Labs 2 & 3 Flashcards
what functions do stems provide for a plant?
- support: stems provide the axis upon which leaves, buds, and flowers form. This elevates the leaves for photosynthesis, flowers for pollen release, and fruits for seed release.
- transport: stems are a pathway for the movement of water and mineral nutrients from roots to leaves and the transport of sugar, hormones, and other metabolites from one area of the plant body to the other
- growth: new cells are produced by mitosis occurring primarily in the shoot apical meristem, housed in the shoot tips of the plant
- storage: stems store water, food, and other plant products that may be required in different areas of the plant body at different times during the year
what is the purpose of many stem modifications?
asexual reproduction
what is a rhizome? what are its functions?
a rhizome is a stem that runs horizontally under the ground. they allow the plant to survive extreme conditions such as drought or winter temperatures when the ariel part of the plant dies.
what is a tuber?
the tip of a rhizome that has become enlarged with food
what are corms?
short underground stems filled with food that are enclosed by papery leaves.
what are tendrils? what is their purpose?
tendrils are modified stems that twine around other plants or structures to help support the plant
what are thorns? what is their function?
sharp branches that protect the plant from herbivores
what are cladodes?
flattened, leaf-like stems modified to store water and to photosynthesize for the plant (found in some cacti)
what is the purpose of the plant cell wall?
adds considerable support to the plant body
what are the contents of a plant cell collectively known as?
protoplasm
what is the protoplasm surrounded by?
plasma membrane
what takes up most of the volume of a plant cell?
a large central vacuole
what is the fluid inside the central vacuole called?
cell sap
what is the the tonoplast?
the vacuole membrane
what are the three tissue systems in plants?
dermal, vascular, and ground tissue systems
what does the dermal tissue system consist of?
a layer of protective cells known as the epidermis, which covers the outer surface of the entire plant
what is the main function of epidermal cells?
to secrete a cuticle (a non-cellular, waxy layer of cutin) onto their external cell walls to reduce water loss
what are trichomes? what are their functions?
specialized appendages that extend from the epidermis of stems, leaves, and flowers in some plants. they function in protection, chemical signaling, or prevention of water loss
what are trichoblasts? what is their function?
epidermal projections of the roots (root hairs) that increase the surface area for water absorption
what are guard cells? what is their function?
specialized epidermal cells that allow for gas exchange in leaves
what is the purpose of the vascular tissue system?
transport
what is the vascular tissue system composed of?
vascular bundles that connect leaves, stems, and roots
what are the two types of vascular tissue?
xylem and phloem
what is xylem composed of?
specialized conducting cells called tracheary elements
what are the functions of tracheary elements?
transport of water and minerals and supporting the ariel part of the plant
how do tracheary elements transport water and minerals?
tracheary elements are dead at maturity, leaving just their thick walls; water is transported through the center of the cell
what are the two types of tracheary elements in flowering plants?
tracheids (elongated cells with tapered ends) and vessel elements (shorted and wider cells with ‘open’ ends called perforation plates)
how do vessel elements form vessels?
by connecting end to end at their perforation plates
what cells does phloem tissue consist of? what are their characteristics
sieve tube elements and companion cells, both are elongated and found in flowering plants. Both are alive at maturity and have only primary cell walls
what is the function of sieve tubes elements? what happens to their nuclei as they mature?
transport hormones and the sugars made in the leaves to all parts of the plant. as they mature their nuclei disintegrate
what is the function of companion cells? what happens to their nuclei as they mature?
control the loading and unloading of sugars within the sieve tube elements. they retain their nuclei
what does the ground tissue system consist of?
any tissue that is not dermal or vascular
what are the functions of ground tissue?
provide support and storage for the plant
what are the three types of ground tissues?
parenchyma, collenchyma, and schlerenchyma
what is parenchyma tissue composed of? what is its function?
a simple tissue composed of parenchyma cells, which have primary cell walls and provide considerable support to the plant via turgor pressure. also act as storage areas for substances such as starch
what is mesophyll?
specialized tissue composed of photosynthetic parenchyma cells
what is collenchyma tissue composed of? what is its function?
collenchyma cells, which have unevenly thickened primary walls and are specialized for support where flexibility is important
where is collenchyma usually found in the plant?
the petiole and midrib of leaves, which allows the leaf to bend with the force of the wind
what are the two types of schlerenchyma cells? what are their functions?
fibres and sclereids. both are adapted for support as they have thick secondary walls and are dead at maturity
what are the characteristics of fibres?
elongated cells that usually occur in strands or bundles and provide support
what are the characteristics of sclereids? what are their functions?
short, variable in shape, and occur in singly or in groups. they function in protection and make up seed coats, nut shells, and stone pits of fruit
what is the cortex?
ground tissue which lies in the region outside of the vascular bundles in a stem or root
what is the pith?
ground tissue in the centre of a stem or root
what is the number of cotyledons (seed leaves) in the embryo of a monocot? a eudicot?
monocot: 1
eudicot: 2
what is the leaf venation in monocots? eudicots?
monocots: parallel
eudicots: reticulate
what is the number of flower parts in monocots? eudicots?
monocots: threes or multiples of threes
eudicots: in fours and fives or multiples of four and five
what type of root system is present in monocots? eudicots?
monocots: fibrous
eudicots: tap
