Page 1 of 50
These notes have been compiled using previous examination papers: SACAI NOV 2020, SACAI NOV 2021, SACAI NOV 2022. NSC – Grade
11 Topic Test: Cellular Respiration. @WCED Revision Booklet 2025. LIFE SCIENCES TASK 6: TEST 2_GRADE 11. (EC/NOVEMBER 2023) &
(EC/NOVEMBER 2024)
Important:
These study notes are revised and updated annually to align with the CAPS curriculum and current
examination requirements. The content is based on past examination papers, tests and typical
assessment question patterns.
The content was adapted and structured for examination preparation purposes. AI tools were used
to assist with formatting, rephrasing and differentiation.
These notes are designed to help learners:
• Understand key concepts
• Practise exam-style questions
• Identify important themes and patterns in assessments
• Revise important content in a structured way
To ensure learners work with the most relevant and up-to-date content, parents and learners are
encouraged to confirm that they are using the latest version of the notes. If you are unsure
whether you have the latest version, please feel free to contact me at:
Please note that these notes are compiled as a structured study aid for examination preparation.
They do not replace the prescribed textbook or classroom instruction.
© 2026 Juffrou Ansie Study Notes. All rights reserved. This material may not be reproduced or distributed without written permission.
, Page 2 of 50
Important: Learners can use the Term 3 notes for focused Term 3 preparation. Where
applicable, it is also recommended that learners revise Term 1 and Term 2 notes together with the
Term 3 notes.
Good luck
Juffrou Ansie
Contents
GAS EXCHANGE ..........................................................................................................................2
EXCRETION IN HUMANS ............................................................................................................ 15
POPULATION ECOLOGY ............................................................................................................. 28
INTERACTIONS IN THE ENVIRONMENT ................................................................................... 28
HUMAN POPULATION GROWTH ............................................................................................. 31
FORECASTING HUMAN POPULATION GROWTH ...................................................................... 36
DETERMINING POPULATION SIZE ........................................................................................... 37
GAS EXCHANGE
The exchange of oxygen (O2) and carbon dioxide (CO2) across a gas exchange
Gas exchange
surface.
Breathing The physical process by which air moves in and out of the lungs.
Cellular A chemical process that occurs within cells by which food molecules such as
respiration glucose are broken down to release energy.
The ventilation/respiratory system in humans consists of the following:
• Nasal cavities
• Trachea
• Two bronchi (bronchi)
• Numerous bronchioles
• Two lungs
• Respiratory muscles
HUMAN RESPIRATORY SYSTEM WCED Revision Booklet 2025
© 2026 Juffrou Ansie Study Notes. All rights reserved. This material may not be reproduced or distributed without written permission.
, Page 3 of 50
Nasal cavities
• The two external nasal openings lead to two nasal cavities that are separated by a septum.
• Small, fine hairs in the nasal openings filter larger particles from the inhaled air
• Each nasal cavity is divided into three passages by three curved turbinate bones.
• The nasal cavities are lined with a mucous membrane consisting of ciliated columnar epithelial cells.
• The epithelial cells are richly supplied with capillary blood vessels that warm incoming air.
• Goblet cells between the columnar epithelial cells secrete mucus that traps dust particles and
microorganisms, moistens incoming air and has an antiseptic effect .
• Cilia move the mucus containing trapped dust particles and microorganisms towards the pharynx
where it can be swallowed or expelled.
Pharynx
• The nasal cavities open into the pharynx.
• The pharynx leads to two openings: the THE VENTILATION SYSTEM
glottis which leads to the trachea and the
opening of the oesophagus which leads to
the stomach.
Trachea
• The trachea is a long, tubular structure located in front of the oesophagus.
• The larynx, which houses the vocal cords, is located at the top of the trachea.
• The epiglottis is located at the top of the larynx and consists of cartilage.
• The epiglottis closes the glottis during the swallowing process, thus preventing food from entering
the trachea.
• The walls of the trachea are strengthened and kept open by C-shaped cartilage rings.
• The trachea is lined with ciliated columnar epithelial cells and goblet cells that secrete mucus.
• The mucus moistens the incoming air and traps dust particles.
• Mucus containing trapped dust particles and microorganisms is moved towards the pharynx by the
beating action of the cilia.
© 2026 Juffrou Ansie Study Notes. All rights reserved. This material may not be reproduced or distributed without written permission.
, Page 4 of 50
Bronchi, bronchioles and alveoli
• The trachea branches into two bronchi that enter the right and left
lungs respectively.
• The bronchi are also lined with a mucous membrane layer and are
held open by C-shaped cartilage rings.
• The bronchi divide into smaller branches within the lung and form
bronchioles.
• The bronchioles have no cartilage rings and their walls consist of
Lungs smooth muscles that can contract and relax to control airflow.
• The two lungs are in the chest and are • Each bronchiole ends in an infundibulum which consists of a
protected by 12 pairs of ribs. group of alveoli.
• The lungs are spongy and elastic and can
expand and contract during breathing.
• The right lung consists of three lobes,
and the left lung consists of two lobes.
• Each lung is surrounded by a double THE VENTILATION SYSTEM
membrane, called the pleura. CONTINUED
• The fluid (interpleural fluid) between the
pleura prevents friction when the lungs
expand and contract.
Respiratory muscles and ribs:
Diaphragm:
The diaphragm is a dome-
shaped muscle plate that Ribs:
separates the chest and Intercostal muscles:
abdominal cavities. The ribs are on either side of the
The intercostal muscles occur
The diaphragm contracts and sternum (breastbone) and
between successive ribs and
flattens to change the volume of protect the lungs from injury.
consist of external and internal
the chest cavity and is
intercostal muscles.
important during breathing.
© 2026 Juffrou Ansie Study Notes. All rights reserved. This material may not be reproduced or distributed without written permission.
These notes have been compiled using previous examination papers: SACAI NOV 2020, SACAI NOV 2021, SACAI NOV 2022. NSC – Grade
11 Topic Test: Cellular Respiration. @WCED Revision Booklet 2025. LIFE SCIENCES TASK 6: TEST 2_GRADE 11. (EC/NOVEMBER 2023) &
(EC/NOVEMBER 2024)
Important:
These study notes are revised and updated annually to align with the CAPS curriculum and current
examination requirements. The content is based on past examination papers, tests and typical
assessment question patterns.
The content was adapted and structured for examination preparation purposes. AI tools were used
to assist with formatting, rephrasing and differentiation.
These notes are designed to help learners:
• Understand key concepts
• Practise exam-style questions
• Identify important themes and patterns in assessments
• Revise important content in a structured way
To ensure learners work with the most relevant and up-to-date content, parents and learners are
encouraged to confirm that they are using the latest version of the notes. If you are unsure
whether you have the latest version, please feel free to contact me at:
Please note that these notes are compiled as a structured study aid for examination preparation.
They do not replace the prescribed textbook or classroom instruction.
© 2026 Juffrou Ansie Study Notes. All rights reserved. This material may not be reproduced or distributed without written permission.
, Page 2 of 50
Important: Learners can use the Term 3 notes for focused Term 3 preparation. Where
applicable, it is also recommended that learners revise Term 1 and Term 2 notes together with the
Term 3 notes.
Good luck
Juffrou Ansie
Contents
GAS EXCHANGE ..........................................................................................................................2
EXCRETION IN HUMANS ............................................................................................................ 15
POPULATION ECOLOGY ............................................................................................................. 28
INTERACTIONS IN THE ENVIRONMENT ................................................................................... 28
HUMAN POPULATION GROWTH ............................................................................................. 31
FORECASTING HUMAN POPULATION GROWTH ...................................................................... 36
DETERMINING POPULATION SIZE ........................................................................................... 37
GAS EXCHANGE
The exchange of oxygen (O2) and carbon dioxide (CO2) across a gas exchange
Gas exchange
surface.
Breathing The physical process by which air moves in and out of the lungs.
Cellular A chemical process that occurs within cells by which food molecules such as
respiration glucose are broken down to release energy.
The ventilation/respiratory system in humans consists of the following:
• Nasal cavities
• Trachea
• Two bronchi (bronchi)
• Numerous bronchioles
• Two lungs
• Respiratory muscles
HUMAN RESPIRATORY SYSTEM WCED Revision Booklet 2025
© 2026 Juffrou Ansie Study Notes. All rights reserved. This material may not be reproduced or distributed without written permission.
, Page 3 of 50
Nasal cavities
• The two external nasal openings lead to two nasal cavities that are separated by a septum.
• Small, fine hairs in the nasal openings filter larger particles from the inhaled air
• Each nasal cavity is divided into three passages by three curved turbinate bones.
• The nasal cavities are lined with a mucous membrane consisting of ciliated columnar epithelial cells.
• The epithelial cells are richly supplied with capillary blood vessels that warm incoming air.
• Goblet cells between the columnar epithelial cells secrete mucus that traps dust particles and
microorganisms, moistens incoming air and has an antiseptic effect .
• Cilia move the mucus containing trapped dust particles and microorganisms towards the pharynx
where it can be swallowed or expelled.
Pharynx
• The nasal cavities open into the pharynx.
• The pharynx leads to two openings: the THE VENTILATION SYSTEM
glottis which leads to the trachea and the
opening of the oesophagus which leads to
the stomach.
Trachea
• The trachea is a long, tubular structure located in front of the oesophagus.
• The larynx, which houses the vocal cords, is located at the top of the trachea.
• The epiglottis is located at the top of the larynx and consists of cartilage.
• The epiglottis closes the glottis during the swallowing process, thus preventing food from entering
the trachea.
• The walls of the trachea are strengthened and kept open by C-shaped cartilage rings.
• The trachea is lined with ciliated columnar epithelial cells and goblet cells that secrete mucus.
• The mucus moistens the incoming air and traps dust particles.
• Mucus containing trapped dust particles and microorganisms is moved towards the pharynx by the
beating action of the cilia.
© 2026 Juffrou Ansie Study Notes. All rights reserved. This material may not be reproduced or distributed without written permission.
, Page 4 of 50
Bronchi, bronchioles and alveoli
• The trachea branches into two bronchi that enter the right and left
lungs respectively.
• The bronchi are also lined with a mucous membrane layer and are
held open by C-shaped cartilage rings.
• The bronchi divide into smaller branches within the lung and form
bronchioles.
• The bronchioles have no cartilage rings and their walls consist of
Lungs smooth muscles that can contract and relax to control airflow.
• The two lungs are in the chest and are • Each bronchiole ends in an infundibulum which consists of a
protected by 12 pairs of ribs. group of alveoli.
• The lungs are spongy and elastic and can
expand and contract during breathing.
• The right lung consists of three lobes,
and the left lung consists of two lobes.
• Each lung is surrounded by a double THE VENTILATION SYSTEM
membrane, called the pleura. CONTINUED
• The fluid (interpleural fluid) between the
pleura prevents friction when the lungs
expand and contract.
Respiratory muscles and ribs:
Diaphragm:
The diaphragm is a dome-
shaped muscle plate that Ribs:
separates the chest and Intercostal muscles:
abdominal cavities. The ribs are on either side of the
The intercostal muscles occur
The diaphragm contracts and sternum (breastbone) and
between successive ribs and
flattens to change the volume of protect the lungs from injury.
consist of external and internal
the chest cavity and is
intercostal muscles.
important during breathing.
© 2026 Juffrou Ansie Study Notes. All rights reserved. This material may not be reproduced or distributed without written permission.
