxins are used in roots to grow towards gravity | In roots, auxins inhibit cell division. There is a higher level of auxin at the bottom side of a root. This side grows slower than the top, so the root grows downwards (towards gravity). |
| How are plant hormones used by gardeners? | Plant hormones are used by gardeners to kill weeds and to encourage roots to grow on plants. |
| What is the first stage in the testing of new drugs? | New drugs are first tested on cells, tissues and animals. This is to make sure that they work, that they are not toxic and to determine the best dose. |
| When drugs are first tested on humans, they are given in very low doses. Explain why. | When drugs are first tested on humans, they are given in very low doses to check that they are safe. Once we know they are safe, further human trials determine the best dose. |
| What is meant by a placebo? | A placebo is a tablet or injection which looks exactly like a treatment but has no active drug. |
| What is meant by a doubleblind drug trial? | In a double-blind drug trial, neither the patient nor the doctors know which patient is receiving the active drug and which patient is receiving the placebo. |
| What are statins used for? | Statins are used to lower the risk of heart and circulatory diseases. |
| What was thalidomide originally developed for? | Thalidomide was first developed as a sleeping pill. It was then found to reduce morning sickness in pregnant women. |
| What was the problem with thalidomide? | Thalidomide had never been tested on pregnant women (or pregnant animals). Many babies born to mothers who had taken thalidomide were born with limb abnormalities. |
| What is thalidomide used to treat now? | Now thalidomide is used to treat leprosy. |
| State two legal recreational drugs? | Two legal recreational drugs are alcohol and nicotine. |
| State three illegal recreational drugs. | Three illegal recreational drugs are ecstasy, cannabis and heroin. |
| Why are ecstasy, cannabis and heroine harmful to the human body? | Ecstasy, cannabis and heroin may have harmful effects on the heart and circulatory system. |
| Why do people smoke cannabis and what are the negative side-effects? | Cannabis makes people feel relaxed and happy. It can cause serious mental illness. People who use cannabis sometimes move onto more severe illegal drugs (eg heroin). |
| Why do legal drugs (both prescribed and recreational) have a greater impact on health than illegal drugs? | Legal drugs (prescribed and recreational) have a greater impact on health than illegal drugs because far more people use them. |
| What is the definition of a drug? | Drugs change the chemical processes taking place in peoples’ bodies. |
| State two highly addictive drugs. | Two highly addictive drugs are heroin and cocaine. |
| If a person is addicted to a drug, what can happen if they stop taking it. | If a person who is addicted to a drug stops taking it, they can suffer withdrawal symptoms. |
| State two examples of performance-enhancing drugs and describe what they do. | Stimulants increase the heart rate. Anabolic steroids increase muscle growth. |
| State four factors that plants compete for with other plants. | Plants compete with other plants for light, space, water and nutrients from the soil. |
| State three factors that animals compete for. | Animals compete for food, mates and territory. |
| What do we call organisms that live in very extreme environments? | Organisms that live in very extreme environments are called extremophiles. This can include living at high temperatures, pH etc. |
| Describe how camels are adapted to living in the dry conditions of the desert. | Camels store fat in their hump. This can be respired, releasing water. By concentrating fat (which is an insulator) in one place, this allows heat to escape from other parts of the body. Camels can tolerate increases in their body temperature, without sweating. Large feet reduce the pressure on the sand, preventing camels from sinking in. Camels have large eyelashes and can close their nostrils to prevent sand entering. |
| Describe how polar bears are adapted to living in the cold conditions of the Arctic. | Adaptations to prevent heat loss: • Thick layer of fat which acts as an insulator • Large body = small surface area • Thick fur • Small ears = small surface area • Fur on soles of feet for insulation Other adaptations • White fur = camouflage - harder for prey to see them |
| What can we say about the surface area of animals living in hot or cold conditions? | Animals living in hot conditions have a large surface area (eg bigger ears) to increase heat loss. Animals living in cold conditions have a small surface area (eg small ears) to reduce heat loss. |
| Describe how plants such as a cactus are adapted to living in dry conditions. | Cacti have no leaves to reduce the surface area that they can lose water from. The stem of a cactus is used to store water for use during very dry conditions. Cacti have an extensive root system to absorb as much water from the soil as possible. |
| State three ways that organisms can be adapted to deter predators. | Adaptations to deter predators include • thorns • poisons • warning colours |
| State three changes in the environment that can affect animals and plants. | Changes in the environment include: • Change in a competitor • Rainfall levels • Temperature |
| Describe how lichens can be used as air-pollution indicators. | Lichens are sensitive to air pollution such as sulphur dioxide. High levels of lichens tell us that there is a low level of air pollution. |
| Describe how invertebrate animals (animals without a backbone) can be used as indicators of dissolved oxygen in water. | Some invertebrates required very high levels of dissolved oxygen (eg mayfly nymphs). If we see these e.g. in a river then that tells us that there are high levels of oxygen in the water. Other organisms (such as Tubifex worms) indicate low levels of dissolved oxygen |
| Describe how energy passes into food chains. | Plants absorb sunlight and convert the light energy to chemical energy in photosynthesis. This chemical energy is stored e.g. in glucose or starch. |
| What is meant by biomass? | Biomass is the mass of living material at each stage of a food chain |
| Why does the biomass decrease at each stage of a food chain? | Some material and energy is lost in waste material released by organisms. Energy is also wasted as organisms respire (eg for movement). Eventually this energy is transferred to the surroundings. |
| State three conditions that increase the rate of decay of waste materials. | Decay is carried out by microorganisms. Microorganisms are more active under the following conditions: • warm • moist • aerobic (oxygen present). |
| How does the process of decay allow plants to grow faster? | When material is decayed, the elements are recycled back into the environment. Plants can use these elements for growth. |
| Describe the stages of the carbon cycle. | • Plants and algae carry out photosynthesis, removing CO2 from the atmosphere and storing the carbon as carbohydrates, fats and proteins. • When plants respire, the carbon can be returned as CO2 • Animals get their carbon by eating plants (or other animals). Some of the carbon is released as CO2 when animals respire. • Animals release waste products. Microorganisms feed on this and respire, releasing CO2. • When plants and animals die, microorganisms feed on their bodies and respire. The remaining carbon is released as CO2. • Combustion of wood and fossil fuels release CO2 into the atmosphere. |
| What is meant by the word gametes? | Gametes are sex cells (sperm and egg in humans, pollen and egg in plants). |
| Why do plants and animals share similar characteristics as their parents? | Plants and animals receive genes from their parents which is why they are similar to their parents. |
| What do we find in the nucleus of cells? | In the nucleus of cells, we find chromosomes which are made of DNA. |
| What is a gene? | A gene is a section of a chromosome that controls the development of a characteristic. |
| Why are organisms of the same species different? | Organisms can have different genetics or have been exposed to different conditions (the environment) or a mixture of both. |
| What is meant by sexual reproduction? | In sexual reproduction, male and female gametes join (fuse). The offspring show variation because they receive genetic information from two different parents. |
| What is meant by asexual reproduction? | In asexual reproduction there is only one parent and no joining of gametes. The offspring are genetically identical clones. |
| How can new plants be produced quickly? | New plants can be produced quickly by taking cuttings. The new plants are genetically identical to the original plant. |
| Describe how plant cloning can be carried out. | In plant cloning, a small group of cells is taken from the original plant. These are treated with hormones and develop into a new plant. |
| Describe how animals can be cloned by embryo transplants. | In embryo transplant, a developing embryo is split into two before the cells become specialised. The two balls of cells (embryos) are transplanted into host mothers and develop into two clones. |
| Describe the stages of animal cell cloning. | First the nucleus is removed from an unfertilised egg cell and the nucleus is thrown away. An adult body cell (eg skin cell) is taken from the adult to be cloned and the nucleus is removed. This nucleus is inserted into the empty egg cell. An electric shock triggers the cell to divide into an embryo. This is transferred into the womb of a female and develops into a clone of the original adult who provided the skin cell. |
| Describe what happens during genetic engineering. | First we identify a gene which is desirable (eg in humans). The gene is “cut out” of the chromosome of a cell. This is done using enzymes. The gene is then transferred into the cells of other organisms |
| What do scientists call crops which have had genes transferred into them from different organisms? | Crops which have received genes from other organisms are called genetically modified crops (GM-crops). |
| Why are genetically modified crops produced? | Genetically modified crops can be made to be resistant to attack by insects or resistant to herbicides (weed killers). GM crops usually show increased yield of crop. |
| What concerns do some people have about GM crops? | Some people worry that GM crops might be harmful to wild flowers and insects as well as human health. |
| What was proposed by Darwin in his theory of evolution by natural selection? | Darwin proposed that all species have evolved from simpler life forms that first developed more than three billion years ago. |
| State three reasons why Darwin’s theory of evolution by natural selection was only slowly accepted. | • Darwin challenged peoples’ belief that God created all the plants and animals on Earth. • There was insufficient evidence • How genetics operates was not known until several decades later. |
| What was Lamarck’s theory on how organisms evolve? Why is this wrong? | Lamarck proposed that when an rganism uses a feature (eg a muscle) that feature develops (eg gets bigger). This developed feature is then passed onto the offspring (for example muscular parents producing muscular children). We know that this is not possible in most cases of inheritance. |
| How can the similarities and differences between organisms give us clues about their evolutionary links? | Organisms that have similar features are likely to be evolutionarily related (eg humans, chimpanzees, orang-utans and gorillas are closely related as they share similar features). |
| Describe how evolution by natural selection takes place. | • Organisms within a species show genetic variation. • If an organism has an advantageous feature, it is more likely to survive and reproduce. • The genes which confer the beneficial feature are then passed on to the next generation. |
| What can cause rapid changes in a species? | When mutations produce a new form of a gene, a species can rapidly change if the environment changes. |
| What is glucose used for in plants? | S.P.a.R.C.S Starch.Proteins.Respiration.Cellulose.Seeds |
| What are glucose and nitrates used for in plants? | GrandmaNapsAtParties Glucose + Nitrates -> Amino Acids + Proteins |
| What are proteins used for? | PCASH Proteins -> Catalysts (Enzymes) Antibodies Structure Hormones |
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