Hydrophytes

Question 1

What are hydrophytes?

Answer 1

plants that live in water

either submerged or on the edge bodies of water

need to have special adaptations to survive in constantly saturated soil

Question 2

What do these plants need to survive?

Answer 2

need to float on the surface of the water so they can gain light needed for photosynthesis

to avoid water-logging, they need air spaces in the plant to be full of air, no water, in order for the plant to survive

Question 3

What adaptations do these plants have to increase gaseous exchange?

Answer 3

many open stomata - maximises gaseous exchange, no risk of loss of turgor pressure

aerenchyma - specialised tissue form in leaves, stems and roots, has large air spaces has several functions including:

• making leaves and stems more buoyant
• low resistance pathway for substances such as oxygen to tissues below the water
• helps the plant cope with anoxic (extreme low O2 condition) in the mud

Question 4

What other adaptations do these plants have?

Answer 4

thin or no cuticle

reduced structure - no need for strong supporting structures

small roots because water can diffuse directlyinto the stem

Question 5

What adaptation do these plants have to access light?

Answer 5

wide/flat leaves - e.g. lillies, to gain as much light as possible

large SA of stems and roots under water - maximises the area for photosynthesis and for oxygen into submerged parts

air sacs to float to the top and reach light

Question 6

What is the problem with aerenchyma?

Answer 6

found in hydrophytes e.g. rice

produces methane which increases climate change