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EDEXCEL AS BIOLOGY REVISION GUIDE PDF

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Edexcel Biology AS Revision Notes - Free download as PDF File .pdf), Text File .txt) or read online for free. Revision Notes for Edexcel Biology AS. Feel free to. Download as PDF, TXT or read online from Scribd. Flag for . Welcome to your Edexcel A2 Biology Revision Guide. can be found at the back of the book. A-level biology edexcel - revision notes AS Watch. start new bio rev resourceone.info ( KB). 1. reply . do you have a pdf for the cgp revision guide plz! 0. reply.


Edexcel As Biology Revision Guide Pdf

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The key to a smarter way of revising. Download sample: REVISE Edexcel AS/A level Biology Revision Guide samples (PDF, Mb). Designed for hassle-free. resourceone.info Authors: REVISION GUIDE BIOLOGY. 3 Classification. 4 Vertebrates and invertebrates. 5 Species. Hi guys, I'm new to the Edexcel system. I sat my no there isnt any as biology revision guide.:(where . resourceone.info

Gene opens up. Hydrogen bonds break between bases 2. RNA nucleotides attracted to complementary bases and form hydrogen bonds. Complementary RNA copy of gene now made. Single stranded mRNA molecule diffuses out of gene 6.

Many mRNA strands are made before gene closes. MRNA is complementary, not a copy! Start AUG codon fits into bottom of P site 2. The amino acids between the two tRNAs join together forming a peptide bond 5.

The tRNA in the P site diffuses into the cytoplasm and binds to another specific amino acid. When the ribosome reaches the stop codon it releases the mRNA and the amino acid chain.

Most ribosomes translate whilst attached to the rER. The completed primary protein is inserted into the rER, where enzymes fold it into its secondary and tertiary shape. Many ribosomes can translate the same piece of mRNA at the same time.

By changing the genetic code mutations ultimately change the sequence of amino acids in primary proteins. This changes the sequence of R groups in the protein and, therefore, the way in which the protein folds up.

This affects on the function of the protein Mutation Explanation The function of the protein is unchanged after the mutation i. There are 2 possible causes; One codon is altered. However, the codon still codes for the same amino acid. Therefore, the protein is the Neutral mutations A codon is changed, leading to a different amino acid in the primary protein.

However, this protein is not in a place crucial for folding, so the protein is still the same shape and functions the same. A nucleotide is deleted from the DNA code, which Deletion mutations changes all the codons after the deletion. This causes frame-shift.

A nucleotide is inserted into the DNA code, which Insertion mutations changes all the codons after the insertion. Normally, this has a huge impact on the function of the protein.

Always consider the ethical b oth to make the data valid. What conclusions p eopl e reach are often coloured by who funded the research they are doing. The optimum temperature. L D D Discuss how understanding of the carbon cycle could carbon cycle help reduce atmospheric C02 levels.

L D D The effects of global Describe the effects of global warming on plants and animals distribution.

Energy transfer Calculate net pnmary productivity from the equation: L D D warming Explain the effects of increasing temperature on enzymes in living things.

L D D Describe succession to a climax community. D1scuss how a person's point of view might affect the conclusions they reach about actio1s to take on L D D global warming. Describe the role of gene mutation and natural Speciation and evolution selection in evolution. L D D Investigating numbers and Describe an ecological study of a habitat to create valid.

L D D Describe an investigation of the effect of temperature on development of organisms. L07 D D abundance and Calculate efficiency of energy transfer between trophic levels. L D D Explain how the concept of niche explains distribution and abundance of organisms.

L08 D D I ecosystems Explain how biotic and abiotic factors control distribution and abundance of organisms. L D D Describe the validation of new evidence supporting the theory of evolution. I Describe the modelling of trends in glcbal warming and the limitations of this approach. The use of a quadrat would gain a mark. Some have an enzyme which breaks A basic answer would mention genetic mutation as the origin of resistance or down the antibiotic.

The number of species in each quadrat to gain full marks. An excellent answer would mention these points and go on to discuss how the selection pressure leads to antibiot ic-resistant bacteria being able to reproduce. The device that could be used along the transect line. The idea that number of species recorded down again until the quadrat would be placed randomly. A transect nota quadrat is used and you need to discuss estimation of distribution and abundance of an organism.

An excellent answer would describe laying out a line. In this case random placing is not appropriate. Many answers discuss the ability of the bacteria to break down the antibiotic. The rest of the answer is not have a pump which pumps the antibiotic out of relevant to the question asked. Some have a resistant mention that antibiotics create a selection pressure when misused. Such an answer gains no credit at all. A line would be laid out and a quadrat placed This is quite a typical answer in which there is some truth.

Note carefully the word 'become' in this questi o n. A basic answer would mention the quadrat but be unclear as to how to place or use it for a specific purpose. This might be because they now bacteria which gives them resistance to antibiotics On the wild side 1 A transect can be used to study trends in the abundance and distribution of organisms Describe one method you could use to estimate the abundance o f an organism at intervals along a transect line.

Tray 3 contained only non-tolerant plants and Tray 2 had a mixture of equal n umbers of both types. June 2 Agrostis tenuis is a grass that g rows near old copper mines in north Wales. Tray 1 contained only tolerant plants. Copper is usually very toxic to plants but some Agrostis plants c a n tolerate copper in the soil and grow on waste tips from the copper mines. The Natural Environment and Species Survival 1 The diagram below summarises the light-dependent reactions of photosynthesis.

Li g ht Product A t. The total dry mass of the plants in each tray was measured. Electron carriers Product B. C electro ns electrons Chlorophyll. The arrangement of the plants and the results are summarised below.. NPP u:: On the wild side 3 Su r '' Aver seed lings were planted and kept under controlled conditions for 20 days.

The I frequency of an allele. The results are shown i n the graph below. June l. NPP a n d respiration. A and B June 4 The tolerance of plants to copper ions in the soil is under genetic control. The table below sh Plants need nutrients such as nitrogen.. Micro-organisms are crucial to the decomposition process These nutrients are locked into the tissues of the plants and any animals that might eat them.

The products of external digestion are absorbed by the m icro-organism and broken down in microbial respiration. Bacteria a n d fungi produce a range o f enzymes that are released on t o the dead organic matter.

The stage of larvae on a dead body can be used to estimate time of death. The process of decomposition allows the nutrients to be recycled The carbon cycle is a good example of how nutrients are recycled a n d how micro-organisms help. There are five m a i n ways that scientists g o about this Decay and decomposition Once the plant or a n i m a l dies the nutrients can be released only through decay.

So the muscles become fixed. This happens within about hours depending on temperature. The community of examin ations where you are asked species present when the body is found allows the stage of to do calculations. Th i s stiffening is called rigor mortis. The stiffness wears off again after about 36 hours in cooler conditions as the muscle tissue starts to break down.

E nzym es in the gut start to break down the wall of the gut and then the surrounding area. During the first 24 hours after death the temperature of the body when it is found can be used to work out how long ago the person died. This provides a n estimate of time of death assuming any eggs were All the m ethods used to indicate laid soon after death. There is a succession of species.

Frequently bought together

U1 Desc ri b e two wa ys in which succ ession on a body is simila1 to succession on a sand dune Q1 List three i nd i cators that can be used to work out time of death. Remember this in change. The stiffness occurs because muscle contraction relies on ATP. The signs of decomposition..

Topic 6: As cells die they release enzymes which help to break down tissues. Otherwise you may the po s itive electrode. The sequences of repeated bases are called short tandem repeats STRs. The fragments separate into invisible bands.

These non-coding sections are called i ntrons. The steps in the production of a DNA profile or fingerprint. The negatively charged DNA moves towards the positive electrode. It is rather like chromatogra phy. The data can also be presented a s a graph o r as a series of numerical values. Scientists look a t the short tandem repeats at many loci to build u p a unique pattern for that individual.

This is because of t h e variety found in the sections of DNA which are not used to code for proteins. DNA fragments continuing the repeated sequences are created using reestriction enzymes or the polymerase chain Do not try just to remember a reactions. People and a l l other organisms vary i n regard to t h e number o f these repeats they carry a t each locus. Green Book 6. If a potential difference diagram like this. DNA is cut into fragments.

The fragments move at different rates according to their size get it in the wrong sequence and and charge. DNA double strands split and stick to the membrane. In addition there is now also a technique called the polymerase chain reaction PCR which allows tiny amounts of DNA to be a mplified into quantities large enough to use in DNA p rofiling.

The technique allows us to identify biological material with a high degree of confidence. Scientists look for short. Together they form one of the most powerful techniques we have for criminal investigation and a range of other situations where total certainty about the identity of a sample is requi red. There can be up to several hundred copies of the STR at a single locus. Everyone's DNA is u nique. Its influence on forensic science has been hJge.

Membrane placed in bag X-ray film is used to detect the with DNA probe. Small fragments with fewer repeats travel faster and end up closer to the not realise it! Topi c 6: Infec tion. Q1 Which parts o f t h e DNA are used for profiling? Q1 The family tree of every ra cehorsP. The process relies on DNA primers. This is a good example of developments in science and technology allowing us to answer questions which we would previously not have been able to add ress.

Confirming the ped i g ree of domestic animals such as racehorses. Explain why it is easi Q2 Why is it necessary for forensic scientists to look at 1 0 or more short to identify humans using DN1 tandem repeats when creating a DNA profile? Transcription means 'to make a full copy of'. A peptide bond is formed template strand A pairs with U. It only becomes a prote in when folded and. The whole process is shown below.: The mRNA copy is not direct. A pairs with T.. We now know this is not correct.

These changes are made to the mRNA before it is used in translation. Using three bases gives the next amino acid to be attachec 64 codons which is more than enough.

As long as the codon starts with CC the amino acid proline will be put into the polypeptide. Amino acids are non-overlapping Each set of three bases forms one triplet. This offers some protection against mutation. The triplets do added one at a time in a repeating not overlap.

Q3 Link each description in list A with the correct term in list B. Explain what this means and why it is significant. Most genes code for many proteins and this is achieved by post-transcriptional changes in the mRNA.

Q2 The DNA code is degenerate. The following responses are non-specific: No cell wall. The initial symptoms of an HIV in fection are fevers. The Natural Environment and Species Survival Infectious diseases in humans are caused mainly by bacteria singular: All symptoms can then then disappear for years but eventually patients suffer from weight loss.

I Can live independently. Nucleic acid enclosed in prote in coat. You need to be aware of the differences between them. Blood bacterial cell walls. In TB the first infection may have no symptoms but tubercles form in the lungs due to the imflammatory response of the person's immune system.

Both viruses and bacteria may enter the bodies of living things and. TB bacteria also target cells of the immune system so the patient cannot fight other infections well. Finally there are severe symptoms such as dementia.

Often have mucus-based cuter May have outer membrane of host cell surface capsule. The patient develops a serious cough. Average diameter 0. We can illustrate this by looking at tuberculosis. Kaposi's sa rcoma and opportunistic infections such as TB and pneumon1a. These phagocytes in clude and capillaries to become by breaking down the neutrophils and monocytes which more permeable. Some bacteria may survive inside the tubercles.

In active TB. In some cases the bacteria invade glands and the CNS central nervous system. All of this can be fatal.: They lie dormant. Circular strand of DNA is the geneti c material. Bacteria have a prokaryotic cellular structure with organelles but viruses do not. Infectio n. B memory cell viru s-infe'.. Macrophages identify 6. T killer and T memory Q2 Why might a fever be a good thing if you have an infectious disease7 cell s.

Both types respond to foreign non-self antigens such as proteins on the surface of bacteria and viruses. The immune response. Use a presenting cell. Q1 Draw a table to distinguish between the roles of B cells including B memory and B effector cells and T cells T Q1 Give two differences and two similarities between viruses and bacteria.

T memory cells a They alert the immune system to the presence of the foreign antigens. Macrophages are also involved. These live naturally on the skin and out-compete pathogens. We can also use antibiotics to f1ght bacterial infections There are two kinds of antibiotics: These antibodies can p rotecti on produces toxins or protect against any against the memory antigen invading pathogen invading cells which fragments that the mother has pathogen they make it means that the encountered.

Major routes of entry ofpathogens and the role of barriers in protecting the body from infection. The mucus is then swallowed and passed into the digestive system. These compete with pathogens for food and space which helps to protect us.

When bacteria are no longer affected by an antibiotic they are said to be resistant to it Green Book 6. We can acquire immunity in different ways: Injected with to ant1gen antibodies cross the antibodies that by getting wea kened I placenta and are also can provide the disease.

Gastrointestinal tract. Sebum is an oily fluid which is made by the skin and can also kill microbes. In addition the gut has its own bacteria. The harmless bacteria also excrete lactic acid which deters pathogens. The Natural Environment and Specie5 Survival Pathogens organisms that cause diseases enter the body through areas not covered by skin: As an additional line of defence the skin has its own microbes.

Respiratory tract. This means A simple procedure can be carried out to investigate bacteria and antibiotics for the that new mutations occur quite core practical It is important to follow safe. Anything in in exams. Bigger areas indicate a better antibiotic antibiotics on bacteria. Q1 What theory would you hope to test with the practical above7 Write a scientific question to answer.

Hospitals try to combat this in a number of ways.

Edexcel A2 Biology Revision Guide Edexcel a Level Sciences

Consequently they will produce A sterile nutrient agar plate is seeded with many mutations in the time it woulc suitable bacteria. IL nl Lack of details like Look for clear areas around the antibiotic discs investigate the effect of different this often lose candidates marks or wells.

The TB bacterium produces a thick waxy coat which protects it from the enzymes of the macrophages. Incubate below 30 oc for about 24 hours. I us1ng a stenle p1pette. This is because bacteria will not grow in an empty plastic dish. The protein coat of HIV is constantly changing which means that the immune system can't target and destroy it. Describe how the polymerase chain reaction can be used to give more DNA for analysis.

L06 0 0 Describe how DNA fragments can be separated by electrophoresis. Explain antigens and antibodies and how plasma cells. Infectious discJscs und Distinguish between the structure of bacteria and viruses. L D D Describe investigations of the effects of antibiotics on bacteria. L D D Describe the way in which our understanding of infections acquired in hospitals can be used to L D D reduce their occurrence through codes of practice.

L D D Explain how people develop natural.: Distinguish between bacteriostatic and bactericidal antibiotics.: Describe how micro-organisms are involved in decomposition L D D Infection prevention and Describe the routes of entry of pathogens into the body and skin. Explain how changes that happen after transcription can give rise to more than one protein L04 0 0 from one gene. L02 overlapping and degenerate.: Distinguish between roles ofT helper. L08 0 D 0 0 the immune Explain the symptoms of bacterial and viral disease L response to include those ofTB and infection by HIV Describe non-specific immune responses: Almost everyone coug hs at some point dur ing most days so.

An excellent answer would suggest qualified coughing i e cough ing up blood or excessive coughing as well as the appearance of tubercle s. It is not TB which does system and therefore become more active.. A 'weakened immune system' does not address TB would take advantage of a weakened immune the specific aspect of the immune system which HIV affects. The diagram below. E Jnd C. One treatment for HCV infection is injections of interferon.

In each case the antibiotic was added at 7 hours. The N atura l Environment and Species Survival 1 The graph below shows the changes in population size of bacterial cultures grown. Suggest an explanation for the change in the response to antibiotic A.

She took the pupae and larvae to her laboratory. She recorded the temperature in the room and she collected the larvae and pupae of several species of insect from the body. June One of the first species to be seen was the blowfly.

It has been found that these resistant 'Jiru. June 4 On 26th September. Records of weather conditions for the area were consulted and the time of death was determined to be 14th or 15th September. June 3 HIV can damage the human immune system. She was asked to determine the time of death. Key ooc. The excited electrons that are taken up by electron carriers follow pathway B.

Give reasons for your answer. The data for four of these trees are given as a percentage of the total tree pollen sample.. An estimate of the age of the sample at each depth was also made. Copy and complete the table by putting a cross in the box if the structural feature is present. J [] 5 b The table below shows the number of new TB cases recorded in and in from four different geographical regions. These data exclude people who are HIV positive.

L I 98 If they had been included suggest how the data would differ. G ive an explanation for your answer. Suggest two reasons tor this. MRSA can survive treatment with several antibiotics. An i nfection with MRSA is difficult to treat It is i mportant to use an a n ti biotic that is effective against specific bacteria. Describe in outline how you could test the effectiveness of an antibiotic on a specific bacterium in the laboratory Include aspects of the method that ensure safe working.

A transect was used which extended i nland from a beach. Quadrats were used at nine positions along the transect. The percentage cover of selected species was recorded in each quadrat as well as the n u m ber of r: The results are shown in the two tables below.

Number of 1 1 5 11 18 7 5 6 7 species found. Mass of organic 0. Common heather Corsica pine Use the Information in the table to suggest how the resu lts of the study could be explained by succession. Bones can move in relat i on to one another at joints. Different types of joint a l low d iffere nt degrees of movement. Ligaments are made of elastic connective tissue. They hold bones together and restrict the amount of movement possible at a joint.

Tendons are cords of non-elastic fibrous tissue that anchor muscles to bones. Skeletal muscles are those attached to bones a n d are normally a r ranged i n antagonistic p a ir s T h i s means that there are pairs o f m uscles which p u l l i n opposite direct ions Flexors contract to flex, or bend a joint, e. Remember that m u s c l e s c a n't stretch themselves. It is the pull Each skeletal muscle i s a bundle of millions of muscle cells called fibres.

Each muscle created by the contraction of the cell may be several centimetres long and contains several nuclei. It conta ins m a n y antagonistic muscle that stretches a myofibrils which are made up of the fibrous proteins actin thin fi l a ments and m u s c l e when it is in a relaxed state. The cytoplasm inside a m u scle cell i s called the sarcoplasm. The specialised synapse see page 63, Topic 8 between neurones and muscle cells is called the neuromuscular junction. The p refi x myo- refe rs to 'muscle' and sarco- to 'flesh' i.

When the muscle contracts the thin actin filaments move between t h e thick myosin f i l a m ent s shorte n i n g the length ,. The arrangement of actm and myosin filaments in a sarcomere when relaxed A and contracted B. Myosin head cannot bind i to move together with the threads of tropomyosin. Actin filaments are associated with two other proteins.

ATP comes from respiration electron transport chain anaerobic respiration glycolysis lots of myoglobin dark red pigment to store little myoglobin and few capillaries The 02 and lots of ca pilla r es to supply Q3 Explain why muscles are arranged in antagonistic pairs. Topic 7: RJn for your life Myosin filaments have flexible 'heads' that can change their orientation. V blocked by Ca2' attaches to actin p tropomyosin.

Jo upright myosin forms position. This muscle has a light colour gives the muscle a dark colour fatigue resistant fatigue quickly low glycogen conten t high glycogen content low levels of creatine phosphate high levels of creatine phosphate Q1 Give one reason why fast-twitch muscles are more likely to get t i red faster than slow-twitch muscles.

Q2 D escribe the role of ATP in m uscle contraction. ATP comes from aerobic few mitochondria. When a nerve impulse a rrives at a neuromuscular junction..

Green Book 7. In aerobic respi r at i on the NAD is produced by the electron transport chai n. During anaerobic respiration. In animals. ATP t glucose hexose 6C Glycolysis means sugar splitting.

Both of these processes make the energy stored in gl ucose available i n the form of ATP. Glycolysis takes place within the cytoplasm of cells. ATP t H NAD m u st come from elsewhere. Starting with one glucose molecule. There are two different ways in which they do this -aerobic respiration using oxygen and anaerobic respiration without oxyge.

All living organisms have to r espire. NAD is formed and can keep glycolys s going. Run for your life Anaerobic respiration allows ani: The extra oxygen required for this process is called tre oxygen debt. Q1 Draw the main stages of glycolysis al o n g si de the! Q3 Describe the role of NAD in anaerobic respi rati on. This y can i nhi bit enzymes and. It is oxidised via the Krebs cycle 2ATP into carbon d i ox i de and water. Once aerobic respi ration resumes most lactate is converted back to py ruvate.

It is an i neffi cient process but it is ra pi d and can supply muscles with ATP when oxygen is not b eing delivered quickly 2ADP enough to ce l l s. The tube on the right. Any C02 p ro d uc ed is absorbed areas such as photosynt hesis.

It is converted from pyruvate 3C example: The main purpose of the cycle is to supply a continuous flow of hydrogen and therefore electrons to the e l ect ron transport chain fo r use in the synthesis of ATP by oxidative phosphorylation.

I t takes place o n the cristae gains ele ctrons or h y d rogen is inner membranes of the mitochondria. Th1s involves the loss of C02 decarboxylation and hydrogen oxid ation. In aerobic respiration. When a molecule is oxidised. This takes place in the matrix of the mitochondria where one substrate i s oxidised and involves the Krebs cycle. A molecule that This involves chemiosmosis and the enzyme ATPase.

The Krebs cycle occurs in the matrix of the mitochondria.

For cytoplasm enters the matrix of the mitochondrion. Aerobic respiration takes place in two stages Many of the rea ctions involved in o F1rst pyruvate IS oxidised into carbon dioxide and hydrogen accepted by the respiration are redox reactions coenzymes NAD and FAD.

The reactions involved in the breakdown of pyruvate in aerobic respiration. Most of the ATP generated in aerobic respiration is synthesised by the electron transport chain. The majority of ATP generated by aerobic respiration comes from the activity of the electron transport chain in the inner membrane of the mitoch ondria cristae.

Q2 Explain what oxidative phosphorylation means. Q1 Sketch a simple diagram o' a. Note that for each glucose molecule entering g lycolysis two acetyl groups are formed.

The overall reaction of aerobic respiration can be summarised as the spli tting and oxidation of a respiratory substrate e. The electron transport chain and chemiosmosis result in ATP synthesis by oxidative phosphorylation. ATPase on 6 Electrons and W ions mitochondrial stalked particle recombine to form hydrogen matrix atoms wh ich then combine ATP with oxygen to create water. If the supply of oxygen stops. A normal ECG pattern in a healthy heart.: H"t Electrical currents caused by the spread of the electrical impulse wave of depol arisat i o n during the cardiac cycle can be detected with an electrocardiogram ECG.

After contracting systole. This is ventricular sys tole. If disease disrupts the heart's normal conduction pathways changes will occur in the ECG pattern which can be used for diagno sis of cardiovascular disease.

This is called atrial sys tole. The route taken by electrical impulses across Purkyne fibres the heart during the cardiac cycle. Unit 5: Exercise and Coordination The impulse to contract originates wit hi n the heart itself from the s i noatrial node.

How much is pumped in a minute cardiac output depends on two factors: Blood is squeezed i n to the arteries. Run for your life The heart rate can be affected by hormones e. We also have voluntary control over breathing.

Impu lses carried by the vagus nerve parasympathetic slow down the heart rate when the demand for 02 and removal of C02 reduces A spirometer trace showing quiet breathing with one maximal breath in and out. The maximum volume of air that can be forcibly exhaled after a maximal intake of ai r is called the vital capacity. It also increases in response of 02 absorbed by the to impulses from the motor cortex and from stretch receptors in tendons and muscles person after exercise.

This is rapid and uncontrolled contractions in the ventricles sometimes caused by a patch of damaged tissue in the ventricle acting as a pacemaker 03 Suggest what might happen to the heart rate if the connection between the sinoatrial node and the vagus and sympathetic nerves was cut. This is often expressed as the volume of air breathed per minute the minute ventilation. The volume of air breathed in or out of the lungs per breath is called the tidal volume.

The ventilation centre in the medulla controls the rate and depth of breathing A canister of soda l i me in response to impulses from chemoreceptors in the medulla and arteries which can be used to remove the. Impulses are sent from the C02 from the exhaled air ventilation centre to stimulate the muscles involved in breathing A small increase in to measure the volume C 02 concentration causes a large increase in ventilation.

The sympathetic nerve speeds up the heart rate in respon:. The cardiovascular control centre in the medulla of the brain controls the sinoatrial node via nerves. The control of core body temperature through negative feedback is called thermoregulation.

Negative feedback helps to keep the internal envi ronment constant. Muscles and glands are effectors. A Conditions controlled by homeostasis fluctuate around the norm value. G reen Book 7. For negative feedback to occur. This can be enough for a 1 oc rise in body temperature every minutes if we can't disperse the heat away from the body. Thermoreceptors in the skin detect changes in temperature. In addition thermoreceptors in the hypothalamus in the brain can detect changes in the core blood temperature.

Negative feedback is t h e key to und erstanding homeostatic responses. To rise above do this you n e e d receptors. A change in the internal environment will trigger a response that counteracts the change. If a rise in temperature is detected above the norm value the heat loss centre in the hypothalamus will stimulate effectors to increase heat loss from the bo d y. Just remember. A homeostatic system therefore requires: We have already seen that the body responds to the demands of exercise by increasing cardiac output and ventilation rate under the control of centres in the medulla see page 51 -The heart.

A summary of the role of negative feedback in maintaining body systems within narrow limits. Exercise and Coordination Homeostasis is the maintenance of a stable internal environment. Negative feedback in thermoregulation. The design of prostheses has improved significantly and many disabled athletes are now able to compete at a very high level. Above or below certain temperatures homeostasis fails e. This is because only a small incision cut is needed so there is less bleeding and damage to the joint.

A prosthesis is an artificial body part designed to regain some degree of normal function or appearance. This can result in hyperthermia: Q1 Usi n g your revision in this Q1 Explain what is meant by the term 'negative feedback'. Damaged joints such as knee joints can also now be repaired with small prosthetic implants to replace the damaged ends of bones. Others may feel they does not necessarily m e a n a need to follow suit because they don't want to be at a disadvantage.

This might c a used t h e other. I n contrast it is thought must provide a reasonable explanation as to why that is the case. There performance. There is some non-specific immune system p a g e evidence that the number and activity of some cells of the immune system may be Here are a few possible effects of a lack of exercise over a prolonged period of time: It may also he the case that damage to muscles during exercise a n d the release of hormones such as adrenaline may cause a n inflammatory response which could also suppress the immune system.

Ligaments can alsc be damaged. In p a rticular it doesn't mean that o n e Some athletes will do anything they can. Too much exercise generally may also increase the amount of wear and tear on joints.

A correlation i n clude the use of illegal performance-enhancing substances. This has been a connection. This could be caused by an increased cells involved i n the specific and exposure to pathogens. It can also result in chronic fatigue and poor athletic performance.

Damage to cartilage in synovial joints can lead to inflammation and a form of Remember that exam questions arthritis. Ethical relativists would rea ise that people and circumstances may be different. If there appears to be a stro ng correlation between subject for debate in the sporting world for many years. Bursae fl u i d-filled sacs that cushion parts of in this unit may refer back to a n y the JOint can become inflamed and tender.

Unit They would take one of two positions: For example testosterone increases protein synthesis in muscle cells.

I DNA Genes remain switched off by failure of the 0 0 transcription initiation transcription factors complex to form and attach to the promoter region. Q1 Describe why a lack of exercise may lead to an increased risk of coronary heart d i sease. This is due to the absence of protein transcription factor s or the action of repressor molecules.

This starts a process that results in the activation of a transcription factor within the nucleus. This means that the blood can carry more oxygen which is an advantage for an athlete. For exa mple erythropoietin EPO stimu lates the production of red blood cells. Run for your life Some 0rugs such as anabolic steroids are closely related to natural steroid hormones They can pass d irectly through cell membranes and be carried into the nucleus bound to a receptor molecule.

Peptide hormones do not enter cells directly. As a r esult more protein synthesis takes place in the cells. They bind to the p romoter region of a gene allowing RNA polymerase to start transcription. You should also know how ECGs can be used.

A Level Biology

D D L0 1 8 Analyse and interpret data on the possible dangers of exercising too little and too much. LO l l Explain what happens to lactate after you stop exercising.

L0 1 3 Explam that tissues need rapid delivery of oxygen and removal of carbon dioxide during exercise a n d that D D changes i n ventilation and cardiac output allow this to happen. D D Homeostasis Explain the principle of negative feedback. L0 1 9 Explain how medical technology helps people with injuries or disabilities to take part in sport.

L0 1 7 Health. You should also be D D a b l e to talk about correlation a n d cause. You should understand how heart rate and ventilat1on rate are controlled. L01 5 D D L0 1 6 Discuss the concept of homeostasis and how it maintains the body during exercise. L Describe how to use data from spirometer traces to investigate the effects of exercise. D D L Outline the ethics of using performance-enhancing substances. L0 1 2 The heart.

D D L04 Recall the way in which muscles. Exercise and Coordination By the e n d of this topic you should be able to: D D L06 Describe a practical to investigate rate of respiration. L03 - Explain how skeletal muscle contracts using the sliding filament theory.

This is because predators tend to be fast and powerful over short distances to catch and kill their prey and therefore use anaerobic respiration to release ATP quickly. The reference to vasod ilation is not enough as it does not describe what change occurs to the blood circulation. Changes to the core temperature are detected by in the correct context of how the change is caused homeostasis.

This is an example of homeostasis using a negative feedback This response is better because it includes key terms and structures mechanism.

Lactate is oxidised back into pyruvate using NAD that has been This response will gain maximum marks because it provides oxidised in the electron transport chain using oxygen. The extra a chemical explanation of the fate of the lactate. Run for your life Animals that are predators often show bursts of very fast movement.. Close examination shows that the muscles of predator and prey show a different composition of fast.

Explain what happens to this lactate after the chase has ended. It also clearly describes the arterioles in the skin. Their prey tend to be able to carry out sustained movement over longer periods of time. Describe how changes in blood circulation help to return their core body temperatures to normal. I t explains away from the muscle to prevent cramp. Where possible use key terms and concepts from your course as part of your description as you will often receive credit for these. This causes vasodilation resulting in increased effect of vasodilation on the blood circulation.

D iscuss tre benefits and potential dangers of exercise i n humans. Explain how this is brought about. Explain the mechanisms involved in control ling this increase in heart rate. Copy and complete the table by inserting the part of the cell in which the stage occurs an:: Explain why the chemoreceptors are particularly im portant during exercise..

Name the part of the brain that controls involu ntary breathing 1 b Suggest one occasion when the depth of breathing is increased voluntarily. Explain one factor which could contribute to this higher infection rate. Run for your life a Breathing can be controlled voluntarily and involuntarily.. Explain the advantages of keyhole surgery on damaged joints. Those who completed the race were three times more likely to develop an infection after the race compared with a control group which did not run.

This ensures that gas exchange is efficient. In mammals sensory neurones carry impulses from receptOis to a central nervous system CNS consisting of the brain and spinal cord. The CN S containing relay neurones processes information from many sources and then sends out impulses via motor neurones to effector organs mainly muscles and glands.

QPeriodic responses. Plants flower and seeds germinate in response to changes in day length. Thephotoreceptor involved is a bl u e-green pigment called phytochrome. Green Book 8. Animal nervous systems are fast-acting communication systems containing nerve cells neurones which carry information in the form of n erve impulses see page This causes the radial muscles to contract and the pupil becomes dilated. These then send impulses along parasympathetic motor neurones to the circular muscles of the iris.

The pupil reflex The iris contains pairs of antagonistic muscles radial and circular muscles that control the size of the iris under the influence of the autonomic nervous system involuntary. Qn absorbing natural or red light phytochrome converts from the inactive form e.. The muscles contract. I n high light intensities photoreceptors such as rods in the retina cause nerve i m pu lses to pass along the optic nerve to a group of nerve cells in the brain.

I - Chemical hormones from - Chemical growth substances I Remember. The effector for the g rowth response th e i r o w n food a n d therefore is cell elongation. This ha ppens just below the tip of the shoot a n d is o c c u p y th e first trophic level on a co ntrolled by the plant growth substance IAA the first auxin discovered.

Response is very local and Response may be widespread. Mechanism of phototropism in shoots. Only those Tro p h i c is connected with how. Some e l ongation.: Q1 Explain what is meant by the term p h otoreceptor. Ql Why i s it an ad va nta g e for Q2 Explain why it is an advantage that shoots have positive phototropism and animals to have a nervous roots have negative phototropism. Fo r example el on gatio n towards the light plant shoots have a pos itive tropic response to l i ght and they are ' It is not c lea r what the receptor for phototro pis m is in shoots.

Tropic responses shaded side of the shoot tip. J Table to compare commun ication and coordination methods in plants and a nimals.: Response may be widespread. Some can be relatively fast. Potassium ion channels allow bundled together i n a p rotective facilitated d iffusion of potassium ions back out of the membrane down sheath. Dendrites conduct impulses their concentration gradient. Action potentials jump from one node of Ranvier to the next increasing the speed of conduction.

This distribution of ions creates a potential d ifference a difference in charge of about -7 0 mV called the resting potential and the membrane is said to be polarised. The main difference between the structures of sensory. The sodium-potassium pump Neurones are individual nerve cells. Schwann cells wrap around the neurone.

Allneurones nerve cells have a cel l body containing the nucleus and most of the cell's organelles within the cytoplasm..

The structure of neurones in a mammar The inside of the resting neurone has a negative charge i n comparison to the outside d u e to the p resence of chloride ions and negatively charged proteins.

The N membrane becomes hyperpolarised. At the site of the first action potential. Topic 8: As the charge reverses. A threshold stimulus m ust be applied to produce an action potentia l.

Straight after a n action potential there i s a short refractory period when a new action potential can't be g enerated because the sodium ion channels can't reopen. Action potentials have an ali-or-nothin g nature the values of the resti n g and action potentials are always the same for a specific n e u rone A bigger sti m u l us increases the frequency of the action potentials not the strength.

Potassium ions leave the axon. This ensu res that action potentials pass along as separate signals and are unidirectional only acle to pass in one direction. Th1s increases the positive charge inside the cell. N second action potential t!

Synapses also summation. An enzyme is often present in the synaptic cleft to hydrolyse the neurotransmitter. The neurotransmitter may also be taken back up into the presynaptic membrane ready to be used a g a m. Exer ci s e a n d Coordination 5 Synapses The point where one neurone meets another is called a synapse.At this point water has to cross the cell membrane and enter the symplast pathway. Start AUG codon fits into bottom of P site 2.

A Gene e. This affects on the function of the protein Mutation Explanation The function of the protein is unchanged after the mutation i. Tumours that split apart and spread around the body metastasis are the most dangerous malignant The rate of cell division is controlled by; Oncogenes — speed cell cycle up Tumour Supressor Genes — slow cell cycle down Mutations in either of these genes can cause tumours.

Quadrats used to investigate distribution and abundance of plant species in grazed and ungrazed areas. Inputs and outputs of energy to the Earth's atmosphere. In the UK the woodland is usually oak.