Plants Exam 2 Review

functions of the pericycle

meristematic tissue that produces lateral roots and pathogen protection

meristematic regions and their functions

apical meristem - root growth downward

protoderm - epidermis

procambium - primary xylem and phloem

ground meristem - pith and cortex

pericycle - lateral roots

how to tell the age of a branch

count internal growth rings and bud scale scars

terminal bud

located at the end of a branch, growth makes it longer

axillary bud

buds that become branches or flowers

function of terminal bud

vertical height growth

function of axillary bud

becomes branches or flowers, outward growth

what would happen if the terminal bud was removed or damaged?

an axillary bud becomes the new terminal bud, becomes bushier outward

what forms leaf scars and what structures do they highlight?

leaf scars are formed calluses from the loss of leaves, highlight nodes

function of leaf primordia and its role with apical meristem

embryonic leaf, protects apical meristem

why is the vascular tissue formed in embryonic tissues?

primary xylem starts a water continuation, so that when it dies it will have water in it

protoderm →

epidermis

procambium →

primary xylem and phloem

ground meristem →

pith and cortex

pericycle →

lateral roots

xylem and phloem start and end in whole plant?

starts at end of root tip and goes to the furtherest point of the shoots

vascular cambium: role and what it builds

drives growth of secondary xylem and phloem, makes stems and roots thicker over time

cork cambium: role and what it builds

replaces herbaceous greens with a thick, waterproof woody layer using cork cells (suberin and phelloderm infused). builds sclerenchyema cells for protection in shoots, as pericycle was in roots.

herbaceous plants

mostly monocots and annuals, exclusively green plants made of cellulose

woody plants

has a secondary xylem, produces bark and grows for multiple years

heartwood

older, darker wood in center of plant, technically dead and infused with resins, oils, and sap

sapwood

younger, lighter wood on the outside of tree, closer to cambium with the xylem still functioning

vascular cambium location and purpose

arises between primary xylem and phloem, produces secondary xylem and phloem

cork cambium location and purpose

located in the outer bark of woody stems, outer structure is protected

why can hollowed out trees keep living and what makes this possible ?

only the outer layer of the tree is living, tree can continue to grow outward because it is still alive

softwoods

wood of conifers, grow fast and are flexible

hardwoods

dicot trees, have resin canals

corms

resemble bulbs, composed almost entirely of stem tissue w/ papery leaves

corms examples

crocus and gladiolus

bulbs

large buds surrounded by numerous fleshy leaves with a small stem at the end

bulbs examples

onions and lilies

tubers

swollen, fleshy underground stem

tubers examples

potatoes

roles of a root

anchor plants in soil, absorb water and minerals, storage of food and water, and specialized functions

dicots vs. monocots root morphology

monocots - fibrous, dicots - taproot

types of advantageous roots

buttress, prop, aerial, pneumatophores

4 regions of roots and their roles

root cap - protects apical meristem, secretes mucilage for chemical signals and acts as microbe food

region of cell division - composed of apical meristem, region of rapid cell division

region of elongation - cells lengthen

region of maturation - cells differentiate into many types

why are root hairs so efficient?

have a wide surface area to absorb water and minerals

why do root hairs need to be constantly produced?

they are fragile and easily damaged

cortex: purpose, cell composition, role in winter

purpose: stores food and nutrients

cell composition: parenchyma cells

role in winter: storage of vital nutrients that prevent plant from dying, allows for respiration

stele: parts and roles of each tissue

xylem - water and minerals

phloem - sugars

pericycle - outer boundary of stele

pith - monocots, storage, support, transport, and shape

endodermis definiton

inner boundary of cortex, single layer of compact cells

casparian strip

located in the endodermis, forces water and other substances to pass through the endodermis

path of water from the soil to xylem and phloem

root hair → endodermis → cortex → pericycle → xylem and phloem

formation of a lateral root

pericycle grows outward towards outside of root, destroying all tissue in between

determinate vs. indeterminate growth

determinate - specific, preprogrammed amount of growth for a specific plant

indeterminate - growth determined by resources, continuous growth

mychorrhizae

fungi that forms a mutualistic association

endomycorrhiza

fungi that grows within plant roots

ectomycorrhiza

fungi that grows around plant roots, not inside

rhizobium purpose

fixes atmospheric nitrogen into usable forms for leguminous plants

bacteria vs. bacteroid

bacteria - singled celled prokaryotic organisms

bacteroid - nitrogen fixing bacteria

formation from bedrock to developed soils

thousands of years of mechanical and chemical breakdown combined with organic accumulation

erosion factors

wind, water, fire, gravity, climate, soil properties

humus

organic material that remains after plant and animal matter decompose

topsoil is composed of the _____ horizons in the top _____cm of soil

A and E, 10-20

A horizon

dark with lots of organic matter

B horizon

subsoil, more clay, lighter in color than topsoil

C horizon

parent material, extends to bedrock

water levels and leaching

water levels drive leaching by pulling out water soluble substances through the soil

decomposers and their role in the soil

recycle organic matter back into the environment

the soil pyramid is composed of ________

sand, silt, clay

agricultural soil composition

40 percent silt, 40 percent sand, 20 percent clay

why is capillary water the best for plants?

water is held against the force of gravity, loosely enough to be absorbed by roots but not enough to be pulled down by gravity

saturation

gravitational water is lost, pores are filled with water

field capacity

water is available for growth

wilting point

no water is available

if pH is too acidic, what happens?

plant and symbionts can die

best pH for plant soil

5.5

purpose of flower and fruit, why are they dominant

flower - attracts pollinators and sexual reproduction

fruit - encases ovule and seeds

dominant due to seed protection, allowed dormancy, strategic dispersion and high efficiency

evolutionary advantage of inflorescence vs. a single flower

inflorescence - multiple flowers, extends window of pollination with a higher success rate by maximizing attraction

stamen vs pistil parts

stamen - anther and filament

pistil - ovary, style, stigma

how do pollinators and plants benefit from eachother

plants get help with reproduction, pollinators get a food source

true fruit vs false fruit and examples

true fruit - develops solely from a ripened ovary post-fertilization, peach or mango

false fruit - develops from other plant parts, non-ovary tissues swell and become the main fleshy part, such as a apple’s receptacle

aggregate vs. multiple fruit

aggregate fruit - derived from a single flower with several/many pistils

multiple fruit - derived from inflorescence

dry vs fleshy fruits, advantages and disadvantages

dry - hard pericarp. advantages - durable and diverse dispersal. disadvantages - limited direct dispersal, predation risk.

fleshy - soft pericarp. advantages - allows for animal dispersal and protection from damage. disadvantages - high resource cost and rapid decay.

variables needed for seed germination

water, oxygen, temperature, light

what is the ground meristem?

divide and differentiate to become hypodermis, pith, and cortex

what are the vascular tissues?

compose of xylem and phloem

what are the dermal tissues?

epidermis, endodermis

epidermis purpose

works as a tough, protective barrier against pathogens and water loss

endodermis purpose

selective diffusion barrier to keep pathogens and spores out of the stele

the secondary xylem is ______ grown in _____

continuously, dicots

monocots only have ______ xylem and phloem

primary

pros and cons of high water/low soil filled pore space

pros: initial nutrient mobility, short term drought buffer. cons: root suffocation and disease and oxygen depletion

pros and cons of high soil/low water filled pore space

pros: high oxygen levels, better nutrient cycling. cons: frequent watering required to avoid drought, reduced microbe activity

what are the major tissues in plants?

ground meristem, vascular system, dermal tissues

______ → root

radicle

_____ → shoot

plume

____ → leaves

buds or leaf primordia

_______ →

lateral roots

root cap roles

protection of apical meristem, gravity sensing, secretes mucislage for microbe food and communication