Respiration & Gas Exchange Flashcards
What is respiration?
Respiration is a chemical reaction carried out in all living organisms where energy is released from glucose.
What are the two types of respiration?
Aerobic respiration (with oxygen) and anaerobic respiration (without oxygen).
What are the waste products of aerobic respiration?
Carbon dioxide and water.
What is ATP, and what is its role in respiration?
ATP (Adenosine Triphosphate) is a molecule that stores and transfers energy for cellular activities.
During the process of cellular respiration, glucose is broken down and several molecules of ATP are produced.
List three processes that require ATP energy.
- Growth: Cell division and growth
- Movement: Muscle contraction / movement
- Temperature: Maintaining constant body temperature.
- Protein synthesis / making large molecules from small ones
- Chemical reactions / breaking down/digesting large molecules to small ones
- Active Transport
- Nerve: Passage of Nerve impulses
What is the word equation for aerobic respiration?
Glucose + Oxygen → Carbon Dioxide + Water (+ Energy in form of ATP)
What is the balanced chemical equation for aerobic respiration?
C6H12O6 + 6O2 → 6CO2 + 6H2O
(Ratio 1 + 6 → 6 + 6)
Where does aerobic respiration occur?
In the mitochondria of cells.
What is anaerobic respiration?
A chemical reaction in cells that releases energy without using oxygen.
Where does anaerobic respiration occur?
In the cytoplasm of the cell.
Why does anaerobic respiration release less energy than aerobic respiration?
Because glucose is not fully broken down in anaerobic respiration.
In aerobic respiration, there is complete breakdown of glucose that releases a relatively large amount of energy.
What is the word equation for anaerobic respiration in animals?
Glucose → Lactic Acid + Energy (ATP)
When does anaerobic respiration take place in animals?
Due to the higher demand for energy (e.g., during vigorous exercise), the body cannot deliver sufficient oxygen to muscle cells for aerobic respiration.
Explain what happens due to the inability to supply sufficient oxygen during respiration (e.g., when exercising vigorously).
- When the oxygen supply does not meet the demand, glucose is only partly broken down and lactic acid is produced.
- This means only a relatively small amount of energy is released (in other words, anaerobic releases less energy than aerobic respiration).
What is oxygen debt?
The extra oxygen that is needed to break down the lactic acid formed following anaerobic respiration (e.g., caused by vigorous exercise) and replace the body’s reserves of oxygen.
How is lactic acid broken down after exercise?
Lactic acid is taken to the liver by the blood, and either:
• oxidised to carbon dioxide and water, or
• converted to glucose, then glycogen - glycogen levels in the liver and muscles can then be restored. These processes require oxygen.
This is why, when the period of activity is over, a person’s breathing rate and heart rate do not return to normal straightaway.
What are the effects of lactic acid buildup?
- Lowers pH, making conditions more acidic.
- Can denature enzymes.
What is the word equation for anaerobic respiration in plants and yeast?
Glucose → Ethanol + Carbon Dioxide (+ Energy in form of ATP)
What is fermentation, and why is it economically important?
- Fermentation is anaerobic respiration in yeast.
- Used in bread making (CO2 helps dough rise).
- Used in brewing (ethanol makes beer).
How do aerobic and anaerobic respiration compare in oxygen use, energy release, and waste products?
Aerobic:
1. Uses oxygen (breakdown of glucose complete)
2. Releases more energy
3. Produces CO2 + H2O.
Anaerobic:
1. Doesn’t use oxygen (breakdown of glucose incomplete)
2. Releases less energy
3. Produces lactic acid (animals) OR ethanol + CO2 (plants/yeast).
Aerobic - occurs in Mitochondria
Anaerobic - occurs in Cytoplasm
What are two practical methods for investigating respiration?
- Measuring carbon dioxide production.
- Measuring heat production.
What apparatus is used to investigate CO2 production in respiration?
Boiling tubes, rubber bungs, cotton wool, hydrogen carbonate indicator, germinating seeds, boiled/dead seeds, and glass beads.
What does hydrogen carbonate indicator show in respiration experiments?
- Red = normal Atmospheric CO2 levels (0.04%).
- Yellow = high CO2 levels (more respiration).
- Purple = low CO2 levels (less respiration).
What substance can be used to remove carbon dioxide?
Soda lime.
What are the expected color results in the CO2 experiment?
- Tube A (germinating seeds) = yellow. respiring
- Tube B (boiled seeds) = red. - dead
- Tube C (glass beads) = red. - not living.
What apparatus is used to investigate heat production in respiration?
Vacuum flasks, thermometers, cotton wool, germinating seeds, and dead/boiled seeds.
What results indicate respiration produces heat?
- The temperature in Flask B (germinating seeds) rises.
- Flask A (dead seeds) remains at room temperature.
Why does the temperature increase in germinating seed flasks?
Because respiration is an exothermic reaction, releasing heat energy.
What is the CORMS evaluation framework for CO2 investigation?
Change: I.V. : Change contents - germinating seeds, dead seeds etc.
Organisms: Seeds: same species, age, and size.
Repeat: repeat investigation to ensure results reliable.
Measurement 1: Observe change in hydrogen carbonate indicator.
Measurement 2: …after 3 hours.
Same: - volume of HCO3- indicator, - number of seeds, - temperature of environment.
What is the CORMS evaluation framework for Heat investigation?
Change: I.V. : Change contents - germinating seeds, dead seeds etc.
Organisms: Seeds: same species, age, and size.
Repeat: repeat investigation to ensure results reliable.
Measurement 1: Observe change in the temperature.
Measurement 2: …after 4 days.
Same: - number of seeds, - starting temperature of the flasks, - material and size of flasks.
What are the controlled variables in respiration experiments?
- Volume of indicator.
- Number of seeds/beads.
- Temperature.
- Flask material.
What is the thorax?
The thorax is the human chest cavity that houses the lungs and structures involved in breathing.
Name the key structures of the breathing system.
- Ribs - Protect the lungs and provide structure.
- Intercostal muscles - Help with breathing by moving the ribs.
- Diaphragm - A muscle that contracts and relaxes to help ventilation.
- Trachea - The windpipe that carries air to the lungs.
- Bronchi - Two branches that lead from the trachea into each lung.
- Bronchioles - Smaller airways branching from the bronchi.
- Alveoli - Tiny air sacs where gas exchange occurs.
- Pleural membranes - Surround the lungs and reduce friction during breathing.
What is the function of the lungs?
The lungs act as the gas exchange surface in humans, allowing oxygen to enter the blood and carbon dioxide to be removed.
What are the four key adaptations of gas exchange surfaces?
- Large surface area - Allows more gases to diffuse at once.
- Thin walls - Short diffusion distance for faster exchange.
- Good ventilation - Maintains a steep concentration gradient.
- Good blood supply - Keeps oxygen and carbon dioxide levels optimal for diffusion.
What other biological structures share these adaptations?
Villi (small intestine) and root hair cells (plants) also have large surface areas, thin walls, and high diffusion rates.
Why do intercostal muscles work in pairs?
Muscles only pull; they cannot push, so two sets of intercostal muscles work antagonistically to facilitate breathing.
What is the role of external intercostal muscles?
They contract to pull the ribs up and out during inhalation.
What is the role of internal intercostal muscles?
They contract to pull the ribs down and in during exhalation.
What is the diaphragm, and what is its role?
The diaphragm is a thin sheet of muscle that separates the thorax from the abdomen and helps with breathing by contracting (causing it to flatten) and relaxing (causing it to revert to dome shape).
What happens during inhalation?
- The diaphragm contracts and flattens.
- The external intercostal muscles contract, pulling the ribs up and out.
- The volume of the thorax increases.
- The pressure inside the lungs decreases.
- Air is drawn into the lungs.
What happens during normal exhalation?
- The diaphragm relaxes and moves back into its domed shape.
- The external intercostal muscles relax, so the ribs drop down and inwards.
- The volume of the thorax decreases.
- The pressure inside the lungs increases.
- Air is forced out of the lungs.
What is forced exhalation?
During strenuous activity, the internal intercostal muscles contract, further decreasing thorax volume and forcing air out more quickly.
Why is forced exhalation necessary?
It helps remove increased levels of carbon dioxide produced during exercise.
What is the difference between inhalation and exhalation?
- Inhalation = Active process (muscles contract).
- Exhalation = Passive process (muscles relax).
What are alveoli?
Alveoli are tiny air sacs in the lungs where gas exchange occurs.
How are alveoli adapted for gas exchange?
- Large surface area.
- Thin walls.
- Good blood supply.
- Ventilation.
- Moist lining.
How does oxygen move into the blood?
Oxygen diffuses from the alveoli into the capillaries, where it binds to haemoglobin in red blood cells.
How does carbon dioxide leave the blood?
Carbon dioxide diffuses from the blood plasma into the alveoli to be exhaled.
How does smoking affect the lungs?
EFFECTS OF SMOKING (ATTCC)
1. Smoking damages the walls inside the alveoli, reducing the surface area for gas exchange and leading to diseases like emphysema.
2. The tar in cigarettes damages the cilia. Cilia together with mucus catch a lot of dust and bacteria and help to keep the trachea clear. When they’re damaged, chest infections are more likely.
3. Tar also irritates the bronchi and bronchioles causing smokers cough and chronic bronchitis.
4. The carbon monoxide in cigarette smoke reduces the amount of oxygen the blood can carry; to make up for this, heart rate increases which could lead to an increase in blood pressure and increases the risk of coronary heart disease.
5. Tobacco smoke also contains carcinogens - chemicals that can lead to (lung) cancer.
What is the effect of nicotine on the body?
- Increases heart rate & blood pressure.
- Narrows blood vessels, increasing the risk of blood clots.
What is the effect of carbon monoxide?
- Binds irreversibly to haemoglobin, reducing oxygen transport.
- Causes increased breathing & heart rate to compensate.
What is the effect of tar?
- Carcinogenic, increasing the risk of lung cancer.
- Damages cilia, leading to mucus buildup and infections (chronic bronchitis).
Why does breathing rate increase during and after exercise?
Frequency of breathing increases when exercising because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with the energy demand.
If they cannot meet the energy demand, they will also respire anaerobically, producing lactic acid.
Why does breathing rate remain elevated after exercise?
After exercise has finished, the breathing rate remains elevated for a period of time because the lactic acid that has built up in muscles needs to be removed as it lowers the pH of cells and can denature enzymes catalysing cell reactions.
It can only be removed by combining it with oxygen - this is known as ‘repaying the oxygen debt.’
