Exchange Flashcards
What is the environment around cells called?
Tissue Fluid
Name two ways exchange can take place
Passively or actively
Name five features of a specialised exchange surface
- A large surface area relative to the volume
- Thin
- Selectively permeable
- Movement of the environmental medium
- A transport system.
What makes up the network for gas exchange in insects?
Trachea which branch out into tracheoles that extend through the insects body
Name three ways gasses move in and out of the tracheal system.
- Along a diffusion gradient,
- Mass transport,
- The ends of the tracheoles are filled with water.
How does the ends of tracheoles filing with water increase the rate of gas exchange in insects during a period of major activity?
Muscles around tracheoles respire and produce lactic acid, reducing the water potential. Cells draw in water and this movement causes water to be pulled in though the spiracles.
Why do insects keep their spiracles closed most of the time?
To prevent water loss.
Describe the structure of the gills in a fish
Made up of gill filaments which are covered in lamellae to increase the surface area.
What is counter current flow?
The blood moves in the opposite direction to the flow of water to maintain a constant high concentration gradient.
How are gasses transported in plants?
Through diffusion
How are leaves of a plant adapted for gas exchange?
- No cell is far from a stomata,
- Numerous interconnecting air spaces in the mesophyll bringing gasses into contact with it throughout the leaf.
- Large surface area of the mesophyll for rapid diffusion
What are stomata?
Small pores which occur mainly on the underside of the leaf and is surrounded by a pair of guard cells which control when it is opened and closed.
Name three insect adaptations to reduce the loss of water.
- Spiracles
- Waterproof coverings
- Small surface area to volume ratio.
What is a xerophyte?
A plant adapted to living in extreme conditions where there is a lack of water.
Name 5 adaptations of plants to reduce water loss.
- Thick cuticle,
- Rolling up leaves,
- Hairy leaves,
- Stomata in pits or grooves,
- A reduced surface area.
Why are the lungs in mammals located inside the body?
- Air is not dense enough to support their delicate structure,
- We would lose a lot of water otherwise.
Describe the human gas exchange system.
The trachea is the tube that air comes through down the throat, this branches off into two bronchi, one going to each lung. These branch out further into bronchioles which end in the alveoli.
Why is there collagen and elastic fibres in between the alveoli?
To allow the alveoli to stretch when they fill with air.
Describe inspiration.
External ICM contract and internal ICM relax. Rips are pulled up and out. Diaphragm contracts. Air in forced in as pressure decreases in the lungs.
Describe expiration.
External ICM relax and internal ICM contract. Rips move own and in. Diaphragm relaxes. Air is forced out as pressure increases in the lungs.
State 4 reasons why transfer of oxygen is rapid in the lung.
- Alveoli and capillaries have a very large surface area,
- Red blood cells are slowed as they pass through the capillaries allowing time for gas exchange,
- Short diffusion pathway as alveoli walls are thin and red blood cells are pressed against capillary walls,
- Breathing ensures there is a high concentration gradient maintained as does blood flow through capillaries.
What are the two stages of digestion?
- Physical breakdown
- Chemical breakdown.
What is the function of amylase?
Breakdown of starch into maltose
What breaks down maltose and what does it breakdown into?
Maltase, a-glucose
Why is maltase considered a membrane bound disaccharide?
It is part of the membranes of the cells which line the ileum.
Describe lipid digestion.
Lipids are broken down into micelles by bile salts produced in the liver. They are then hydrolysed by lipases.
Name three proteases.
Endopepdidase, exopeptidase, dipeptidase.
How are triglycerides digested?
The micelles break down into fatty acids and monoglycerides which diffuse across the membranes of the cells lining the ileum. They reform into triglycerides at the endoplasmic reticulum then are associated with cholestrol and lipoproteins at the golgi. The they leave the cell.
Whats a triglyceride that has been associated with cholesterol and lipoproteins called?
Chylomicrons.
