Ch.7.4 Flashcards
Both respiration and photosynthesis involve ________________________________________________________________________________________________________.
exchange of carbon dioxide and oxygen between living things and their environment
What is the colour of hydrogencarbonate indicator if the carbon dioxide level is >0.03%?
yellow
What is the colour of hydrogencarbonate indicator if the carbon dioxide level is =0.03%?
red
What is the colour of hydrogencarbonate indicator if the carbon dioxide level is <0.03%?
purple
Green plants can carry out both ________________ and ________________.
photosynthesis, respiration
What does net gas exchange in plants depend on?
The relative rates of photosynthesis and respiration.
During daytime, ________________________________________________ take place, but the __________________________________ is higher than the ______________________________________.
both photosynthesis and respiration, rate of photosynthesis, respiration
Name the two net gas exchange indicators we can measure in daytime.
- net uptake of carbon dioxide
- net release of oxygen
At night, ________________________________. Only ________________________ takes place.
photosynthesis stops, respiration
Name the two net gas exchange indicators we can measure at nighttime.
- net uptake of oxygen
- net release of carbon dioxide
Where is gas exchange carried out in plants?
The tiny pores on the leaf epidermis, aka stomata
Why are stomata only found on the lower surface of the leaf?
It is to avoid direct contact with sunlight.
Surrounding each stoma are _________________________________.
two guard cells.
What are the functions of guard cells?
They control the opening and closing of the stoma.
In the daytime, the guard cells are ________________________. They ___________ the stoma.
full of water, open
Why do guard cells open in the daytime?
So that the plants can take in carbon dioxide from the air for photosynthesis, and give out the oxygen produced through the stomata.
At night, the guard cells _______________ as they _____________ ______________, and so the stoma _______________.
shrink, lose water, closes
When the stoma is open in the ________________, the guard cells are ________________/ ________________.
daytime, swollen, turgid
When the stoma is closed at ________________, the guard cells are ________________/ ________________.
night, shrunken, flaccid
Stomata are very ________________ in size. They can only be observed using a ________________ with the magnification of about x__________.
small, microscope, 400
We need to take in ________________ from the air and remove ________________ ________________ from our bodies. There is _____________ ________________ between our ________________ and the ____________________.
oxygen, carbon dioxide, gas exchange, body, environment
How can we find evidence for gas exchange between us and the environment?
By comparing the composition of the air we breathe in (inhaled air) and the air we breathe out (exhaled air)
How is the oxygen content of inhaled/ exhaled air tested? Why?
With a burning splint. This is because a glowing splint requires a large amount of oxygen to relight, but both inhaled air and exhaled air do not have enough oxygen to relight a glowing splint.
How is the carbon dioxide content of inhaled/ exhaled air tested?
With hydrogencarbonate indicator.
Exhaled air contains ______________ oxygen than inhaled air.
less
Exhaled air contains ______________ carbon dioxide than inhaled air.
more
How is the water vapour content of inhaled/ exhaled air tested?
With dry cobalt chloride paper.
Inhaled air contains _____________ water vapour than exhaled air. Why?
less; this is because exhaled air is saturated with water vapour, which comes from the moist surface of air sacs and the mouth cavity.
The temperature of inhaled air is ____________ than that of exhaled air.
lower
Why can’t exhaled air be as warm as our body temperature?
This is because heat is continuously lost to the environment.
Humans have a ____________________________________ for gas exchange.
breathing system
What is the importance of gas exchange in the human body?
It allows our body cells to have…, so that….
At the same time,…
a continuous supply of oxygen for respiration, energy stored in food can be released for use by the body; carbon dioxide produced during respiration will not build up and it will be removed from the body
Name the 9 main parts of the human breathing system.
nasal cavity, trachea, bronchus, bronchiole, air sac, intercostal muscle, rib, lung, diaphragm
State the pathway of air flowing through the breathing system.
nasal cavity, trachea, bronchi, bronchioles, air sacs
What is the shape of the cartilage in the trachea? Why?
It is c-shaped.
It reinforces the front and sides of the trachea to prevent it from collapsing and blocking the airway. the open ends also allows the trachea to collapse slightly to allow food to pass down the oesophagus.
Please describe the colour and texture of a pig lung.
pink, soft and spongey
Is the trachea hard or soft?
hard
When air is pumped into lungs, ___________________________________________________.
the volume of the lungs increases
Why do lungs float?
This is because there are many air sacs, which are filled with air, in the lungs, and it makes the lung tissue less dense than water
Where does gas exchange in humans take place?
At our lungs/ air sacs
Inside the lungs, the air sacs are surrounded by _______________________.
capillaries
What are capillaries?
Small blood vessels.
Gas exchange takes place between ______________________________ and the ______________________________.
air in the air sacs, blood in the surrounding capillaries
Oxygen passes from the air sacs, through the ______________________________, into the ______________________________. The blood then _________________________________________________________.
thin walls of the air sac, blood capillaries, carries the oxygen to the body cells for respiration
_________________________ is produced during respiration. It is carried by ___________________________________. It passes from the ______________ into the _________________; then it is breathed out.
Carbon dioxide, blood flowing to the lungs, blood, air sacs
Blood from body cells contain a _________________________________ (___%) after ____________________, and a _________________________________ (___%) after ____________________.
high carbon dioxide contents, 16, concentration, low oxygen content, 4, diffusion
Blood flowing to body cells contain a _________________________________ (___%) and a _________________________________ (___%).
high oxygen content, 21, low carbon dioxide content, 0.03
What are the 4 requirements for efficient gas exchange?
- large number of air sacs, which provides a large surface area for gas exchange by diffusion
- the wall of the air sac is only one-cell thick, which provides a short distance for diffusion of gases
- the air sacs are surrounded by blood capillaries, which ensures a rapid transport of gases
- the inner wall of the air sac is moist, which allows oxygen to dissolve in the fluid for diffusion
In a healthy person, the airway all along the ______________________, ________________, ________________ and some ____________________ ____________________ are lined with _____________________________ and ___________________________.
nasal cavity, trachea, bronchi, larger bronchioles, mucus-producing cells, ciliated cells
What is the use of the mucus produced by mucus-producing cells?
It traps dust particles and bacteria entering the breathing system.
What is found on the surfaces of ciliated cells?
Tiny hair-like cilia
What is the function of cilium?
They move back and forth to sweep out the mucus in which the dust particles and bacteria are trapped.
Inside the airway of a smoker, the ________ in cigarette smoke causes ______________________________________, and also _______________________________________.
tar, the cilia to stick together, increases mucus production
Why is tar found in the lungs of a smoker?
This is because it is deposited there when smokers breathe in cigarette smoke.
What problem is caused when mucus production is increased?
- It builds…
- It is…
- The mucus…
It builds up in the airway, making the airway narrower. It is more difficult for air to pass into and out of the lungs.
The mucus may also block the air sacs, making gas exchange even more difficult
Cigarette smoke contains many harmful substances, such as ________, ______________ and __________________________________.
tar, nicotine, carbon monoxide
What is tar?
It is a brown sticky substance.
-
-
causes lung cancer
causes coughs and respiratory diseases, eg bronchitis
stains teeth and nails to become yellowish
What is nicotine?
It is an oily liquid.
What are the harmful effects of nicotine?
causes addiction
increases heart rate and blood pressure, leading to heart diseases in the long term
What is carbon monoxide?
It is a colourless, odourless and toxic gas
-
reduces the oxygen content in blood
the heart needs to beat faster to provide enough oxygen to body cells, leading to heart diseases in the long term
Why does carbon monoxide reduce the oxygen content in blood?
It sticks to red blood cells, and is not removed, which means that there is less space for the blood cells to carry oxygen.
Which substance in cigarettes is found to be the main cause of lung cancer?
Tar.
How many harmful substances are there in a cigarette?
Over 4000.
Name two diseases that may be caused by long term smoking.
Chronic bronchitis (bronchi and bronchioles inflamed, too much mucus) and Emphysema (walls of the air sacs are damaged, making gas exchange less effective as the surfaces area for gas exchange is reduced)
