Chapter 9 Plant transport Flashcards
What is the structure of a leaf, top to bottom?
Waxy cuticle
Upper epidermal layer
Mesophyll layer, made up of first palisade mesophyll then spongy mesophyll
Air spaces and side vascular bundle
Lower epidermal
Stoma/Guards cells
What are xerophytes? Give examples
Xerophytes are plants which have adapted to living in areas of lower water availability
e.g Cacti, Marrum Grass
State general adaptations of xerophytes
Thick waxy cuticle
Creating moist microclimate via sunken stomata, hairy leaves and curled leaves
Reduce water loss by transpiration through reduced number of leaves, stomata and losing leaves
Root adaptation of long, deep taproots and/or widespread high SA roots
Succulents
Don’t cope, die, future generation
How does the waxy cuticle prevent water loss?
Prevents loss of water through evaporation through the epidermis
What are adaptations of cacti and how do they help reduce water loss?
Sunken stomata and spines to produce a moist microclimate, reducing rate of transpiration by lowering water potential gradient
Thick waxy cuticle to reduce water loss by epidermis
Long deep tap roots to collect water metres below and widespread high SA roots to quickly take up rainwater
What are adaptations of Marram Grass?
Thick wavy cuticle to reduce water loss through epidermis
Curled leaves and hairs to produce microclimate to reducing water potential gradients and water loss by transpiration
What are succulents and how do they help reduce water loss?
Specialised parenchyma tissue used to store water when there is a plentiful supply
What are hydrophytes? Give an example
Plants adapted to a very high potential environment living in or on the surface of water, or in permanently saturated soil
e.g Water lilies
What are general adaptations of hydrophytes?
Many stomata on the upper surface of the leaf always open
Short roots as supply of water is abundant
Thin waxy cuticle
Lack of extensive support system
Wide flat leaves to increase photosynthesis
Large SA of stems and roots for increased diffusion of O2 and increased photosynthesis
Air sacs for floating
Aerenchyma
What are the main problems faced by hydrophytes?
Water logging, when air spaces filled
Need to maximise photosynthesis, e.g leaves close to the surface
What is aerenchyma? What is its function?
Specialised parenchyma with large air spaces, produced by apoptosis
Increases buoyancy
Low resistance internal pathways for movement of 02
What is the function of the air space?
Promotes efficient gas exchange
Facilitate movement of water
Mechanical support- buoyance
Thermal Insulation
What are the structures between the xylem and roots?
Endodermis, which includes the endodermal cells with casparian strip
Root cortex cells
Root hair cells
Why do plants need a transport system?
High metabolic demands, with the need to transport glucose from photosynthetic tissue to to roots, and removal of waste products, diffusion too slow
The size of plants are often very large, creating very large diffusion distances would be too slow to rely on
Low surface area to volume ratio apart from leaves, so low rate of diffusion
What are dicotyledonous plants (dicots)?
Plants which produce seeds containing two cotyledons, which are food stores for the developing embryo and form the first leaves
