botany Flashcards
global population estimated
7.8 billion 9.7
Photosynthesis
the process by which green plants and some other organisms use sunlight to synthesise nutrients from carbon dioxide and water
Photoperiodism
the response an organism has to the changes in day length
Transpiration
the action of releasing water through the stomata
photosynthesis
6CO2+ 6H20- C6H1206+6O2
respiration
C6H1206+6O2 6C02+6H20
regulations of plant growth and development
Light, CO2, O2, Temperature, Water
how many tonnes of carbon from atmosphere fixed annually through photosynthesis via stomatal pores in land plants and through oceans
200 billion
O2 required for aerobic respiration, cell repair, reproduction decrease in O2 <15% reproduction X <2.5% reproduction Y
X reduced, Y fails
anaerobic conditions in flooded soil can lead to o XXX
ethanol toxicity in plant roots
plant enzymes best operate at what temp ?
25 degrees
viscosity of water
the measure if resistance of fluid to deformation at a given rate
viscosity X as temperature increases
decreases
viscosity if H20 is 2X as great @ 0 degrees as at 25 degrees
True
leaf scorch may occur when
Early spring (when the soil is cold and the evaporating power of the atmosphere is high)
weed
any plant not intentionally sown or propagated by the grower that requires management to prevent it from interfering from crop of livestock production
what makes a plant a weed
wrong place
wrong time
yield loss through competition
reservoir for pest and disease
when did weeds come about
10,000 years ago ice age
when were row crops weeded by horses
1731
when were tractors introduced
1920
first herbicide when and name
1946 (2,4 D dicots)
first herbicide when and name
1946 (2,4 D dicots)
How many species of weeds
30,000
Annual eg
completes lifecycle in 1 season/year eg fat hen
ephemeral
completes more than one lifecycle in 1 season year hairy bittercress
Biennial
develops vegetatively in the first yr and then flowers and sets in the second year and dies ragwort
periennel
lives for three or more years dock
reasons for weed success
rapid seedling growth
ability to grow in unfavourable conditions
competition
high photosynthetic rate
agronomic characteristics of weeds
look similar to crops
mature at the same time
tolerance to herbicide
seeds remain viable in the soil for a long time
Allelopathy -
one organism produces biochemicals which influence the growth survival development and reproduction of another organism
weed dispersal characteristic
Prolific
water
wind
animals
ragwort toxic to who
Cattle, horses, deer, goats pigs and chickens
Creeping thistle
affects crop yields and causes grassland problems
Non native weeds
Japanese knotweed
giant rhubarb
giant hog weed
Root functions
- water uptake
- anchoring
- binding the soil together
- nutrient capture
Sporophytes
Plants that has spores
First structure to appear when a seed germinates
Primary root
roots that branch off the primary root
secondary root
storage roots
adapted to store products photosynthesised in the shoot
Air roots
roots grow above ground of water and allow O2 to be transported to the inner cortex of the root system and C02 escape from the root interior
buttress roots
vertical flattened roots that project out of the ground and lower trunk
Prop/silt roots
adventitious roots that develop on a trunk or lower branch that begin as aerial roots but eventually grow into a substrate of some time
Sexual reproduction
Produces offspring by the fusion of egg and sperm genetically different parents
asexual reproduction
produced offspring without the fusion of egg and sperm. offspring are genetically identical to the parent (clones)
X% pollination in biotic Y% is abiotic
80%. 20%
Self pollination
pollen from one flower pollinates the same flower of other flowers on the same plant wheat, barley, rye
Sexual reproduction produces what
Seeds
Advantages of sexual reproduction
- variation
- adaptable to new environment
- reduced competition
Disadvantages of sexual reproduction
- two parents
- fertilisation is random so harmful variations
- flowers and seeds energetically expensive
Advantages to asexual reproduction
- 1 parent plant
- rapid colonisation
- no genetic variation ( benefit in commercial horticulture)
Disadvantage to asexual reproduction
- increased competition
- cant adapt
- adverse conditions likely to affect all individuals
seed dormancy
- extremely low metabolic rate
- suspension of growth and development
- germination occurs when seedling is like to survive
Certified seed
seed that is handled so as to satisfactory maintain genetic identity and purity and that has been approved and certified by the certifying agency
seed storage
maintenance of high seed germination rate and vigour from harvest until planting
Prinicples of seed storage
- conditions dry and cool
- pest control
- proper sanitation in seed stores
- moisture limits
- store high quality seed only well cleaned treated
natural selection
natural adjustment of genetic make up through generations over time .
Genetic engineering
involves the created of recombinant DNA which is inserted into the genetic material of a cell or virus
N2O
3rd most important long lived anthropogenic GHG
Ammonia volatilisation
process of ammonia volatillization commonly takes place when nitrogen is in an organic form called urea. most likely to take place when soils are moist and warm and source of urea is on or near the soil surface . will also take place on alkaline soils (ph > than 8)
role of S
protein - enzymes
S-S bonds link amino acids
Photosynthesis N fixation
Plant deficiency- chlorosis and stunted growth
virus move through cell junctions called
plasmodesmata
who spreads the Potatoe virus (PVY)
Aphids
Stages off Zadoks scale development
1.tillering
stem extension
heading
4. ripening
GS 31
first node detectable
key timing in crop management
-nutrient application
- growth regulator
-fungicide applied for control of fungal disease
- herbicide use to control weeds
yield components in cereal crops
ears/m^2 x grains/ear x grain weight (mean 1,000 grain weights)
non chemical control of weeds
topping
grazing
dense scar
avoid reintroduction on weed seeds in FYM
10% Weed infestation =
10% loss in forage yield
withdrawal of livestock after spraying
7-14 days
cutting interval after spraying
1-4 weeks
Pseudomonas syringae
infects a range of species
market value for cut flowers and fresh foliage is around X billion annually
16
shot hole disease on cherry laurel is a serious problem number of nursey stock with it
30%
Procambium
meristematic tissue concerned with providing the primary vascular system
osmosis
diffusion of water across a semi permeable membrane
cell sap
Is the liquid inside the large central vacuole of a plant
where do annuals thrive
frequently disturbed sites
biennials where do they thrive
not tolerant of tillage
permanent pasture waterways roadside areas
can prenennials regrow after removal of aboveground biomass?
yes
chemical control spraying control
overall spraying
patch spraying
spot spraying
thicker perennial stems what do they form
thinner ‘’ ‘’ ‘’
form conduits to distribute water and nutrients serve as stores and support above ground structures
thinner longer structures to absorb water and nutrients
Monocotyledon
typically elongated stalkless leaves with parallel veins
grasses
lilies
orchids
Dicotyledon
TWO cotyledons
broad stalked leaves
net like vines
oaks
spinach
rose
the root
is the organ of a plant that typically lies below the surface of the soil
typically develops from the radicle
growing downwards into the soil anchoring the plant and absorbing nutrients and moisture
Adventitious roots
roots that arise from anything other than the radicle
Apomixis
is asexual reproduction that produces seeds without the fusion of egg and sperm i.e it is clonal.
can occur in 2 ways :
embryo arises from an unfertilised egg cell
embryo is formed directly from some part of egg cell
Sexual reproduction is good in what environment
unstable
Seed germination
imbibition
serotiny- fire required to release seeds from plant
stratification - cold period to break dormancy( low metabolic rate, won’t germinate until it will survive, growth and development suspended)
Scarification- seed coat damaged
substantial rainfall- desert plants
dark (most seeds)
light (lettuce, celery)
largest clonal colony fungi
blue mountains Oregon
largest clonal colony- tree
Utah, 47,000-60,000 trees
roots- 80,000 years old
agaves can sprout what within 5 hours
new roots
coco de mer
mature fruit 15-30kg
requires 6-7 years to reach maturity
2 years to germinate
why don’t plants freeze to death
bud protected by hairs , wax, pitch
sugar concentration lowers freezing point
alter lipids in membrane
largest undivided leaf
giant ornamental rhubarb
largest aquatic leaf
giant amazonian waterlily
VOC
Volitile organic compounds
worlds largest individual flower
stinking corpse lily
worlds largest inflorescence
Talipot palm
worlds smallest plant
wolffia spp
xylem
carries the water taken in by the root hairs and epidermis UP the plant to the stems and leaves
Phloem
carries food produced by the leaves DOWN to the roots to be stored in the cortex
Endodermis
the inner boundary of the cortex: one cell layer thick controls the movement of water and minerals into the xylem and phloem
pericycle
a layer found inside the endodermis which may produce lateral roots
in contrast with the rests of the cortex the endodermis lacks X
cell walls contain SUBERIN in a band ( the Caspian strip)
air space
Apical meristem
region of cells capable of division and great on the root and shoot
cells divide once or twice a day
protoderm
a thin outer layer of the meristem in embryos and growing points of roots and stems which gives rise to epidermis
Ground meristem
forms the ground tissue(cortex)
Procambium
forms the primary phloem and xylem (vascular cylinder)
Root hairs are X
Short lived and older parts of the roots are hairless
Mucilage (Mucigel)
gelatine like substance secreted by root which allows organisms live underground
Water potential is measured in
megapascals (MPa)
water potential
is the measure of the tendency go theses molecules to diffuse to another area. the more free water molecules the higher the water potential
Plasmolysis
it will exhibit shrinkage
Turgid
swollen
Active transport
water is absorbed due to activities going on in the roots. absorption of water occurs with the help of energy in the form of ATP. absorption takes place AGAINST concentration gradients. even when the conc of cell say is lower than that of water.
Passve transport
passive absorption is by osmosis. takes place along the concentration gradients- when conc of cell sap is higher than that of soil water. water is absorbed when transpiration rate is high or soil is dry.
root hairs
collectively provide enormous surface area
almost always turgid because their water potential is > than that of soil
Apoplast route
movement through the cell WALLS and space between cells
symplast route
a cytoplasm continuum between cells connected ny plasmodesmata
Transmembrane route
membrane transport between cells and across the membrane of vacuoles within cells.
Cortical cells
numerous interconnections both via cell walls and via plasmodesmata which link the protoplasm of each cell…
Aquaporins
water Chanels that exist in the calomel and cell membrane
they speed up osmosis without changing the direction of water movement
Mechanisms of water movement through Xylem
Transpiration Pull
it is the pulling force responsible for lifting the water column. As water is lost in form of water vapour to atmosphere from the mesophyll cells by transpiration, a negative hydrostatic pressure is created in the mesophyll cells which in turn draws water from veins of the leaves.
Cohesion Adhesion Forces;
the water molecules in the chain are held together by hydrogen bonds which exist between neighbouring water molecules ….
Root pressure
caused by active transport of mineral nutrient ions into the root xylem.
factors affecting water absorption in plants
Soil Factors
water content
soil temp
soil aeration
flooding
texture and structure
speed of water movement
effective root zone
Atmospheric factors
temperature
relative humidity
Vapour pressure deficit ( VPD)
Wind speed
Endophytes
bacteria or fungi that live within plants
endophytes form what kind of relationships
beneficial symbiotic to parasitic
beneficial associations with both bacteria and fungi
Mycorrhizae increase the effective surface area of the roots
bacteria can supply an available source of N to the plant (in exchange for carbohydrates )
fungi and oomycetes reproduce
Asexually and sexually via spores zoospores
fungi and oomycetes grow via
hyphae
Fungi and Oomcyeyes are X closely related
fungi related to animals
oomyctes related to algae
Cell wall
rigid layer composed of cellulose.
protects and provides structural support
cell membrane
semi permeable helps in regulating what substances come in and out
nucleus
vital part of the cell. contains DNA info for growth and division
Vacuole
most of the cell surrounded by vacuole
support against pressure of cell wall stores toxins swell
ribosomes
site of protein synthesis protein factory
mitochondria
breaks complex molecules down and provides energy powerhouse cell
Ground tissue
parenchyma- thin walls photosynthesis in leaves and storage roots
collenchyma-shoot support
sclerenchyma -dead thick cells
where are endophytic bacteria mostly found
above ground tissue (intercellular spaces xylem vessels)
