unit 11

• Nonvascular plants live in damp and shady areas because they do not have the ability to carry water from soil
• Ferns are seedless vascular plants that reproduce through spores
• gymnosperms are naked-seed plants, their seeds are on the uotside
• angiosperms are flowering plants
• The root system of a plant supports and anchors it to the soil
• The cylindrical shape of roots permits water to be absorbed from all sides and allows it to penetrate the soil when growing deeper
• Root hairs are epidermal projections from root-hair cells. They are tiny but numerous thus increasing the absorption surface and absorption capacity of plants.
• The stem of a plant is the main axis of the plant; it helps leaves be exposed to sunlight as much as possible
• the terminal bud allows the stem to grow more elongated and produce new leaves
• the node is where leaves are attached with the stem, and the region in between is called the internodes
• rhizome is a horizontal underground stem capable of producing new roots below and new shoots above
• leaves vary widely, aquatic duckweeds may be >1 mm in diameter, while palms may be <6m in length.
• Plants that bear leaves throughout the year are called evergreens and those that only have leaves on growing seas are called deciduous
• The wide portion of the foliage leaf is called blade
• The petiole is a stalk that attaches the leaf to the stem. While the leaf axil which is between the petiole and stem is where the axillary bud is found
• The tracheids and vessel elements of xylem are composed of modified sclerenchyma cells.
• The sieve tubes are composed of elongated tube-like structures placed end-to-end. These tubes transport sugars and nutrients.
• A mineral is an inorganic substance usually containing two or more elements.
• Soil is defined as a mixture of mineral particles, decaying organic material, livingorganisms, air, and water, which together support the growth of plants.
• Translocation is the movement of organic molecules through the phloem where molecules flow from a source to a sink.
• Sucrose is the most common sugar that moves through the phloem.
• A nutrient is considered essential if no other nutrient can substitute it, it has an identifiable role, and a deficiency of this nutrient causes a plant to die
• Topsoil - organic matter that has been added to provide the best medium for plants
• humus- decayed plant and animal matter
• litter - undecayed plant and animal matter
• subsoil- smaller particles of soil, mostly clay
• The last layer of the soil is composed of parent material where weathered rock can be found
• Water and mineral transport within a plant via a single pathway
• water and minerals from the soil can enter the root of flowering plants by passing between the porous cell walls
• Casparian strip - a waxy barrier that stops water and solute from entering the xylem
• water enters root cells when osmotic pressure in the root tissues is lower than that of the soil solution
• Water can enter the epidermis then progress through cells across the cortex then endodermis through cytoplasmic strands in plasmodesmata
• Plants take up minerals until they are as much as 10,000 times more concentrated than the surrounding soil
• Minerals move into the xylem and are transported to the leaves by upward movement of water
• plant cells absorb minerals in the ionic form: nitrogen is absorbed as nitrate, phosphorus as phosphate, potassium as potassium ions
• ions are polar, so they cannot cross the plasma membrane which have a nonpolar portion in the lipid bilayer
• plant cells use energy to actively take up mineral ions, hence, active transport
• plants lose water through transpiration where water evaporates through leaves
• the heat from the sun causes the water in the cells to evaporate and be stored in the spaces between the leaf's cells as water vapour
• Water vapor diffuses to the outside air when the concentration of water molecules inside the leaf is higher than the surrounding air