Module 6 - Plant Form and Function Flashcards
Autotroph vs heterotroph
Autotroph
- self-sufficient without eating other living organisms
- produce their own energy
- plants, algae, certain protists, some prokaryotes
Heterotroph
- live on compounds produced by other organisms
- humans, cows, meerkats etc.
Chlorophyll a vs Chlorophyll b
What is the name of other accessory pigments?
a - main photosynthetic pigment
b
- an accessory pigment
- absorbs different wavelengths of light
- pass the energy to chlorophyll a
What is the name of other accessory pigments?
Carotenoids
What happens when a pigment absorbs light?
It goes from a ground state to an excited state which is unstable.
What are photosystems?
a reaction centre in the plasma membrane surrounded by a number of light-harvesting complexes
How is type I different from type II?
Photosytem II comes before photosystem I in the thylakoid membrane, so energy flows from II to I.
What are light-harvesting complexes? What is their role?
- pigment molecules bound to proteins
- funnel the energy of photons of light to the reaction centre
What happens when a reaction-centre chlorophyll molecule absorbes energy?
One of its electrons get pumped up to a primary electron acceptor
How do C4 plants minimize the cost of photorespiration?
C4 plants spatially confine the Calvin cycle to very internal cells
- CO2 is incorporated into four carbon organic acids (C4_ in mesophull cells rather than three carbon chains by Rubisco as in C3 plants
- C4 is exported to bundle sheath cells where they release CO2 used in Calvin Cycle
5 differences between C3 and C4 plants
- C4 photosynthesis uses two extra ATP molecules
- C4 plants have a lot less photorespiration
- Optimum temperature for C4 photosynthesis is higher than C3 photosynthesis
- C3 plants produce a 3 carbon sugar whereas C4 plants produce a 4 carbon sugar.
- C4 plants use PEP carboxylase instead of Rubisco to fix carbon
CAM vs C4 plants
CAM
- 4 carbon sugar
- temporal separation
- carbon fixation and the Calvin cycle occur in the same cells at different times
- stoma open at night to incorporate CO2 into organic acids - carbon fixation
- stoma closed during the day, and CO2 released from the organic acids used in Calvin cycle
C4
- 4 carbon sugar
- spatial seperation
carbon fixation and calvin cycle occur in different types of cells
- mesophyll cell - carbon fixation, organic acids produced
- bundle-sheath cell - calvin cycle
Light reactions vs Calvin cycle (dark) reactions
Light
- take place in thylakoid membranes
- convert light energy to the chemical energy of ATP and NADPH
- split H2O and release O2 to atmosphere
Dark
- take place in stroma
- use ATP and NADPH to convert CO2 to the sugar G3P
- returns ADP, inorganic phosphate and NADP+ to light reactions
Three basic organs of plants and their function
Roots
- anchors the plant
- absorbs minerals and water mainly through root hairs
- often stores organic substances
Stems
- Consist of alternating system of nodes were leaves are attached:
- internodes - stem segments between nodes
- axillary buds - structures with the potential to form a lateral shoot or branch
- terminal bud - located near the shoot tip, cause elongation of the shoot
- flowers are a modified stem
Leaves
- the main photosynthetic organ of most vascular plants
How many times more efficient are C4 plants at photosynthesising than C3 plants at optimal temperature?
2 to 3 times
Three tissue systems in plants and role
Dermal tissue
- outer layer for protection
Vascular tissue
- long-distance transport of materials
- two tissues: xylem and phloem
Ground tissue
- specialised cells for functions such as storage, photosynthesis and support
- fill up the plant body
eudicot vs monocot
Eudicot - embryo with 2 cotyledons
Monocot - embryo with 1 cotyledon
Tissue organisation of stems (eudicot vs monocot)
Eudicot
- vascular bundles arranged in a ring
Monocot
- vascular bundles scattered throughout the ground tissue rather than in a ring
Xylem vs Phloem
Xylem
- empty dead cells (cellulose)
- conveys water and dissolved minerals upward from roots into the shoots
- moves bottom to top ONLY
Phloem
- live cells
- transports organic nutrients from where they are to where they are needed
- either direction
Apical vs lateral meristems
Apical meristems
- located at the tips of roots and in the buds of shoots
- elongate shoots and roots through primary growth
- grow up or down
Lateral meristems
- add thickness to plants through secondary growth
- restricted to woody plants
Includes cork cambium and vascular cambium
2 types of lateral meristem and roles
Cork cambium
- adds secondary dermal tissue
- outer
Vascular cambium
- adds secondary xylem and phloem
- inner
Primary vs Secondary growth
Primary growth
- produces primary plant body including roots and shoot systems by apical meristems
Secondary growth
- adds girth to steams and roots in woody plants
- rarely in leaves
Primary growth of roots
- tip is capped
Process - zone of cell division
- zone of elongation (cells increase in size)
- zone of maturation (cell differentiation)
Phase changes in plants
Juvenile phase
- first set of true leaves
Adult vegetative phase
- more shoots, branches, leaves etc.
Adult reproductive phase
- flower to fruit or nut
Four concentric whorls of a flower, position and ABC model combination
Sepals - outside - A
Petals - A + B
Stamens (male) - B + C
Carpels (female) - inside - C
