GCSE Biology B5

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  • Created by: Ruqayya11
  • Created on: 16-04-17 21:24
What is the role of the skeleton?
To support the body and allow it to move, as well as protecting vital organs
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What advantages does an internal skeleton have over an external?
Provides internal framework for the body. Grows with body. Flexible-due to many joints. Allows easy attachment of muscles
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Where is cartilage located on a bone?
A long bone consists of a long shaft containing bone marrow with blood vessels. At each end there is a head covered with cartilage
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Why are bones and cartilage easily infected by bacteria and viruses?
This is because they are both living tissues containing living cells. However, they are able to grow and repair themselves
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Explain the process of ossification?
This is the deposition of calcium and phosphorus, where the cartilage is slowly replaced by bone. If some cartilage remains between the head and shaft, the bone and the person is still growing
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Explain the process of osteoporosis?
The bones of elderly people can lack calcium and phosphorus, which can result in osteoporosis, making them prone to fractures
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What does a synovial joint contain?
Synovial fluid, synovial membrane, ligaments and cartilage
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Examples of synovial joints?
Ball and socket joint- wider range of movement. Hinge joint- restricted to an up-and-down movement
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What is the function of the synovial fluid?
It acts as a cushion against shock and a lubricant for easy movement
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What is the function of the synovial membrane?
A synovial membrane holds in the synovial fluid
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What is the function of the cartilage?
Cartilage protects the bone head and stops it from rubbing
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What is the function of the ligaments?
The ligaments hold the bones in place
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How are bones attached to muscles?
By tendons
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What is meant by antagonistic muscles?
To raise the forearm. the biceps contract and the triceps relaxes. To lower the forearm, the biceps relaxes and the triceps contract
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Raising and lowering the forearm is an example of what?
A lever, with the elbow acting as a fulcrum (pivot). The effort is multiplied resulting in greater force
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Why do animals need a blood circulatory system?
To ensure all their cells receive enough food and oxygen and to remove waste products, such as carbon dioxide
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Describe the circuit in a single circulatory system?
A single blood circuit of the heart, gills and body
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Describe the circuits in a double circulatory system?
The heart and lungs form one. The heart and the rest of the body from the other
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Why does a double circulatory system require a four chambered heart?
This is because it needs two atria to receive blood from the lungs and body, and two ventricles to distribute blood to lungs and body. It ensure high blood pressure for efficient and fast circulation of food and oxygen
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Why does a single circulatory system require a two chambered heart?
It needs one to receive and one to distribute blood
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What did Galen do?
He knew that the heart acted as a pump and the importance of the pulse. However, he though that the liver made blood that flowed backwards and forwards
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What did William Harvey do?
He knew that blood circulated around the body, that the heart has four chambers and about the capillaries
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What is the cardiac cycle?
It is the sequence of events as blood flows into the two atria. The atria contract, pushing the blood into ventricles. The ventricles contract, forcing the blood into the aorta and pulmonary artery
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How is blood prevented from flowing in the wrong direction?
By the atria-verntricular and semilunar valves
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What does more muscular activity cause?
It causes a greater demand for oxygen and food. Heart rate therefore increases with increasing muscular activity
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Why is heart rate increased by the presence of adrenaline?
It is increased by the presence of the hormone adrenaline to prepare the body for 'fight or flight'
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What is the role of pacemaker (group of cells in the heart)?
They control the rate of the heart beat by producing a small electric current to stimulate muscle contraction
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What is the role of an artificial pacemaker?
It can be placed near the heart to send an electrical signal to the heart muscle
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What does an electrocardiogram show?
It shows changes in electrical impulses in heart muscle. Heart attacks
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What does an echocardiogram show?
It displays a video of the heart in action and can be used to investigate irregular heart action. Enlarged heart. Decreased pumping ability. Valve function
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What do the SAN and AVN generate?
The two pacemakers generate electrical impulses to cooridinate heart muscle contraction. Impulses from the SAN cause the atria to contract and stimulate the AVN. Impulses from the AVN cause the ventricle to contract
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What does a hole in the heart allow?
It allows blood to flow from one side of the heart to the other, so blood leaving leaving the heart in the aorta carries less oxygen, causing muscles to have less energy
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What does a hole in the heart cause?
It causes the mixing of oxygenated and deoxygenated blood, resulting in the arterial blood carrying less oxygen
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Why doesn't unborn baby need a double circulatory system?
This is because the lungs do not function before birth. Before birth, a hole exists between the two sides of the heart, which closes at birth
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How are damaged and weak valves repaired?
They can be replaced by surgery. Damaged and weak valves produce a low blood pressure and poor circulation as blood will leak backwards
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What does a blocked coronary artery cause?
A blocked coronary artery reduces the blood flow to the heart muscles. It can be by-passed by transplanting a blood vessel from another part of the body
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How can major heart problems be repaired?
They can be corrected by transplanting donor hearts. Small electrical pumps can be used to provide extra pressure to blood leaving the heart- allowing time for damaged muscle to recover
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What are the advantages of artificial pacemakers and valves?
No problems of donor shortages or matches. No need for immuno-suppressive drugs
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Explain the process of blood clotting?
Cascade process. When blood platelets are exposed to air in a wound, it triggers a complex sequence of a chemical reaction, eventually leading to the formation of a clot
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What to blood clots prevent?
They prevent too much bleeding. A clot is a mesh of protein fibres that plugs the damaged area
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Identify the drugs that reduce clotting?
Warfarin, Heparin and Aspiring to prevent clotting, which can block blood vessels
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What does too little and too much clotting mean?
Too little means you bleed to death. Too much can cause strokes and deep vein thrombosis
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What do people with haemophilia suffer from?
They are at risk of internal bleeding from the slightest knock, as the blood does not clot
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What is meany by a blood transfusion?
A blood transfusion puts the correct blood type into the patients blood system, replacing blood lost
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What is an antigen?
An antigen is a substance that can trigger a response from a persons immune system
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Explain the reaction of agglutination?
This takes place when different blood groups are incompatible. When agglutinins in red blood cells and blood plasma react, the blood transfusion endangers the patients life
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What agglutinins cause agglutination?
Antigen A will react with anti-A and Antigen B will react with anti-B
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Why are amphibians restricted to moist conditions?
This is because of their respiratory system. Fish gills only work in water
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How do amphibians obtain oxygen?
They have simple lungs but use their moist, permeable skin to obtain oxygen. The permeable skin makes them susceptible to excessive water loss, which can result in death. They obtain oxygen from water being forced over filaments, so don't work in air
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What does breathing in consist of?
Intercostal muscles (which connect the ribs) and the muscles in the diaphragm contract. The chest volume increase and the pressure to decrease. The higher outside pressure causes air to enter the lungs
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What does breathing out consist of?
Intercostal muscles and diaphragm relax, causing the ribs to move down and the diaphragm to curve upwards. The chest volume therefore decreases, which increases the pressure, forcing the air out of the lungs
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What does the total lung capacity consist of?
Tidal air- amount of air normally breathed in and out while at rest. Vital capacity- maximum amount of air which can be exchanged. Residual air- amount of air which cannot be forced out of the lungs
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What are alveoli?
Air sacs where gas exchange takes place, in lungs
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Where does gaseous exchange take place?
Between the alveoli by diffusion and the air in the air sacs. Diffusion occurs because the oxygen concentration in the air is higher than in the deoxygenated blood capillaries around the alveoli
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What makes gaseous exchange as efficient as possible?
Large surface area to increase diffusion. Moist surface to help oxygen and carbon dioxide dissolve. Permeable surface to help gases exchange easily. Thin lining so gases don't diffuse very far. Good blood supply
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What does the human respiratory tract consists of?
The trachea, bronchi. Its lined with mucus and cilia
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What is the role of cilia?
They catch dust and microbes before they reach the lungs. The cilia beat, pushing microbe-filled mucus out of lungs as phlegm
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What is asbestosis?
Asbestosis is an industrial disease resulting from breathing in asbestos fibres. The fibres cause inflammation and scarring if lung tissue, reducing gaseous exchange
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What is a genetic form of lung disease?
Cystic fibrosis. A single defective gene, where too much mucus is produced in the bronchioles causing breathing difficulties
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What lifestyle factors increase risk of lung cancer?
Smoking increases the risk of lung cancer. Lung cells grow rapidly, reducing the surface area available for gaseous exchange
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What occurs during an asthma attack?
The lining of the airways becomes inflamed, mucus and fluid build up in airways and the muscles around the bronchioles contract, narrowing the airways- difficult to breathe
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What are the symptoms of an asthma attack?
Wheezing. Tight chest. Difficulty breathing
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What is digestion?
Digestion is the breaking down of the nutrients in your food , so that they can be absorbed
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What is the aim of digestion?
The aim is that food molecules need to be able to pass through the walls of the small intestine and dissolve in the blood or lymph. This means they have to be small and soluble
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What is physical digestion?
Breaking food into smaller pieces by chewing it, and then churning it around in the stomach
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What is the importance of physical digestion?
Allows food to pass more easily through the digestive system. Prepares the food for chemical digestion by giving it a larger surface area
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What is chemical digestion?
Carbohydrates, fats and proteins are broken down by specific enxymes
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Where does chemical digestion take place?
In the mouth, where carbohydrates break down starch to sugar. In the stomach, where protease breaks down protein to amino acids. In the small intestine, where lipase breaks down fat into fatty acids and glycerol
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What does the chemical breakdown of starch involve?
Breakdown of starch to maltose. Breakdown of maltose to glucose
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Where is bile made and stored?
It is made in the liver and stored in the gall bladder
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What is emulsification?
Breaking down fat into tiny droplets. It gives a much bigger surface area of fat for efficient digestion
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What does carbohydrates and protein molecules being soluble mean?
This means they are able to diffuse through the walls of the small intestine and into the blood
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What does the fat molecules being insoluble in water and plasma mean?
They would block up blood vessels. They diffuse through the walls of the small intestine and into the lymph
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How is the small intestine adapted for efficient absorption of food?
Having an extensive system of blood capillaries and lymphatic system of lacteals, which contain lymph.
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What is the small intestines large surface area created by?
Many villi in the walls. Many microvilli from the walls of the villi. Villi have a single permeable layer of surface cells and a very good blood supply to allow quick absorption
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What are the 3 main roles of the kidneys?
Removal of urea from the blood. Adjustment of salt levels in the blood. Adjustment of water content of the blood
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How is urea formed?
Excess and unwanted amino acids are broken down in the liver, forming urea, which is taken in blood to the kidneys
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How is urea removed from the blood?
Blood containing waste such as urea enters each kidney by the renal artery. Blood without waste leaves by the renal vein. Waste removed from the kidney leaves through the ureters as urine
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What is a nephron?
Each kidney has millions of microscopic kidney tubules where filtration takes place to form urine
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What does each nephron have?
A network of capillaries (glomerulus) surrounded by a capsule- filtration unit. Region where materials such as glucose are selectively reabsorbed. A region where reabsorption of salt and water takes place
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What is ultrafiltration?
A high pressure squeezes urea, water, salts and glucose out of the blood and into capsule. Big molecules like protein are not squeezed out
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What is reabsorption?
As liquid flows along the nephron, useful substances are reabsorbed- Sugar, some Water, some Salt
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What is release of waste?
Urea, excess salt and excess water are not reabsorbed. They continue out of the nephron, into the ureter and down to the bladder as urine
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Why is important to keep a constant concentration of water molecules in blood plasma?
This prevents too much water moving into or out of the tissues by osmosis. Keeps blood pressure constant
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What is the amount of water released in kidney nephrons controlled by?
A hormone called Anti-Diuretic hormone. ADH makes the nephron more permeable so that more water is reabsorbed back into blood
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Where is ADH produced?
ADH is produced in the pituitary gland. The brain monitors the water content of the blood and instructs the pituitary gland to release ADH into the blood
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How does the pituitary gland control the concentration of urea?
By increasing the permeability of kidney tubules so that more water is reabsorbed. Using a negative feedback mechanism to control ADH production
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What does the concentration of urine depend on?
After drinking a large quantity of water. During strenuous exercise. Heat
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How does water intake effect the concentration of urine?
Drinking a large quantity of water, the quantity of urine produced increases and the urine concentration decreases
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How does strenuous exercise effect the concentration of urine?
During strenuous exercise the body produces more sweat to cool down, so the quantity of urine produced decreases and the urine concentration increases
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How does heat effect the concentration of urine?
Sweat contains water so sweating causes water loss. This causes the release of ADH into the blood so that the kidneys reabsorb more water. This leaves a small amount of excess water that needs to be removed- little concentrated urine is produced
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When is a dialysis machine used?
Patients who have kidney failure can't filter their blood, so use a dialysis machine to filter it for them
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What are the components of a dialysis machine?
The machine has many tubes containing blood, surrounded by a liquid. The machine acts as am artificial kidney and removes urea from the blood. As urea molecules are small, they diffuse through the membrane
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What does dialysis fluid contain?
Sodium salts, so it is the same that the desired blood concentration. This maintains the sodium levels in blood
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Why must dialysis be done regularly?
To keep dissolved substances at the right concentrations, and to remove waste
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Why is the body more sensitive to the level of carbon dioxide than oxygen?
This is because high concentrations of carbon dioxide is toxic and must be removed from the body
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How is an increase in carbon dioxide detected?
It is detected by receptors in the carotid artery. Nerve impulses inform the brain, which cause the rate of breathing to increase to remove CO2 via the lungs
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Stages in Menstrual Cycle?
1- Menstruation starts for 4 days. The uterus lining breaks down. 2- Uterus lining builds up again into thick spongy layer full of blood vessels- day 4-14. 3- An egg develops and is released from ovary
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Stages in Menstrual Cycle?
4- Wall is maintained for about 14 days until day 28. If no fertilised egg lands on uterus wall by day 28, the spongy lining breaks down and cycle starts again
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Follicle-stimulating hormone?
FSH stimulates and egg to develop in an ovary. Stimulates the ovaries to produce oestrogen. Produced in the pituitary gland
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Oestrogen?
Causes the lining of the uterus to repair, thicken, grow. Stimulates the production of LH and inhibits the production of FSH. Produced in ovaries
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Luteinising Hormone?
Stimulates the release of an egg. Indirectly stimulates progesterone production. Produced by pituitary gland
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Progesterone?
Maintains the lining of the uterus. When the level of progesterone falls, lining breaks down. Inhibits the production of LH. Produced in the ovaries
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What controls the levels of sex hormones in menstrual cycle?
Negative feedback mechanism controls the levels of sex hormone in menstrual cycle. This cycle is triggered by the receptors in the hypothalamus
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What happens if fertilisation does not occur?
Levels of oestrogen and progesterone decrease. Menstruation occurs when these levels are low
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What happens if an egg is fertilised?
The levels of progesterone remain high and no FSH is produced, so no more eggs develop and the uterus lining does not break down
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How can fertility in humans be controlled?
The use of artificial sex hormones by controlling egg release and implantation. The contraceptive pill prevents ovulation as it contains oestrogen and fertility drugs help to ensure ovulation
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How is fertility prevented?
Artificial sex hormones prevent ovulation by making the body think it is pregnant. If oestrogen is taken every day, it mimics pregnancy and inhibits the release of FSH. Egg in the ovary are therefore not stimulated to develop
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Methods of treating infertility?
Artificial Insemination- sperm is inserted into vagina. Using FSH to stimulate egg development. IVF- where an egg is fertilised outside the body. Egg donation- egg is donated from another female, fertilised and placed inside the uterus
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Methods of treating infertility?
Surrogacy- fertilised egg is placed inside a surrogate mother. Ovary transplant from another female
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Ethical issues surrounding infertility treatments?
Disposal of eggs-considered human life. Unknown paternity for AI. Treatments are very expensive with a low success rate
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Methods of foetal screening?
Amniocentesis- testing cells in amniotic fluid. Chromosomal analysis- blood test to test cells for any chromosome abnormalities
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Ethical issues surrounding foetal screening?
Increased risk of miscarriage. Parents may consider abortion if baby has abnormalities. Is it right to interfere with natural process
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What increases growth?
Balanced diet and regular exercise
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What extremes of height caused by?
Hormone imbalance or by genes
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Where is human growth hormone produced?
By the pituitary gland and it stimulates general growth, especially in long bones
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Baby's growth?
Different parts of a baby grow at different rates, the head grows and develops earlier than the rest of the body
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Why has human life expectancy increased?
Fewer deaths from industrial diseases. Better housing. Healthier diet and lifestyle. Advances in modern medicine
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Advantages and Disadvantages of increased life expectancy?
A- personal and national consequences, such as longer retirements to enjoy. D- burden on pension funds and health services
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Why is the supply of donors limited?
By a shortage of donors and also by restrictions of use due to the necessity of tissue matches as well as those of size and age. Dead donors must have died recently
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How can these problems be avoided?
Using mechanical replacements. However, these have other problems such as the dependence on a power supply, materials used, large sizes and body reactions do 'foreign' materials
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What can a living person donate?
Blood, bone marrow- as the body replaces them. A kidney as we can survive with only one
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What criteria must a donation from the dead meet?
Approval from donor or relatives and requirement that donor is 'brain dead'
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Ethical issues surrounding organ donations?
Religious reasons- body must be intact when buried. Life and death is up to God, so receiving organs is wrong. Others worry doctors won't save them if their organs are needed. People may be pressured into donating
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Why do recipients receive immuno-suppressive drugs?
To reduce risk of transplant being rejected. They can lead to the body not being able to protect itself from microorganims
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What is the opt out system?
This assumes that organs can be donated without asking permission. Some people object, saying it is against human rights
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Other cards in this set

Card 2

Front

What advantages does an internal skeleton have over an external?

Back

Provides internal framework for the body. Grows with body. Flexible-due to many joints. Allows easy attachment of muscles

Card 3

Front

Where is cartilage located on a bone?

Back

Preview of the front of card 3

Card 4

Front

Why are bones and cartilage easily infected by bacteria and viruses?

Back

Preview of the front of card 4

Card 5

Front

Explain the process of ossification?

Back

Preview of the front of card 5
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