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5.12Chapter 5: Respiration and the Respiratory System

Chapter 5 Review: Respiration and Gas Exchange — Alhussan Biology - Stage 8 Revision Notes & Topical Questions

5 min read 7 parts Lesson 12 of 12 1 quiz

📚 Alhussan Biology - Stage 8 Hub / Topical Revision
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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

Part 1 of 5Diffusion and respiration

Diffusion
  • 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
  • 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
  • Anaerobic respiration it releases less energy from glucose without oxygen.
  • In muscleglucose → lactic acid (+ energy).
  • In yeastglucose → ethanol + carbon dioxide (+ energy).
Oxygen debt
  • Oxygen debt extra oxygen after exercise breaks down lactic acid.
Mitochondria
  • Mitochondria cells that use a lot of energy, such as muscle cells, have many, and cells with few mitochondria are not very active.
Chloroplasts
  • 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.

Part 2 of 5Breathing and gas exchange

Breathing and gas exchange
Airway
  • Airway air passes through the nose and mouth, trachea, bronchi, bronchioles and alveoli.
Structures
  • 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
  • Inhaling the diaphragm and intercostal muscles contract, the chest volume increases and the pressure falls, so air flows in.
Exhaling
  • Exhaling the muscles relax, the volume decreases and the pressure rises, so air flows out.
Bell jar model
  • 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
  • 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.
Breathing and respiration
  • Breathing and respiration breathing moves air, while respiration is the chemical release of energy in cells.

Part 3 of 5Exercise and the respiratory system

Exercise and the respiratory system
Exercise
  • Exercise breathing rate rises because muscles produce more carbon dioxide and need more oxygen, and the heart rate rises too.
Mean breathing rate
  • Mean breathing rate the sum of the readings divided by the number of readings, found separately for rest and exercise.
Graph
  • 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
  • Reliability repeating readings and using class data makes the results more reliable.

Part 4 of 5Blood

Blood
Components
  • Components plasma, red blood cells, white blood cells and platelets.
Plasma
  • Plasma it transports dissolved food, carbon dioxide, urea, hormones and heat.
Red blood cells
  • Red blood cells they carry oxygen using haemoglobin, and have no nucleus.
White blood cells
  • White blood cells they defend against pathogens, by engulfing them or making antibodies.
Platelets
  • Platelets they help the blood to clot.

Part 5 of 5Conditions and adaptations

Asthma
  • 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
  • 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
  • Whales they survive long dives with apnea, bradycardia, capillary shutdown and myoglobin stores.

Key terms

TermMeaning
DiffusionThe net movement of particles down a concentration gradient.
Aerobic respirationThe release of energy from glucose using oxygen.
Anaerobic respirationThe release of energy from glucose without oxygen.
AlveolusA tiny air sac where gas exchange occurs.
PlasmaThe liquid part of blood.
MeanThe average of a set of values.

Avoid these mistakes

1
Plotting the independent variable on the wrong axis — put the students or conditions on the horizontal axis.
2
Forgetting to divide by the number of values when finding a mean — divide the sum by the count.
3
Saying plant cells have chloroplasts instead of mitochondria — they have both.
4
Confusing respiration with breathing — respiration is a chemical reaction in cells.

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