Water & Desert Adaptations

Question 1

Define: water balance

Answer 1

When water gain = water loss

Question 2

Name the 3 ways in which water is gained, and some ways in which water is lost.

Answer 2

Gained through eating, drinking and metabolic water

Lost through sweating, breathing, excretion, lactation etc..

Question 3

Define: dehydration

Answer 3

When more water is lost than gained

Question 4

What percentage of the body (in weight) is made up of water in male and female humans?

Answer 4

50-55% in females

60-65% in males

Question 5

In humans, what percentage of water is intracellular and extracellular?

Answer 5

2/3 intracellular

1/3 extracellular

Question 6

Name 2 behavioural adaptations of the tarrkawarra (hopping mouse)

Answer 6

• Nocturnal and collects seeds at night, which contain greater humidity
• Compensates for water loss in lactation by drinking young’s piss

Question 7

Name 3 physiological adaptations of the tarrkawarra

Answer 7

Concentrated faeces and urine
Water is lost not through sweat glands but through diffusion
Water loss through breathing reduced by heat exchange system in nasal passageways

Question 8

Explain how the water-holding frog survives with little water

Answer 8

THROUGH DORMANCY

• Digs chamber under drying-out waterhole and creates a chamber sealed with mucous
• Goes into dormancy (slowing of metabolic rate, eg. heart and breathing) until the next rain comes
• In rain, they feed and breed

Question 9

Explain how banded stilts survive when their inland lakes, containing brine shrimps, dry up.

Answer 9

They migrate to another lake.

Question 10

Name 4 structural adaptations of camels.

Answer 10

• Long eyelashes and closable nostrils
• Bony structures in nose: retain water vapour from exhaled air
• Oval shaped red blood cells: still circulate through viscous (Thickened) blood, caused by dehydration
• Fat store in hump

Question 11

Name 4 physiological adaptations of camels

Answer 11

• Tolerates dehydration: 40% of water can be lost, rbc’s can double in size before bursting
• Kidneys produce concentrated urine, dry faeces due to long colon
• Body temp varies between 34-42, sweating only begins at 42.

Question 12

In animals that live in cold places, why is it important for their body temperature to be above freezing point?

Answer 12

Some chemical reactions that are vital for life must occur in liquid water, not solid water.

Question 13

Name 2 ways in which animals’ body fluids can be kept above freezing point

Answer 13

• By releasing antifreeze substances, which lower freezing point
• Having insulating layers of feathers, fur or fat.