Plant Form and Function Flashcards
Define cell
the fundamental unit of life
Define tissue
a group of cells consisting of one or more cell types that together perform a specialized function
Define organs
consists of several types of tissues that together carry out particular functions
Describe the arrangement of xylem and phloem in monocots
a core or parenchyma cells (pith) surrounded by alternating rings of xylem and phloem
Describe the arrangement of xylem and phloem in dicots
the xylem is a star with phloem between the arms
Do dicots or monocots have two layers of leaf mesophyll?
Dicots
Do dicots or monocots have common or rare secondary growth
rare-monocot, common-dicot
Describe nodes
nodes are where leaves/branches are attached, they alternate with internodes
What is the general function of apical buds?
To elongate young roots and shoots
What is the general function of axillary bud?
to form a lateral branch, thorn, or flower
What is the general function of stems?
to elongate and orient the shoot for photosynthesis
What are some examples of stems with specialized functions? Describe them
Rhizomes are underground stems, stolons serve in asexual reproduction, tubers
What are some functions of roots (3 main)?
Anchor, absorb minerals and water, stores carbohydrates
Describe the formation of roots in large or non-trailing plants
the primary root is the first to emerge, it branches to form lateral roots which improve anchorage and water absorption (most of the absorption happens here)
Describe the formation of roots in small or trailing plants
the primary root dies early on and adventitious roots come from the stem to make lateral roots
What is the main function of root hairs? How are they able to achieve this?
Root hairs (extensions of epidermal cells) form from the root tip and increase the absorptive surface
Make up 70-90% of the surface area
Name some generalized specialized functions of some roots
Support, oxygen, storage
What is the main function of leaves?
they are the main photosynthetic organ of most vascular plants (green stems do a little)
What are some side/minor functions of leaves (3)?
Exchange gas, dissipate heat, defend from herbivores and pathogens
What is the difference between gross primary productivity and net productivity in relation to plants?
The gross primary productivity is all the food made, the net is what we get
What is the function of a chromoplast?
it produces bad-tasting or poison compounds
What is the function of stomata?
They are pores in the epidermis that allow for gas exchange
Where are stomata located? Why?
Major avenues for evaporation loss (so most are on the lower side of the leaf)
What is the function of guard cells?
they open and close to control stomata
What are some specialized functions of leaves?
spines, reproduction, storage, tendrils
What basic plant organ is a flower? What special thing do they have? (not like petals or stuff like that)
Specialized leaves that have meristems
Do trees produces leaves on the previous year’s stem, other branches, or both?
Branches
Where do leaves develop from? Where do axillary buds develop from?
Leaf primordia along the sides of the shoot apical meristem, meristematic cells left at the base of apical meristems
What are the two major parts of a leaf?
A flattened blade and a stalk (petiole) (the petiole is not an actual part of the leaf but it connects the leaf to the stem)
Describe compound leaves
one blade divided into leaflets
How does a bud scar form?
it is the remainder of last year’s apical bud
(Leaves) What kind of tissue is between the upper and lower epidermis? What general category does it belong to? What kind of cells does it have?
Mesophyll, ground tissue, parenchyma
(Leaves) Describe the two layer tissue setup that is between the upper and lower epidermis in eudicots
mesophyll has two layers: the palisade in the upper part and the spongy in the lower part (loose arrangement for gas exchange)
Palisade is lined up in rows
What two functions do veins serve in leafs? What encloses them?
Veins are the leafs vascular bundles and skeleton
Each vein is enclosed by a protective bundle sheath
What type of tissue makes up most of a plant?
Secondary xylem
What are the three tissue systems in plants?
Dermal, vascular, ground
What is the function of the periderm?
a protective layer that replaces the epidermis in older spots (woody plants only, impermeable to water and gases)
What is the type of dermal tissue in nonwoody plants?
Epidermis
What is the function of a cuticle? What kind of tissue is it?
Prevents water loss, in the epidermis
What are some functions of trichomes? What kind of tissue are they?
reduce water loss, reflect light, and can help defend against insects (can also secrete oil), epidermis
What are the four groups that make up vascular plants?
Angiosperms, gymnosperms, ferns, lycophytes
Describe the movement of water in xylem
water and minerals go upwards from the roots into the shoots
Describe tracheids. What type of tissue are they are part of?
Long, thin cells with tapered ends (all vascular plants)
Water moves between these through pits, thin regions lacking secondary walls
a type of cell in xylem
Describe vessel elements. What type of tissue are they part of? What kinds of plants are they found in?
Common to most angiosperms, and a few gymnosperms and a few seedless vascular plants
End walls have perforation plates so water can flow freely
Xylem
Describe the movement of sugars in phloem
from the production area (mostly leaves) to storage structures or areas of growth
What kinds of plants have sieve cells?
seedless vascular plants and gymnosperms
Describe sieve tubes using the words sieve-tube elements, sieve plates, companion cell, and plasmodesmata
Chains of cells are called sieve-tube elements
Sieve plates are porous end walls between sieve-tube elements that allow fluid to flow between cells
Each sieve-tube element is connected to a companion cell (that has organelles) by plasmodesmata
Their nucleus and ribosomes also serve adjacent ones
Sieve tube elements are food-conducting tubes that are located in the phloem
What is weird about the cells that make up phloem?
they are alive, but lack organelles
Describe pith
ground tissue internal to the vascular tissue
Describe cortex
ground cells that are external to the vascular tissue
Parenchyma, collenchyma, or sclerenchyma- dead at functional maturity
sclerenchyma are dead at functional maturity
Parenchyma, collenchyma, or sclerenchyma- lack secondary walls, have thin and flexible primary walls
parenchyma lack secondary walls, have thin and flexible primary walls
Parenchyma, collenchyma, or sclerenchyma- purpose is to provide flexible support without restraining growth
collenchyma provide flexible support without restraining growth
Parenchyma, collenchyma, or sclerenchyma- most of the ground tissue
parenchyma make up most of the ground tissue
Parenchyma, collenchyma, or sclerenchyma- retain the ability to divide and differentiate
parenchyma retain the ability to divide and differentiate
Parenchyma, collenchyma, or sclerenchyma- a large central vacuole
parenchyma have a large central vacuole
Parenchyma, collenchyma, or sclerenchyma- rigid because of thick secondary walls with lignin
sclerenchyma are rigid because of thick secondary walls with lignin
Parenchyma, collenchyma, or sclerenchyma- unevenly thickened primary cell walls
collenchyma have unevenly thickened primary cell walls
Parenchyma, collenchyma, or sclerenchyma- perform the most metabolic functions (ex: photosyntesis)
parenchyma perform the most metabolic functions
Parenchyma, collenchyma, or sclerenchyma- grouped into strands to help support young or herbaceous parts of plant shoots
collenchyma are grouped into strands to help support young or herbaceous parts of plant shoots
Describe the two types of sclerenchyma cells
Sclereids are short and irregular in shape and have thick, lignified secondary walls
Fibers are long and slender and arranged in threads
What kind of tissues are in “bark”?
everything that is external to the vascular cambium, including secondary phloem and periderm
What is the function of lenticels?
Lenticels in the periderm allow gas exchange between the living parts of the stem/root and air
What is the term for continuous growth?
indeterminate
What are meristems?
unspecialised tissues made of dividing cells
What are initials?
Initials (stem cells) remain in the meristem and produce more cells
What is the process that is responsible for increase in plant size? How does it work? How does it relate to microfibrils?
cell elongation
Cells grow rapidly with little energy by taking in water, storing in vacuoles
Cellulose microfibrils in the cell wall restrict the direction of elongation
Describe the difference between annuals, biennials, and perennials
Annuals complete their life cycle in a year or less
Biennials require two growing seasons (first year is non-reproductive)
Perennials live for many years
What is developmental plasticity?
the effect of environment on development
What is morphogenesis?
the development of body form and cell organization
What determines cell differentiation in plants?
Differentiation depends on gene expression, but is determined by position
What is the symmetry of cell division in plants?
Asymmetrical division signals many key events in development. The first division of a zygote is asymmetrical and initiates polarization
Relate polarity and the structure of plants
Polarity is the condition of having structural or chemical differences at opposite ends
Plants have an axis with a root end and a shoot end
What is pattern formation? What are the two theories as to how it relates to the fate of plant cells?
the development of specific structures in specific locations
Lineage-based mechanisms (Cell fate is determined early in development and passed on to daughter cells) or
Position-based mechanisms
(Cell fate is determined by final position)
Give an example of how gene activation depends on cell-to-cell communication
Arabidopsis root epidermis forms root hairs depending on the # of cortical cells it touches
Formation of root hairs is dependent on the differential expression of the GLABRA-2 gene
Describe the ABC hypothesis of flower formation
A gene activity makes sepals, A and B gene activity makes petals, B and C gene activity makes stamens, and C gene activity makes carpels
Mutants lacking A have only carpels and stamens, mutants lacking B have only carpels and sepals, and mutants lacking C have only sepals and petals
Give some examples of why Arabidopsis is a model organism
Small size, short generation time, prolific seed production, and small genome size (first plant to have genome sequenced,
27,000 genes divided among five pairs of chromosomes)
Outward appearance varies markedly with different environmental conditions
Where are apical meristems located? What function do they serve?
Located at the tips of roots and shoots
Elongate shoots and roots
Describe apical dominance
Apical merstems Send out hormones that prevent the growth of lateral branches/axillary buds
The closer they are, the more inhibited it is
The apical dominance is stopped if the shoot tip is removed or shaded
What three things do apical meristems produce? What do those make?
Protoderm, which makes dermal tissue
Ground meristem (middle), which makes ground tissue
Procambium, which makes vascular tissue
What is the function of a root cap?
protects the apical meristem
What are the three zones of growth in roots?
Cell division
Elongation (by taking up lots of water)
Differentiation/Maturation
What kind of cells fill the cortex?
ground tissue (mostly parenchyma)
What is the innermost layer of the cortex called? What does it do?
endodermis
Regulates passage of substances from soil to vascular cylinder
Protects against poisons and viruses
What is the function of pericycle? Where is it?
The vascular cylinder of roots has a solid core of xylem and phloem surrounded by a cell layer called pericycle
Lateral roots arise from the pericycle and destructively push through the outer tissues
What is the general product of the vascular cambium?
layers of secondary xylem (wood) and phloem
What does secondary xylem consist of? (3)
tracheids, vessel elements (in angiosperms), and fibers
Relate early and late wood
Early wood is formed in the spring in temperate region and has thin cell walls to maximize water delivery
Late wood is formed in the summer and has thick cell walls for support
Define dendrochronlogy
Tree rings are visible where late and early wood meet and can be used to estimate a tree’s age
Dendrochronology is the analysis of tree ring growth patterns and can be used to study climate change
Thick rings=warm/wet year
Thin rings=cold/dry year
Relate heartwood and sapwood
Heartwood is older layers of xylem that no longer function
Sapwood is outer layers that still transport materials
What happens to old secondary pholem?
sloughs off and does not accumulate
What is the direction of production for secondary xylem and phloem?
Xylem is towards the core, phloem is towards the outside
What is the function of elongated initials? How are they arranged?
Oriented parallel to the axis of the stem or root
Produce tracheids, vessel elements, fibers of xylem, sieve-tube elements, companion cells, axially oriented parenchyma, and phloem fibers
What is the function of shorter initials? How are they arranged?
Oriented perpendicular to the axis of the stem or root
Produce vascular rays (Radial files of parenchyma cells that connect secondary xylem and phloem)
What is the function of the cork cambium?
Replaces the epidermis with periderm (towards the outside)
