iGCSE Biology Section 2 lesson 4

Structures and functions in living organisms Content Section 2 Structures and functions in living organisms a) Levels of organisation b) Cell structure c) Biological molecules d) Movement of substances into and out of cells e) Nutrition f) Respiration g) Gas exchange h) Transport i) Excretion j) Coordination and response

Lesson 4 Content f) Respiration g) Gas exchange f) Respiration 2.33 understand that the process of respiration releases energy in living organisms 2.34 describe the differences between aerobic and anaerobic respiration 2.35 write the word equation and the balanced chemical symbol equation for aerobic respiration in living organisms 2.36 write the word equation for anaerobic respiration in plants and in animals 2.37 describe experiments to investigate the evolution of carbon dioxide and heat from respiring seeds or other suitable living organisms.

Lesson 4 Content f) Respiration g) Gas exchange g) Gas exchange 2.38 understand the role of diffusion in gas exchange Flowering plants 2.39 understand gas exchange (of carbon dioxide and oxygen) in relation to respiration and photosynthesis 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 2.41 explain how the structure of the leaf is adapted for gas exchange 2.42 describe the role of stomata in gas exchange 2.43 describe experiments to investigate the effect of light on net gas exchange from a leaf, using hydrogen-carbonate indicator Humans 2.44 describe the structure of the thorax, including the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes 2.45 understand the role of the intercostal muscles and the diaphragm in ventilation 2.46 explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries 2.47 understand the biological consequences of smoking in relation to the lungs and the circulatory system, including coronary heart disease 2.48 describe experiments to investigate the effect of exercise on breathing in humans.

What is gaseous exchange? What is respiration? What is gaseous exchange?

What is gaseous exchange? What is respiration? Respiration is the release of energy from the breakdown of glucose, by combining it with oxygen inside living cells. What is gaseous exchange?

What is gaseous exchange? What is respiration? Respiration is the release of energy from the breakdown of glucose, by combining it with oxygen inside living cells. What is gaseous exchange? Gaseous exchange is the movement of gases (oxygen and carbon dioxide) into and out of an organism.

Respiration – two sorts Aerobic respiration - in the presence of oxygen. Involves the complete breakdown of glucose. Provides more energy. End products in animals and plants: carbon dioxide and water

Respiration – two sorts Aerobic respiration - in the presence of oxygen. Involves the complete breakdown of glucose. Provides more energy. End products in animals and plants: carbon dioxide and water Anaerobic respiration - in the absence of oxygen. Involves the incomplete breakdown of glucose. Provides less energy. End product in animals – lactic acid. End product in plants - ethanol

Glucose + oxygen  carbon dioxide + water + energy Aerobic respiration Glucose + oxygen  carbon dioxide + water + energy

Glucose + oxygen  carbon dioxide + water + energy Aerobic respiration Glucose + oxygen  carbon dioxide + water + energy C6H12O6 + 6O2  6CO2 + 6H2O + energy

Glucose + oxygen  carbon dioxide + water + energy Aerobic respiration Glucose + oxygen  carbon dioxide + water + energy C6H12O6 + 6O2  6CO2 + 6H2O + energy What do you notice?

Photosynthesis Light 6CO2 + 6H2O C6H12O6 + 6O2 Chlorophyll

Glucose Blood capillary Muscle cell

Glucose and oxygen diffuse from the blood into the muscle cell Blood capillary Glucose + Oxygen Muscle cell Glucose and oxygen diffuse from the blood into the muscle cell

Glucose and oxygen diffuse from the blood into the muscle cell Deoxygenated red blood cells Blood capillary Glucose + Oxygen  Carbon dioxide + Water Muscle cell Glucose and oxygen diffuse from the blood into the muscle cell Carbon dioxide and water diffuse from the muscle cell into the blood

Glucose and oxygen diffuse from the blood into the muscle cell Deoxygenated red blood cells Blood capillary Energy Glucose + Oxygen  Carbon dioxide + Water Muscle cell Glucose and oxygen diffuse from the blood into the muscle cell Carbon dioxide and water diffuse from the muscle cell into the blood Energy is used for muscle contraction

Levels of Organisation A. Cells

Levels of Organisation A. Cells Mitochondria - organelles inside the cell where cellular respiration takes place. They absorb glucose and oxygen, release the energy and then convert it into forms that are usable by the cell. Mitochondria are more numerous in active cells such as muscle cells.

Why anaerobic respiration? If it is so inefficient compared with aerobic respiration, why do cells bother? Sometimes our muscles are working so hard that the lungs and bloodstream cannot deliver oxygen fast enough, so the muscles must respire anaerobically. This can lead to a build up of lactic acid in the muscle.

Why anaerobic respiration? If it is so inefficient compared with aerobic respiration, why do cells bother? A lactic acid build-up in muscles can result in cramp, an unpleasant and often painful sensation caused by muscle contraction or over-shortening.

Why anaerobic respiration? If it is so inefficient compared with aerobic respiration, why do cells bother? In order to break down the lactic acid the body needs more oxygen  OXYGEN DEBT

Why anaerobic respiration? If it is so inefficient compared with aerobic respiration, why do cells bother?

Anaerobic respiration in plants

Anaerobic respiration in plants Glucose  ethanol + carbon dioxide + energy

Anaerobic respiration in plants Glucose  ethanol + carbon dioxide + energy C6H12O6  2C2H5OH + 2CO2

Anaerobic respiration in plants Glucose  ethanol + carbon dioxide + energy C6H12O6  2C2H5OH + 2CO2 In plants, anaerobic respiration (respiration without oxygen) is known as fermentation. This process is commonly used to our advantage in the production of beer and ales, and wine.

Aerobic v Anaerobic

Aerobic v Anaerobic AEROBIC ANAEROBIC A very efficient method of producing energy. Inefficient (incomplete breakdown of glucose) – releases 1/20th energy compared to aerobic.

Aerobic v Anaerobic AEROBIC ANAEROBIC A very efficient method of producing energy. Inefficient (incomplete breakdown of glucose) – releases 1/20th energy compared to aerobic. Occurs during normal daily activity. Produces energy much faster over a short time period. Eg. sprinting

Aerobic v Anaerobic AEROBIC ANAEROBIC A very efficient method of producing energy. Inefficient (incomplete breakdown of glucose) – releases 1/20th energy compared to aerobic. Occurs during normal daily activity. Produces energy much faster over a short time period. Eg. sprinting Produces energy more slowly than anaerobic. Build-up of waste products eventually stops the muscle from working

Lesson 4 Content f) Respiration g) Gas exchange g) Gas exchange 2.38 understand the role of diffusion in gas exchange Flowering plants 2.39 understand gas exchange (of carbon dioxide and oxygen) in relation to respiration and photosynthesis 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 2.41 explain how the structure of the leaf is adapted for gas exchange 2.42 describe the role of stomata in gas exchange 2.43 describe experiments to investigate the effect of light on net gas exchange from a leaf, using hydrogen-carbonate indicator Humans 2.44 describe the structure of the thorax, including the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes 2.45 understand the role of the intercostal muscles and the diaphragm in ventilation 2.46 explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries 2.47 understand the biological consequences of smoking in relation to the lungs and the circulatory system, including coronary heart disease 2.48 describe experiments to investigate the effect of exercise on breathing in humans.

What is gaseous exchange? What is respiration? Respiration is the release of energy from the breakdown of glucose, by combining it with oxygen inside living cells. What is gaseous exchange? Gaseous exchange is the movement of gases (oxygen and carbon dioxide) into and out of an organism.

What is gaseous exchange? Gaseous exchange is the movement of gases (oxygen and carbon dioxide) into and out of an organism. Gaseous exchange is brought about by the actions of the breathing system (also referred to in some textbooks as the respiratory system)

The Breathing System

The Breathing System Trachea – surrounded by rings of cartilage to stop it collapsing

The Breathing System Trachea – surrounded by rings of cartilage to stop it collapsing Ribs – these protect the contents of the thorax. There are 12 pairs of ribs in both men and women.

The Breathing System Trachea – surrounded by rings of cartilage to stop it collapsing Ribs – these protect the contents of the thorax. There are 12 pairs of ribs in both men and women. Rib muscles - the intercostals. Raise and lower the rib cage

The Breathing System Trachea – surrounded by rings of cartilage to stop it collapsing Ribs – these protect the contents of the thorax. There are 12 pairs of ribs in both men and women. Left lung Rib muscles - the intercostals. Raise and lower the rib cage

The Breathing System Trachea – surrounded by rings of cartilage to stop it collapsing Ribs – these protect the contents of the thorax. There are 12 pairs of ribs in both men and women. Left lung Rib muscles - the intercostals. Raise and lower the rib cage Diaphragm – a sheet of muscle used in the mechanism of breathing

The Breathing System Trachea – surrounded by rings of cartilage to stop it collapsing Ribs – these protect the contents of the thorax. There are 12 pairs of ribs in both men and women. Left lung Rib muscles - the intercostals. Raise and lower the rib cage Right bronchus – a branch of the trachea Diaphragm – a sheet of muscle used in the mechanism of breathing

The Breathing System Trachea – surrounded by rings of cartilage to stop it collapsing Ribs – these protect the contents of the thorax. There are 12 pairs of ribs in both men and women. Left lung Rib muscles - the intercostals. Raise and lower the rib cage Bronchiole - a smaller branch of the bronchus Right bronchus – a branch of the trachea Diaphragm – a sheet of muscle used in the mechanism of breathing

The Breathing System Trachea – surrounded by rings of cartilage to stop it collapsing Ribs – these protect the contents of the thorax. There are 12 pairs of ribs in both men and women. Left lung Rib muscles - the intercostals. Raise and lower the rib cage Bronchiole - a smaller branch of the bronchus Right bronchus – a branch of the trachea Alveoli - clusters of grape-like air sacs where gas exchange takes place Diaphragm – a sheet of muscle used in the mechanism of breathing

The Breathing System Trachea – surrounded by rings of cartilage to stop it collapsing Ribs – these protect the contents of the thorax. There are 12 pairs of ribs in both men and women. Left lung Rib muscles - the intercostals. Raise and lower the rib cage Bronchiole - a smaller branch of the bronchus Right bronchus – a branch of the trachea Alveoli - clusters of grape-like air sacs where gas exchange takes place Diaphragm – a sheet of muscle used in the mechanism of breathing

Alveolus (plural alveoli) Where oxygen and carbon dioxide move between the lungs and the blood stream.

Bronchiole Alveolus There are millions of alveoli in each lung, very close to blood capillaries

1. Deoxygenated blood flow from the tissues, rich in carbon dioxide Bronchiole Alveolus 1 1. Deoxygenated blood flow from the tissues, rich in carbon dioxide

Bronchiole Alveolus 2 2. Carbon dioxide diffuses out of the blood stream into the alveoli, and then into the bronchiole

Bronchiole Alveolus 3 3. Oxygen diffuses from the bronchiole into the alveoli and then into the red blood cells.

Bronchiole 4 Alveolus 4. Oxygenated blood now leaves the alveoli and carries oxygen to the tissues.

Features of the alveoli:

Features of the alveoli: 1. A very large, moist surface area.

Features of the alveoli: A very large, moist surface area. An excellent capillary blood supply

Features of the alveoli: A very large, moist surface area. An excellent capillary blood supply Very thin cell membrane separating blood and lung

Ventilation INHALATION = taking air into the lungs EXHALATION = removing air from the lungs

Ventilation IN OUT Nitrogen 79% Oxygen 21% Oxygen 16% Carbon dioxide 0.04% Carbon dioxide 4%

Ventilation BREATHING IN Rib cage moves upwards and outwards. Overall effect: volume of the thorax increases, pressure decreases, so air is drawn IN Diaphragm moves downwards and becomes flatter.

Ventilation BREATHING OUT Rib cage moves downwards and inwards. Overall effect: volume of the thorax decreases, pressure increases, so air is pushed OUT Diaphragm moves upwards and becomes dome shaped.

Lesson 4 Content f) Respiration g) Gas exchange g) Gas exchange 2.38 understand the role of diffusion in gas exchange Flowering plants 2.39 understand gas exchange (of carbon dioxide and oxygen) in relation to respiration and photosynthesis 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 2.41 explain how the structure of the leaf is adapted for gas exchange 2.42 describe the role of stomata in gas exchange 2.43 describe experiments to investigate the effect of light on net gas exchange from a leaf, using hydrogen-carbonate indicator Humans 2.44 describe the structure of the thorax, including the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes 2.45 understand the role of the intercostal muscles and the diaphragm in ventilation 2.46 explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries 2.47 understand the biological consequences of smoking in relation to the lungs and the circulatory system, including coronary heart disease 2.48 describe experiments to investigate the effect of exercise on breathing in humans.

Leaf adaptations Cross section through a leaf Inter-cellular air spaces Lower epidermis – note the presence here of stomata (tiny pores surrounded by guard cells).

Leaf adaptations Cross section through a leaf Lower epidermis – note the presence here of stomata (tiny pores surrounded by guard cells).

Leaf adaptations Cross section through a leaf Oxygen is absorbed and carbon dioxide is released direct from cells to air spaces during respiration.

Gaseous exchange in plants 6CO2 + 6H2O  C6H12O6 + 6O2 C6H12O6 + 6O2  6CO2 + 6H2O

Gaseous exchange in plants PHOTOSYNTHESIS! 6CO2 + 6H2O  C6H12O6 + 6O2 RESPIRATION! C6H12O6 + 6O2  6CO2 + 6H2O

+ Oxygen production 12 midnight 12 mid-day 12 midnight - Time of Day

+ Oxygen production 12 midnight 12 mid-day 12 midnight - Time of Day

+ Oxygen production 12 midnight 12 mid-day 12 midnight - Time of Day

+ Oxygen production 12 midnight 12 mid-day 12 midnight - Time of Day

+ Oxygen production 12 midnight 12 mid-day 12 midnight - Time of Day

+ - Time of Day Oxygen production photosynthesis 12 midnight 12 mid-day 12 midnight - respiration Time of Day

+ - Time of Day Oxygen production Compensation point 12 midnight 12 mid-day 12 midnight - Time of Day

End of Section 2 Lesson 4 In this lesson we have covered: Respiration Gaseous exchange