Gas Exchange in Insects Flashcards
Properties of gas exchange
- Large surface area
- Thin (one layer of epithelial cells) - provide short diffusion pathway across gas exchange surface
What does the organism do for gases across exchange surface?
Maintain concentration gradient
How does single-celled organisms utilise diffusion?
Absorb and release gases by diffusion through their outer surface
Why does single-celled organisms not need gas exchange?
- Large surface area
- Short diffusion pathway
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What are trachea?
Insects having microscopic air-filled pipes used for gas exchange
What are spiracles?
Air moves into the trachea through the pores on surface
How does oxygen travel in insects?
Down the concentration towards the cell
How does oxygen diffuses directly into respiring cells?
Tracheae branch into smaller tracheoles which have thin, permeable walls and go to individual cells
Why does insect’s circulatory system doesn’t transport CO2?
Carbon dioxide from the cells move down its own concentration gradient towards the spiracles to be released into the atmosphere
How does insect move air in out and out of spiracles?
Use rhythmic abdominal movements to move air in and out of the spiracles
What is the unfortunate consequence of exchanging gases?
Lose water
How are insects specialised if they are losing too much water through exchanging gases?
- They close their spiracles using muscles
- Waterproof waxy cuticles all around body and tiny hairs around spiracles to reduce evaporation
Name the process by which carbon dioxide is removed from a single-celled organism?
Diffusion across body surface
Explain why there is a conflict in terrestrial insects between gas exchange and conserving water
Gas exchange requires a thin permeable surface with a large surface area
Conserving water requires a thick waterproof surface with a small area.
Explain how the tracheal system limits the size of insects
Relies on diffusion to bring oxygen to the respiring tissue
If insects are large it would take long for oxygen to reach the tissues rapidly enough to supply their needs
Describe and explain what happens to the concentration of oxygen in the trachea when the spiracles are closed
Falls steadily and remains at the same level
Suggest an explanation for this change in the concentration of oxygen when the spiracles are closed
Cells use up oxygen during respiration and so it diffuses out of the trachea and into the cells
With the spiracles are closed , no oxygen can diffuse in from outside to replace it
All oxygen used up and level fall
Suggest what causes the spiracles to be open
Increasing level of carbon dioxide
Suggest an advantage of this spiracle movement to a terrestrial insect.
Helps to conserve water because spiracles are not open continuously
therefore water does not diffuse out continuously
Fossil insects have been discovered that are larger than insects that occur on Earth today.
What does this suggest about the composition of the atmosphere at the time where fossil insects lived.
It contained more oxygen
The insects lives in a dry conditions
Suggest an advantage of the pattern of spiracle movements
Spiracles will not be open all the time
Therefore less water loss
Abdominal pumping increases the efficiency of gas exchange between tracheoles and muscle tissue of the insect
Explain why
Increases efficiency
increase rate of air moving into the trachea through the spiracles
maintain a greater diffusion gradient
Abdominal pumping is an adaptation not found in many small insects. These small insects obtain sufficient oxygen by diffusion
Explain how their small size enables gas exchange to be efficient without the need of abdominal pumping
Small size offer a short diffusion pathway to obtain oxygen
The insects open its spiracles at a lower frequency in very dry conditions
Suggest one advantage of this
No water loss
The ends of the tracheoles connect directly with the insect muscle tissue and filled with water. When flying, water is absorbed into the muscle tissue. Removal of water from tracheoles increase the rate of diffusion of oxygen between the tracheoles and muscle tissue.
Suggest one reason why:
They have gases able to diffuse more oxygen at a faster rate
How does oxygen diffuse through respiring cells?
Air enters through holes called spiracles
O2 diffuses down the concentration gradient along the trachea
02 diffuses into the cells
Why is ventilation helpful for insects?
Help to maintain a high concentration gradient
