Method
- Sit as still as possible for 5 minutes
- Time 1 minute and count the number of breaths you take
- Do 5 minutes of exercise
- Immediately after, time 1 minute and count the number of breaths you take
- Repeat experiment 3 times to ensure an accurate result (and remove any anomalies).
Conclusion
If all goes well, your results should show that exercise increases heart rate (increased breaths = increased heart rate)
NOTE: during the experiment you will need to control all things that could affect your results. E.g level of exercise, time spent exercising, temperature in room/test area, size of person etc
Showing posts with label gas exchange. Show all posts
Showing posts with label gas exchange. Show all posts
Monday, 28 March 2016
2.47 understand the biological consequences of smoking in relation to the lungs and the circulatory system, including coronary heart disease
Smoking can damage the walls of the alveoli which will reduce the surface area of the lungs. This will reduce the surface area for gas exchange and lead to diseases such as emphysema.
Cilia (the hairs that line the trachea and lungs) catch dust and bacteria before they reach the lungs. However, they can be damaged by the tar in cigarettes, which leads to an increased possibility of chest infections (as lots of dust and bacteria can enter).
As well as damaging cilia, tar irritates bronchi and bronchioles. This encourages mucus to be produced which can not be cleared if the cilia is damaged. This leads to smokers cough and chromic bronchitis.
Carbon monoxide in cigarette smoke reduces the amount of oxygen the blood can carry by binding with Haemoglobin. To ensure enough oxygen gets to the cells in your body, the heart rate must increase - this can lead to an increase in blood pressure, which will damage artery walls, this makes blood clots much more likely, increasing the chance of coronary heart disease.
Coronary heart disease is caused by a blockage of the coronary arteries that supply heart muscle with blood. If you have coronary heart disease, glucose and oxygen is not transported to the heart muscle (as there is a blockage), therefore the heart can't keep contracting (as it has no glucose/oxygen, so no energy). This will lead to heart attack.
Tobacco smoke contains carcinogens - these are chemicals that can lead to cancer.
Cilia (the hairs that line the trachea and lungs) catch dust and bacteria before they reach the lungs. However, they can be damaged by the tar in cigarettes, which leads to an increased possibility of chest infections (as lots of dust and bacteria can enter).
As well as damaging cilia, tar irritates bronchi and bronchioles. This encourages mucus to be produced which can not be cleared if the cilia is damaged. This leads to smokers cough and chromic bronchitis.
Carbon monoxide in cigarette smoke reduces the amount of oxygen the blood can carry by binding with Haemoglobin. To ensure enough oxygen gets to the cells in your body, the heart rate must increase - this can lead to an increase in blood pressure, which will damage artery walls, this makes blood clots much more likely, increasing the chance of coronary heart disease.
Coronary heart disease is caused by a blockage of the coronary arteries that supply heart muscle with blood. If you have coronary heart disease, glucose and oxygen is not transported to the heart muscle (as there is a blockage), therefore the heart can't keep contracting (as it has no glucose/oxygen, so no energy). This will lead to heart attack.
Tobacco smoke contains carcinogens - these are chemicals that can lead to cancer.
2.46 explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries
NOTE: we need to know like how alveoli does the gas exchange and stuff but i can't really find it in the spec so I'm just going to put it here in red (if you already know it, skip past the red)
Okay so the lungs contain millions and millions of alveoli. The blood passing next to the alveoli has just returned back to the lungs (from going around the body). This blood contains lots of CO2 and little O2. Oxygen (from the air you've just breathed in) diffuses out the alveolus into the blood (from a high concentration, in the alveolus, to a low concentration, in the blood). CO2 diffuses out of the blood (high concentration) into the alveolus (low concentration) to be breathed out.
How are alveoli specialised for gas exchange...
- Millions of them (gives a really big surface area)
- Moist lining for O2 and CO2 to dissolve in
- The alveoli walls are only 1 cell thick (which is very thin) - meaning the gas doesn't have far to diffuse
- Their walls are permeable - meaning O2 and CO2 can easily diffuse across them
Okay so the lungs contain millions and millions of alveoli. The blood passing next to the alveoli has just returned back to the lungs (from going around the body). This blood contains lots of CO2 and little O2. Oxygen (from the air you've just breathed in) diffuses out the alveolus into the blood (from a high concentration, in the alveolus, to a low concentration, in the blood). CO2 diffuses out of the blood (high concentration) into the alveolus (low concentration) to be breathed out.
How are alveoli specialised for gas exchange...
- Millions of them (gives a really big surface area)
- Moist lining for O2 and CO2 to dissolve in
- The alveoli walls are only 1 cell thick (which is very thin) - meaning the gas doesn't have far to diffuse
- Their walls are permeable - meaning O2 and CO2 can easily diffuse across them
2.45 understand the role of the intercostal muscles and the diaphragm in ventilation
Ventilation is the fancy name for breathing in and out.
Breathing in...
- Intercostal muscles contact (pulling ribcage and sternum 'up and out')
- diaphragm contracts (pulling the thorax 'down')
- Volume of thorax increases
- Pressure inside thorax decreases - this draws air in
Breathing out...
- Intercostal muscles and diaphragm relax
- Thorax volume decreases
- Air is forced out (as the volume decreases and pressure increases)
Breathing in...
- Intercostal muscles contact (pulling ribcage and sternum 'up and out')
- diaphragm contracts (pulling the thorax 'down')
- Volume of thorax increases
- Pressure inside thorax decreases - this draws air in
Breathing out...
- Intercostal muscles and diaphragm relax
- Thorax volume decreases
- Air is forced out (as the volume decreases and pressure increases)
2.44 describe the structure of the thorax, including the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli, and pleural membranes
The thorax is basically just the top part of your body, kind of...
When you breathe in, air goes into the trachea (the trachea is just your windpipe). It splits into two tubes called the bronchi, one bronchus goes into each lung. Cartilage supports the airways and keep them open (for breathing).
The bronchi split into smaller and smaller tubes, known as bronchioles.
The bronchioles end at a 'bag' called alveoli (this is where gas exchange takes place)
Pleural membrane surrounds the lungs, protecting them (along with the ribs. It is a continuous envelope around lungs, forming airtight seal.
The diaphragm separates the thorax from the lower half of the body
Image source: igcse-biology
When you breathe in, air goes into the trachea (the trachea is just your windpipe). It splits into two tubes called the bronchi, one bronchus goes into each lung. Cartilage supports the airways and keep them open (for breathing).
The bronchi split into smaller and smaller tubes, known as bronchioles.
The bronchioles end at a 'bag' called alveoli (this is where gas exchange takes place)
Pleural membrane surrounds the lungs, protecting them (along with the ribs. It is a continuous envelope around lungs, forming airtight seal.
The spaces between the two pleural membranes are called the pleural cavity. The pleural cavity filled with layer of liquid called pleural liquid which lubrication so lungs do not stick onto chest wall during breathing.
Ribs Protect the lungs (they are always the light coloured one and first one)
Intercostal muscles join ribs together. They contract and relax as air moves in and out of the lungs.
Intercostal muscles join ribs together. They contract and relax as air moves in and out of the lungs.
The diaphragm separates the thorax from the lower half of the body
Image source: igcse-biology
2.43 describe experiments to investigate the effect of light on net gas exchange from a leaf, using hydrogen-carbonate indicator
Hydrogen-carbonate indicator changes colour with different levels of CO2. In little CO2, it goes purple, in normal CO2, it's orange and in lots of CO2, it goes yellow. We need to know an experiment to show how light effects gas exchange, heres how its done...
Method
- Add the same volume pf hydrogen-carbonate indicator to four test tubes.
- Put a similar sized (healthy) leaf in 3 of the tubes and seal all four with a bung - trap the leaf stem in the bung to ensure it doesn't fall in the indicator. NOTE: the empty test tube is a control.
- Wrap one tube in aluminium foil (this ensures no light will get to that leaf - meaning photosynthesis can't occur)
- Wrap one tube in gauze (this means it has some light, but not full light - slowing the rate of photosynthesis)
- Place all four tubes in bright light
- Leave tubes for 1 hour
- Record the colour of the indicator
Conclusion
If all went well, there shouldn't be any colour change in the control tube, as no photosynthesis (so no gas exchange) occurred there. In the tube with aluminium foil around it, the hydrogen-carbonate indicator will be dark yellow. This is because it was not able to photosynthesise but respiration still took place, meaning the CO2 level in the tube will increase (as CO2 has been given out by respiration, but not taken in by photosynthesis). There will be no change as a little photosynthesis and respiration have taken place, so the CO2 level won't have changed much. The tube with access to full light will have gone purple. This is because the level of CO2 would have decreased as there will be some respiration, but lots of photosynthesis, meaning lots of CO2 was taken in by the leaf (but not much given out).
Method
- Add the same volume pf hydrogen-carbonate indicator to four test tubes.
- Put a similar sized (healthy) leaf in 3 of the tubes and seal all four with a bung - trap the leaf stem in the bung to ensure it doesn't fall in the indicator. NOTE: the empty test tube is a control.
- Wrap one tube in aluminium foil (this ensures no light will get to that leaf - meaning photosynthesis can't occur)
- Wrap one tube in gauze (this means it has some light, but not full light - slowing the rate of photosynthesis)
- Place all four tubes in bright light
- Leave tubes for 1 hour
- Record the colour of the indicator
Conclusion
If all went well, there shouldn't be any colour change in the control tube, as no photosynthesis (so no gas exchange) occurred there. In the tube with aluminium foil around it, the hydrogen-carbonate indicator will be dark yellow. This is because it was not able to photosynthesise but respiration still took place, meaning the CO2 level in the tube will increase (as CO2 has been given out by respiration, but not taken in by photosynthesis). There will be no change as a little photosynthesis and respiration have taken place, so the CO2 level won't have changed much. The tube with access to full light will have gone purple. This is because the level of CO2 would have decreased as there will be some respiration, but lots of photosynthesis, meaning lots of CO2 was taken in by the leaf (but not much given out).
2.42 describe the role of stomata in gas exchange
Guard cells control the opening and closing of stomata. During daytime (when photosynthesis occurs) stomata are open allowing for CO2 and O2 to enter (by diffusion). At night time, the stomata close. This is because photosynthesis doesn't occur so there is no need to have stomata open all the time (as no CO2 needs to be taken into the leaf). However, during the night stomata may open periodically to allow oxygen to diffuse in for respiration of cells.
2.41 explain how the structure of the leaf is adapted for gas exchange
The leaf is adapted for gas exchange in many ways, here are a few...
- It is thin, meaning gases only have to travel a short distance (to reach the cells where they are needed)
- They are broad, meaning there's a large surface area for diffusion
- Air spaces inside the leaf let CO2 and O2 move easily between cells (they also increase the surface area for gas exchange)
- Stomata let CO2 and O2 diffuse - they also allow water to escape (transpiration)
- Stomata close when its dark as photosynthesis doesn't occur in the dark so there is no need for stomata to let in CO2. When stomata are closed no water can escape - this stops the plant drying out.
NOTE: the opening and closing of stomata is controlled by guard cells
- It is thin, meaning gases only have to travel a short distance (to reach the cells where they are needed)
- They are broad, meaning there's a large surface area for diffusion
- Air spaces inside the leaf let CO2 and O2 move easily between cells (they also increase the surface area for gas exchange)
- Stomata let CO2 and O2 diffuse - they also allow water to escape (transpiration)
- Stomata close when its dark as photosynthesis doesn't occur in the dark so there is no need for stomata to let in CO2. When stomata are closed no water can escape - this stops the plant drying out.
NOTE: the opening and closing of stomata is controlled by guard cells
2.40 understand that respiration continues during the day and night, but that the net exchange of carbon dioxide and oxygen depends on the intensity of light
Photosynthesis happens when light is available (as it takes energy from the light source). However, plants must respire all the time, else they would die. In the day (when light intensity is strong) plants make more O2 from photosynthesis than they use in respiration, so in daytime they release this O2 (by diffusion), they also use up more CO2 than they produce, so they take in CO2 (by diffusion). At nighttime (when light intensity is low) plants only respire. This is because there is not enough light for photosynthesis (this means they take in oxygen and release CO2).
2.39 understand gas exchange (of carbon dioxide and oxygen) in relation to respiration and photosynthesis
During respiration - plants use up oxygen and produce CO2 (as a waste product).
During photosynthesis - plants use up CO2 and produce O2 (as a waste product). As CO2 is being used up, it diffuses from outside the leaf into the leaf.
During photosynthesis - plants use up CO2 and produce O2 (as a waste product). As CO2 is being used up, it diffuses from outside the leaf into the leaf.
2.38 understand the role of diffusion in gas exchange
When plants photosynthesise, they use up CO2 and produce O2. When plants respire, they use up O2 and produce CO2. This means there is a lot of gas exchange in plants, this happens by diffusion.
When a plant is photosynthesising it uses up CO2 (so there is barely any left in the leaf). This causes more CO2 to enter the leaf (by diffusion) - from an area of high concentration (outside the leaf) to an area of low concentration (inside the leaf). At the same time, O2 is being produced (as a waste product of photosynthesis), some of this is used for respiration whilst the rest diffuses out of the leaf (through the stomata) - moving from an area of high concentration (in the leaf) to an area of low concentration (outside the leaf).
When a plant is photosynthesising it uses up CO2 (so there is barely any left in the leaf). This causes more CO2 to enter the leaf (by diffusion) - from an area of high concentration (outside the leaf) to an area of low concentration (inside the leaf). At the same time, O2 is being produced (as a waste product of photosynthesis), some of this is used for respiration whilst the rest diffuses out of the leaf (through the stomata) - moving from an area of high concentration (in the leaf) to an area of low concentration (outside the leaf).
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