Chapter 6- Exchange Flashcards
Explain the purpose of stomata in plant cells
Stomata have guard cells around them in order to open to allow water to enter into cells by osmosis when water potential is more negative
Explain the structure of the human exchange system
Lungs- two lobed muscles
Trachea - pipe
Alveolus- exchange surface
Bronchi- beaches off the trachea to transfer respiratory gases
Explain the process of inspiration
External intercostal muscles contract whilst internal intercostal muscles relax
Ribs move upwards and outwards
Diaphragm contracts increasing the pressure of the thorax
Increased pressure of thorax allows atmospheric pressure to be higher
Air is forced into the lungs to
Explain the process of expiration.
Internal intercostal muscles contract and external intercostal muscles relax
Ribs move onwards and downwards decreasing pressure of the thorax
Diaphragm relaxes,decreases pressure of thorax.
Air is forced out of the lungs
How does a small surface are to volume ratio affect gas exchange
A smaller surface area to volume ratio means cells are closer to the point of diffusion
How is water loss prevented in plants
A thick waxy cuticle Waterproofing Rolled leaves Hairy leaves Stomata in pits and grooves Small surface area to volume ratio of leaves
How is water loss prevented in insects
Waterproofing
Small surface area:volume
Spiracles closing
Describe how respiratory gases move in and out of tracheal system along a diffusion gradient.
During respiration oxygen is used up so there is a lower concentration gradient towards the end of the trachea.
Carbon dioxide is produced during respiration.
Diffusion gradient is created in the opposite direction.
The respiratory gases are quickly exchanged.
Describe how respiratory gases move in and out of tracheal system by mass transport.
Contraction of muscles allows mass movements of air.
Describe how respiratory gases move in and out of tracheal system when the ends of the tracheoles are filled with water.
During anaerobic respiration lactate is produced which lowers the water potential allowing water to enter the cell by osmosis so air draws further into the trachea.
Explain the structure of the gills
Gill filaments are stacked up in a pile. At right angles are gill filaments which increase the surface area of the gills.
Explain countercurrent flow.
The flow of water over the gill lamellae and the flow of blood within them are in opposite directions. The blood is already well loaded with oxygen when letting with water therefore diffusion of oxygen from water to blood takes place.
How does the structure of a leaf aid it’s gas exchange.
Many stomata meaning no cell is far from a stoma so diffusion pathway is short.
Numerous interconnecting air spaces allow gases to readily come in contact with mesophyll cells
Leaves have a large surface area of mesophyll cells for rapid diffusion.
Why are the lungs located inside the body
Air is not dense enough to support and protect the delicate structures.
Explain the process of how peptidases work.
Endopeptidases hydrolyse the peptide bonds in the central region.
Exopeptidase hydrolyse the peptide molecules formed by endopeptidases.
Dipeptidases hydrolyse the bond between two amino acid of a dipeptide.
