Flashcards in Module 6 - Plant Form and Function Deck (58)
Autotroph vs heterotroph
- self-sufficient without eating other living organisms
- produce their own energy
- plants, algae, certain protists, some prokaryotes
- 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
- an accessory pigment
- absorbs different wavelengths of light
- pass the energy to chlorophyll a
What is the name of other accessory pigments?
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
- 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
- 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
- take place in thylakoid membranes
- convert light energy to the chemical energy of ATP and NADPH
- split H2O and release O2 to atmosphere
- 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
- anchors the plant
- absorbs minerals and water mainly through root hairs
- often stores organic substances
- 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
- 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
- outer layer for protection
- long-distance transport of materials
- two tissues: xylem and phloem
- 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)
- vascular bundles arranged in a ring
- vascular bundles scattered throughout the ground tissue rather than in a ring
Xylem vs Phloem
- empty dead cells (cellulose)
- conveys water and dissolved minerals upward from roots into the shoots
- moves bottom to top ONLY
- live cells
- transports organic nutrients from where they are to where they are needed
- either direction
Apical vs lateral meristems
- located at the tips of roots and in the buds of shoots
- elongate shoots and roots through primary growth
- grow up or down
- add thickness to plants through secondary growth
- restricted to woody plants
Includes cork cambium and vascular cambium
2 types of lateral meristem and roles
- adds secondary dermal tissue
- adds secondary xylem and phloem
Primary vs Secondary growth
- produces primary plant body including roots and shoot systems by apical meristems
- adds girth to steams and roots in woody plants
- rarely in leaves
Primary growth of roots
- tip is capped
- zone of cell division
- zone of elongation (cells increase in size)
- zone of maturation (cell differentiation)
Phase changes in plants
- 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
What is cotransport?
A mechanism in which a transport protein couples the passage of one solute to the passage of another
What is the apoplast?
the continuum of cell walls plus extracellular spaces
What is the plasmdesmata?
the cytoplasmic channels ('gap junctions' of plant cells)
What is the symplast?
The cytoplasmic continuum
Three transport pathways in plants
- out of one cell, across a cell wall and into another cell
Symplastic route - through the continuum of cytosol connected by plasmadesmata
Apoplastic route - through the continuum of cell walls and extracellular spaces
Role of Casparian strip
controls the kind and amount of molecules that enter the plant
Cohesion vs adhesion
Cohesion - stickyness between water molecules
Adhesion - attraction between water molecules and walls of xylem tissue
What is translocation?
transport of photosynthesis products in the plant
What is phloem sap?
- an aqueous solution that is mostly sucrose
- travels from a sugar source to a sugar sink
- the direction of travel is variable
Sugar source vs sugar sink including examples
Source - a plant organ that is a producer or sugar e.g. mature leaves
Sink - an organ that is a net consumer or storer of sugar e.e. roots, growing buds, stems, growing eaves, tubers, fruit
What is etiolation?
growing in darkness
What is tropism?
any growth response that results in curvatures of whole plant organs toward or away from a stimulus e.g. phototropism - response to light
6 plant hormones
- Abscisic Acid (ABA)
Role of the plant hormone ethylene
- produced in response to stresses
- apoptosis (programmed cell death)
- fruit ripening
- slows down primary growth but NOT secondary growth
- regulated by ACC synthase
Role of plant hormone Abscisic Acid (ABA)
- stress hormone
- seed dormancy
- drought tolerance
Role of the plant hormone Brassinosteroids
- the plant sex hormones
- induce cell elongation and division
- plants die without it
Role of the plant hormone Gibberellins
- stem elongation
- fruit growth
- seed germination
Role of the plant hormone Cytokinis
- stimulates cell division
- works together with zuxin in apical dominance
- retard the aging of some plant organs
Role of the plant hormone Auxin
- promotes cell elongation
effects of light on plant morphology
2 types of photoreceptors
- control hypocotyl elongation, stomatal opening and phototropism
- regulate many of a plant's response to light throughout its life
2 types of phytochrome
- sensitive to red light
- starting state
- dimers seperate
- sensitive to far-red light
- signals responses
- dimers together
photoperiod - the relative lengths of night and day used by plants to detect the time of year required for certain developmental processes such as flowering
physiological response to photoperiod
Short day vs long day plants
Short day - flower in autumn and winter
Long day - flower in spring and summer
Define gravitropism, and explain how is can be positive or negatice
Gravitropism - response to gravity
Positive - go with gravity e.g. root growth
Negative - go against gravity e.g. shoot growth
changes in form that result from mechanical perturbations
e.g. daily disturbance such as wind results in short, bushier trees
What is a GM plant?
A plant to which we had added extra DNA using recombinant techniques in the lab
What bacterium transfers genes to plant genomes? What does it typically cause?
Causes 'crown gall' disease and is natures genetic engineer
What is the role of phytohormone synthesis genes in GM plant procedures?
cell proliferation to create the bacterium's gall
What is the role of opine biosynthesis genes in GM plant procedures?
Nutrient secretion for Agro bacterium
What is the 3 step process of inserting a gene into a plant?
1. Cut out the disease-producing DNA
2. Insert the DNA that we want to transfer
3. Let Agro bacteria do its work (which is to infect the plant tissue)
Is Agrobacterium effective on dicots or monocots? Why?
Dicots as they are its natural host