Topic 9: Plant Biology Flashcards
Transpiration
Loss of water vapour from plants
Xylem vessels
Hollow tubes on dead plant cells
Stomata
Allows water to move out of the xylem into the leaves
Transpiration stream
Water evaporating from the leaf via stomata
Guard cells
Special leaves in the lower leaf epidermis, Controls how much water vapour can exit theleaf
Tracheids
Long thin tube structures withoiut perforation at the end
Vessel elements
Enables easy water transfer
Xerophytes
Plants are able to tolerate dry condition, adaptations (store water inside them)(reduce exposure to sun)
Halophytes
Plants that have adapted to live in saline environments. Live at higher concentrations, avoid salt. Pig face, tolerates by increasing water uptake
Factors that affect transpiration
Light temperature humidity and wind
Phloem
Tube system in plants that allow runic molecules to move, bidirectional. Consists of sieve tubes cells and companion cells
Translocation
The movement of organic molecules via active transport
Pressure flow hypothesis
allows translocation to occur high concentration at the source draws water via osmosis, hydrostatic pressure leading to mass flow
Vascular bundles
Made up of both xylem and phloem
Flowering
The meristematic cells in the shoot apex of an angiospermophyte needs to express specific genes. Flowers will develop in response to specific conditions both externally and internally
Photoperiodism
Plants response to the relative periods of darkness and light
Long-day Plant
Flower in extended periods of light, when days are the longest and the nights are short. Increased amounts of Pfr promotes flowering, so flowering is induced when night period is short and Pfr levels are high. E.g. clovers
Short-day Plant
Stimulated by long periods of uninterrupted darkness. Pfr is an inhibitor of flowering, thus is only induced when night is long and Pfr levels are low. Eg. chrysanthemum
Pollination
Transfer of pollen from the anther to the stigma
Fertilisation
Fusion of the male gamete nuclei inside the pollen grain with the female gamete in the ovule to form zygote
Seed Dispersal
Seeds move away from parental plant to new locations before germination
Mutualism
Relationship between organisms of different species, where both partners benefit
Germination
Process by which a seed emerges from a period of dormancy and starts to sprout into a new plant
