Friday, January 21, 2011

Adaptations - Group 4

1. How do mangrove plants such as Avicennia obtain oxygen when their roots are buried in the mud?
-have pencil-like pneumatophores
(roots that stick upward from the trunk)
-spongy tissue and small holes allow oxygen to be transferred from the roots to the rest of the plant

2. How are xerophytes adapted to survive prolonged drought?
-Some plants avoid drought by surviving as seeds or tubers and then start again when water is available
-Some (Ocotillo) shed their leaves when water is scarce and then sprout a new set.

- Some are adapted to sit out the drought and they have adaptations like being able to extract water from soil (by having very salty cell sap and therefore a very low water potential in the roots / by having very extensive or deep roots or very shallow roots which pick up the slightest dew and survive on that).

Others have special features about their shape or structure (xeromorphs):

- Thick leathery cuticle (Aloe)

- Hairy surfaces (Edelweiss)

- Dense packing of leaves, reduced leaf size (Cupressus)

- Reduced density of stomata (Cactus)

- Pitted and grooved position of stomata (Ammophila)
- Water storage in stem and tubers, etc. (Baobab)

- Protection (by spines and chemicals) of this water store.

3. How do polar bears survive in regions where temperatures are constantly freezing?

-The polar bears have thick fur.
-The furs traps and warms the air.
-The Ultra-violet light is funneled from the sun down the hairs to the bear’s black skin, changing it into warmth.
-The dense undercoat is covered with an outer coat of long guard hairs and that helps to keep the polar bear dry and warm while it is swimming.
-The polar bear has rounder body and is bulkier. Its legs, ears and tail are shorter so that they could conserve heat.
-Its football-shaped outlook makes this mammal very warm.

4. How do deep-sea anglerfish locate its prey in darkness?

-Male anglerfish bite the female Angler Fish and as a result it releases an enzyme that will digest the skin of the Female Anglerfish and the mouth of the male. Once it's attached he releases his sperm in response of the female hormones. The Male becomes one with the Female Angler fish.
-The female wave a luminous, which emits to lure the prey.
-It lays motionless and waits for the prey to come near it.
-The light is created by large number of bacteria that enter the luminous, and produce a bluish or greenish light.

5. Why can't saltwater fish survive in freshwater aquarium?

Both saltwater and freshwater fish are stenohaline
They have mechanisms to stay alive in fresh/salt water
Saltwater fish
-- Lose water through osmosis
-- Have to drink seawater
-- Have kidneys that excrete urine with high concentrations of salt
Freshwater fish
-- Gain water though osmosis
-- Have kidneys that excrete large amounts of urine
-- Saltwater fish in freshwater
-- will gain water through osmosis
-- will die from an high amount of water in their bodies


Differences in pH between seawater and freshwater
Seawater pH is alkaline
-Due to the presence of dissolved ions
-Mg+, Ca2+
Freshwater pH can fluctuate
- Due to runoff from rain and dissolved minerals in the rainwater.

Done by: Victor, Cherin, Jun Hong, Si Yuan, Min Suk and Jonan

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