Plant Adaptations To Water Availability

Question 1

what is a xerophyte?

Answer 1

plants in dry habitats that have develpoed adaptations that enable them to live and reproduce in places with low water availability.

Question 2

what are ways of conserving water in xerophytes?

Answer 2

• thick waxy cuticle
• sunken stomata
• reduced numbers of stomata
• reduced leaves.
• hairy leaves
• curled leaves
• succulents
• leaf loss
• root adaptations
• avoiding the problem

Question 3

how do sunken stomata conserve water?

Answer 3

if stomata are located in pits, air movement is reduced so it creates a microclimate of humid air that reduces the water vapour potential gradient and reduced transpiration.

Question 4

how does reduced leaves conserve water?

Answer 4

by reducing leaf area to thin needles, the surface area : volume ratio is reduced

Question 5

how do hairy leaves conserve water?

Answer 5

hairy leaves create a microclimate of still, humid air, reducing the water potential gradient and minimising the loss of water by transpiration from the surface of the leaf.

Question 6

how do curved leaves conserve water?

Answer 6

confines all stomata within a microclimate of still, humid air to reduce diffusion of water vapour from the stomata.

Question 7

how do succulents conserve water?

Answer 7

store water in parenchyma tissue in stem and roots. water is stored and used in times of drought.

Question 8

how do root adaptations conserve water?

Answer 8

roots can be long to penetrate several metres of soil and access water below the surface.

Question 9

what are hydrophytes?

Answer 9

plants that live in water.

Question 10

what are adaptations of hydrophytes to not be full of water?

Answer 10

• very thin or no waxy cuticle
• many stomatao on upper surface which are always open.
• reduced structure to the plant.
• wide, flat leaves.
• small roots.
• large surface areas of stems and roots under water.
• air sacs
• aerenchyma

Question 11

how does reduced structure to the plant reduce water?

Answer 11

water supports leaves and flowers so there is no need for structural support.

Question 12

how do wide flat leaves help hydrophytes?

Answer 12

spread across the surface of water so they can capture as much light as possible for photosynthesis.

Question 13

why do hydrophytes not have long roots?

Answer 13

water can diffuse directly into stem and leaf tissue so don’t need root water uptake.

Question 14

how does a large surface area of stems and roots help hydrophytes?

Answer 14

maximises the area for photosynthesis and for oxygen to diffuse into submerged plants.

Question 15

how do air sacs help hydrophytes?

Answer 15

air sacs allow leaves or flowers to float on the surface of water.

Question 16

what is aerenchyma?

Answer 16

specialised parenchyma tissue forms in the leaves, stems and roots. It has many large air spaces.

Question 17

what are the functions of aerenchyma?

Answer 17

• making leaves and stems moer buoyant.
• forming a low resistance internal pathway for the movement of substances such as oxygen to tissues below the water. this allows them to cope with anoxic conditions.