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| Question | Answer |
|---|---|
| Name the components of the circulatory system. | the blood, the blood vessels, and the heart |
| What is the liquid in the blood called? | plasma |
| Name the components of the blood. | plasma, red blood cells, white blood cells, platelets, and many disolved substances |
| How much blood does the average person have? | 4.5 to 5 litres of blood |
| What colour is plasma? | it is a yellow liquid |
| What is the role of plasma? | to transport cells and substances around the body |
| Name the main substances that are carried by the blood. |
• carbon dioxide waste is carried to the lungs • oxygen is carried to the body • hormones and enzymes distributed to different parts of the body • urea produced in the liver is carried to the kidneys to be removed from the blood • digested food pass into the blood from the small intestines and are carried to the cells of the body |
| How many red blood cells are there? | about 5 million in each cubic millimetre of blood |
| What do red blood cells do? |
• they pick up oxygen at the lungs and deliver it to the cells where it is needed • they collect carbon dioxide from the cells and deliver it to the lungs to be expelled from the body |
| Describe the adaptations of the red blood cells. |
• they are biconcave to increase surface area • they contain red haemoglobin that carries oxygen • they have no nucleus making more space for haemoglobin |
| Describe the reversible reaction between oxygen and haemoglobin. |
• haemoglobin combines with oxygen at the lungs to make oxyhaemoglobin • oxyhaemoglobin breaks down into oxygen and haemoglobin at the cells |
| Compare the size of red and white blood cells? | white blood cells are much larger than red blood cells |
| Compare the number of red and white blood cells. | there are fewer white blood cells than red blood cells |
| What is the role of white blood cells? | they form part of the body's defence system |
| Name the three functions of white blood cells. |
• some produce antibodies; these white blood cells are called lymphocytes • some produce antitoxins • some engulf and digest bacteria and viruses; the process is called phagocytosis |
| Name the process of engulfing and digesting pathogens. | phagocytosis |
| Name the white blood cells that perform phagocytosis. | phagocytes |
| What are platelets? | small fragments of cells |
| What is the role of platelets? | they are key in clotting blood at the site of a wound |
| What is blood clotting? | a series of enzyme-controlled reactions that convert fibrinogen into fibrin |
| What happens as a result of the blood clotting process? | fibrinogen is converted to fribrin which forms a network of protein fibres that capture red blood cells and platelets which dry to form a scab |
| What does a scab do? |
• stops bleeding • protects the new skins as it grows • stops bacteria entering through the wound |
| Do white blood cells have a nucleus? | yes,they have a nucleus |
| Do red blood cells have a nucleus? | no, they do not have a nucleus |
| Do platelets have a nucleus? | no, they do not have a nucleus |
| Question | Answer |
|---|---|
| Name the smallest blood vessel in the body. | a capillary |
| How far away are cells from capillaries? | every cell in the human body is within 0.05mm of a capilliary |
| Name the different types of blood vessels | arteries, veins, capillaries |
| What is an artery? | a blood vessel that carries blood away from the heart |
| What is a vein? | a blood vessel that carries blood to the heart |
| What is the colour of oxygenated blood? | bright red |
| What do arteries do as blood passes through them? | they stretch as blood is forced through them and go back to shape afterwards |
| What do you feel as the pulse in your blood vessels? | the arteries stretching and returning to shape as the blood is forced through them |
| Describe the walls of an artery? | they are thick containing muscles and elastic fibres |
| Why is it dangerous to cut an artery? | blood in an artery is under pressure so will spurt out rapidly if cut |
| What is the colour of deoxygentated blood? | a deep purple-red |
| Can you feel a pulse in an vein? | No, only in arteries |
| Describe the walls of a vein. | they have thinner walls than arteries |
| Why do veins often have valves? | to prevent the back flow of blood because blood pressure is low in veins |
| How do the valves of the vein work? | they open when blood is forced through the veins and close when it runs back |
| How is the blood squeezed back to the heart? | by the action of the skeletal muscles? |
| How are arteries linked to veins? | by a huge network of blood vessels called capilliaries |
| Describe the structure of capillaries. | they are narrow with very thin walls only one cell thick |
| Why do capillaries have a thin wall? | to allow substance like oxygen diffuse easily out the blood and carbon dioxide diffuse easily into the blood |
| What is the space inside blood vessels called? | the lumen |
| What type of circulatory system is found in mammals? | a double circulatory system |
| What is meant by double circulation? | blood leaves and travels to the heart twice through two separate loops to circulate around the whole body |
| Describe how the blood moves through the double circulatory system? | from the heart to the lungs and back to the heart, then from the heart to the body and back to the heart |
| What does the blood collect and release on its journey around the double circulatory system? |
• in the lungs oxygen is collected and carbon dioxide released • in the body carbon dioxide is collected and oxygen released |
| Describe how the blood provides oxygen to the body |
• oxygen diffuses from the lungs into the blood • the blood travels from the lungs to the body • oxygen diffuses from the blood into the cells |
| Describe how the blood facilitate the removal of carbon dioxide from the body |
• carbon dioxide produced by the cells diffuses into the blood • the blood travels from the cells to the lungs • carbon dioxide diffuses from the blood into the lungs |
| Question | Answer |
|---|---|
| Name the organ that pumps blood around the body. | the heart |
| How many times a minute does the heart beat? | about 70 times a minute |
| How many pumps in the heart? | two |
| How many chambers does the heart have? | four |
| Name the four chambers of the heart. | the right atrium, the left atrium, the right ventricle and the left ventricle |
| Where does blood enter the heart? | the top chambers of the heart called the atria |
| Where does blood leave the heart? | the bottom chambers of the heart called the ventricles |
| What does the vena cava do? | it carries deoxygenated blood into the right atrium of the heart |
| What does the pulmonary vein do? | the pulmonary vein brings oxygenated blood from the lungs into the right atrium |
| What happens when the atria are full? | the atria contract together and force blood down into the ventricles |
| Why does blood not flow back from the ventricles into the heart? | valves close to prevent back flow |
| What happens when the ventricles are full? | the ventricles contract and force blood out the heart |
| Name the blood vessel through which blood leaves the heart for the body. | the aorta |
| What leaves the right ventricle? | the right ventricle forces deoxygenated blood out through the pulmonary artery to the lungs |
| What leaves the left ventricle? | the left ventricle forces oxygenated blood out through the aorta around the body |
| Why does blood not flow back into the ventricles? | valves close to prevent blood flowing back |
| What is the importance of the heart valves? | it ensures that blood flows in the right direction |
| What is the main tissue in the walls of the heart? | the walls of the heart are almost entirely muscle |
| How is the muscle of the heart supplied with oxygen? | the coronary arteries |
| What instrument does a doctor use to listen to the beat of the heart? | a stethoscope |
| What causes the sound of a heart beat? | the sound of the valves closing in the heart |
| Which muscle wall is thicker? | the muscle wall of the left ventricle is much thicker than the wall of the right ventricle |
| Why is the muscle of the left ventricle thicker than that of the right ventricle? | the left ventricle needs to develop a high enough pressure to push the blood all the way around the body |
| What happens to the coronary arteries in coronary heart disease? | they become narrow reducing the blood flow to the heart muscle |
| Name a common cause of the narrowing of the coronary arteries. | a buildup of fatty material on the lining of the vessels |
| What is the impact of reducing blood flow through the coronary arteries? | less oxygen reaches the heart muscle causing pain, a heart attack or even death |
| How is coronary heart disease often solved by doctors? | using a stent |
| What is a stent? | a metal mesh cylinder that forces the vessel open to allow better blood flow |
| How is a stent inserted? |
• the collapsed stent is inserted into position with a deflated balloon inside • the balloon is inflated expanding the stent so that it opens the blood vessel • the balloon is deflated and removed leaving the expanded stent in place |
| Name an alternative to using a stent for a blocked artery? | heart bypass surgery |
| What is heart bypass surgery? | doctors replace the narrow or blocked arteries with vein taken from other parts of the body |
| What are the advantages of using a stent? |
• it is cheaper than heart bypass surgery • it does not require a general anaesthetic |
| When is heart bypass surgery appropriate? | when the arteries are so badly damaged or blocked that a stent cannot open them to allow blood flow |
| What are the disadvantages of heart bypass surgery? |
• it is very expensive • it requires general anaesthetic which involves risks |
| Name a popular treatment for people at risk from cardiovascular disease. | statins |
| What do statins do? | they reduce cholestrol levels which slows down the rate at whch fatty material is deposited in the coronary arteries |
| Question | Answer |
|---|---|
| What can go wrong with heart valves? | they can start to leak, or become stiff not opening properly |
| What is the main cause for heart valves going wrong? | they have to withstand a lot of pressure |
| Name some of the symptons of leaky heart valves. | breathless and without treatment, death |
| What can be done about a leaky heart valve? | doctors can operate and replace the faulty valve with a mechanical or biological replacement valve |
| What are mechanical valves made from? | materials such as titanium and polymers |
| What is the main advantage of mechanical valves? | they last for a very long time |
| What is the main disadvantage of mechanical valves? | the patient needs to take medication for life to prevent blood from clotting around the valve |
| Where do biological valves come from? | they are based on valves taken from animals such as pigs and cattle, or even human donors |
| What is the advantages of biological valves? | the work extremely well and the patient does not need to take medication for the valve |
| What is the disadvantage of biological valves? | they only last 12 to 15 years |
| What is the resting rate of a healthy heart? | around 70 beats per minute |
| What controls the beating of the heart? | a group of cells (a natural pacemaker) in the right atrium of the heart that keeps the heart beating regularly |
| What happens if the natural pacemaker stops working properly? | the heart will beat too fast or too slow |
| What happens if the heart beats too slowly? | the person will not get enough oxygen |
| What happens if the heart beats too fast? | it will struggle to pump blood properly |
| How can problems with the rhythym of the heart be solved? | using an artificial pacemaker |
| What is an artifical pacemaker? | an electrical device implanted in the chest to correct irregularities in the heart rhythym |
| What is the mass of an artificial pacemaker? | between 20g and 50g |
| How is an artifical pacemaker attached to the heart? | it is attached to the heart by two wires |
| What does an artificial pacemaker do? | it sends strong, regular signals to the heart to stimulate it to beat regularly |
| What developments have occurred with modern pacemakers? |
• some only work when the natural rhythym goes wrong • some make the heart beat faster during exercise |
| What follow up action is required once a pacemaker has been fitted? | the patient must have regular check-ups for life to ensure that the pacemaker is working correctly |
| What is the best option when a patient's heart fails and not just the beating rhythm? | a heart transplant from a donor |
| What is the main medical requirement for a heart transplant? | the heart must be a tissue match |
| What is the biggest problem currently faced by people needing a heart transplant? | there are not enough donor hearts available, let alone ones which are a tissue match |
| What is the consequence of there being insufficient donor hearts? | many people die waiting for a donor heart |
| What can be done for a patient whose heart fails while waiting for a donor heart? | an artificial heart can be fitted |
| Why are artificial hearts not used for longterm heart transplants? |
• artificial hearts require a lot of machinery to keep them working • many patients with artificial hearts have to stay in hospital • artificial hearts have a limited life span |
| How does the medical profession use artificial hearts? | an artificial heart can be used to support or replace a failing heart until a transplant becomes available |
| What is the main risk with an artificial heart? | blood clotting leading to death |
| What can an artificial heart be used to do other than supporting a patient waiting for a donor heart? | it can be used to give a diseased heart a rest and time to recover |
| How does an artifical heart give the heart a rest? | it removes the strain of keeping the blood circulating for a few weeks or months |
| Why are artificial hearts not widely available yet? |
• the resources needed to develop artificial hearts • the cost of an artificial heart |
| Question | Answer |
|---|---|
| What is needed for the a gas exchange system to work efficiently? | a steep concentration gradient |
| What does it mean to have a steep concentration gradient in an exchange system? | a large difference in concentration of the gas on either side of the exchange membrane |
| Why do animals move air in and out of the lungs? | by constantly changing the air in the lungs, a steep concentration gradient of oxygen diffusing into the blood and carbon dioxide out of the blood is maintained in the lungs |
| What is the scientific term for breathing? | ventilation |
| Where are the lungs found? | in the thorax (chest) |
| What does the ribcage do for the lungs? | it protects the lungs |
| What separates the lungs from the digestive organs in the abdomen? | the diaphragm |
| What is the diaphragm? | a strong sheet of muscle that helps with ventilation |
| What is the job of the ventilation system? | to move air in and out of the lungs for gas exchange |
| What is the job of the lungs? | to provide an efficient surface for gas exchange spefically for oxygen and carbon dioxide |
| What are the two phases of ventilation? |
• inhalation - air is drawn into the lungs • exhalation - air is forced out the lungs |
| Describe the process of inhalation. |
• the ribs move up and out • the diaphragm flattens • the volume of the chest increases • air pressure in the lungs reduces • air is drawn in because outside is at a higher pressure |
| Describe the process of exhalation. |
• the ribs move down and in • the diaphragm relaxes and curves upwards • the volume of the chest decreases • air pressure in the lungs increases • air is forced out because outside is at a lower pressure |
| What moves the ribs during ventilation? | the intercostal muscles |
| What causes air to be forced in and out of the lungs? | differences in pressure between inside the lungs and the atmosphere |
| Sketch and label the gas exchange system. |
|
| Name the components of the gas exchange system. |
• nose • mouth • trachea • bronchi (a bronchus) • bronchioles • lungs • alveoli (an alveolus) • ribcage • intercostal muscles • diaphragm |
| Why must air be drawn into the lungs constantly? |
• breathing in draws oxygen-rich air into the lungs • this creates a steep concentration of oxygen with the blood • oxygen diffuses from the alveoli into the blood continuously |
| Why must air be expelled from the lungs constantly? |
• breathing out expels carbon dioxide-rich air from the lungs • this creates a steep concentration of carbon dioxide with the blood • carbon dioxide diffuses from blood into the alveoli continuously |
| What are the lungs made up of? | clusters of alveoli connected by bronchioles |
| How are the lungs adapted for efficient gas exchange? |
• the many alveoli together provide a large surface area for gas exchange • the alveoli walls are only one cell thick to provide as short a distance as possible for diffusion • the large number of capillaries ensure a rich supply of blood to maintain a high concentration gradient |
| What is the gas content of the blood reaching the lungs? | it is always relatively low in oxygen and high in carbon dioxide |
| Describe in detail what happens in the lungs in respect to oxygen. |
• inhalation moves air containing oxygen into the alveoli • the air that enters is high in oxygen by comparison to the blood • a steep concentration gradient between the air in the alveoli and the blood in the capillaries is set up for oxygen • oxygen diffuses down the concentration gradient from the alveoli into the blood • the oxygenated blood is quickly removed from the alveoli to maintain the concentration gradient |
| Describe in detail what happens in the lungs in respect of carbon dioxide. |
• blood high in carbon dioxide is delivered to the alveoli • the air in the lungs is low in carbon dioxide by comparison to the blood • a steep concentration gradient between the air in the alveoli and the blood in the capillaries is set up for carbon dioxide • carbon dioxide diffuses down the concentration gradient from the blood into the alveoli • exhalation expels the carbon dioxide from the lungs |
| What is the advantage of having thousands of alveoli? | the many alveoli together provide a large surface area for gas exchange |
| What is the benefit of the walls of alveoli being one cell thick? | diffusion is slow and a thin wall enables it to take place as quickly as possible |
| Why are the capillaries needed by the alveoli? |
• to receive and remove oxygen quickly to maintain a high concentration gradient from the lungs to the blood • to deliver carbon dioxide continuously to the alveoli for removal by exhalation |
| Sketch a diagram showing the exchange of gases in an alveolus. |
|
| Question | Answer |
|---|---|
| What is an elephant yam? |
a plant that produces a large flower that releases a smell like rotting meat to attract carrion beetles
|
| What happens to the beetles when they land on the flower of the elephant yam? |
• the beetles are trapped in the flower by the slippery, waxy walls • the flower releases pollen 24 hours after it begins to smell • the beetles are coated in the pollen • the walls of the flower become rough • the beetles crawl out the flower • a second flower releases its rotting meat smell attracting the carion beetles • the pollen from the first flower is rubbed off onto the walls of the second flower pollinating it |
| Is a flower as tissue, plant organ, or plant system | a plant organ |
| What is the role of the flower in plants? | for reproduction |
| Name four organs in plants. |
• leaves • roots • stem • flowers |
| What is the function of the leaf? | to carry out photosynthesis |
| What is the function of the stem? | to support leaves and flowers |
| What is the function of the roots? | to take up water and minerals from the soil |
| List five plant tissues. |
• epidermal tissue • palisade mesophyll tissue • spongy mesophyll tissue • xylem • phloem |
| What is the function of epidermal tissue? |
• covers surfaces • provides protection • often secretes a waxy substance that waterproofs the surface |
| What is the function of palisade mesophyll tissue? | contains lots of chlorophyl to carry out photosynthesis |
| What is the function of spongy mesophyll tissue? |
• contains some chlorophyl so carries some photosynthesis • has big air spaces and a large surface area to make the diffusion of gases easier |
| Describe the function of xylem. | a transport tissue that carries water and dissolved mineral ions from the roots up to the leaves |
| Describe the function of phloem. | a transport tissue that carries disolved food around the plant |
| Where is meristem tissue found? | at the growing tips of roots and shoots |
| What is the role of meristem tissue? | it is made up of rapidly dividing plants ells that grow and differentiate into all the other cell types needed |
| List the tissues in the leaf. |
• upper epidermis • pallisade mesophyll • ploem • xylem • spongy mesophyll • lower epidermis |
| What allows gases to move in and out of the leaf? | the stomata |
| How do the stomata control the amount of gas moving in and out of the leaf? | by opening and closing the guard cells |
| Which organs contain xylem and phloem? | the leaves, stem, and roots |
| Name a plant organ system. | the whole body of the plant including the roots, the stem, and the leaves |
| Name a function of the plant organ system the body of the plant. | the transport of substances around the plant |
| What are the oldest and largest land organisms? | trees |
| Question | Answer |
|---|---|
| What do plants make during photosynthesis? | glucose |
| Where does photosynthesis take place? | in the leaves and other green parts of the plant |
| How do plants get water and mineral ions? | from the soil through the roots |
| How many transport systems does a plant have? | two |
| Name the two transport tissues in plants. | phloem and xylem |
| What does phloem tissue do? | it transports the sugars made by photosynthesis from the leaves to the rest of the plant |
| How do the growing areas of the stems and the roots get the sugars they need? | via the phloem |
| Why do the growing areas of the stems and the roots need sugars? | for building new plant cells |
| How is food transported to the storage organs? | via the phloem |
| Why do plants store food? | it provides an energy store for winter |
| Is phloem tissue live or dead? | phloem cells are alive so it is living tissue |
| What is the movement of sugars from the leaves to the rest of the plant called? | translocation |
| Name a pest that attack the phloem. | aphids like greenfly |
| How do aphids attack the plant? | they push their sharp mouthparts into the phloem and feed on the sugary liquid contents |
| What is the impact of aphids are a plant? | if too many attack a plant, they can damage even kill it |
| What does the xylem tissue do? | it carries water and mineral ions from the soil to the stem and the leaves |
| Is xylem tissue live or dead? | xylem cells start out live but die to create xylem tissue |
| In woody plants like trees, where is the xylem and the phloem | the xylem makes up the bulk of the wood and the phloem is found in a ring just underneath the bark |
| Why are young trees vulnerable to animals like deer? | if an entire ring of bark is eaten, transport in the phloem will stop and the plant will die |
| How are young trees protected in managed forests? | they have protective collars |
| Are sugars important to the plant? | they are vital for the survival and growth of the plant |
| Why do cells need sugars? | for respiration and growth |
| Why do cells need mineral ions? | for the production of other substances like proteins |
| Why does a plant need water? |
• for photosynthesis when it combines water and carbon dioxide to make glucose • to hold the plant upright |
| How does water keep the plant upright? |
• when a plant cell is full of water, the vacuole presses the cytoplasm against the cell walls • the pressure of the cystoplasm against the cell walls provides supportfor the plants |
| Question | Answer |
|---|---|
| How does air enter the leaf? | via the stomata |
| What are the stomata? | they are holes in the leaf |
| Can a plant control the amount of water leaving the leaf? | yes, by opening a closing the stomata |
| How are the stomata opened and closed? | by manipulating the guard cells |
| How do the leaves acquire carbon dioxide? | carbon dioxide from the atmosphere enters the leaf into the air spaces through the stomata, then diffuses down a concentration gradient into the cells of the leaf |
| How is oxygen produced during photosynthesis removed from the leaf? | oxygen diffuses from leaf cells into the air spaces in the leaf and then diffuses out the leaf through the stomata |
| How is water lost by a plant? | the water evaporates from the cells lining the air spaces and then passes out the leaf via the stomata |
| What is the loss of water via the leaves called? | transpiration |
| What happens when water is lost from the leaves via the stomata? | water is pulled up from the roots through the xylem to the leaves to replace the lost water |
| What is the water pulled up from the roots to the leaves through the xylem called? | the transpiration stream |
| What drives the transpiration stream? | the evaporation of water through the leaves |
| Question | Answer |
|---|---|
| List 4 factors that affect the rate of transpiration. |
• temperature • humidity • light intensity • air flow |
| Is there a link between factors affecting the rate of photosynthesis and transpiration? | Anything that increases the rate of photosynthesis will increase the rate of transpiration |
| Why does photosynthesis affect the rate of transpiration? | when the rate of photosynthesis increases, it opens the stomata more to let in more carbon dioxide and this allows more water to escape the leaf |
| What is the effect of light intensity on transpiration? | an increase in light intensity causes an increase in photosynthesis and thus an increase in transpiration |
| How do hot conditions affect transpiration? | more water evaporates and diffusion happens quicker thus increasing the rate of transpiration |
| How do dry conditions affect transpiration? | water vapour diffuses more rapidly into dry air than humid because the concentration gradient is steeper and thus increases the rate of transpiration |
| How do windy conditions affect transpiration? | windy conditions maintain a high concentration gradient by moving water vapour rapdily as it evaporates thus increase the rate of transpiration |
| How does temperature affect the rate of transpiration? |
an increase in temperature, increases the rate of transpiration for two individual reasons • as temperature increases, the molecules move faster so diffusion speeds up • as temperature increases, photosynthesis speeds up so the stomata open more to allow in more carbon dioxide |
| Name two adaptations that help to reduce transpiration while photosynthesis takes place. |
• a waxy cuticle on the top of the leaf • stomata on the underside of the leaf |
| How does the waxy cuticle reduce transpiration? |
• the waxy cuticle is waterproof preventing water from evaporating from the leaf • the waxy cuticle is on the top of the leaf where the light strikes heating water in the leaf |
| How does stomata on the underside of the leaf reduce transpiration? | the underside of the leaf is not exposed to direct sunlight |
| What happens if the plant loses water faster than it is replaced by the roots? |
• the plant may wilt • the stomata close |
| What happens when a plant wilts? | the leaves collapse and hang down reducing the surface area from which water can evaporate |
| What is the effect of closing stomata? |
• water is prevented from escaping from the leaf via the stomata • photosynthesis slows down as the supply of carbon dioxide is shut off • the plant may overheat as evaporation enables the plant to get rid of excess heat |
| When the plant no longer wilt? | until it rains, night falls, or the temperature drops, the plant will remain wilted |
| What equipment is used to investigate the rate of transpiration? | a potometer |
| What does a potometer do? | it can be used to show how the update of water in a plant changes in different conditions |
| How much of the water taken up by a plant is lost through transpiration? | almost all the water taken up by a plant is lost through transpiration |
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