Download energy - Maaslandcollege

2 tto
respiration and breathing
2
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 the next 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
Section 1.3 – Changing energy.
Energy can be transformed into another sort of energy. But it can not be created AND it
can not 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.
3
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 a 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 types. Which two types are meant here?
2. What type of energy is the energy in glucose?
3. Explain which of the two types is heat energy.
4. A more difficult example is light. What type of energy is light?
5. If you were asked to give me a cup of energy, what could you give me?
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. Close up of a cell surface membrane.
4
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.
Active transport
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:
-
moving; when muscles contract (e.g. 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
-
creating new chemicals (substances); in the cell new proteins are formed by linking
together amino acids (see Fig. 2)
-
heating; 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
5
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 the energy is released. 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 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
Figure 3. Phloem and xylem veins.
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). For every
one molecule of glucose broken down, 36
Mitochondria
Figure 4.
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.
6
This can be the contraction of muscle for movement, active transport of glucose into the
cell (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 active and passive transport and diffuse into
the mitochondrion. Carbon dioxide and water and ATP are formed during respiration. Part of
the ATP is used to actively transport new glucose molecules into the cell. Carbon dioxide will
leave the cell by diffusion and find its way to the lungs to be exhaled (uitgeademd).
The word equation for aerobic respiration is:
glucose + oxygen → carbon dioxide + water + (energy)
substrates
products
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?
7
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. 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 producing
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 removed as soon as possible. The muscle cell s
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?
8
17. Copy and complete table 1.
18. How do you write carbon dioxide
and oxygen as a chemical
formula?
Table 1. Respiration.
Section 3.3 – Lime water.
Substances like iodine and Benedict’s solution can be used to indicate starch and sugar
(glucose), 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:
19. 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?
20. 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 ................ .
21. Explain why a runner must stop after a period of anaerobic respiration.
22. Why does beer production give off bubbles during fermentation?
9
23. 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. 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. Experiment on germinating seeds.
Table 2. Results.
10
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 meanwhile
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 the diaphragm
(see fig. 7). In the chest the lung 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).
Figure 7. Chest cavity.
Figure 8. Pneumothorax (klaplong).
Go to the Biology website and watch the animations on breathing and on the
diaphragm.
11
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.
Go to the Biology website and watch the figure on lungs and alveoli.
When the diaphragm relaxes, the lungs pull the diaphragm upwards again, causing the
volume of the chest cavity to decrease and thereby pushing 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 to 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:
24. The two muscles in the pair of intercostal muscle have opposite functions. What do
we call such muscles?
25. How can you use the abdominal muscles to exhale actively?
What actually happens?
12
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, and their branches the bronchioles
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.
Go to the Biology website and watch the animation on beating cilia.
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 (singular:
alveolus). 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 capillaries that surround the air 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
Figure 10. Diffusion of oxygen into and
the body.
carbon dioxide out of the blood.
questions:
26. What is the function of the ciliated epithelium?
27. What is the advantage of having so many small capillaries around the alveoli instead
of just one large blood vessel?
13
28. A lung is not just two big bags but millions of small sacs called alveoli. What is the
advantage of having so many small sacs?
29. Explain that the blood in the pulmonary artery (going to the lungs) is carrying carbon
dioxide–rich blood that is low in oxygen.
30. Explain that carbon dioxide and oxygen are exchanged by diffusion and not by active
transport. Name two arguments.
14
Glossary with respiration and breathing
energy
potential energy
kinetic energy
unit
quantity
joule (J)
digestion
passive transport
diffusion
facilitated diffusion
active transport
respired
to require energy
to absorb
to release energy
aerobic respiration
mitochondria
15
ATP (adenosine triphosphate)
word equation
substrate
product
anaerobic respiration
lactic acid
oxygen debt
to excrete
yeast
to catalyse
to ferment / fermentation
to rise
substrate
product
lime water
to indicate / indicator
cloudy, milky
to precipitate / precipitation
16
respiratory system
diffuses
circulatory system
ventilation
gas exchange
chest cavity
diaphragm
alveoli
exhaling
intercostal muscles
gas exchange
larynx
trachea
bronchi
epiglottis
cilia
germs
bronchioles
17
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 from
- difference between aerobic and anaerobic respiration
- you must be able to draw and explain Fig. 5 yourself
- 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 respire anaerobically by forming lactic acid whereas others
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 by the 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
18