Lecture 5 Flashcards
what is 80-90% of a plant’s fresh mass?
water
what is 96% of a plant’s dry mass?
CO2
what is 4% of a plant’s dry mass?
inorganic substances from soil
plants can absorb nitrogen as either:
NO3- or NH4+
why is nitrogen important?
limiting nutrient because of amino acids
Mycorrihaze has mutualistic associations with who?
fungi and roots
host plants:
provides the fungus with a steady supply of sugar
how do fungi increase the surface area for water uptake?
host plant and supplies the plant with mineral nutrients from the soil
two major types of mycorrhizal associations:
- ectomycorrhizae
- Arbusuclar mycorrhizae
ectomycorrhizae:
outside; between epidermis and cell wall
Arbusuclar mycorrhizae:
inside; most of mycorrhizae, within the cell, more direct, more common
Arbusuclar mycorrhizae:
inside; most of mycorrhizae, within the cell, more direct, more common
response to light is an example of cell signal processing in three stages:
reception, transduction, and enzymatic response
hormones:
are chemical signals that modify or control one or more specific physiological processes within a plant
plant hormones::
plant growth regulators
photomorphogenesis:
effects of light on plant morphology
photoperiodism:
physiological response to a photoperiod such as circadian rhythm and governed internal “clock”
phototaxis:
the movement of plants towards or away from a light source
two major classes of light receptors/hormones:
- blue-light photoreceptors
- phytochromes
blue-light photoreceptors:
initiates a variety of plant responses such as hypocotyl elongation, stomatal opening, and phototropism= higher energy
phytochromes:
pigments that regulate many of a plant’s responses to light throughout its life. In addition to de-etiolation, these responses include seed germination and shade avoidance
epiphyte:
grows on another plant and obtains water and minerals from rain; no negative effect to the tree it grows on
parasitic plants:
absorb sugars and minerals from their living host plant
carnivorous plants:
- have adaptations for trapping insects and other small animals
- the are photosynthetic, but obtain nitrogen by killing and digesting mostly insects
chemical defenses:
compounds including terpenoids, phenolics, and alkaloids can be produced to deter attackers
cells may be specialized to form:
trichomes, store chemical deterrents, or produce irritants
how can leaves be toughened?
with sclerenchyma cells ground tissue within or outside on the cuticle
primary metabolites:
perform their function as molecules signaling to trigger defense response
secondary metabolites:
substances manufactured by plants that make them competitive in their own environment
what led to pollination?
adaptations
what did humans use to modify wild angiosperms into modern crop species?
artificial selection and genetic engineering
