3.3.11 The Adaptations of Xerophytic and Hydrophytic plants

Question 1

What are xerophytes?

Answer 1

Xerophytes are plants that are adapted to dry and arid conditions

Question 2

What is the impact of fleshy succulent leaves on xerophytes?

Answer 2

Water stores for times of low availability.

Question 3

What is the impact of ‘Hinge cells’ which shrink when flaccid on xerophytes?

Answer 3

Causes leaves to roll exposing the thick, waterproof cuticle to the air and creates a humid space in the middle of the rolled leaf.

Question 4

What is the impact of leaves reduced to scales, spines or needles or curled or rolled when flaccid on xerophytes?

Answer 4

Reduced transpiration due to reduced surface area available.

Question 5

What is the impact of stomata closed during light/open in dark on xerophytes?

Answer 5

CAM metabolism to minimise photorespiration; CO2 fixed at night, day time water loss is minimised

Question 6

What is the impact of sunken stomata and fine hairs on xerophytes?

Answer 6

Water loss is minimised by trapping moist air close to the area of water loss reducing the diffusion gradient

Question 7

What is the impact of reduced numbers of stomata on xerophytes?

Answer 7

Less water loss due to fewer pores

Question 8

What is the impact of stomata only on upper epidermis on xerophytes?

Answer 8

Open to the humid space created by the hairs and rolled shape

Question 9

What is the impact of thick waxy cuticle on xerophytes?

Answer 9

Water loss reduced via the cuticle

Question 10

What are hydrophytes?

Answer 10

Plants that are adapted to living in freshwater are known as hydrophytes

Question 11

Why is excess water uptake not a concern for plants?

Answer 11

Excess water uptake is not a major concern for plants as their cells possess a cell wall
The cell wall prevents too much water from being absorbed

Question 12

Why are water transport mechanisms in hydrophytes not needed?

Answer 12

The abundance of water in the surrounding environment means there is little need for water transport mechanisms or adaptations that reduce water loss

Question 13

What is the main challenge that hydrophytes face?

Answer 13

The main challenge that hydrophytes face is receiving enough carbon dioxide during the day and enough oxygen during the night
Water contains less oxygen and carbon dioxide than the air

Question 14

What is the impact of floating leaves on hydrophytes?

Answer 14

the leaves are thin, flat and have large air spaces inside to give them buoyancy. This keeps them close to the surface of the water where there is more light for photosynthesis

Question 15

What is the impact of thin waterproof waxy cuticle on hydrophytes?

Answer 15

it is very thin as there is little need to prevent water loss

Question 16

What is the impact of stomato only on upper surface of leaves in hydrophytes?

Answer 16

this allows for gas exchange to occur with the air instead of the water

Question 17

What is the impact of a reduced root system in hydrophytes?

Answer 17

only small roots are required as they can also extract nutrients from the surrounding water through their tissues

Question 18

What is the impact of reduced veins in the leaves of hydrophytes?

Answer 18

the xylem is significantly reduced as there is no need to transport water throughout the plant

Question 19

What is a common hydrophyte?

Answer 19

A water lily