Download As discussed in the chapter on digestion, nutrients can be used for

2 tto
respiration and
breathing
Section 1 - What is energy?
Energy causes things to happen around us. Look out the window. During the
day, the sun gives out light and heat energy. At night, street lamps use
electrical energy to light our way. When a car drives by, it is being powered
by gasoline (benzine), a type of stored energy. The food we eat contains
energy. We use that energy to work and play. What is the definition of
energy:
Energy is the ability to do work (to move things).
Energy can be found in a number of different forms. It can be chemical
energy, electrical energy, heat (thermal energy), light (radiant energy),
mechanical energy, and nuclear energy.
Section 1.1 – Stored and moving energy
Energy makes everything happen and can be divided into two types:

Stored energy (opgeslagen energie) is called potential energy.

Moving energy is called kinetic energy.
With a pen, try this example to know the two types of energy.
Put the pen at the edge of the desk and push it off to the floor. The moving
pen uses kinetic energy. “Kinetic” means related to movement.
Now, pick up the pen and put it back on the desk. You used your own energy
to lift and move the pen. Moving it higher than the floor adds energy to it. As
it rests on the desk, the pen has potential energy. The higher it is, the further
it could fall. That means the pen has more potential energy. “Potential”
means having the ability to ...
Sections 1.2 – Joule is the unit that goes with the quantity “energy”
One joule is the amount of energy required to lift a small apple one meter
straight up. A piece of buttered toast contains about 315 kilojoules (315,000
joules) of energy. With that energy you could:

Jog for 6 minutes

Bicycle (fietsen) for 10 minutes

Sleep for 1-1/2 hours

Run a car for 7 seconds at 80 kilometres per hour

Light a 60-watt light bulb for 1-1/2 hours
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Section 1.3 – Changing energy
Energy can be transformed into another sort of energy. But it cannot be
created AND it cannot be destroyed. Energy has always existed in one form
or another.
Here are some changes in energy from one form to another.
Stored energy in a flashlight's (zaklantaarn) batteries becomes light energy
when the flashlight is turned on.
Food is stored energy. It is stored as a chemical with potential energy. When
your body uses that stored energy to run, it becomes kinetic energy.
If you overeat, the energy in food is not "burned" but is stored as potential
energy in fat cells.
When you talk on the phone, your voice is transformed into electrical energy,
which passes over wires (or is transmitted through the air). The phone on the
other end changes the electrical energy into sound energy through the
speaker.
A car uses stored chemical energy in gasoline to move. The engine changes
the chemical energy into heat and kinetic energy to power the car.
A toaster changes electrical energy into heat and light energy. (If you look
into the toaster, you'll see the glowing wires.) Heat is quick movement of
molecules. The faster water molecules move the warmer the water feels.
from: http://www.energyquest.ca.gov/story/chapter01.html
questions:
1. Energy always exists in only two forms. Which two forms are meant here?
2. What form of energy is the energy in glucose?
3. Explain which of the two is heat energy.
4. A more difficult example is light. What form of energy is light?
5. If you were asked to give me a cup of energy, what could you give me?
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Section 2 – Energy in the cell
As discussed in the chapter on digestion, nutrients can be used for two
purposes: for growth and repair and for respiration (energy). Some people
may say that storage is a third purpose, but eventually (uiteindelijk) these
nutrients will be used for growth and energy as well.
Some of the nutrients we absorb contain little or no energy, like water and
minerals. Other substances like proteins, fats and carbohydrates contain a lot
of energy. In this section we will discuss how the cell can get the energy
from the nutrient called glucose.
Figure 1.
Passive transport
Substances like water, carbon dioxide and
oxygen can go through the cell membrane
by diffusion (movement of substances
from a high to a low concentration).
Other substances need proteins to help
them to diffuse (facilitated diffusion) by
forming little holes in the cell membrane.
This does not cost energy either.
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Active transport
Uptake of substances with a high
concentration inside the cell, need to
be taken up by force. For this, special
enzymes are located in the cell
membrane.
This costs energy.
Active transport is always from a low
concentration to a high concentration.
Section 2.1 – Use of energy
When glucose is burned (respired) inside the cell, the energy is used for
chemical reactions and processes. These processes include:
- movement; when muscles contract to make arms move this costs energy
- active transport across the cell membrane (see Fig. 1); amino acids
produced during digestion are taken up by the cell; they can use them to
make new proteins
- making new chemicals (substances); in the cell new proteins are formed
by linking together amino acids (see Fig. 2)
- heat; to keep mammals and birds at a constant body temperature
Figure 2.
questions:
6. Name four processes in a cell that require energy.
For each explain into what kind of energy the energy is converted (kinetic
or potential energy).
7. Use Fig. 1 for this question.
During passive diffusion substances move from a .... to a ....
concentration. During active transport substances are transported from a
.... to a .... concentration.
8. In a cell there is a lot of glucose. The cell wants to take up some more
glucose.
Will transporting glucose into the cell cost energy or won’t it?
9. Which of the following cell types will have the most mitochondria?
Explain your answer.
a human cheek cells
b ciliated epithelial cells in the breathing airways
c muscle cells
d cells that store fat
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Section 3 - Respiration
All organisms must have a source of energy. Animals eat food containing
energy rich chemicals (energierijke stoffen) like fat and starch. The
chemicals are broken down by the digestive system into smaller molecules
such as glucose. The digested molecules are absorbed into cells (see Fig. 1).
Respiration takes place inside cells. In the cell glucose is broken down to
give carbon dioxide and water. This process also releases energy (maakt
ook nog energie vrij).
Plants get their energy from sunlight. This light energy is transferred
(overgebracht) to the energy rich chemicals glucose and starch. When the
plant needs energy, these substances are broken down and release the
energy. Plants need energy as much as animals do. The process of
respiration occurs all the time in plants, just as it does in animals.
The reactions inside the cells need enzymes to carry them out. The
enzymes regulate that energy is released when the cell needs it. If a cell does
not need much energy, some of the enzymes stop working.
Section 3.1 – Aerobic respiration
Aerobic respiration means the release
of energy using oxygen.
In animals, oxygen is carried to the
cells by the blood, from where it diffuses
into cells. Glucose and other nutrients
also travel to the cells via the blood.
In plants, phloem carries sugars from
the leaves, where it is formed, to the
Figure 3.
whole plant. Phloem is found in the veins
in leaves and in the stem (see Fig. 3).
Oxygen, however, diffuses to all cells (in the leaves, stem or roots) from
the surface of the plant. It diffuses through the cell walls between the cells.
This means that phloem, is not involved in the distribution of oxygen.
In the cytoplasm of cells, there are specialised organelles called
mitochondria (see Fig. 4) which contain the enzymes needed for
respiration. Oxygen diffuses into the mitochondria and is used to react with
glucose to produce carbon dioxide and water (see Fig. 5). The chemical
energy is transferred to a substance called ATP (adenosine triphosphate).
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For every one molecule of glucose broken
down, 36 molecules of ATP are made.
Each molecule of ATP has a small amount
of energy. The ATP can move around the
cell to take the small packets of energy to
all the reactions that need it. This can be
the contraction of muscle for movement,
active transport of glucose into the cell
mitochondrion
Figure 4.
(see Fig. 5) or the production of new
proteins (see Fig. 2).
Once the energy in ATP has been released, the broken down ATP returns
to the mitochondrion to be rebuild once again. Sometimes ATP is referred to
as a rechargeable (oplaadbaar) battery. Batteries can also be used and
recharged many times.
Figure 5. Glucose and oxygen enter the cell by passive and active
transport and diffuse into the mitochondrion. Carbon dioxide and
water and ATP are formed during respiration. ATP is here used to
actively transport glucose into the cell. Carbon dioxide will leave the
cell by diffusion and find its way to the lungs to be exhaled
(uitgeademd).
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The word equation for aerobic respiration is:
glucose + oxygen → carbon dioxide + water + (energy)
When the glucose molecules are broken down inside a cell, some of the
chemical energy cannot be transferred into ATP. About 60% of the energy is
given off as heat. This is why your muscles get warm when they are working
hard. All organisms give off heat to the environment.
questions:
10. What is the source of energy for animals?
What is the source of energy for plants?
11. Where in the cell does respiration take place?
12. In animals oxygen is carried around by the blood.
How does oxygen reach the cells in a plant?
13. What is the function of ATP in a cell?
14. Is ATP potential or kinetic energy?
Section 3.2 – Anaerobic respiration
Anaerobic respiration is the release of energy without oxygen. If a person
runs very quickly then breathing might not bring in enough oxygen to the
muscles. The person still needs to move so the muscle cells short cut the
respiration process. The glucose is only partly broken down but this happens
very quickly. Only a little of the energy can be transferred to the ATP. Most of
the energy is left in the remaining substance which is called lactic acid.
Lactic acid in Dutch is melkzuur. Lactic acid is found in spoiled milk and in
yoghurt. If bacteria have used up all of the oxygen in the milk, they start
using their special enzymes. The enzymes that can turn glucose into lactic
acid. This way these bacteria can survive under bad conditions.
The word equation for anaerobic respiration in muscles and in lactic acid
bacteria is:
glucose → lactic acid + (some energy)
There is enough energy released for the muscle to keep on working
without oxygen. However, lactic acid is a poison (gif) and makes the
muscle get tired. Too much lactic acid causes cramp and so it must be
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removed as soon as possible. The muscle cells need extra oxygen after the
runner has stopped to turn the lactic acid into carbon dioxide and water.
This extra oxygen is called the oxygen debt (zuurstofschuld). It is why
runners pant (hijgen) at the end of a sprint race.
In plants and micro-organisms (yeast) a different temporary (tijdelijk)
substance is released instead of lactic acid. It is alcohol which is slightly
less toxic (poisonous, giftig). Some types of yeast can stand (weerstaan)
up to 14% alcohol in their cells. The word equation for anaerobic
respiration in plants and yeast is:
glucose → alcohol + carbon dioxide + (some energy)
The alcohol is usually excreted (uitgescheiden) from the plant or yeast
cells and they lose the energy in the molecules.
An organism can not choose whether to produce lactic acid or
alcohol. Lactic acid bacteria only have the enzymes with which they can
speed up the formation of lactic acid. Yeast cells don’t have this enzyme
but they do have an enzyme that speeds up the formation of alcohol.
Enzymes can only catalyse one particular chemical reaction.
Humans have made use of the process of anaerobic respiration. It is
called fermentation (gisting). One type of fungus called yeast is used to
produce the alcoholic drinks wine and beer. Yeast is also used to make
bread. Bread rises because the yeast gives off carbon dioxide both in
aerobic and anaerobic respiration. The gas carbon dioxide gets trapped in
the sticky dough and forms bubbles. The bread becomes light and airy
(luchtig).
question:
15. What is the advantage to a yeast cell to use anaerobic respiration?
16. Why can’t we make beer with more than 14% alcohol?
17. Copy and complete this table.
Table 1.
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Section 3.3 – Lime water
Substances like iodine and Benedict’s solution can be used to indicate starch
and sugar, respectively. Similarly, lime water (kalkwater) is used to
indicate the presence of carbon dioxide. If carbon dioxide is present, the
limewater solution becomes cloudy, unclear or milky.
What happens?
Lime water contains calcium hydroxide. When calcium hydroxide is mixed
with carbon dioxide the calcium binds to the carbon dioxide. This so called
calcium carbonate is unsolvable (onoplosbaar) and forms a precipitation
(een neerslag, een niet opgeloste stof).
Why does it become cloudy?
If you dissolve a salt in water, the mixture is unclear at first because the
salt doesn’t all dissolve at once. As soon as the salt is dissolved the solution
is clear. In this experiment it is the other way around: at first the solution is
clear because the salt (calcium hydroxide) is dissolved in water. Then the
solution is mixed with carbon dioxide and calcium carbonate is formed.
Calcium carbonate cannot be dissolved in water and the solution becomes
cloudy again.
There is one more consequence of this. The carbon dioxide that is
combined with calcium is no longer in the air.
questions:
18. A mouse is placed in an airtight (luchtdicht) box. The mouse consumes
the gas oxygen for respiration. This means that the volume of the air in
the box is reduced (20 percent of the air is oxygen). During respiration
the gas carbon dioxide is formed so the volume increases again. It turns
out that the volume of carbon dioxide formed is equal to the volume of
oxygen used.
As a result, the volume in the airtight box will not change.
What will happen when the box contains a dish with lime water?
19. Copy and complete the following sentences. Respiration is the
................... of energy in cells. Glucose is broken down into carbon
dioxide and ....................... . The released energy can be used by the
cell. Aerobic ...................... releases more energy for the cell than
anaerobic respiration. Lactic acid causes cramp. Alcoholic drinks are
made by a chemical reaction called ................ .
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20. Explain why a runner must stop after a period of anaerobic respiration.
21. Why does beer production give off bubbles during fermentation?
22. The amount of respiration in seeds was measured in an experiment.
Some germinating seeds (kiemende, zaden die aan het uitkomen zijn,
zaden die een wortel aan het maken zijn) were put into a test tube
with some lime water. A hollow tube was attached and the position of
the dye (kleurstof) measured at the start and after 10 minutes. The
apparatus is shown in Figure 6 and the results in Table 2 (see next
page). A second tube containing sterilised, dead seeds was also set up
and the results recorded.
a) By how much does the volume of the gases in the respiration
chamber of tube A decrease in the 10 minutes?
b) Explain why the volume of gas decreased, step by step.
c) Give a conclusion about germinating seeds.
In other words, what is happening inside germinating seeds?
d) What was the scientific question in this experiment?
Figure 6.
Table 2.
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Section 4 - lungs
As you learned in the previous sections, our body needs oxygen to release
energy stored in glucose. This process takes place in the mitochondria of
every cell. How do cells get their oxygen when oxygen is in the air around us
and the cells are on the inside of our body. Two organ systems are involved
in the uptake and the distribution of this important gas. In the respiratory
system (ademhalingsstelsel) oxygen diffuses into the blood and the
circulatory system (bloedvatenstelsel) transports it throughout the body.
In the mean while carbon dioxide is brought to the lungs by the circulatory
system and removed from the blood by the lungs.
In our lungs two processes take place. One is ventilation and the other is
gas exchange. Ventilation is getting the air into and out of the lungs. Gas
exchange is the diffusion of oxygen into and carbon dioxide out of the blood.
Section 4.1 – Ventilation
The chest cavity (borstholte), containing
the lungs and the heart, is a space that is
enclosed by the rib cage and a muscle called
diaphragm (see fig. 7). In the chest the lung,
which is very small outside the chest, is
stretched out because it is attached to the
chest and diaphragm. If it wasn’t attached it
would look like the left lung in fig. 8. Since it is
stretched, the lungs are actually pulling at the
ribs and the diaphragm all the time.
When you inhale (breathe in), your
diaphragm contracts (becomes shorter) and
moves downward (fig. 7). This increases the
space (volume) in your chest cavity. As your
lungs expand, air is sucked in through your
nose or mouth. The air travels down your
windpipe and into your lungs. After passing
through your bronchial tubes (see fig. 9), the
air finally reaches and enters the alveoli (air
sacs).
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Figure 7.
Figure 8.
Figure 9. Figure A shows the location of the respiratory structures in the body.
Figure B is an enlarged image of airways, alveoli, and the capillaries. Figure C shows
the location of gas exchange between the capillaries and alveoli.
When the diaphragm relaxes, the lungs pull the diaphragm upwards again,
causing the volume of the chest cavity to decrease and pushes the air out of
your mouth and nose. This makes exhaling a passive process. It costs no
energy.
The intercostal muscles between your ribs may (kunnen) also help
enlarge the chest cavity. They contract to pull your rib cage both upward and
outward when you inhale. Here, relaxation of the intercostal muscles enables
the lungs to pull the ribs downward and inward again, leading to exhalation.
To see if exhalation is passive indeed, try it yourself. Take a deep breath
and then let go. Don’t blow the air out but just stop inhaling. You’ll see that
the air comes out without you doing any effort (inspanning).
To actively blow the air out, however, you need a different set of
intercostal muscles and your abdominal muscles (buikspieren).
questions
23. The pair of intercostal muscle have opposite functions. What do we call
such muscles?
24. How can you use the abdominal muscles to exhale actively?
What actually happens?
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Section 4.2 – Airways and gas exchange
The airways are pipes that carry oxygen-rich air to your lungs and carbon
dioxide, a waste gas, out of your lungs. The airways include your (see fig. 9):

Nose and mouth

Larynx , or voice box

Trachea , or windpipe

Tubes called bronchial tubes or bronchi, and their branches
Air first enters your body through your nose or mouth, which wets and
warms the air (cold, dry air can irritate your lungs). The air then travels
through your voice box and down your windpipe. The windpipe splits into two
bronchi that enter your lungs.
A thin flap of tissue called the epiglottis covers your windpipe when you
swallow. This prevents food or drink from entering the air passages that lead
to your lungs.
Except for the mouth and some parts of the nose, all of the airways have
special hairs called cilia that are coated with sticky mucus (slijm). The cilia
trap (vangen) germs (bacillen, ziektekiemen) and other foreign particles that
enter your airways when you breathe in air. These fine hairs then sweep the
particles up to the nose or mouth. There, they're swallowed, coughed, or
sneezed out of the body. Nose hairs and mouth saliva also trap particles and
germs.
Within the lungs, your bronchi branch into thousands of smaller, thinner
tubes called bronchioles. These tubes end in bunches of tiny round air
sacs called alveoli. Each of these air sacs is covered in a mesh (netwerk) of
tiny blood vessels called
capillaries (haarvaten). The
capillaries connect to a network of
arteries and veins (slagaders en
aders) that move blood through
your body.
The pulmonary artery
(longslagader) and its branches
deliver blood rich in carbon dioxide
(and lacking in oxygen) to the
Figure 10. Diffusion of oxygen into and
capillaries that surround the air
carbon dioxide out of the blood.
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sacs. Inside the air sacs, carbon dioxide diffuses from the blood into the air
(see Fig. 10). Oxygen diffuses from the air into the blood in the lungs. The
oxygen-rich blood then travels to the heart through the pulmonary vein
and its branches. The heart pumps the oxygen-rich blood out to the body.
questions:
25. What is the function of the ciliated epithelium?
26. What is the advantage of having so many small capillaries around the
alveoli instead of just one large blood vessel?
27. A lung is not just two big bags but millions of small sacs called alveoli.
What is the advantage of having so may small sacs?
28. Explain that the blood in the pulmonary artery (going to the lungs) is
carrying carbon dioxide–rich blood that is low in oxygen.
29. Explain that carbon dioxide and oxygen are exchanged by diffusion and
not by active transport. Name two arguments.
Watch this animation on lungs and breathing:
http://www.nhlbi.nih.gov/health/dci/Diseases/hlw/hlw_when.html
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Glossary with respiration and breathing
energy
potential energy
kinetic energy
unit
quantity
joule
respired
to require energy
to absorb
to release energy
aerobic respiration
mitochondria
ATP (adenosine triphosphate)
word equation
anaerobic respiration
lactic acid
oxygen debt
to excrete
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yeast
to catalyse
to ferment / fermentation
to rise
substrate
product
lime water
to indicate / indicator
cloudy, milky
to precipitate / precipitation
respiratory system
diffuses
circulatory system
ventilation
gas exchange
chest cavity
diaphragm
alveoli
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exhaling
intercostal muscles
gas exchange
Larynx
Trachea
bronchi
epiglottis
cilia
germs
bronchioles
alveoli
capillaries
pulmonary artery
air sacs
What do you need to be able to explain:
- the difference between potential and kinetic energy (and examples)
- list what energy is used for in organisms
- difference between passive and active transport across the cell membrane
- where plants and animals get their energy
- difference between aerobic and anaerobic respiration
- you must be able to draw and explain Fig. 5 yourself
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- give the word equation of every chemical reaction mentioned in the booklet
- explain how lime water can be used – why it turns cloudy
- what happens when dough rises
- what the advantage is of respiration (in general)
- what the advantage is of respiring anaerobically
- explain that some organisms are only able to respire anaerobically by
forming lactic acid whereas others can only ferment (make alcohol)
- explain what diffusion is and that it depends on the difference in
concentration and on a large surface area
- explain how ventilation is caused by contraction and relaxation of the
diaphragm
- explain how ventilation is caused contraction of the intercostal muscles
- explain what the effect is of the lungs actually being very small on the
passive ventilation (exhalation)
- be able to name all the parts of the respiratory system and their roles /
functions
- explain what the function is of ciliated epithelium
- explain how having capillaries and alveoli positively influences diffusion
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