BSC 196 Biology Unit 3: Key Concepts and Definitions

plant hierarchical organization

organs, tissues, and cells

roots stems and leaves

root and shoot system above ground

shoot system

major site of CO2 and light uptake

root and shoot system below ground

root system

major site of mineral and water uptake

roots

anchor, absorb, and store carbohydrates

primary root first to emerge and forms lateral roots

root hairs increase the root surface area

taproot system

large central dominant root and sprouts lateral roots

anchors plant in soil

fibrous root system

thick bunch of thin roots

prevents erosion

adventitious roots

root adaptation

same functions as lateral roots but develop from aerial tissues

prop roots

root adaptation

roots that grow partially in the air and partially in the ground

buttress roots

root adaptaion

large, above ground roots that provide stability in tropical trees

increase nutrients around trees

storage root

stores plant food in the form of starchy carbohydrate

also a tap root

potato, carrot, cassava

stems

organ bearing leave and buds

nodes

points where leaves are attached to stem

internodes

the stem segments between nodes

buds

apical- elongation of the stem

axillary- goes on to form lateral branch or flower cluster

rhizomes

horizontal underground stems

stolons

"runners"

asexual reproduction

mother plant produces daughter plants

tubers

the thick, fleshy parts of underground stems, potatoes

asexual reproduction

potatoes

leaves

flattened blade attached to petiole (stalk) petiole attaches to node

main photosynthetic organ (most are specialized for it)

intercept light

exchange gases

dissipate heat

defend from herbivores and pathogens

simple leaf

single undivided blade

compound leaf

single blade is separated into leaflets

are not separate leaves

argued to be important defense against pathogens

monocots

have one cotyledon (seed leaf)

parallel veins

eudicots

have two cotyledon (seed leaf)

branching veins

tendrils

leaves that are adapted to attach to a supporting structure

storage leaves

Present on bulbs which have a short underground stem and modified leaves that store food

onions

3 main basic tissue types

Dermal - blue

Vascular - purple

Ground - yellolw

dermal tissue system

in non woody plants tissue is the epidermis

has a waxy coating (cuticle) to help prevent water loss

in woody plants periderm replaces the epidermis in older regions of stems and roots

vascular tissue system

transports resources and provides mechanical support

xylem conducts water and dissolved minerals upward from roots to shoots and dead at maturity and a one way system

phloem transports sugars from where they are made (primary leaves) to where they are needed (growth/storage) and a two way system

ground tissue system

primary growth

lengthens roots and stems and leaves

apical meristems

secondary growth

increases a plant's width or thickness

lateral meristems

vascular cambium

adds layers of vascular tissue called secondary xylem (wood) and secondary phloem

cork canbium

meristem that produces cork on the outside and produces periderm

morphogenesis

the development of body form and cell organization

cell differentiation

cells with same genes become different from one another

cell elongation

process directly responsible for growth with a water intake around 90%

Unequal expansion perpendicular to cellulose microfibrils supporting cell

pattern formation

development of specific structures in specific locations

depends on gene expression

cell fate is determined by final position

plant development- flowering

involves phase change from vegetative ti reproductive growth

indeterminate vegetative meristem to determinate reproductive meristem

combination of environmental cues and internal signals

ABC hypothesis

A model of flower formation identifying three classes of organ identity genes that direct formation of the four types of floral organs.

A- seplas

B- petals

C- stamens and carpals

Resource Aquisition and transport in plants

diffusion, active transport, and bulk flow act together

natural selection in vascular plants favored

taller plants, flat appendages (stems and leaves), multicellular branching roots and efficient transport

xylem and phloem allows for long distance resource

Adaptations for acquiring resources:stems

Stems for water and nutrient transport and providestructural support for leaves

finite resources

trade off between growing tall and branching out

Adaptations for acquiring resources:leaves

Generally, positive correlation between water availability and leaf size

phyllotaxy

arrangement of leaves on a stem, important for light capture

self-pruning

nonproductive shaded leaves undergo programmed cell death and drop

low light conditions

horizontal leaves capture more sunlight

sunny conditions

vertical leaves are less damaged by sun and allow light to reach lower leaves

Adaptations for acquiring resources: roots

roots respond to local changes in conditions to maximize nutrient uptake

increase surface area for absorbing water and minerals

mycorrhizae

roots and hyphae of soil fungi form mutualistic associations

soil horizons

Layers of soil

topsoil

top layer of soil, most important layer

consists of mineral particles, living organisms and humus(decaying organic material)

b horizon

less organic matter

C horizon

partially broken down rock

soil solution

water and dissolved minerals in the pores between soil particles

half water half air

loams

most fertile topsoils and contain equal amounts of sand, silt, and clay

balances aeration

soil properties: composition

include cations and anions

cations adhere to negatively charged soil particles reducing leaching from soil, are displaced from soil particles by other cations during cation exchange, and are taken up by plant roots

most particles are anions as well as many nutrients, they do not bind with soil particles and can be lost from the soild by leaching

soil properties: organic components

humus prevents clay particle packing and retains water but is porous, increases soils cation exchange capacity, and acts as mineral nutrient reservoir

soil management

use of plowing methods and fertilization to prevent or reduce soil depletion and erosion for agriculture and settlements

agriculture

depletes mineral content of soils, taxes water reserves,

ands encourages erosion

sustainable agriculture

conservation-minded, environmentally safe, and profitable

irrigation issues

huge drain on water resources, especially in arid regions

primary source of irrigation water are underground reserves

irrigation solutions

Drip irrigation - slow release of water directly at plant root

erosion solution

Planting trees as windbreaks

Including perennials in crop rotations,

Using cover crops,

Terracing hillside crops,

Cultivating in a contour pattern,

Practicing no-till agriculture

resource incorporation into plants

essential elements

17 essential elements , researchers use hydroponic systems that are stacked to determine which elements are essential

essential macronutrients

9 essential ones and required in relatively large amounts

essential micronutrients

8 essential ones and required in relatively small amounts

dead plants

provide energy needed by soil-dwelling microorganisms

living roots

their secretions support microbes in near root environment

rhizosphere

layer of soil closely surrounding the plant's roots

rhizobacteria

bacteria in the rhizosphere or in close association with plant roots

depend on nutrients secreted by plant and in return helps enhance plant growth

produce chemicals, antibiotics, and absorb toxic metals

endophytes

nonpathogenic bacteria living between hostplants cells

depend on nutrients secreted by plant and in return helps enhance plant growth

produce chemicals, antibiotics, and absorb toxic metals

nitrogen cycle

series of natural processes that transform nitrogen and nitrogen-containing compounds

Ammonium process in plants

Nitrifying bacteria oxidize ammonia (NH3) to nitrite (NO2-)

Different nitrifying bacteria oxidize NO2- to NO3-

Plant enzymes convert NO3- to ammonium

nitrogen fixation

the conversion of nitrogen gas into ammonia

legume nitrogen fixation

along legume roots are swelling called nodules

nodules are composed of plant cells infected by nitrogen fixing rhizobium bacteria

bacteroid

A form of the bacterium Rhizobium contained within the vesicles formed by the root cells of a root nodule.

legume nitrogen fixation steps

chemical signals attract bacteria and an infection thread forms

Bacteroides form

growth continues and a root nodule forms

the nodule develops vascular tissue

the mature nodule grows to be many times the diameter of the root

crop rotation

takes advantage of the agricultural benefits of symbiotic nitrogen fixation

one-year legumes planted and the other year non legumes planted

Ectomycorrhizae

A type of mycorrhizae in which the mycelium forms a dense sheath, or mantle, over the surface of the root. Hyphae extend from the mantle into the soil, greatly increasing the surface area for water and mineral absorption.

arbuscular mycorrhizae

microscopic fungal hyphae extend into the root and penetrate cell wall but not plasma membrane

Epiphytes

an alternative nutritional strategy

grow on another plant and obtain water and mineral from air and rain

do not tap into hosts for nutrition (not parasites)

parasitic plants

an alternative nutritional strategy

absorb water, sugars, and minerals from their living host plant

carnivorous plants

alternative nutritional strategies

photosynthetic but obtain nitrogen by killing and digesting mostly insects

key features of angiosperms

double fertilization, flowers, fruits

angiosperm male

pollen develops from microspores within the microsporangia (pollen sacs) of anthers

microspore undergoes mitosis to produce generative and tube cell

pollen grain

structure that contains the entire male gametophyte in seed plants

angiosperm female gametophyte

within ovule 2 integuments surround megasporangium except gap (micropyle)

pollination

transfer of pollen from anther to stigma

double fertilization

2 sperm reach female gametophyte

one sperm fertilizes egg, forming zygote

one combines with two polar nuclei forming food storing endosperm

seed development

seed develops after fertiloization

surrounding ovary develops into fruit

in germination embryo develops into new sporophyte

endosperm development

endosperm stores nutrients for use by seedling

some eudicots food reserves exported to cotyledons (seed leaves)

embryo development

first miotic division splits the zygote into basal and terminal cell

basal cell

produces a multicellular suspensor, which anchors the embryo to the parent plant

terminal cell

gives rise to most of the embryo

cotyledons form and the embryo elongates

seed dormancy

Seed dehydrates and enters a state of dormancy until conditions are favorable for germination

breaking this often requires specific enviornmental cues like temperature, rain , and fire

germination and seedling development

depends on imbibition (the uptake of water due to low water potential of the dry seed)

radicle

embryonic root

emerges first and developing roots system anchors plant

flowering

Flowers of a given plant species are synchronized to appear at a specific time of the year to promote outbreeding

triggered by a combination of environmental cues and internal signals

fruits

mature ovary of a flower

protects enclodes seeds and aids in dispersal by wind or animals

some fruits ovary dries out and some remain fleshy