3.1.3 e adaptations of plants Flashcards
what are mesophytes?
plants that are adapted to a habitat with adequate water
what are xerophytes?
plants that are adapted to a dry habitat
what are halophytes?
plants that are adapted to salty habitat
what are hydrophytes?
plants that are adapted to a freshwater habitat
what are the adaptations of xerophytes?
- thick cuticle
- small leaf surface area
- low stomata density
- suken stomata
- stomatal hairs (trichomes)
- rolled leaves
- extensive roots
what does a thick cuticle do?
stops uncontrolled evaporation through leaf cells
what does a small leaf surface area do?
less surface area for evaporation
what does a low stomata density do?
smaller surface area for diffusion
what do sunken stomata do?
traps humid air around it
what do trichomes do?
traps humid air around the stomata
what do rolled leaves do?
confines all the stomata in a microclimate of humid air
what do extensive roots do?
can access water way below the surface
shallow roots can absorb any available water before a rain shower
what is the root system of marram grass?
long vertical roots that penetrate deep into sand.
have a mat of horizontal rhizomes that have many more roots develop to form extensive network that helps to change their environment and enable sand to hold more water
why do surface water plants need to float?
to get light needed for photosynthesis
what is a major problem for hydrophytes?
water logging- air spaces need to be full of air not water for plant to survive
what are the adaptations of hydrophytes?
very thin or no waxy cuticle
many open stomata on the surface of the leaves
reduced structure of the plant
wide, flat leaves
small roots
large surface area of roots and stems underwater
air sacs
aerenchyma
why do hydrophytes have a very thin or no waxy cuticle?
do not need to conserve water as there is lots of water available
why do hydrophytes have many open stomata on the surface of the leaves?
maximising gas exchange
why do hydrophytes have a reduced structure of a plant?
water supports leaves and flowers
why do hydrophytes have wide, flat leaves?
spread across surface to capture as much light as possible
why do hydrophytes have small roots?
less need for uptake of water because water can move into stems and leaf tissue directly
why do hydrophytes have large surface area of roots and leaves that are underwater?
maximises area for photosynthesis
allows oxygen to diffuse into submerged plants
why do hydrophytes have air sacs?
to enable leaves to float on water
what are aerenchyma?
specialised parenchyma tissue that forms in the leaves, stems and roots
has many large air spaces that seemed to be formed by apoptosis in normal parenchyma cells
function of aerenchyma
making leaves and stems more buoyant
forming a low resistance internal pathway for the movement of oxygen to tissues below water
