Exchange and Transport

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  • Created by: efg150
  • Created on: 26-03-21 17:06
Why do organisms need to exchange substances with their environment?
Cells need to take in things like oxygen and glucose for aerobic respiration and other metabolic reactions. They also need to excrete waste products from these reactions - like carbon dioxide and urea.
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What does the exchange of substances depend on?
Surface area to volume ratio (SA:V)
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Why do single-celled organisms not need exchange surfaces?
The substances can diffuse quickly into the cell across the cell surface membrane. The diffusion rate is quick because of the small distances the substances have to travel.
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Why do multicellular organisms need exchange surfaces?
Diffusion across the outer membrane is too slow. There's a big distance between the cells within the body and the outside environment. They have a low SA:V ratio. They have a higher metabolic rate than single-celled organisms, so they use up oxygen and gl
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What special features do exchange surfaces have to improve their efficiency?
Large surface area, Thin membrane, Good blood supply and/or Ventilation
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What are the exchange organs in mammals?
Lungs
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What are goblet cells?
They line the airways and secrete mucus. The mucus traps microorganisms and dust particles in the inhaled air, stopping them from reaching the alveoli.
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What is cilia?
They are on the surface of cells lining the airways and beat the mucus. This moves the mucus (plus the trapped microorganisms and dust) upward away from the alveoli towards the throat, where it's swallowed. This helps prevent lung infections.
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What are elastic fibres?
They are in the walls of the trachea, bronchi, bronchioles and alveoli. They help the process of breathing out. On breathing in, the lungs inflate and these are stretched. Then, they recoil to help push the air out when exhaling.
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What are smooth muscles?
They are in the walls of the trachea, bronchi and bronchioles and allows their diameter to be controlled. During exercise these relax, making the tubes wider. This means there's less resistance to airflow and air can move in and out of the lungs more easi
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What are rings of cartilage?
They are in the walls of the trachea and bronchi provide support. It's strong but flexible - it stops the trachea and bronchi collapsing when you breathe in and the pressure drops.
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What is ventilation in mammals?
It's breathing in and out.
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What does ventilation consists of?
Inspiration (breathing in) and expiration (breathing out)
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What is ventilation controlled by?
The movements of the diaphragm, internal and external intercostal muscles and ribcage.
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What is the process of Inspiration?
Diaphragm muscles contract, causing diaphragm to move downwards and flatten, air flows in, volume increases, air pressure decreases, external intercostal muscles contract, causing ribs to move outwards and upwards
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What is the process of Expiration?
Diaphragm muscles relax, causing diaphragm to become curved again, volume reduces, air pressure increases, external intercostal muscles relax, causing ribs to move inwards and downwards, air is forced out.
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What is tidal volume?
The volume of air in each breath (usually about 0.4dm3)
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What is vital capacity?
The maximum volume of air that can be breathed in or out
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What is breathing rate?
How many breaths are taken (usually in a minute)
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What is oxygen consumption/ oxygen uptake?
The rate at which an organism uses up oxygen (e.g. the number of dm3 used per minute)
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What is a spirometer?
A machine that can give readings of tidal volume, vital capacity, breathing rate and oxygen uptake.
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What system do fish use for gas exchange?
Counter-Current system
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Why do fish have special adaptations to get enough oxygen?
There's a lower concentration of oxygen in water than in air.
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How do fish ventilate?
Water, containing oxygen, enters the fish through its mouth and passes out through the gills.
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How does the the structure of gill filaments/ primary lamellae fit its function?
They are made of lots of thin branches, which give it a big surface area for exchange gasses.
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What are the gill filaments covered by?
They are covered by lots of tiny structures called gill plates/ secondary lamellae.
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What do gill plates/ secondary lamellae do?
Increases the surface area.
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What is each gill supported by?
Gill arch
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What do gill plates have that speed up diffusion?
They have lots of blood capillaries and a thin surface layer of cells.
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What is a counter-current system?
Blood flows through the gill plates in one direction and water flows over in the opposite direction.
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What does the counter-current system maintain?
It maintains a large concentration gradient between the water and the blood.
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What is a buccal cavity?
The space inside the mouth.
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What is a operculum?
A bony flap covering the gill which protects the gill.
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What do insects use to exchange gases?
Tracheae
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What is tracheae?
Microscopic air-filled pipes
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What are spiracles?
Pores on the insect's surface that allows air to move into the tracheae.
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What do tracheae branch off to?
Tracheoles
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What do tracheoles do?
They have thin, permeable walls and go to individuals cells and also contain fluid, which oxygen dissolves in.
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What are rhythmic abdominal movements?
Insects use this to change the volume of their bodies and move air in and out of the spiracles.
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What happens when larger insects are flying?
They use their wing movements to pump their thoraxes.
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Other cards in this set

Card 2

Front

What does the exchange of substances depend on?

Back

Surface area to volume ratio (SA:V)

Card 3

Front

Why do single-celled organisms not need exchange surfaces?

Back

Preview of the front of card 3

Card 4

Front

Why do multicellular organisms need exchange surfaces?

Back

Preview of the front of card 4

Card 5

Front

What special features do exchange surfaces have to improve their efficiency?

Back

Preview of the front of card 5
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