Breathing and Gas exchange Flashcards
What is respiration?
Process of releasing energy from the breakdown of glucose
Describe the differences between aerobic and anaerobic respiration
Aerobic: Respiration with oxygen, it’s the most efficient way to release energy from glucose.
Anaerobic: without oxygen. It’s less efficient because it releases much less energy, glucose is only partially broken down and lactic acid is produced. Only used when your body can’t supply enough oxygen to your muscles for aerobic respiration.
Write the word equation and the balanced chemical symbol equation for aerobic respiration in living organisms
Glucose + Oxygen –> Carbon Dioxide + Water
C6,H12,O6 + O2 –> 6CO2 + 6H20
Write the word equation for anaerobic respiration in plants and in animals
Animals: Glucose —> Lactic Acid
Plants: Glucose —> Ethanol + Carbon Dioxide
Describe experiments to investigate the evolution of carbon dioxide and heat from respiring seeds or other suitable living organisms.
- Number of germinating seeds placed in test tube.
- A rubber bung is used to seal the test tube.
- Use a retort stand to hold test tube in place.
- An angled glass tube is connected to the rubber bung.
- Half fill the second test tube with hydrogen carbonate.
- Use a retort stand to hold the second test tube in place. 7. Ensure that the glass tube is immersed in the hydrogen carbonate indicator.
- After a several hours, observe and record the colour changes. (Yellow = increased CO2 conc. | Purple = decreased CO2 conc.
- Wrap test tube with an insulating material (vacuum flask).
- Use a rubber bung to seal the test tube.
- Attach a thermometer in the hole of the rubber bung to measure temperature change in test tube.
Describe gas exchange (of carbon dioxide and oxygen) in relation to respiration and photosynthesis
While plants photosynthesise, they use lots of CO2 (which means that there’s hardly CO2 left in the leaf) so more CO2 moves into the leaf by diffusion. At the same time O2 is made as a waste product of photosynthesis, and is sometimes used in respiration. The rest diffuses out through the stomata.
How does the net exchange of carbon dioxide and oxygen depends on the intensity of light?
During the day, plants make more oxygen by photosynthesis than they use in respiration. So in daylight, they release Oxygen. They also use up more Carbon Dioxide than they produce, so they take in Carbon Dioxide.
At night, plants only respire because there isn’t enough light for photosynthesis. This means they teak in Oxygen and release Carbon Dioxide.
Explain how the structure of the leaf is adapted for gas exchange
Upper and Lower Epidermis is covered by the cuticle. This reduces water loss by evaporation and acts as a barrier to pathogens.
Stomata allows CO2 to diffuse into the leaf to reach the photosynthetic tissues. They also allow Oxygen and water vapour to diffuse out. Guards cells alter their shape to open or close the stomata.
Palisade layer contains hundreds of chloroplasts and is the main site of photosynthesis. Palisade cells are close to the source of light and upper epidermis is transparent allowing light to pass through to the chloroplasts.
Spongy layer is the main site of gas exchange. it absorbs CO2 and releases O2 and water vapour. Air spaces allow gases to diffuse in and out of he mesophyll.
Xylem supplies water and mineral ions to the leaf. Water is absorbed by the roots and passes up through the stem and through the veins in the leaves in the transpiration stream.
Describe experiments to investigate the effect of light on net gas exchange from a leaf, using hydrogen-carbonate indicator
10cm3 of the indicator solution is places in the bottom of each of four boiling tubes. Three larges leaves are detached from a suitable plant and placed in the tips of three of the tubes. Each tube is sealed with a bung.
One tube is placed in bright light, one in the dark with silver foil and the third covered in translucent material to restrict the intensity of light reaching the leaf. Fourth tube without a leaf acts as a control.
Light - purple
Dark - Yellow
Dim - Orange
Control - Orange
Describe the structure of the thorax, including the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes
Thorax: Top part of the body, from the neck to the abdomen.
Ribcage: Protects the lungs.
Intercostal muscles: In between the ribs, which help the lungs ventilate by changing the volume of the ribcage.
Diaphragm: Separates the lungs from the abdomen, and moves up and down while ventilating.
Pleural membranes: Allows the lungs to move easily during ventilation.
Once air is breathed in from the mouth or nose, it travels down the trachea, then splits up and goes down a left and right bronchus. This further splits up to form bronchioles and then alveoli (which are tiny air sacs, where gas exchange happens).
What is the role of the intercostal muscles and the diaphragm in ventilation?
Breathing in: External intercostal muscles contract, pulling ribs up. Muscles of diaphragm contract, pulling it down into a flattened shape. Volume of chest increases and pressure decreases
Breathing Out: External intercostal muscles relax, internal intercostal muscles contract, pull the ribs down and in. Muscles of diaphragm relax, it goes back to normal dome shape. Volume of thorax decreases, pressure raised slightly above atmospheric pressure. Exhalation is helped by the facts that the lungs are elastic.
Explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries
Blood from the heart to the lungs passes through the capillaries surrounding the alveoli. Blood has come from respiring tissues so contains a lot fo CO2 and little O2. Around the lungs, the blood is separated from the air inside each alveolus by only two layers: cells of alveolus wall and capillary wall.
Because air in alveolus has a higher concentration of oxygen than the blood, oxygen diffuse into the blood and CO2 diffuse into the alveolus.
Alveoli gives lungs enormous Surface area
Moist lining for gases to dissolve in
Thin and permeable walls so gases don’t have to diffuse far and easily
Great blood supply to maintain high concentration gradient
What are the biological consequences of smoking?
Tar destroys cilia. Reduced numbers of cilia means that the mucus is not swept away from the lungs but remains to clog the airways. Smoke irritates the lining of the airways, stimulating the cells to secrete more mucus. Clogging of the mucus is the source of smokers cough. Irritation of the bronchial tree, along with infections from bacteria in the mucus can cause bronchitis which blocks normal air flow.
Smoke damages the walls of the alveoli which break down and fuse together again, forming irregular air sacs. This greatly reduces the surface area for gas exchange, which becomes very inefficient. Blood therefore carries less oxygen.
Carbon Monoxide can combine with haemoglobin more tightly than oxygen can, forming carboxyhaemoglobin. Haemoglobin combines with CO in preference to oxygen. Therefore the blood carries much less oxygen around the body. CO is a major cause of heart disease.
Describe experiments to investigate the effect of exercise on breathing in humans
- Sit still for 5 minutes; for 1 minute, count the number of breaths you take
- Do 5 mins. of exercise and then count your breaths for a min.
- Repeat with two other people
The more exercise you do, the more your breathing rate increases: muscles respire more, as they need more oxygen in the body and more carbon dioxide removed
