Section 3: Organisms exchange substances with their enviroment Flashcards
What is metabolism
sum of all chemical reactions in the body
what is the relation between surface area to volume ratio and the size of an animal
As the size of an animal increases the surface area to volume ratio decreases
What are the three main uses of metabolism
muscle contraction and movement
building larger molecules from small ones
maintain body temperature
Name the key parts of a tracheal system in an insect
spiricales
Trachea
Chitin
Tracheoles
How is the insect gas exchange system adapted
- large number of tracheoles
- thin tracheole walls and short diffusion pathway ( spiricales —> tracheoles)
- steep concentration gradient as uses O2 and produces CO2
Do insects have a transport system
No
As oxygen needs to be transported directly to tissues which are undergoing respiration
Name the process by which carbon dioxide is removed from a single-cell organism
diffusion over the 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 thick waterproof surfaces with a small area
Explain how the tracheal system limits the size of insects
because it relies on diffusion to bring oxygen to the respiring tissues. If insects were large it would take too long for oxygen to reach the tissues rapidly enough to supply their needs
How do insects prevent water loss
• Waterproof covering – The rigid outer skeleton (exoskeleton) made of chitin is covered by a waxy cuticle to reduce evaporation.
• Spiracles – Open and close to regulate water loss, especially when the insect is at rest.
• Internal gas exchange system – The tracheal system reduces the need for water loss through the surface by allowing direct gas exchange within the body.
What are the insects three methods of moving gas
- simple diffusion through spiricales - usage and production of O2 and CO2 provide conc gradient from tracheoles to outside
- mass transport - mass flow of air into tracheal system by closing spiracles and contracting and relaxing abdominal muscles pressure changes
- Anaerobic respiration and production of lactate
Describe anaerobic respiration in insects
anaerobic repiration produces lactate
lactate lowers water potential in cells
water moves from tracheoles to cells (osmosis)
tracheal fluid reducing draws more air to tracheoles
What is the exoskeleton of an insect made up of?
Polysaccharide chitin
What is on the surface of the exoskeleton and what do they lead to? ( relating to gas exchange system )
Spiricales lead to trachea which have tracheoles
What is the role of chitin rings? Where are they found?
In the insect gas exchange system, chitin rings in the tracheae prevent structural collapse. They are impermeable to gases, ensuring diffusion occurs only through the tracheoles.
Describe the structure of the fish gills
gills located behind head of fish
gill arch
made up of gill filaments
at right angles are gill lamellar which inc surface area
What are the adaptations of gill lamellae
Maintain concentration gradient: Generous supply of capillaries
Short diffusion pathway: Single layer of flattened cells/ thin membrane
High surface area
In relation to fish gills, describe what is meant by countercurrent flow
The movement of water and blood in opposite directions across gill lamellae
Outline why countercurrent flow is an effiecint means of exchanging gasses across the gills of fish
Because a steady diffusion gradient is maintained over the whole length of the gill lamellae. Therefore more oxygen diffuse from the water into the blood
Mackeral are active, fast-swimming dish whole plaice spend most of their lives moving slowly on the sea bed. suggest the differences in their gills
Mackerel have more gill lamellae / gill filaments / larger surface area compared to plaice
Water flow over fish gills is one way when’s the flow of air in and out of lungs is two-way suggest why one-way flow is an advantage to fish
Less energy is required because the flow does not have to be reversed ( important as water is dense and difficult to move)
Is an equilibrium ever reached between water oxygen concentration and gill oxygen concentration
No
countercurrent exchange system
What is the role of the operculum
hard boney flap-protection