Human Biology Exam PDF

HUMAN BIOLOGY EXAM Cells, Tissues, Metabolism 1.Describe the structural organisation within the body Cell->tissues->organs->organ system->organism Cells-Basic structural and functional units of the body Tissues-Groups of cells that have similar structure and function Organs-Made up of 2 or more diCerent types of tissues Systems-Groups of organs that work together 2. Label the following structures of a cell on a diagram and know their functions Cell membrane -surrounds the cell and forms the outer boundary of the cell Cytoplasm-the ﬂuid that ﬁlls the cell and the suspended structures(except nucleus). Made up of cytosol(liquid) and cell organelles(structure) Nucleus-contains genetic material, is separated from cytoplasm by a nuclear membrane and contains the nucleolus Nuclear membrane-separates nucleus from cytoplasm Nucleolus-composed many of RNA(ribonucleic acid) Endoplasmic reticulum(smooth and rough)-the rough ER has ribosomes attached and is synthesis of proteins. The smooth ER has no ribosomes attached and is storage of lipids Chromosomes-contain DNA and make each of us diCerent Ribosomes-small and spherical, may be free in cytoplasm or attached to membrane. Site of protein synthesis Golgi body-modify proteins and package them in vesicles for secretion from the cell. Mitochondria-releases energy of the cell through the process of respiration Centrioles-Pair of cylindrical structures usually located near the nucleus and involved in reproduction of the cell Cilia-projections that are short and numerous resembling tiny hairs. For example lining of trachea Flagella-Projections that are long and usually one or two Lysosomes-small spheres that contain enzymes able to break down proteins, lipids, nucleic acids and some carbs. Break down materials and taken into cell 3.Describe the structure of the cell membrane. Label and discuss how it works The phospholipid bilayer is composed of the hydrophilic head and hydrophobic tail. It is semi permeable which means it chooses what goes in or out. Cholesterol, carbohydrates and proteins are embedded. The cell membrane acts as a physical barrier, regulates the passage of materials, it is sensitive to changes and helps support the cell -Cholesterol is wedged between phospholipids and is important for the structural integrity and stability of the membrane -Carbohydrate consists of either glycoproteins(bound to proteins) and glycolipids(bound to lipids/fats) -Proteins there are 4 types which are receptor proteins(facilitate the communication between cell and extracellular environment), channel proteins(proteins that allows for ions, water and small molecules to pass through the membrane), carrier proteins(proteins that carry substances from one side of the membrane to another) and cell identity markers(helps identify/classify the cell) 4. Deﬁne and compare diCusion and osmosis DiCusion is the movement of substances form areas of high concentration to areas of low concentration. Osmosis is the movement of water from areas of high concentration to areas of low concentration. The diCerence is the substances that are moved as diCusion carries some substances whereas osmosis only carriers water. They both have the similarity that they are both passive meaning they require no energy and the both rely on the concentration gradient of high to low concentration DiCusion consists of 5. Outline the diCerences between passive and active transport Passive transport is transport that requires no ATP and relies on the concentration gradient of going from a high concentration to a low concentration whereas active transport requires ATP and goes against the concentration gradient which means going from a low concentration to a high concentration Passive consists of 1.Simple diCusion -Movement of substances from areas of high concentration to areas of low concentration such as alcohol, steroids, fat soluble substances, oxygen and carbon dioxide 2.Osmosis -Movement of water from areas of high concentration to areas of low concentration across a selectively permeable membrane -They are transported by aquaporins that serve as channels for water -They can either by hypertonic(water will leave the cell and cell will shrink), hypotonic(water will come into the cell and cell will burst) or isotonic(no net movement of water meaning no change in cell size) 3.Facilitated diCusion -Proteins in the membrane that allow molecules to be transported across the cell membrane -Uses channel protein which provides a pathway for hydrophilic particles to cross the cell membrane such as water and ions which are small enough to pass -Uses carrier protein which are open to one side of the membrane at a time. Substances will bind to the binding site which causes the protein to change shape and open to other side. Moves things such as glucose and amino acids Active consists of 1.Active transport -Which is when it uses carrier proteins to move substances against the concentration gradient. -Moves things such as certain ions, glucose and amino acids 2.Vesicular transport -Movements of substances across the cell membrane-bound sacs called vesicles -Consists of endocytosis and exocytosis 6.Explain the processes of endocytosis and exocytosis including phagocytosis and pinocytosis Endocytosis is taking liquids or solids INTO the cell and exocytosis is contents of vesicle from inside the cell to outside the cell. Phagocytosis is of solids and pinocytosis is liquids. -Endocytosis occurs when contents migrates to the cell membrane and fuse with the cell membrane, contents are pushed into the intercellular environment inside of the cell and then a vesicle is formed inside the cell -Exocytosis occurs when a vesicle is formed inside the cell, the cintents migrate to the cell membrane and fuse to the cell membrane then contents are pushed into the extracellular ﬂuids *Both processes are active transport which mean they require ATP and go against the concentration gradient of low concentration to high concentration 8.Describe how surface area to volume ratio and the concentration gradient can aCect exchange of material Concentration gradient is the diCerence in concentration of substances from the cell membrane and outside of the cell. The steeper the concentration gradient, the faster the movement of substances. The greater SA to volume ratio it can exchange nutrients and remove waste more eCiciently. This is due to the fact that as a cell gets larger it cannot exchange enough materials to support the increasing volume 9. Name, describe functions of and sketch examples of the four tissue types Epithelial tissue -It is a covering or lining tissue and can vary in shape -It is closely packed which forms a smooth surface -They can vary in shape from thin and ﬂat to column and cube shaped -Examples include outer layers of the skin, lining of internal surfaces of heart and stomach, covering of the heart Connective tissue -It provides support for the body and helps to hold all the parts of the body together -It is separated apart by large amounts of matrix. -Cells are often spread apart -Examples include bones, cartilage, tendons, ligaments and fat storage Muscular tissue -They are long and thin and can contract to become shorter -It’s purpose is to help us move and perform daily activities -3 types which are skeletal muscle which are muscle attached to bones, have voluntary control and are striated, smooth muscle which are walls of stomach, intestines and blood vessels, are spindle shaped, have involuntary control and are non striated, cardiac make up most of the heart and have involuntary control 10.Deﬁne metabolism Metabolism is all the chemical reactions occurring in the body 11. Deﬁne and distinguish between catabolism and anabolism, providing examples of each -Catabolism is when objects are broken down into smaller pieces and one example is digestion. With catabolism energy is released into the body -Anabolism is reactions in which smaller molecules are built up into larger ones and one example is protein synthesis. With anabolism energy is required by the body -The main diCerence is that catabolism turns bigger molecules into smaller molecules whereas with anabolism it turns smaller molecules into bigger molecules 12. Write the word equation and the chemical equation for cellular respiration Glucose+oxygen->water+carbon dioxide+ATP 602+C6H1206+6H20+6C02+ATP 13. Describe the similarities and diCerences between aerobic and anaerobic respiration -Anaerobic respiration has no oxygen needed whereas aerobic respiration requires energy -Anaerobic respiration only occurs in the cytosol of the cell whereas aerobic respiration occurs in the cytosol and mainly in the mitochondria -Anaerobic respiration only produces 2 ATP compared to aerobic respiration where it produces 38 ATP -Anaerobic respiration converts glucose into lactic acid molecules whereas with aerobic glucose is converted into water and carbon dioxide -They both produce energy to be used by the body -They both produce pyruvate molecules -They both have some processes occur in the cytosol 14. Explain the importance of ATP in the body and describe the relationship between ATP and ADP ATP is important as it provides energy for many essential process in the cell including and not limited to cell division and growth, movement of the cell, active transport -ATP is made up of adenosine(adenine and ribose sugar) and three phosphate -ADP is made up of adenosine(adenine and ribose sugar) and two phosphate -The main relationship is that when the energy stored in the bond between the second and the third phosphate group is broken, ATP turns into ADP 15. State reasons why cells of the body require energy -Build complex molecules -Cell division and growth -Movement of cell organelles -Movement of the whole cell, -Maintaining cell organisation -Active transport and transmission of nerve impulses 16.Describe why cells require nutrients -To supply energy for metabolism -Matter for synthesis -Regulate cell processes 18.Describe the characteristics and functions of enzymes Enzymes are an organic substance which are usually proteins that increase the spped of a chemical reaction occurring at body temperature which is roughly 37 degrees -They are not altered or destroyed in the chemical reaction - Acts as a catalyst by lowering the activation energy required 19.Describe how enzymes work using lock and key and induced ﬁt Lock and Key Enzymes work in lock and key by being complementary to each other -Each enzyme will only interact with one substrate as the shape and the structure allows them to ﬁt together 1.Substrate-enetring active site of the enzyme 2.Enzyme-substrate complex forms 3.Enzyme-product complex forms 4.Products leave the active site of the enzyme Induced ﬁt -When the enzyme and substrate join, they form weak bonds that causes the shape of the enzyme to change creating complementary shapes 1.Substrate entering the active site of the enzyme 2.Enzyme changes shape slightly to complement substrate 3.Enzyme product complex 4.Product leave the active site 20. Describe factors that inﬂuence the ac4vity of enzymes 1.Concentration -the higher the concentration the faster the chemical reaction 2.Substrate concentration -the higher the substrate concentration the higher rate -there is point of saturation 3-Products -they have to be continually removed otherwise it’s slow 4-Temperature -the higher the temperature the faster the rate of reaction 5-pH -each enzyme is sensitive to the ph it is taking place in 6-Ions -many enzymes require the presence of certain ions or non protein molecules 7-inhibitors -they slow the process or even stop it Respiratory and Circulatory system 1.Label a diagram and state the structure and describe the func4on of the following structures Nasal cavity-lysozyme, mucus and covered in capillaries. The func4on of the nasal cavity is to that air is cleaned, moistened and warmed before entering into the body Pharynx-made up of mucus and cilia. It is a passage of air to enter larynx and lungs and food and water to enter epigloRs Layrynx-it is a car4lage structure and has hyoid bone. The air passes from the larynx and travels to and from the lungs. Inside the vocal chords vibrate to produce sound Trachea-It is made of c shaped car4lage rings. It carries air to and from the lungs lined with mucous membrane and cilia beat to move mucous and trapped par4cles upward Lungs-it is covered by pleural membrane which covers the chest. Bronchi-c shaped car4lage rings and as the bronchi gets smaller, car4lage spread out more Bronchioles-made up of smooth muscle and elas4n. The func4on is to carry the air into the alveoli Pleural membrane-hold the chest inside Diaphragm-it is a large muscle and it’s main job is to contract and ﬂaUen which either increases or decreases lung cavity Intercostal muscles-external and internal layers of muscle in between ribs. They move the rib cage up or down Vocal chords-Made up of 2 bands of muscle in the voice box and allows you to vocalise or make sounds 2.Describe where gas exchange occurs and explain how it occurs Gas exchange takes place in the alveoli. It works as air ﬂows in and out as we breathe and there is a constant source of blood capillaries which means that the blood capillaries have deoxygenated blood with high level of C02 while the alveoli is rich in 02. This sets up a concentra4on gradient and the 02 moves from the alveoli into the blood and C02 moves from the blood into the alveoli. 3.Describe the characteris4cs of the raspatory surfaces that enable eﬃcient gas exchange Lots of blood capillaries-this allows as much blood as possible Moist-gases cannot diﬀuse unless they are dissolved ﬁrst High surface area-this means that gas exchange can work on mul4ple surfaces making it quicker Very thin-both the alveoli and blood are one cell thick meaning the distance the gases have to travel is very minimal 4.Describe the factors that maintain a diﬀusion gradient between gases in air, alveoli and blood -Some factors that maintain a diﬀusion gradient is a close supply of blood vessels to allow blood to constantly ﬂow in and makes a diﬀerence between the concentra4on of oxygen in the blood and the alveoli -Another factor is the constant inhale and exhale of air, to allow for the concentra4on of oxygen and carbon dioxide to be diﬀerent from the air inhaled and the air in the body 5.Describe the role of red blood cells and plasma in the transport of oxygen and carbon. Red blood cells are biconcave making them able to carry oxygen more around the body as we breathe in air. CO2 is dissolved directly in the blood and is bound to plasma proteins which it can moved out of the body 6.Describe how the following aﬀect exchange of gases in lung Emphysema-The irrita4ng par4cles cause damage to the alveoli and breathing in ad out becomes voluntary, which decreases surface area and decreases eﬃciency of gases Lung cancer-Smoke par4cles irritate the mucus membrane and cause excessive mucus causing the trapped mucus to rupture the alveoli Pneumonia-the inﬂamma4on causes a secre4on of ﬂuid and mucus and decreases the amount of air the alveoli can contain, surface area is also reduced Tuberculosis- The lung 4ssue is impaired making it diﬃcult for gas exchange to occur Asthma-muscles that control bronchioles go into spasm and causing a narrowing of air passage, reduced volume go into lungs and red blood cells do not carry oxygen 7.Outline the mechanics of breathing Inspira4on -The intercostal muscles go out and upwards and the diaphragm contracts and ﬂaUens while moving down. This increases the thoracic cavity while lowering the pressure. This sets up a concentra4on gradient and the air outside is more pressured then inside. The air outside therefore moves from high pressure to low pressure Expira4on -The intercostal muscles go in and downwards and the diaphragm expands and moves up. This decreases the lung cavity and therefore increases the pressure inside the body. This sets up a gradient and air outside is less pressured then inside. The air inside the lungs will then move from high pressure to low pressure moving out 8. Compare the composi4on of inhaled and exhaled air Inhaled air is 20.95% O2 and 0.04% CO2 Exhaled air is 15.80% O2 and 4.03% CO2 9.Dis4nguish between breathing and respira4on Breathing is a mechanical process whereas respira4on is a chemical process happening in every single cell. 11.Iden4fy and label chambers of the heart, the valves, the vessels leading into and out of heart. 1. Superior vena cava 2.pulmonary artery 3.Right atrium 4.Truscupid valve 5. Inferior vena cava 6.Right ventricle 7.Septum 8.Lec ventricle 9.Mitral valve 10.Right atrium 11. Pulmonary vein 12.Pulmonary artery 13. Pulmonary vein 14.Aorta 15.Aor4c valve 16.Pulmonary valve 12.Describe the direc4on of blood ﬂow through the heart Body->R.A->R.V->Lungs->L.A->R.V->body -deoxygenated blood goes towards the lungs and oxygenated blood goes to the body -goes in to the right and out of the lec side 13.Describe the factors aﬀec4ng the rate of blood ﬂow around the body We can change it by aﬀec4ng the output of blood from the heart and by changing the diameter of blood vessels supplying the 4ssues 14.Deﬁne terms of cardiac cycle, systole, diastole Systole-pumping phase and contracts Diastole-relax and ﬁll phase Cardiac cycle-the process of ﬁlling the heart with blood and then pumping it to the rest of the body 17.Describe the structure and func4on of arteries, arterioles, veins, venules and capillaries Arteries-the walls are smooth and have elas4c ﬁbres. The lumen inside is small. The func4on is to carry blood away from the heart Arterioles-small arteries and have smooth muscle walls. The func4on is to supply blood to blood capillaries and can contract and relax to regulate blood Capillaries-microscopic blood vessels and have one layer of cells. They enable cells to get their requirements and paste waste into the blood Veins-blood pressure is low, walls are thinner and they contain valves. They carry blood towards the heart Venules-they can not change in the diameter and don’t have muscular walls so they have a wide lumen. They join up to make larger veins and carry blood to veins 18. List the func4ons of blood -transport oxygen and nutrients to all cells of the body -transport carbon dioxide and other waste products away from the cell -transpor4ng chemical messengers, called hormones to cell -maintaining the pH of body ﬂuids -distribu4ng heat and maintaining body temp -maintaining water content and ion concentra4on of body ﬂuids -protec4ng against disease -cloRng when vessels are damaged preven4ng blood loss 19. List the components if blood-blood, cells and substances present in plasma -red blood cells -white blood cells -platelets -plasma-nutrients(glucose, amino acids, lipids), ions, gases, plasma proteins and waste 20.Describe the structure and func4on of plasma, erythrocytes, and leucocytes Plasma -91% is water and the rest is dissolved substances of nutrients, ions, plasma protein, waste and gases -Transport components of blood around the body Erythrocytes -biconcave shape and they do not contain a nucleus -transport oxygen to lungs and other parts of the body Leucocytes -larger then red blood cells -protect the body from infec4on 21.Describe the role of thrombocytes and ﬁbrinogen in blood cloRng 1.Vascular spasm -smooth blood vessel wall will constrict and decreases blood ﬂow and decreases blood loss 2.Platelet plug -collegen ﬁbres are exposed and aUracts the platelets -this ac4vates the prothrombin ac4vator which converts prothrombin into thrombin and ﬁbrinogen to ﬁbrin 3.Coagula4on -ﬁbrin ﬁbres reinforce the cell -clot retrac4on and remodelling of the blood vessel wall by puRng in connec4ve 4ssue Diges9ve and Excretory system Q1. State the simplistic form of protein, carbohydrates, fats and describe their role in the body(include vitamins and minerals) -The most simplistic form of proteins is amino acids which has a role in the body to build new tissue, antibodies, hormones and bring substances into the cell -The most simplistic form of carbohydrates is simple sugars which has a role in the body to provide the major fuel/energy source -The most simplistic form of fats is fatty acids and glycerol which has a role in the body to provide long term energy, insulation and protection -The simplest form of minerals and vitamins is glucose and they have a role in the body to boost the immune system, support normal growth and development and help cells and organs do their job. Q2. Distinguish between the alimentary canal and the digestive system -The alimentary canal is a continuous tube that food physically passes through. The route consists of the mouth, oesophagus, stomach, small intestine, large intestine, rectum and then anus. -The digestive system is a system that contains all structures involved in the break down and the absorption of food such as the liver, gall bladder and pancreas -The diCerence between them is that alimentary canal is the direct passage of food and digestive contains all structures to do with the absorption of food Q3.List the 6 basic activities carried out by the digestive system 1.Ingestion of food and water 2.Mechanical digestion 3.Chemical digestion 4.Movement of food along alimentary canal 5.Absorption of digested food and water into blood and lymph 6.Elimination of material not absorbed Q4.Describe the role played by mechanical digestion and structures involved -Mechanical digestion is the physical breakdown of food into smaller particles. The aim is to increase the surface area upon which enzymes can act on -The teeth aid in mechanical digestion by increasing the surface area through the 4 diCerent types of teeth of incisors(biting and cutting), canines(tearing) and premolars and molars(grinding and crushing) -The oesophagus provides peristalsis which are waves of muscular contractions that push the food along the alimentary canal -The stomach provides mechanical digestion by having 3 layers of muscle which are oblique, circular, longitudinal allowing the stomach to contract in a variety of waves. The stomach mechanically digests food by churning it and mixing it with digestive juices to form chyme -The gallbladder helps to produce bile. It is released in the ﬁrst smart of the small intestine Q5 Describe the four types of teeth -There are 4 types of teeth which are incisors, canines, molars and premolars -Incisors are used for cutting and biting food, canines are used for tearing food, molars and premolars are used for crushing and grinding food Q6. State the function of bile, where it is produced and where it is stored -Bile plays a role to emulsify fats and break them down into smaller droplets of fat to increase the surface area for enzymes to act on -It is produced in the liver -It is stored in the gall bladder Q7. Describe the chemical digestion of food-where it takes place, the enzymes involved(amalyse, lipase, protease and nuclease), where they are produced and the substrates and end products -There is salivary glands in the mouth which release saliva turning starch into a disaccharide -The stomach has gastric protease(pepsin) to turn proteins into polypeptides -The pancreas has pancreatic protease(trypsin) to turn polypeptides into peptides, pancreatic amylase to turn starch into disaccharides, pancreatic lipase to turn fats into fatty acids and glycerol -The small intestine has peptidase to turn peptides into amino acids, intestinal lipase to turn fats into fatty acids and glycerol and disaccharide enzyme turning disaccharides into monosaccharides Q8. Outline the features of the stomach that facilitates the mechanical and chemical digestion of food -The stomach has gastric juice containing HCL, mucous and pepsin -The stomach has HCL which helps create an acidic environment and allows pepsinogen to be converted to pepsin -The stomach has mucous to help protect the stomach against the HCL Q9. Outline the features of the small intestine that facilitate absorption of nutrients -The small intestine has villi which increases the surface area of the small intestine -It is quite long meaning there is a long time for the nutrients to be absorbed -It has microvilli which are cells covering the outside of villi -Inner linin called the mucosa have folds Q10.State the simplest form that nutrients are in when they are absorbed and how they are absorbed -Amino acids are absorbed by active transport into blood capillaries -Simple sugars are absorbed by active transport into blood capillaries -Fatty acids and glycerol are absorbed by simple diCusion into the lacteal -Substances absorbed into the lacteal are transported into lymphatic system which eventually empties into blood through veins in upper chest. -Substances absorbed into blood are carried by ‘Heptic Portal Vein’ to the liver where it may be removed for further processing or remains in blood to be transported to body cells Q11.Outline the functions of the large intestine and the features that assist in the breakdown of remaining organic compounds -The large intestine’s function is to create faeces to removed from the body -It has bacteria which break down remaining organic compounds -It has mucous which lubricates the intestinal contents as it moves through -Some bacteria produce vitamins which are absorbed into blood and mineral nutrients are absorbed Q12.Distinguish between elimination and excretion Elimination is the removal of unwanted products from the body and excretion is the removal of metabolic waste from the body -Elimination is done by the digestive system and excretion is done by the kidneys -Faeces is eliminated and urine is excreted Q13-Describe how diet can aCect absorption in the alimentary canal -Constipation can occur when a person does not eat enough roughage. It is a condition where defection is diCicult as faces are hard and dry -movements in large intestine is reduced and contents stay for a long time. The faeces become harder and drier and harder causing defecation to be diCicult and more painful -Diarrhoea occurs when foods are spicy, fried, fatty or sugary. It is the frequent passing of watery faeces -Irritation of small or large intestine which increases peristalsis, so contents move before absorption of water Q14. Deﬁne excretion and list excretory structures and their products -Excretion is the removal of metabolic wastes from the body -The lungs create carbon dioxide from gas exchange -The sweat glands create sweat composed mostly of water, lactic acid, salt and urea -The alimentary canal create bile pigments which are broken down pigments of haemoglobin -The kidneys create nitrogenous waste, urea and uric acid -Liver processes a lot of the substances Q15-Deﬁne the deamination and how urea is formed -Deamination is the removal of the amino group from an amino acid -When amino acid is added to O2 it turns into a carbohydrate and ammonia -Ammonia is highly toxic and water soluble meaning that it has to be further processed’ -Energy and CO2 and ammonia can turn into urea and water Q16-Describe the structures of the kidney and blood supply and explain it’s overall function -The kidneys ﬁlter waste from blood and regulate the balance of water and salts in the blood plasma Q17-Describe the structure of the nephron Q18. Name the three major processes responsible for the formation of urine. State what happens in each process and where it happens 1.Glomerular ﬁltration is the ﬂuid force out of the blood due to high pressure and it collected by the glomerular capsule. This is due to the aCaernet arteriole has a wider diameter than eCerent. The narrowing increases resistance to blood ﬂow and increase pressure. The ﬁltrate consists of all materials except for RBC, WBC and plasma proteins. It occurs in the renal corpuscle 2.Selective reabsorption is when many components ﬁltered out are of use to the body and their removal is undesirable. This occurs when it goes from the nephron into the blood. Reabsorption occurs in the proximal convoluted tubule, loop of henle and passively K+, Cl-, HCO3- and H20, actively it is glucose and Na+. It also occurs in the distal convoluted tubule actively with sodium and H20. 3.Secretion is when there is still materials in the body that need to be placed back into the blood. This occurs when it goes from blood to nephron. This occurs in the distal convoluted tubule by passive or active with H+, K+, creatinine and drugs Q19. Describe how increased surface area, good blood supply and increased pressure contribute to the production of waste and regulation of water content of the body -Increased surface area allows for the maximum amount of time to create urine in the body -Good supply creates eCiciency and allows for a large number of materials to be ﬁltered and turned into waste -Increased pressure allows ﬂuid to force out of blood Q20. Describe the normal composition of urine Water-96% Urea-2% Various ions-1.5% Other-0.5% Muscular skeletal system 1.Three special properties of muscles Elasticity-the ability of the muscle to return to the original length after being stretched Extendibility-the ability of the muscle to be stretched when pulled Contractability-the ability of muscles to shorten Excitability-the ability of a muscle to react with a stimulus 2.Three types of muscle Skeletal-multi nucleated, striated, many mitochondria to produce many ATP -these form the muscles that we need to move, these compartmentalised to diCerent tissues to perform diCerent purposes around the body -the skeletal muscles are attached to bones through tendons. The origin is the end of the muscle attached to the stationary bone while the insertion is the end of the muscle attached to the movable bone. Some examples are triceps and biceps Smooth-single and central nucleus, not striated and spindle shaped myoﬁbrils -these expand organs such as lungs and kidneys, they are responsible for involuntary contraction, peristalsis and contract to change the shape of the lens in the eye -the smooth muscle is found in the wall of blood vessels and hollow organs and they are present in the eye Cardiac-single nucleus, more sarcomeres large and muscular which are connected by discs -to generate enough contractile force for the heart to beat eCectively and contract together in unison and cause enough pressure to force blood around the body -the cardiac muscle is only found in the heart 3. Explain what is meant by the Sliding ﬁlament theory of contraction -This represents how the myoﬁbrils are the contractile force of the muscle and they include actin and myosin. The length of the actin and the length of the myosin(the A band) always stay the same but they contract the sarcomere. The actin is the thin ﬁlament and the myosin is the thick ﬁlament so the actin slides over the myosin which shorten the myoﬁbril 4. Explain how the structure of proteins-actin and myosin enable a muscle ﬁbre to contract There is the A band which is the length of the myosin There is the I band which is the actin only due to the gap in myosin There is the H zone which is myosin only due to gap in actin There is the m zone which is the centre of the sarcomere There is the Z line which are the boundaries of the sarcomere -When there is ATP and nerve impulse it causes thin and thick ﬁlament to slide past each other. This secretes calcium which binds to troponin and therefore unlocks tropomyosin. The breakdown of ATP deforms the myosin head and cocks it into position into a high erect energy state. When the myosin head binds to the active site on the actin it forms a cross over bridge. The energy from the ATP causes a power stroke causing the myosin head to slide past actin. The more ATP causes more powerstrokes therefore further shortening the muscle. If there is no longer ATP or calcium it causes muscle fatigue. Therefore the Z line moves closer which shortens the sarcomere therefore decreasing H zone, I band but the A band stays the same 5.Label the sarcomere during contraction and relaxation 6. Understand the role of ATP in muscle contraction -the use of ATP and nerve impulse means that the thick and thin ﬁlaments slide over each other. Having no ATP available means that muscle fatigue occurs and there is a decrease in maximum force produced by the sarcomere. This is because more ATP is needed to create more power strokes allowing more myosin to slide over the actin further shortening and contracting the muscles 7.Explain the terms muscle tone, muscle fatigue, antagonistic and synergistic muscles Muscle tone is the partial contraction of skeletal muscle. This means that some muscle ﬁbres are being contracted while the others are relaxed but not the same muscle ﬁbres are contracted at one time. It tightens the muscle while not producing enough to move the muscle. It holds many parts of our body in the desired position. Posture depends on muscle tone, the partial contraction of muscles that hold the muscles in position Muscle fatigue is the decrease in maximal force or power that the involved muscles can produce. It is due to insuCicient ATP due to an excessive consumption and decreases the muscles’ ability over time due to muscle activity Antagonistic muscles are the muscles that work opposite to the prime movement. As one muscle contracts or shortens the other muscle lengthens and relaxes. The antagonist is the muscle that relaxes while the agonist is the muscles that contract over time Synergistic muscles are muscles that assist the prime mover for a speciﬁc action at the joint. It is not the main muscle but works in synergy with the primary muscle making it more accurate and more ﬂuid. They can either produce same movement or steady a joint which is called a ﬁxator so that the action can happen more eCiciently 8. Explain the role of synergistic muscles Synergistic muscles are very important as they stabilise the muscle and help against the muscles that perform their action. It can produce force to support the movement, promote stability increase power and strength. Some synergist muscles are ﬁxators meaning that they stabilise one part of the body during the movement of another part of the body. These ﬁxator muscles act as a ﬁrm origin for many muscles 9. Describe the action of antagonistic muscles in movements such as ﬂexion and extension Antagonistic muscles are muscles that go against the movement desired and performed by the prime mover. Antagonistic muscles often relax when the prime mover contracts. They maintain body or limb position and control rapid movement 10. Name the ﬂexor and extensor muscles in elbow and knee movements the ﬂexor muscles are the ones that contract while extensor are the ones that are relaxed In the elbow, the ﬂexor is the bicep while the extensor is the tricep In the knee, the ﬂexor is the hamstring and the extensor is the quadricep 11. Describe the main functions of the skeletal system There are many functions of the skeletal system which are provider scaCold to support weight for the rest of the body, provide points of attachment for muscle, store minerals and fats, protects organs and produces red blood cells 12. Describe the structure of the long bone A-epiphysis-which is the enlarged ends of the bone covered in a thin layer of cartilage -the epiphysis is responsible for the articulation of bones which is where bones meet B-Diaphysis-which is the shaft making up the main portion of the bone -the diaphyisis is for structural functionality, transport of oxygen, immune support and fat and mineral storage C-Articular cartilage is a thin layer of connective tissue -the articular cartilage is used for providing a smooth and lubricated surface for articulation D-Spongy bone-large spaces ﬁlled with marrow inside -the spongy bone provides balance to the dense and heavy bone making it lighter and therefore the muscles can move easier E-ephyseal line-it is a boundary between the epiphysis and the diaphyisis -the thickness of the line shows how much growing there is left for the human. If it is thicker, there is more growing to do for a person whereas if the line is thin, there is not much growing to do for a person F-Red bone marrow-it is the spongy tissue inside the bones -the red marrow is where blood cell production occurs as there are blood cell stems that can turn into either red blood cells, white blood cells or platelets G-Compact bone-this is the dense form of the bone -the high density in the compact bone is what gives the bone the protection and the strength of the bone that it needs. H-medullary cavity-the hollow part of the bone that contains yellow marrow -it makes blood cell, It also stores fats I-Yellow bone marrow -has adipose tissue meaning that it no longer produces red blood cells so it is yellow. -fat storage site J-Periosteum-dense, ﬁbrous outer covering of the bone -supplies them with blood they need and helps them grow and heal K-Nutrient artery-high blood pressure to reach distant locations -provides the bone with the nutrients it needs 13. Describe the microscopic structure of compact and spongy bone Compact bone -compact bone is made up of osteons. Osteons run up and down the compact bone -Each osteon has a central canal which is ﬁlled with lymph vessels and blood vessels. Central canals provide strength to the compact bone, bring nutrients to the osteocytes and bring waste away from the osteocytes -Around the central canal is lamellae which are concentric rings of bone. The lamellae are the matrix of the compact bone -There are lacunae in the lamellae which are the small spaces which are where osteocytes are found. The lacunae provide home for cells while keeping it alive and functional -From all directions of the lamellae there are canaliculi which are minute canals which bring nutrient to the osteocytes Spongy bone -spongy bone is made up of trabecula which are thin and bony plates. -The bone cells occupy spaces in the trabeculae meaning that the nerves and blood vessels pass irregular spaces in the matrix 14. Name the major components of the appendicular and axial skeleton Appendicular skeleton-consists of the bones of the upper and lower limbs which allow for articulation of the limbs with axial skeleton. Some bones include the clavicle, humerus and ulna Axial-consists of bones that lie down central axis of the body and provide main support, protect organs and the CNS. Some bones include the cranium, sternum and the vertebrae Functions of bones Support-the weight of the body Protection-of the body parts Movements-muscle attached to bone to allow movement Mineral storage-stores minerals Haematopoiesis-forms red blood cells Describe what osteoporosis and osteoarthritis including symptoms Osteoporosis -it is the loss of bone mass which impairs normal functioning -as bone density decreases, risk of fractures increases -need an adequate supply of calcium, vitamin D and plenty of exercise Symptoms-bones that easily break Osteoarthritis -exposed bone begins to ear away and bone spurs or growths may develop from exposed ends of the bone forming the joint -decreases the space within joint cavity, restricting movement of the joint -there is no cure, medication to relieve pain, physio to strengthen muscles and surgery to realign bones Symptoms-pain and stiCness in joints, more severe after exercise and when weight/pressure is put on the joint DNA, Protein synthesis and Epigene9cs.1.Describe the structure of DNA DNA is in a double helix shape which means that there are 2 strands of DNA which twist into a spiral shape. The DNA is made up of repeating units of nucleotides which are made up of a phosphate group, deoxyribose sugar and nitrogenous base(adenine, thymine, cytosine and guanine). The back bone of each strand is made of alternating sugar and phosphates. DNA strands wrap around a group of 8 proteins which are called histones to form a nucleosome. Chromatin is the tangled network of loose DNA when a cell is not dividing and a chromosome is highly coiled DNA when a cell is dividing 2.Describe the func4on of DNA DNA contains the instruc4ons needed for an organism to develop, survive and reproduce. 3.Describe where DNA is found in the cell DNA is found in the nucleus and the mitochondria Nuclear DNA is in the form of the double helix and has genes from both parents whereas mitochondrial DNA is in a circular shape which has 37 genes only from the male side of the family 4.Explain the process of DNA replica4on 1.The enzyme helicase separates the 2 strands of DNA by breaking the weak hydrogen bonds between the bases 2.Each strand serves as a template strand for the nucleo4des which will form the new strand 3.Primase adds the RNA nucleo4de which directs the DNA polymerase to start(RNA nucleo4des are later removed). DNA polymerase is the enzyme that adds the complementary nucleo4des. With the leading strand the nucleo4des are added con4nuously from 5’-3’ where as the lagging strand the nucleo4des are added in short sec4ons called Okazaki fragments as they have to be read from the 5’-3’. 4.DNA ligase is the enzyme that joins the sec4ons of DNA together 5.Explain the process of mitosis including the cells that undergo it All body cells undergo mitosis, these cells are called diploid cells as they have 2n number of chromosomes. The ﬁrst stage in mitosis is prophase which is where chroma4n becomes 4ghtly coiled which makes it easier to distribute, the nucleolus disappears and the nuclear membrane breaks down. The centrioles become visible and moves to opposite ends of the cell. The second phase is metaphase which is where the chroma4d pairs line up at the equator and the centromeres are aUached to the spindle ﬁbre The third phase is anaphase which is where each pair of chroma4ds are separated at the centromere and are pulled towards opposite ends of the cell The fourth phase is telophase which is where two sets of chromosomes form 4ght groups at each pole, nuclear membrane forms around each group, the nucelolus reappears and the chromosomes uncoil to become chroma4n The ﬁnal phase is cytokinesis which is where the cytoplasm of the cell divides into 2 each with a nucleus. 6.Describe how the uncontrolled division of cells can result in the development of tumours and cancer -Certain condi4ons can cause normal cells to divide uncontrollably -Cancer cells have a gene muta4on that can turn normal cells into cancer cells -tumour is developed by many cancer cells clumping together -The cancer can be malignant meaning that it can spread to other parts of the body or it can be benign meaning it does not spread to other parts of the body 8.Compare the structure and func4on of DNA and RNA Structure -DNA is in a double stranded shape where as RNA only has a single strand -DNA has four bases of adenine, thymine, cytosine and guanine where as RNA has the four bases of adenine, uracil, cytosine and guanine -DNA has deoxyribose sugar whereas RNA only has ribose sugar Func4on DNA’s func4on is to contain the instruc4ons of codes and RNA’s job is to make proteins by using that code through transcbring and then transla4ng that informa4on onto ribosomes 9.Explain the process of protein synthesis using transcrip4on and transla4on Transcrip4on occurs in the nucleus and is where gene4c instruc4ons are copied from the DNA template strand onto the mRNA 1.Helicase enzyme seperates the double stranded DNA 2.RNA polymerase uses one strand of DNA to make complementary mRNA strand -template strand is the DNA strand being copied -coding strand is the other DNA strand -speciﬁc base sequences act as a stop signal Transla4on is the produc4on of a protein using the informa4on that is coded in the mRNA molecule which occurs in the cytosol 1.The ribosome aUaches to one end of the mRNA at a par4cular sequence of bases(AUG start codon) which ensures ribosome aUaches to the correct end) 2.Ribosomes move along the mRNA 3 bases at a 4me 3. tRNA which have complementary an4codon join to mRNA as ribosome reads mRNA codons -amino acids are brought in by the sequence of tRNA 4.Amino acids are bonded together by pep4de bonds which are made by rRNA 10. Describe 3 types of RNA 1.Messenger RNA(mRNA) -made in the nucleus and takes gene4c code to the cytoplasm allowing it to be read by ribosomes 2.Ribosomal RNA(rRNA) -Ensures the correct alignment of mRNA, tRNA and the ribosomes -forms pep4des bonds between the amino acid 3.Transfer RNA(tRNA) -small molecule of RNA that carries a speciﬁc amino acid 11.Deﬁne codon and an4 codon A codon is a group of 3 bases which is on the mRNA strand An an4codon is a group of 3 bases on the tRNA strand which has the complementary nucleo4des to the mRNA strand 12. Explain how the environment can aﬀect gene expression. The environment factors that aﬀect a cell such as cell age, 4me of day, signals from other cells, environment of cells can either change the amount of methyl groups on histone or DNA or acetyl groups on the histone. If there is a high number of methyl groups the gene will not be expressed and the gene will be turned oﬀ. If there is a high number of acetyl groups the gene will be expressed and turned on. 13. Deﬁne epigene4cs & describe the role of epigene4cs in changing gene expression. Epigene4cs is altering the gene expression without changing the gene structure. Epigene4cs can change gene expression as if there is a high number of acetyl groups the DNA will be relaxed which enhances access of RNA polymerase. This would allow easy access meaning that more proteins of that speciﬁc thing will be made. For example insulin is only produced in the pancreas due to the dna and histone being relaxed compared to the gene in the bone with insulin which would be 4ghtly wound due to high number of methyl groups. 14.Describe histone modiﬁcation and DNA methylation -Gene expression may change the way DNA is wrapped around histone proteins. -If some of the amino acids in the histone proteins are changed, this will change the shape of the histone. The modiﬁed histone shape may be copied each time a new DNA molecule is formed. -The modiﬁed histone would ensure that a stem cell that diCerentiated into a liver cell remained as a liver cell (& not revert back to stem cell). -Methylation is the addition of a methyl group to DNA or histone. It occurs at CpG sites which is cytosine, phosphorus and guanine and restricts the access to DNA polymerase which inhibits gene expression. This will increase or decrease transcription depending on where methyl group is attached -Acetylation is the addition of acetyl groups to histone protein. This will decrease the attraction between the histone and DNA, relaxing chromatin promotes transcription by allowing RNA polymerase access which enhances gene expression. 15.Deﬁne the term homozygous, heterozygous, hemizygous, genotype, phenotype, autosomal, sex linked, dominant, recessive, codominant, allele, F1 generation and F2 generation Homozygous-Two copies of the same allele for a particular characteristic Heterozygous-DiCerent alleles for a particular characteristic Hemizygous-When a person has one gene instead of two Genotype-Genetic makeup of an individual as determined by alleles for a particular trait Phenotype-Physical characteristic of the individual determined by the expression of the alleles Autosomal-Characteristic on chromosome pair 1-22 Sex linked-Trait that carries on sex chromosome. X linked is speciﬁcally carried on the X chromosome Dominant-An allele that masks the eCect of another allele Recessive-An allele that is masked by the alternate dominant allele and needs to copies to be expressed Co dominant-Both alleles are expressed Allele-Alternative forms of a gene F1 generation-First ﬁlial generation which is ﬁrst gen of oCspring F2 generation-Second ﬁlial generation which is the second gen of oCspring 16. Analyse pedigrees Autosomal dominant-aCected parents can have unaCected children, typically do not skip generations Autosomal recessive-unaCected parents can have aCected children, more likely to skip generations X linked dominant-trait never transfers from father to son and aCected males will have aCected daughters X linked recessive-more common in males, trait never transfers from father to son and aCected females will have aCected sons 17.Multiple alleles using the ABO blood system A blood-Antigen A’s and anti-b-antibodies B blood-Antigen B’s and anti-a-anitbodies AB blood-Antigens A and B and no antibodies O blood-No antigens and Anti-a-antibodies and anti-b-antibodies 18. Explain the inheritance of the following genetic disorders and describe the eCects of the body(PKU, red-green colour blindness, haemophilia and Huntington’s’ disease) PKU -An inherited disease resulting to damage in the growing brain and thus extreme intellectual disability. The symptoms are tendency to epileptic seizures and failure to produce normal skin pigmentation. It is recessive and autosomal. Red-green colour blindness- A sex linked recessive trait that causes the colours of red and green to be perceived as identical. Symptoms are decreased attention span when colouring, exclusively colouring with wrong colours and head or eye ache when looking at red on green backgrounds or green or red backgrounds. It is recessive and sex-linked Haemophilia- An inherited disorder in which the blood clots slowly or not at all. Symptoms are nosebleeds that take long to stop, bleeding from wounds that last a long time, bleeding gums, skin that bruises easily and pain and stiCness around joints. It is a recessive and sex linked Huntington’s disease- A hereditary disease, the symptoms of which appear before 40 years of age, characterised by occasional involuntary sailing movements of arms and legs. Symptoms are the person has diCicultly making voluntary movements of the limbs, writhing movements in the hands, head, trunk and feet and progressive loss of the ability to think clearly. It is dominant and autosomal Reproductive system and pregnancy 1.Label the male and female reproductive systems. 2.Describe the functions of the main parts of the reproductive systems. Male Scrotum-the pouch outside the abdominal cavity where testes are located Testes-male sex organs which produce sperm and the hormone of testosterone Seminiferous tubules-tightly coiled duct in the testes where sperm is located Epididymis-this is the location where sperm mature Interstitial cells-cells located in mature testes that secrete testosterone Vas deferens-carries sperm out of the urethra Urethra-Carries semen and urine out of the body Seminal vesicle-Secretes seminal ﬂuid which is very rich in sugars and is the main part of semen Prostate gland-Secretes alkaline ﬂuid that helps activate sperm and neutralise the acidity of the vagina Bulbo-urethral gland-secretes a clear mucous which acts as a lubricant Erectile tissue-helps with erections when ﬁlled with blood Female Ovaries-produces eggs and the hormones of oestrogen Fallopian tubes-tubes that carry eggs from the ovaries to the uterus Fimbriae-ﬁnger like projections of the fallopian tube Uterus-nurturing the fertilised ovum Endometrium-preparation of implantation, maintenance of pregnancy if fertilisation occurs and shedding if not fertilised Cervix-neck of uterus leading to vagina and is dilated to push the foetus out of the body Vagina-it is a canal leading from the uterus to the exterior of the human body Hymen-It is a fold of tissue that covers external opening of the vagina Vulva-female external genitalia Labia majoria-2 ﬂeshy folds of skin made of fat and ﬁbrous tissue Labia minora-2 smaller folds of skin, pink without fat and pubic hair Clitoris-erectile organ of the female 3.Deﬁne meiosis and describe the process of meiosis. Meiosis is the cell division that results in sperm or eggs which have half the number of chromosomes of a parent cell. Meiosis undergoes -prophase 1(Chromosomes become visible, the nuclear membrane breaks down and spindle ﬁbres are formed. This is where crossing over happens) -metaphase 1(Homologous chromosomes line up on the equator) -anaphase 1(Homologous chromosomes move to opposite ends of the cell) -telophase 1(-the new nuclear membrane forms and cytoplasm will split into 2) -prophase 2(Nuclear membrane disappears and spindle ﬁbres form) -metaphase 2(chromosomes line up on the equator) -anaphase 2(daughter chromosomes move to opposite ends of the into separate chromatids) -telophase 2(new nuclear membrane forms and forms 4 non identical daughter cells) 4.Compare meiosis to mitosis. Meiosis Mitosis Type of cells/purpose Body cells Sex cells Growth and repair Sexual reproduction # duplication of One duplication of One duplication of chromosomes & # of chromosomes and 1 chromosomes and 2 nuclear division? nuclear division nuclear division Number of daughter cells? 2 daughter cells 4 daughter cells Diploid or haploid? Diploid Haploid Homologous No they do not pair up Yes they pair up in chromosomes pair up? metaphase 1 What happens at each Chromatids seperate 1.Chromosomes separate division? 2.Chromatids seperate Daughter cells identical or Identical Non identical non-identical? 5. Describe the process of spermatogenesis. Spermatogenesis is process that take place to form spermatozoa in the testis which occurs in the seminiferous tubules At puberty spermatogonia(immature cells that line seminiferous tubules) divide via mitosis to provide sources of new cells for production of spermatozoa Primary spermatocytes are spermatogonia that are pushed towards the centre of the tubule and undergo period of growth to form. They are diploid and undergo ﬁrst stage of meiosis which each produce 2 secondary spermatocytes which are haploid -Secondary spermatocytes undergo second stage of meiosis which each form 2 spermatids each -spermatids mature into sperm by removing most of the cytoplasm and forming a tail 6. List the hormones involved in spermatogenesis. LH-intertistial cells to produce testosterone FSH-seminiferous tubules to help with sperm production 7. Describe the process of oogenesis. Oogenesis is the formation of ova in the ovaries -Before a female is born oogonia(diploid and divide by mitosis) develop in the ovaries which at birth ovaries have several thousand oogonia which have undergone growth phase to be primary oocyte -Primary oocyte begin prophase 1 but stops at birth. They are surrounded by a single layer of cells which form a primary follicle -At puberty follicle growth and maturation begins -Primary oocytes completes 1st meiotic division each producing 2 haploid cells which are unequal in size. The bigger one is the secondary oocyte which receives half chromosomes and almost all the cytoplasm and the smaller is the ﬁrst polar body and receives other half of chromosomes but little cytoplasm -Secondary oocyte commences second meiotic division but stops at metaphase. Meiosis 2 is only completed if penetrated by sperm, -2 haploid cells produced and the larger is the ootid and smaller is the second polar body -First polar body undergoes meitotic division to produce 2 additional polar bodies which all will disintegrate 8. Outline the main diCerences between spermatogenesis and oogenesis. -Spermatogenesis produces 4 haploid cells while oogenesis produces one haploid cell and up to 3 polar bodies -Oogenesis does not complete meiosis unless penetrated by sperm whereas sperm can -Oogenesis begins with primary oocytes at birth where as spermatogenesis begins with spermatogonia at birth 9. Describe the main events of the ovarian cycle. 1.Primordial follicle(single layer of ﬂat granulosa cells) cells divide and enlarge to produce a primary follicle 2.The primary follicle(single or multiple layers of cuboidal granulosa cells) divide and enlarge to produce secondary follicle 3.Secondary follicle has the secretions from the granulosa cells which create a ﬂuid ﬁlled space that forces the oocyte to the edge of the follicle. This then divides and enlarges and ﬂuid accumulates to move cell to surface to form graaﬁan follicle 4.The graaﬁan follicle has reached the surface of the ovary and then ovulation happens 5. When the egg is expelled the follicle without the egg forms a corpus luteum which secretes progesterone and oestrogen -If fertilisation does not occur corpus luteum disintegrates to form corpus albicans roughly 8-10 days -If fertilisation occurs ovarian cycle stops and corpus luteum is maintained by hCG and it degenerates when placenta is formed to produce own oestrogen and progesterone 10. Describe the main events of the menstrual cycle. Menstruation(Day 1-4)-Uterine bleeding and the shedding of the endometrium Preovulation(Day 5-12)-Endometrial repair begins, development of ovarian follicle and uterine lining gradually thickens Ovulation(13-15)-Rupture of the Graaﬁan follicle producing an egg Secretion(16-20)- Secretion of watery mucous by glands of endometrium, cervix and uterine tubes, movement and breakdown of unfertilised egg, development of corpus luteum Pre menstruation(21-28). Degeneration of corpus luteum and thinning of the endometrium 11. List the hormones involved in the ovarian and menstrual cycles and describe their eCects. Reproductive hormones Male FSH targets the seminiferous tubules in the testis to produce sperm by stimulating epithelial tissue LH-targets the interstitial cells of testis to produce hormone testosterone(development of immature sperm, role in reproductive organs and sex drive) Oxytocin-movement of sperm and production of testosterone in testes and vas deferens Female FSH-targets the ovarian follicle and stimulates the development and maturation of the ovarian follicle in females LH-targets the cells of ovaries which is targeted for ﬁnal maturation, ovulation and formation of the corpus luteum Oxytocin-movement of milk in breats and uterus contractions Prolactin-Production, preparation and maintenance of milk production in breasts 12. Describe the role of hCG (human chorionic gonadotropin) in pregnancy. hCG is needed as to nurture the embryo the uterus needs to be thick which is done by oestrogen(vascularising) and prpgesterone(mucous). Progesterone and oestrogen are secreted by the corpus luteum and hCG maintains corpus luteum until placenta is formed 13.Describe the process of fertilisation and state where and when this occurs. Fertilisation is when the sperm and the egg fuse together which occurs in the fallopian tube when the sperm reaches the egg. 1.Insemination-sperm is released into the vagina when the male ejaculates 2.Sperm travel through the cervix+uterus to uterine tubes through muscular contractions. Ova move towards the uterus after ovulation by muscular contractions 3. Secondary oocyte is released at ovulation in meiosis 2. Surrounded by 2 layers of corona radiata and zona pellucida 4.Enzymes in acrosome are capable of breaking down the acid in the cementing material that holds the corona radiata together. Amount of enzyme in single sperm is small & ineCicient (several thousand sperm work to loosen cells of the the corona). 5.Acrosomal reaction: once sperm reaches zona pellucida, digestive enzymes from the acrosome are released to break down the glycoprotein matrix of the zona pellucida, giving the sperm access to the plasma membrane of the oocyte. 6.Plasma membrane of oocyte and spermatozoa fuse, the nucleus of the sperm enters the ovum. 7.Entrance of one sperm into the secondary oocyte stimulates the formations of the fertilisation membrane a round the oocyte (prevents other sperm from entering). 8. Male pronucleus (head of sperm with haploid nucleus) moves through cytoplasm. 9. Entrance of sperm stimulates secondary oocyte to complete second meiotic division. 10. Oocyte nucleus develops into female pronucleus (haploid nucleus of oocytes). 11. Male and female pronuclei fuse to form a single nucleus the is diploid in number. 12. Fertilisated oocyte is called a zygote. This cell undergoes mitosis to develop into an embryo. 14. Describe the features of the reproductive systems which facilitate fertilisation and implantation. -The muscular contractions of the uterus and fallopian tubes and the beating cilia -The enzyme of the acrosome located in the head of the sperm to break the outer layers of the secondary oocyte 15. Describe the events that take place from the fertilisation of the zygote to the blastocyst stage when implantation. 1. Fertilisation -zygote formed -travels down fallopian tubes and divides by mitosis 2.Early cleavage 3.Late cleavage 4.Blastocyst formation -happens 6 days after fertilisation and reaches the uterus -it is a hollow ball of cells that surround a ﬂuid ﬁlled cavity -inner cell mass(group of 30 cells at one end) made up of pluripotent stem cells 16. Describe cell diCerentiation & deﬁne and provide examples of totipotent, pluripotent and multipotent stem cells. Cell diCerentiation is the process by which unspecialised cells develop characteristics to suit particular actions. They are diCerent as they can undergo mitosis, are not specialised and have the potential to become specialised. Totipotent means having the ability to create any type of cell necessary for the human body. One example is the zygote Pluripotent means having the ability to form most type of stem cells but not all of an organism. One example is the inner cell mass of blastocyst Multipotent means stem cells that can only turn into a limited number of other cells. One example of this is a blood stem cell 17. Describe some of the tissues/structures that are developed from the primary germ layers (ectoderm, endoderm, mesoderm). The primary germ layers can diCerentiate into diCerent layers of the human body. -The ectoderm is the outermost germ layer and therefore forms the outer layers of the body -Some examples are skin, hair, nervous system, hair and nails -The mesoderm is the middle germ layer and forms skeleton and muscle -Some examples are skeletal, smooth and cardiac muscle, cartilage/bone/blood and other connective tissue -The endoderm is the inner germ layer and therefore forms the lining of the body -Some examples include the epithelium lining of alimentary canal, epithelium lining of tonsils and of lungs 18. Describe the role and development of the amnion, chorion and placenta. -The amnion is developed the ﬁrst out of all the embryonic membranes and surrounds the embryo by the 8th day of posy fertilisation -It’s role is to secrete an amniotic ﬂuid which protects the embryo against physical injury acting as a shock absorber, maintain constant temperature, allows embryo/foetus to move freely and ruptures at birth -The chorion is formed from the outer cells of blastocyst and the layer of mesodermal cells. It surrounds the embryo and all other embryonic membranes -As the amnion enlarges, it fuses with the inner layer of the chorion, with the chorion eventually becoming the main part of the foetal portion of the placenta. 19. Describe the structure and function of the placenta. -The placenta is the organ that supplies nutrients to the foetus , removes waste from the foetus and produces large number of hormones of oestrogen and progesterone 1.It plays a role with endocrine as it secretes a large number of hormones to help with pregnancy 2.It plays a role with excretory. It transports nitrogenous waste such as urea, uric acid and ammonia from foetal blood to the mother’s blood so it can be excreted by the mothers kidneys 3.It plays a role in the immune system. It transports the antibodies from the mother to the foetal supply so the foetus can have some immune from infectious diseases 4. It plays a role in nutrition. It tranpsorts nutrients such as glucose, amino acids from mothers blood to foetus and stores some essential nutrients in early pregnancy and releases them when demand is higher 5.It plays a role in respiratory. As it transports oxygen from the mother to the feotus and carbon dioxide away from the foetus and to the mother 20. Summarise the signiﬁcant events that occurred during the embryonic stage (week 0 to 8). -In the ﬁrst four weeks, the brain is beginning to form, heart and liver begin to develop, 30 pairs of mesodermal tissue and tail is evident -In the ﬁfth week arm and leg buds start to appear, arm buds slightly more advanced then leg buds -In the 8th week, it is recognisably a human, jaw and nose fully developed, eyes appear like slits, small earlobes, external sexual organs evident, toes well formed and all organs present except some may not be fully functional 21. Describe the major events that occur during foetal development. 16th week-ﬁngerprints are evident, posture erect and foetus moves 20th week-foetal movements such as kicking and turning can be felt clearly by the mother 24th week-eyebrows and eyelashes are made as well as toothbuds are evident 28th week-this is a period of greater growth and all systems are functional apart from the respiratory system 32nd week-accumulation of fat below the skin and growth is slowed 36th week-eyes open, nose well formed, ﬁne body hair shed and sucking and grasping reﬂexes are apparent 22. Describe the changes that occur in the mother during pregnancy. 1.There is growing of the abdomen -growth of uterus causes the abdomen to bulge -internal organs(stomach, liver and intestines) move outwards and upwards 2.Enlargement of breasts -pregnancy hormones cause the development of the milk secreting tissues leading to increase in size 3.Increase in heart size and blood volume -this is to cater for the extra blood ﬂow ﬂowing through the placenta which means the heart size needs to increase to increase blood ﬂow and size 4.Emotion changes -hormonal balance change the emotional state of the mother -fear accompanying pregnancy and birth 5.Increase urine production -increased blood ﬂow leads to increased blood ﬂow to the kidneys which increases urine production -during the ﬁrst 3 months, expanding uterus presses on bladder making the bladder feel full -as the uterus grows the pressure is released -last stages of pregnancy the foetus pushes on bladder again 23. Name and outline the main events that occur during the three stages of labour. 1.Prior to labour -Hormone changes meaning soften pelvic ligaments and increased response of uterus to stimuli and strength of contractions -Foetus faces right or left hip bone -knees drawn to abdomen, legs crossed(to take as little room as possible) -one side of head pressed on bladder, other on bowel -cervix softened to begun to open(a little) First stage of labour -waves of contractions travel from the upper part of the uterus down towards the cervix(similar contractions to peristalsis) -muscle ﬁbres in uterus pull on cervix as they shorten -contractions become more frequent and stronger -head of foetus forcefully pushed against foetus -dilation of the cervix=10 cm dilated -1st child=8-9 hours and 2nd child=4 hours -birth process starts when contractions become 30 minutes apart -birth canal=single curved passage, formed by uterus, cervix and vagina Second stage of labour 1.Water breaks -usually begins with the bursting of the membrane, surrounding foetus and gush of ﬂuid from the vagina -can occur earlier in labour 2.Full dilation to birth(20minutes to 2hrs) -Foetus heads stretches vagina -distention stimulates women to contract abdominal muscles -this along with uterus contractions push foetus through vagina -baby’s head turns to face mother’s back 3.Head moves through external opening of the vagina with each contraction -once head has emerged it turns sideways again(facing mother’s hips) -THE BONE OF SKULL IS PLIABLE. PRESSURE OF BIRTH CANAL MAY PUSH HEAD OUT OF SHAPE BUT BRAIN IS NOT DAMAGED AND WILL RETURN TO NORMAL FEW DAYS AFTER BIRTH Third stage of labour -blood clots form to stop leakage -large area of exposed tissue increasing risk of infection -umbilical cord is clamped in 2 places + cut in between(arteries and veins constrict) -expulsion of the placenta which remains of umbilical cord, amnion and chorion -blood vessels constrict and uterus contractions squeeze shut vessels supplying blood to the placenta. Decreased blood loss 24. Compare fetal and neonatal circulation before and after birth, and describe the role played by the foramen ovale, ductus venosus and ductus arteriosus in the foetus. Before birth the foetal lungs do not function(received O2 from the placenta) and alimentary canal does not function(receives nutrients from the placenta) -Before birth foetuses have a foramen ovale, ductus venosus and ductus arteriosus -The foramen ovale is the opening between the atria of the heart and allows blood to ﬂow directly from the right atrium into the left atrium -Most of the blood travels from the right atrium into the left atrium due to the fact that the blood coming into the right atrium is oxygenated from the placenta and can ﬂow to developing foetal tissue quickly -Foetus also have a ductus arteriosus which is a blood vessel that bypasses the lungs allowing blood in the pulmonary artery to ﬂow directly through the aorta -Blood may go from RA-RV-lungs but as lungs are collapsed there is great resistance to blood ﬂow(little blood reaches lungs). Most blood goes through the ductus arteriosus into the aorta -Ductus venosus is a blood vessel that enables blood to pass from the liver into the right atrium. This is because the liver doesn’t need to detoxify the waste as the placenta does this -After birth all these openings and vessels must close in order for the lungs and liver to be fully functional -The ductus arteriosus closing is triggered by the ﬁrst breath of life triggered by the shock of birth, if this fails the cut of the umbilical cord increased CO2 in the blood which triggers the respiratory centre of the brain and the lungs begin to function -As lungs expand there is decreased resistance to blood ﬂow and decreased blood ﬂow through ductus arteriosus -The foramen ovale is closed by increased blood returning to the heart(from the lungs) increasing the pressure in the left atrium. This forces the ﬂap against the wall of the atrium closing the opening -If the foramen ovale didn’t close, the baby will be born with a hole in it’s heart which is indicated by a baby blue colour due to insuCicient O2(not enough blood ﬂow to lungs) -The ductus venosus is closed when the umbilical cord is cut, blood no longer ﬂows through umbilical vessels or ductus venosus. Decreased blood ﬂow to the ductus venosus means it gradually constricts until it is closed. All blood to liver must ﬂow through the liver 26. Outline how the following reproductive technologies assist in diagnosis of fetal health – ultrasound, chromosomal analysis (CVS, amniocentesis), fetal monitoring, biochemical analysis and DNA probs. Ultrasound -a technique which inaudible and high frequency sound waves are used to produce an image of the foetus -probe is placed on abdomen of a pregnant woman and sound waves are reﬂected of the foetal tissue to obtain a visual echo -monitors growth of the foetus, conﬁrm pregnancy, stage of pregnancy, number of foetuses, gender of foetus, birth defects, position of the foetus Genetic analysis -foetal cells can obtained for analysis using amniocentesis or chronic villi sampling -amniocentesis is done on the 16th-20th week of pregnancy -living foetal cells ﬂoating in amniotic ﬂuid -CVS is done by specimen of foetal cells from the chorion -examine foetal chromosomes to detect defective, missing or additional chromosomes -Foetal monitoring -regular recording of the baby’s heart rate in order to indicate the stress -takes place during labour and birth -electrocardiography is procedure for obtaining electrical changes in the heart -shows an ECG which shows the series of waves related to electrical impulse -identify any risk of injury to the foetus Fetoscopy -The direct visual examination of a foetus through a small telescope like instrument -a fetoscope is used other stethoscope to hear heart beat or ﬁre-optic scope -detect abnormalities in the foetus Foetal blood sampling -Blood can be taken from the umbilical cord, foetal blood vessel which is usually the liver or the heart by a fetoscope -diagnose chromosomal abnormalities, diagnose foetal anaemia, check foetal oxygenation, identify indications Biochemical analysis -It is detected by testing the blood for excessive amounts of phenylaninine or analysing urine for phenylyruvic acid -AFP measured by samples of amniotic ﬂuid -If this is very high they may have malformation of spinal cord like spina biﬁda -detect PKU, detect AFP DNA probes -A section of DNA that complements the gene of interest -A segment of DNA is used structurally identical to the gene being detected -some units DNA have dye -the DNA probe is joined to the gene in question -if it is normal the prove will join to DNA segments -if not normal a gap appears --detection of a range of genetic disorders 27.List some possible causes for infertility 40% males, 40% females and 20% both Sperm production -problems with sperm to be produced in suCicient quantities, able to move in a forward direction or able to penetrate the corona radiata and zona pellucida. High number of sperm need to be made with correct structure -Other factors are semen may ﬂow into bladder not the urethra, males immune system might develop antibodies for their own sperm, blockages in the male reproductive system, hormonal imbalance Ovulation -as females get older the number of healthy eggs decreases which reduces chance of pregnancy especially after 36 -PCOS is where ovaries contain partially formed follicles thatg fail to mature. This means that eggs are not released and can not be fertilised -Cancer treatment may cause primary ovarian insuCiciency Other factors -Endometriosis is where the cells of endometrium grow outside of the uterus. The resulting scar tissue or distortion of uterine tubes can aCect the fertility by blockin egg’s release path -Fibroids aCect fertility when their location distorts the uterine cavity or block uterine tubes -Blockages of the uterine tubes, problems with menstrual cycle 28.Explain the following assisted reproductive technology procedures Artiﬁcial Insemination -It is a process where sperm is released into the uterus by a catheter being inserted through the cervix. The sperm sample is injected through the catheter, from the uterus, the sperm are able to move naturally through the uterine tubes where they may fertilise an egg. It increases chance of pregnancy for aCected couples with increasing number of sperm that reach the uterine tubes. -It has the advantage of allowing control over the sperm being inseminated. Sperm is collected, analysed, processed and concentrated meaning high quality sperm is used GIFT -Gamete intra fallopian transfer -It is a procedure which can be performed when there are normal fallopian tubes and adequate sperm. -It involves hormonal treatment used to stimulate female to produce more than one egg, sperm and egg are collected and analysed, sperm and egg are mixed together in a factory, sperm and egg mixture is injected into uterine tubes during laparoscopic surgery. It is hoped the sperm will then fertilise with egg naturally and implanting in the uterus IVF -In vitro fertilisation -Used to stimulate ovaries so multiple follicles develop, control ovulation and prepare uterine lining -A series of blood tests and ultrasounds are used to monitor the development of the follicles. When the eggs are mature, they are collected by a needle passing through the vagina to the ovaries -The eggs are then mixed with sperm in a suitable environment at 37 degrees to maximise their chances of fertilisation and development -2-6 days after collection an embryo is inserted into the uterus via a catheter placed through the cervix Intra-cytoplasmic Sperm Injection -It is similar to IVF -once the eggs are collected, they are examined to ensure they are suitable -a sperm is then injected into the cytoplasm of the egg, the resulting cells are monitored, and any that are developing normally and any developing normally are inseminated 29.Explain what is meant by an egg donor or embryo and surragcy -An egg donor is the process by which a woman donates eggs to enable another woman to conceive as part of an assisted reproduction treatment - Surrogacy is an arrangement, often supported by a legal agreement, whereby a woman agrees to childbirth on behalf of another person who will become the child's parent after birth 30.Describe the STI’s Chlamydia -It is transmitted by vaginal or anal sex with an infected person. It is caused by a bacterium which is only able to reproduce inside a living human cell making it diCicult to isolate -Some symptoms are painful urination, vaginal discharge/discharge from penis, painful vaginal sex, lower belly pain, bleeding between periods, swollen/tender testicles -It can be treated with antibiotics but the bacterium may never be completed eliminated from the body Trichomoniasis -It is an infection caused by protozoan which causes inﬂammation of the mucous membranes of the vagina in women and urethra of men. It is a parasite STI -Some symptoms include vaginal discharge and sever vaginal itch, men usually do not have symptoms -It can be cured with antibiotics Gonorrhoea -It is an infectious disease that mainly aCects the mucous membranes of the excretory and reproductive systems. It is caused by bacterium that is transmitted during sexual intercourse -Some symptoms are unsual vaginal discharge, heavier periods after sex, pain or tenderness in lower abdominal area -Gonnorhea is usually cured by antibiotics and normally result in an easy and eCective cure if treatment began early enough. Some strains of gonococcus are resustant to all antibiotics Syphilis -It is a bacterial infection caused by direct sexual contact. It is caused by bacterium and it only survive for a brief time outside human tissues, therefore infefctions by indirect contact are extremely rare -Some symptoms are rash, growth on genitals, white patches in your mouth, high temperature/fever, headaches and tiredness -Antibiotics is the usual treatment for all stages and during primary stage, cure is relatively easy. Surgery becomes necessary in the later stages. Herpes -It is a common STI caused by the Herpes simplex virus. There are 2 forms there is Herpes simplex type 1 which produces cold sores on lips but could also aCect the genitals and Herpes simplex type 2 creating blisters on the genital organs -Some symptoms are blisters in genital area, ﬂu like symptoms, rash -There is no way of removing the herpes from the body, the treatment includes medication to reduce pain, saline dressing to clean up blisters and antiviral drugs speciﬁc to herpes can be prescribed Genital Warts -They are warts found in the genital area but may be occasionally found in anus or thriat. They are caused by a virus of HPV. They are passed on by a sexual partner infected by the virus and the warts can not be seen. -Some symptoms are itching around the genital area, mild bleeding, burning sensation when peeing -They can be treated with some creams/gels, some vaccine to prevent you from getting it, cryotherapy to remove warts but not the birus HIV -It is a retrovirus and is unable to reproduce by itself. It aCects white blood cells known as T-lymphocytes. It is transferred when body ﬂuid enters the bloodstream or comes in contact with mucus membranes of another -Goes through 3 stages, acute infection, chronic infection and AIDS -Some symptoms of the ﬁrst stage is ﬂu like symptoms such as fever, fatigue, headache, sore throat, rash second stage is asymptomatic where the person appears ﬁt and well, the third stage has symptoms of rapid weight loss, recurring fever, extreme tiredness, diarrhea, pneumonia and swelling of lymph glands -It is no cure or vaccine to prevent infection. There is a number of antiretroviral drugs that inhibit the reproductive cycle of the virus Pubic Lice -It is when pubic lice and scabies cause intense itching in the genital area. They are usually conﬁned to the pubic and anal areas if the body -Some symptoms are itching which is worse at night, small red or blue dots on your skin, white/yellow dots attached to your hair, dark red/brown spots in your underwear -It can be treated with cream or lotion that contains permethrin 31.Distinguish between the vasectomy, tubal ligation and essure -Vasectomy is a form of male birth control that cuts the supply of sperm to your semen. It's done by cutting and sealing the tubes that carry sperm which are vas deferens. -Tubal ligation is surgery to close a woman's fallopian tubes - Essure is a permanently implanted birth control device for women with a metal coil

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