Plant Form and Function Flashcards
What is a tissue?
A group of cells consisting of one or more cell types that together perform a specialized function.
What is an organ?
Consists of several types of tissues that together carry out particular function
What are apical meristems?
Populations of pluripotent stem cells that divide to produce new tissues and act as localization regions of cell growth.
What are lateral meristems?
Stem cells that add thickness to woody plants during secondary growth.
What are the types of meristems?
Shoot apical meristem (SAM): primary growth and axial growth, make up primary tissues
Root apical meristem (RAM): Primary growth and axial growth, make up primary tissues
Vascular cambium (VC): grows before CC; bifacial meristem that makes up secondary xylem (wood) and secondary phloem
Cork cambium (CC): grows after VC; replaces epidermis with periderm (cork, cork cambium, and phelloderm)
What are the three tissue systems in a plant?
Dermal tissues, vascular tissues and ground tissues.
What does the dermal tissue system consist of?
- Epidermis
- Cuticle
- Periderm (woody plants)
- Trichomes
What is the cuticle of a plant?
Waxy coating that covers the leaves of land plants and stems of non-woody plants to prevent water loss from the epidermis and act as a reflective surface to cool down.
What are trichomes?
Biotic outgrowths of shoot epidermis that reduce water loss, defend against insects, increase relative humidity by trapping water.
What does the vascular tissue system consist of?
Xylem: conducts water (+dissolved minerals) from roots to shoots
Phloem: transports nutrients from where they are made (typically leaves) out to the rest of the plant
What is a stele? What is the difference between the steele of roots, stem, and leaves?
The collective term for vascular tissue.
Roots: xylem in middle, phloem outside
Stem: xylem in middle, phloem on outside, sclerenchyma outisde phloem
Leaves: Xylem upwards, phloem downwards
What is the ground tissue?
Tissues that are neither dermal not vascular, made of specialized cells for storage, photosynthesis, support and transport
What is the pith and the cortex?
Pith: ground tissue internal to vascular tissue
Cortex: ground tissue external to vascular tissue
What are the type of differentiated cells of the ground tissue?
- Parenchyma cells
- collenchyma cells
- sclerenchyma cells
What do parenchyma cells do? How are they structured?
Least specialized cell in ground tissue that performs metabolic functions, store cellulose, sugar and proteins, and divides and differentiates. They have thin and flexible primary walls strengthened by lignin, but lack secondary walls.
What do collenchyma cells do? How are they structured?
Provide flexible support without restraining growth to support young parts of the plant shoot. They are grouped in strands and have thicker, uneven cell walls.
What is the structure of sclerenchyma cells?
Have thick secondary walls strengthened with lignin and are dead at maturity. Either sclereid (short and irregular) or fibers (long and slender, arranged in threads)
What does an angiosperm embryo develop into?
- Primary dermal, ground and vascular tissue
- SAM and RAM
- Cotyledons
What is the difference in the structure of eudicot seeds and monocot seeds?
Eudicot: embryo consists of two thick cotyledons
Monocots: embryo has one cotyledon
What is the purpose of seed dormancy?
Increases the chances that germination will occur at a time and place most advantageous to the seedling.
What triggers breaking of seed dormancy?
environmental cues such as temperature or lighting changes.
What does germination depend on?
Imbibition: uptake of water due to low water potential
What is the radicle?
Embryonic root that emerges first to anchor the shoot that follows.
What is the function of a root?
- Anchoring the plant
- Absorbing minerals and water
- Storing carbohydrates in the form of starch
What is the difference between the primary root and lateral root?
Primary: anchor the system into the soil by growing downwards
Lateral/secondary: explore the soil through environmentally responsive radial growth and determine the overall root system size
What occurs at the root apical meristem?
Primary root growth: RAM produces root cap to protect the root tip as it grows through the soil and produces no lateral appendages.
What are the three zones of cells following the root cap?
- Zone of cell division
- Zone of elongation
- Zone of differentiation/maturation
What is the purpose of root hairs?
to give more surface area for absorption of water and nutrients
What is the root cap?
Secretes polysaccharide slime and continually sloughs off as the root pushes through the soil. It produces signals to attract beneficial microbes and senses gravity to grow down into the soil.
What does the cross section of a eudicot root look like?
Xylem forms a cross in the centre, with phloem between the arms. The cortex is filled with parenchyma cells that store starch which form the endodermis in the centre.
Where is the endodermis and what does it do?
Innermost layer of cells in the root cortex that surrounds the vascular cylinder and regulates passage of substances from soil into the vascular cylinder.
What does the cross section of a monocot look like?
Core parenchyma cells are surrounded by a ring of xylem (inward) and ring of phloem (outward)
What is the pericycle?
The outermost cell layer in the vascular cylinder where lateral roots arise.
What is the difference between the tap root system and the fibrous root system?
Tap: tall plants with large shoot masses (found in eudicots and gymnosperms)
Fibrous: adventitious roots (lateral roots) that come from the stem (found in monocots)
What are root adaptations?
Prop roots (hold up plant)
storage roots (store sugar)
Green roots (photosynthesize)
Pneumataophores (allow roots to obtain air)
strangling aerial roots (support)
What are the functions of the shoot (stem and leaves)?
- Photosynthesis
- Transpiration (loss of water through open stomata)
- Transport (xylem and phloem)
- Reproduction (flowers, cones, leaves)
What are the parts of the stem organ?
- Nodes: where leaves attach
- Internodes: between leaves
- Axilliary Bud: Buds that have the potential to form a lateral shoot
- Apical bud: elongation of the main shoot (dominant)
What does the cross section of a eudicot stem look like?
Vascular tissue consists of vascular bundles arranged in a ring. The bundle has an outer sclerenchyma, middle phloem, and an inner xylem.
What does the cross section of a monocot stem look like?
Vascular bundles are scattered throughout the ground tissue rather than forming a ring