Lecture Sixteen - Animal adaptations II Flashcards
What is diffusion?
Movement of molecules across a permiable membrane.
Tends to spread out evenly into the avaliable space.
Is movement down a concentration gradient.
What is osmosis?
The movement of water across a semipermiable membrane.
What is tonicity?
The ability of a solution to cause a cell to gain or lose water.
Has a great impact on cells without walls.
What are iso- hypo- and hyper-tonic solutions?
Isotonic = The concentration of solutes is the same as it is inside the cells. There will be no net movement of water.
Hypertonic = The concentration of solutes is greater than it is inside the cell. The cell will lose water.
Hypotonic = The ceoncentration of solutes is less than it is inside the cell. The cell will gain water.
What does turgid and flacid mean?
If a plant cell is turgid - it is in a hypotonic evironment and it is very firm, a healthy state in most plants.
If a plant is flaccid - it is in an isotonic or hypertonic environment.
What is osmolarity and what are osmoconformers and osmoregulators?
Sum of osmotically active particals in a solution. Water moves from hypoosmotic to hyperosmotic.
Osmoconformers - do not adjust internal concentration, isoosmotic with surroundings.
Osmoregulators - use energy to change concnetration and control internal osmolarity.
What are stenohaline and euryhaline animals?
Stenohaline - Can only tolerate narrow range of salinity (most animals).
Euryhaline - Can tolerate wide range of salinity (very few animals). E.g. Salmon.
What are ionoconformers and ionoregulators?
Ionoconformers - Have the samr concnetration of ions as the surroundings.
Ionoregulators - Maintain specific ions in their fluids at different concentrations to the surroundings.
How can animals lose and gain water?
Water loss:
Evapouration - from body and from respiratory surfaces.
Faeces.
Urine.
Other secretions.
Water gain:
Drinking.
Uptake via body surface - from water and from air.
Water in food.
Metabolic water.
What are characteristics of most mairne invertebrates and vertebrates?
Invertebrates:
Most invertebrates are osmoconformers but ionoregulators.
They do not need to cope with the movement of water, but must regulate their ion concentrations.
Vertebrates:
Most marine vertebrates are osmoregulators and ionoregulators.
Tend to lose water and gain salt by osmosis.
Do not produce concentrated urine.
Chloride cells on gills.
Exceptions:
Sharks - Osmoconformers and ionoregulators. Convert nitrogen waste to urea. High concentrations of urea in body fluids.
What are charcteristics of fresh water fish?
Invertebrates and vertebrates similar in freshawater.
Low environmental osmolarity.
Tendency to gain water and lost salts.
Reducing permiability helps.
Active transport required.
usually respiratory surfaces take up ions.
Passove loss of ions to environment.
Active uptake of ions.
Copious dilute urine.
Explain the characteristics of air breathing marine animals.
Reptiles, birds and mammals.
Body osmolarity about 400mmol/L.
Can be considered terrestrial in water balence.
Need specialised structures or efficient kidney.
Mammals use disnet to excrete salt.
Reptiles and birds use salt glands - more efficient than kidneys.
What are anhydrobiosis animals?
Organisms which do not require water to live.
During anhydrobiosis the animal enters an almost completely desiccated state which stabilizes its membranes and other cellular structures, preventing otherwise lethal damage caused by environmental extremes.
How is water balence on land achieved?
Water loss to environment is a consistent problem.
Economical water use.
Two adaptations:
- Vapour limited systems e.g. frogs.
- Membrane limited systems e.g. insects.
