Plant adaptations to the availability of water - xerophytes

Question 1

What must land plants do to survive?

Answer 1

live in a constant compromise between getting CO2 for photosynthesis and losing the water they need for turgor pressure and transport

they must have a large SA:V for gaseous exchange and the capture of light, but this greatly increases the risk of water loss by transpiration

Question 2

What adaptation do plants have to conserve water?

Answer 2

waxy, waterproof cuticle

stomata found mainly on the underside that can be closed

roots that grow down to the water in soil

Question 3

What are xerophytes?

Answer 3

plants that have adapted to survive in hot/dry/breezy places where water availability is low or transpiration rate is very high

e.g. cacti

Question 4

Why are plants the survive in arctic conditions considered xerophytes despite an abundance of water?

Answer 4

the water is not freely available to them because it is frozen

Question 5

What are ways of reducing the rate of transpiration?

Answer 5

thick waxy cuticle - e.g. evergreen plants e.g. holly

sunken stomata - located in deep pits that reduce air movement, creates a microclimate of humid air, found in cacti and marram grass

reduced number of stomata

reduced leaves - reduce SA available for water loss - confiders are reduced to thin needles, greatly reduced sa:v

loss of leaves in dry seasons

Question 6

What are other ways of reducing water loss?

Answer 6

succulents:
succulent plants store water in their stems and roots,used in times of drought, he.g. cacti and aloe vera

root adaptations:
long tap roots that grow deep,
mass of widespread shallow roots

avoiding the problems:
die during drought and leave seeds behind for once rain falls again

others survive as storage organs, e.g. potatoes, they appear dead but become turgid and recover