BIOLOGY · Stage 8 · Chapter 5: Respiration and the Respiratory System
Biology 5.12 Chapter 5 Review: Respiration and Gas Exchange
5 min read 5 parts Lesson 12 of 12
Lesson summary
Biology 5.12 Chapter 5 Review: Respiration and Gas Exchange — Alhussan International Academy — Biology (Stages 7–9) notes: Summarise the key ideas of chapter 5: diffusion, aerobic and anaerobic respiration, breathing, gas exchange, asthma, blood and adaptations to extreme conditi…
- Oxygen debt
- Mitochondria
- Chloroplasts
- Structures
- Bell jar model
- Breathing and respiration
Section 1 of 5Diffusion and respiration
- Diffusion
- the net movement of particles in a liquid or gas down a concentration gradient, from high to low concentration, with no energy needed.
- Aerobic respiration
- it releases energy from glucose in a controlled way using oxygen, in the mitochondria of animal and plant cells.
- glucose + oxygen → carbon dioxide + water (+ energy).
- Anaerobic respiration
- it releases less energy from glucose without oxygen.
- In muscle: glucose → lactic acid (+ energy).
- In yeast: glucose → ethanol + carbon dioxide (+ energy).
- Oxygen debt
- extra oxygen after exercise breaks down lactic acid.
- Mitochondria
- cells that use a lot of energy, such as muscle cells, have many, and cells with few mitochondria are not very active.
- Chloroplasts
- they are found only in the green cells of plants,
- so a plant cell can have both chloroplasts and mitochondria,
- while an animal cell has only mitochondria.
Section 2 of 5Breathing and gas exchange
- Airway
- air passes through the nose and mouth, trachea, bronchi, bronchioles and alveoli.
- Structures
- rings of cartilage hold the trachea open, cilia and mucus clean the airways, and the pleura let the lungs slide as they change size.
- Inhaling
- the diaphragm and intercostal muscles contract, the chest volume increases and the pressure falls, so air flows in.
- Exhaling
- the muscles relax, the volume decreases and the pressure rises, so air flows out.
- Bell jar model
- the jar is the chest, the rubber sheet the diaphragm and the balloons the lungs, but it has limitations such as no ribs or alveoli.
- Alveoli
- they have a large surface area, thin walls and a rich blood supply for fast diffusion,
- and oxygen and carbon dioxide diffuse down concentration gradients between air and blood.
- they have a large surface area, thin walls and a rich blood supply for fast diffusion,
- Breathing and respiration
- breathing moves air, while respiration is the chemical release of energy in cells.
Section 3 of 5Exercise and the respiratory system
- Exercise
- breathing rate rises because muscles produce more carbon dioxide and need more oxygen, and the heart rate rises too.
- Mean breathing rate
- the sum of the readings divided by the number of readings, found separately for rest and exercise.
- Graph
- students go on the horizontal axis and breaths per minute on the vertical axis, with a bar for rest and a bar for exercise.
- Reliability
- repeating readings and using class data makes the results more reliable.
Section 4 of 5Blood
- Components
- plasma, red blood cells, white blood cells and platelets.
- Plasma
- it transports dissolved food, carbon dioxide, urea, hormones and heat.
- Red blood cells
- they carry oxygen using haemoglobin, and have no nucleus.
- White blood cells
- they defend against pathogens, by engulfing them or making antibodies.
- Platelets
- they help the blood to clot.
Section 5 of 5Conditions and adaptations
- Asthma
- the airways narrow, as muscles contract and the lining swells and makes extra mucus.
- Relievers relax the muscles around the airways, and preventers reduce inflammation and swelling.
- High altitude
- people make more red blood cells, and people born at altitude have larger chests, more small airways and alveoli, and extra capillaries.
- Whales
- they survive long dives with apnea, bradycardia, capillary shutdown and myoglobin stores.
Last updated: