Plant Form and Function

Genetic difference between individuals --initially influences an organism's genes heavily

Differences between individuals due to the environment --subjected to the environment can lead to change or an organisms morphological diversity and differentiation between species

--Underground part of a plant that anchors the plant and absorbs water and nutrients; conduct water and selected ions to the shoot and store material produced in the shoot for later use.
--snorkel: function in gas exchange --adventitious root: develops from the shoot system instead of the root system (ex: ivy plant roots help them cling to brick walls)

Above ground part and function to harvest light and elevate leaves fro maximum light exposure.
--cacti: water storage-- stolon (above soil) and rhizomes (below soil)-- asexual reproduction-- tubers: carbohydrate storage--Thorns: defense

Appendages that project from a stem laterally to provide photosynthetic organs.
--cactus spines: protect the stem--onion leaves: store food--Aloe vera leaves: store water--Pea tendrils: aid in climbing--Poinsetta leaves: attract pollinators--Pitcher plant leaves: trap insects--Flowerpot plant leaves: collect soil

One grown in light-open sunny habitat--- no light competition
One grown in a forest-- competition for light is intense
example of how environment creates phenotypic plasticity of two trees that began with similar genes

More living cells in sapwood No living cells in heartwood , wet wood, discolored wood and false wood
Wood is highly ordered arrangement of living, dying and dead cells-- cell wall are made up of cellulose, lignin, hemicllulose.--Vessel/tracheids are very large compared to parenchyma cells --Vessels, fibers and tracheids live only a short time
Volume basis-- sapwood is mostly dead#-of-cell basis-- sapwood is mostly alive

--key for plant growth and development--site of cell division--cells are undifferentiated undifferentiated cells: retain the ability to undergo mitosis and produce new cells

Axillary meristem and a leaf internode: distance between nodes (place where stems expand)

Apical meristem- located at the top of each root and shoot-Group of undifferentiated plant cells that is responsible for primary growth
Axillary meristem: -also known as the bud apical meristem-may develop into a lateral branch
Branching:-axillary meristems lead to branching whereas apical meristems lead to vertical growth.

Promote internode elongation--in an environment where trees are close to one another and light competition is intense (trees taller, internodes longer)
Inhibit internode elongation-promoted in environments where there is no competition for light (shorter trees, shorter internodes)

Promote Branching-environments of open areas where there is a lot of sunlight and no competition
Inhibit Branchingthere is high competition for sunlight because the plant has to focus on certain branches getting tall in order to compete for sunlight

1. meristematic cells-undifferentiated cells (go on to become specialized cells)-undergo cell division in meristem-small/similarly look cells 2. parenchyma cells-usually spherical or oblong-only primary cell walls-store starch deposits and basic metabolic cell functions -universal cell type-living3. collenchyma cells-elongated cells -primary cell walls (plastic)-function mainly in support-even when mature their cell walls hold the ability to stretch and elongate -living4. sclerenchyma cells-specialized support cells that produce a thick secondary cell wall in addition to a think primary cell wall-secondary cell wall has lignin-non-expandable secondary cell wall-Supporting stems and other structures after active growth -usually dead at maturity (NO CYTOPLASM)-protection

Sieve elements-long, thin cells that have perforated ends (sieve plates)-responsible for transporting sugars and other nutrients -lack nuclei/chloroplasts/ most other major organelles
Companion cells-contain all of the organelles normally found in a plant cell
-companion cells are not conducting cells that provide materials to maintain the cytoplasm and plasma membrane of sieve-tube members-Load and unload carbohydrates and other nutrients from the solution inside sieve-tube members
Tracheids-in all vascual plants-water-conducting cells -long, slender with tapered ends-pits (gap in primary and secondary cell wall)
Vessel Elements-shorter/wider-angiosperms-conducting cells-perforations ( opening that lacks primary cell wall, still has secondary cell wall)
-tracheids and vessel elements are DEAD at maturity and interact with fluids they conduct instead of the cytoplasm-don't need companion cells to maintain a cytoplasm or plasma membrane

Epidermal -complex tissue consisting of...1. epidermal cells2. guard cells3. trichome cellsFUNCTION: protection, gas exchange