Respiration Worksheet

4th Biology Unit 2
Ms. Guerra Respiration
Respiration
Respiration has two common meanings in biology.
1. Respiration is the process of oxidising food to release energy. It is the opposite

of photosynthesis. If this is the type of respiration you are looking for see cellular
respiration.
2. Respiration is the process or processes involved in the exchange of oxygen and carbon
dioxide between an organism and the environment. It is this meaning of respiration that
is addressed on this page.
Respiration uses oxygen and fuel (food) to produce energy for cells. The products of respiration
are carbon dioxide and water.
Respiration in animals is divided into:
1. Internal respiration, or the interchange of oxygen and acid between the cells of the body
and the bathing them, which in one sense is a process of nutrition.
2. External respiration, or the gaseous interchange taking place in the special
respiratory organs, the lungs. This constitutes respiration proper. In the respiration of
plants oxygen is likewise absorbed and carbonic acid exhaled, but in the light this process
is obscured by the light-phase of photosynthesis in which the plant inhales and absorbs
carbon dioxide and exhales oxygen.
3. Respiration can be measured using a device called a respirometer.
4. Plant respiration is limited by the process of diffusion. Even a baobab tree is mostly dead
because air can penetrate only skin deep. However, most plants are not involved in highly
metabolic activities like hunting, i.e. they do not need the energy necessary for predators,
and thus their breathing is limited.
5. Insects use a system of tracheae, thin channels, through their exoskeleton, to improve on
simple diffusion and let air flow more freely throughout the organism. However, this
simple system limits their size. No modern insect exists that is larger than a foot or so
(in metric units, about half a meter). Many people fear big bugs, and they should be
comforted by this fact, which has to do with respiration. A bug, however annoying, cannot
be large, although it can be long. Nevertheless, a large number of insects like locusts can
do a lot of damage.
6. In tissue engineering, respiration is an essential problem. The small depth of diffusion
respiration sufficient to support the metabolism of an average human cell is less than a
millimetre in metric units, or less than a quarter of a quarter of an inch in Imperial units.
Various substances can be used to enhance this depth, essentially having a
haemoglobising role.
4th Biology Unit 2
4th Biology Unit 2
https://www.liveworksheets.com/worksheets/en/Science/Respiratory_System/
Respiratory_system_tr168738dn
Respiratory System Flow chart. Arrange the following terms into the correct spot to show
how air flows in the respiratory system.
TRACHEA LUNGS DIAPHRAGM
BRONCHI BRONCHIOLES ALVEOLI

4th Biology Unit 2
The respiratory system

1 Use the following words to label the diagram below
air sac bronchiole bronchus diaphragm intercostal
muscles lung pleural membrane rib trachea
2 List the parts of the respiratory system that:

1. a molecule of oxygen passes through before entering the blood, starting with
the trachea
Trachea 
2. a molecule of carbon dioxide passes through after leaving the blood, starting
with an air sac
Air sac 
The action of the diaphragm and intercostal muscles
The diagram below shows inhalation and exhalation.
Complete the following sentences to explain how we breathe in.

3 The intercostal muscles between the _______________ contract.
4 This moves the ribs _______________ and _______________.
5 At the same time, the diaphragm muscle _______________ and moves
_______________.
6 The volume of air inside the chest _______________.
This decreases the pressure inside the chest. The air pressure outside the chest is
higher so air enters the lungs.
Complete the following sentences to explain how we breathe out.
7 The intercostal muscles _______________.
8 The ribs are moved _______________ and _______________.
9 At the same time, the diaphragm muscle _______________ and moves
_______________.
10 The volume of air inside the chest __________________.
This increases the pressure inside the chest. The air pressure outside the chest is now
lower so air leaves the lungs.
4th Biology Unit 2
Name: _____________ Date: _________
Using words from the box fill in the gaps in the text. Some of the words need to be
used more than ones.
Aerobic Anaerobic carbon Energy enough glucose poisonous
lactic acid little not all not enough oxygen oxygen debt pant water
Organisms respire in order to release energy.

………………………… respiration is respiration requiring
…………………………. In aerobic respiration the reactants are
………………………… and …………………………. The products are water
and ………………………… dioxide. ………………………… is also released.
Glucose + oxygen carbon dioxide + water + ENERGY
………………………… respiration is respiration without oxygen.
Anaerobic respiration takes place when there is
…………………………oxygen available but energy is required. This
happens when an athlete runs very fast but the body cannot supply
………………………… oxygen.
In anaerobic respiration the reactant is only …………………………. The product is
………… ……………..
A ……………… energy is released. This is because not all the energy is released
from each glucose molecule.
Glucose lactic acid + energy

Lactic acid is ………………………….
To get rid of lactic acid the person will ………………… in order to get a good
supply of oxygen.
You have to keep breathing hard for a while after you stop to get oxygen into your
muscles to convert the painful lactic acid which has built up to
harmless…………………dioxide and …………………
The amount of oxygen required to do this is called
……………………… ……………….
4th Biology Unit 2
What type of molecules Write a word equation for aerobic What part of the cell do most
control the rate of respiration. stages of aerobic respiration
reactions inside cells? take place in?
2.6 Aerobic and Why does anaerobic

What do plants use the energy from Anaerobic Respiration respiration release so much
respiration for? less energy than aerobic
When does anaerobic respiration take
respiration?
place?
Give two changes that

Why do birds and mammals have a higher rate of What is the product of
happen in the body when you
respiration than reptiles and fish? anaerobic respiration?
exercise.
Graph to show how heart rate Why do muscle

changes with exercise
cells have lots of
200 What is meant by an
Why do athletes ‘carb load’ mitochondria?
Heart reate / bpm
100
oxygen debt?
before a big race?
0
0 2 4 6 8 10
Time / minutes
The graph above shows how Fred’s heart rate

changed during a 1500m race, )minutes is when he
What is fermentation?
started the race and 4 minutes is when he finished,
Write an equation.
Describe and explain the shape of the graph,
What happens to muscles when

they are subject to long periods
of vigorous activity and why?

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4th Biology Unit 2

Ms. Guerra Respiration

1. Respiration is the process of oxidising food to release energy. It is the opposite

Respiration in animals is divided into:

TRACHEA LUNGS DIAPHRAGM

BRONCHI BRONCHIOLES ALVEOLI

The respiratory system

2 List the parts of the respiratory system that:

Complete the following sentences to explain how we breathe in.

Organisms respire in order to release energy.

Glucose lactic acid + energy

2.6 Aerobic and Why does anaerobic

Give two changes that

Graph to show how heart rate Why do muscle

The graph above shows how Fred’s heart rate

What happens to muscles when

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