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75 Cards in this Set

  • Front
  • Back
Plants acquire their nutrients from...
Soil and Air
What percentage of a plant's dry weight is organic?
96%
Plants leaves absorb what from the air?
Carbon Dioxide
What do plants get from soil?
Water, Minerals, and Some Oxygen
What happens to the minerals a plant takes up from the air and soil?
The sugars made by photosynthesis are used to construct all other organic materials primarily carbohyrdates. Cellular respiration is used to break down some of the other sugars and give off more oxygen then they use.
What does a plant do with the minerals it absorbs from the soil?
Moves it to its leaves and specific areas of its body.
What three elements do plants take up as inorganic ions?
Nitrogen, Magnesium, Phosphorous
What inorganic nutrient is obtained in the greatest quantities from each source?
Carbon Dioxide from the air and water from the soil.
The plasma membranes of root cells control...
Solute Uptake
Expand the surface area of plant roots
Root Hairs
All substances that enter a plant root are in...
Solution
Water and Solutes move through the ____ and ____ of the root and then into the ____-____ ____ tissue in the central cylinder of the root
Epidermis, cortex, water-conducting xylem
Via cell interiors, through plasmodesmata moving inward from cell to cell without crossing any other plasma membranes all the way to the roots endodermis
Intracellular Route
Channels through the walls of adjacent cells
Plasmodesmata
Via cell walls, stopped by Casparian Strip, solution moves inward within the hydrophilic walls and extracellular spaces of the root cells but does not enter the cytoplasm of the epidermis or cortex cells, no selection of solutes until the endodermis is reached.
Extracellular Route
Continuous waxy barrier that stops water and solutes from entering the xylem via cell walls, forces water and ions that travel the extracellular route to cross a plasma membrane into an endodermal cell.
Casparian Strip
What is the function of the Casparian Strip?
It regulates the passage of minerals (inorganic ions) into the xylem by blocking access via cell walls and requiring all minerals to cross a selectively permeable plasma membrane
Transpiration...
Pulls water up xylem vessels
A solution of water and inorganic nutrients that can flow through the tubes and from the plant's roots through the shoot system to the tips of the leaves
Xylem Sap
What force moves xylem sap up against the downward pull of gravity?
Root cells actively pump inorganic ions into the xylem, and the root's endodermis holds the ions there. As ions accumulate in the xylem, water tends to enter by osmosis pushing xylem sap upward ahead of it.
The force that can push xylem sap op a few meters when water enters by osmosis
Root Pressure
Is xylem sap pushed upward or pulled upward?
Xylem sap is pulled upward by the leaves.
Loss of water from the leaves and other aerial parts of the plants
Transpiration
1. Water molecules leave the leaf through the stoma. When the stoma is open water diffuses out of the leaf

2. Hyrdogen bonds make the water molecules stick to one another

3. Cohering water molecules in the xylem tubes form continuous strings from the leaves to the roots

4. Water molecules adhere via hydrogen bonds to hydrophilic cellulose molecules in the walls of xylem cells
The flow of water up a tree
The sticking together of molecules of the same kind
Cohesion
Sticking together of molecules of different kinds
Adhesion
What effect does transpiration have on a string of water molecules that tend to adhere to the walls of xylem tubes?
Transpiration keeps the string tense and is pulled upward as one molecule exits the leaf and the one right behind it is tugged into its place.
Transpiration-Cohesion-Tension Mechanism
Transpiration exerts a pull that is relayed downward along a string of water molecules held together by cohesion and helped upward by adhesion. Transpiration is an effective means of moving large volumes of water upward from roots to shoots.
Transpiration is controlled by?
Guard Cells
Control the opening of stoma by changing shape, widening or narrowing the gap between two cells
Guard Cells
What actually causes guard cells to change shape and thereby open or close stomata?
A stoma opens when guard cells gain potassium and water from neighboring cells, the cells actively take up potassium and water enters by osmosis, vacuoles in the guard cells gain water and become turgid causing the cell to buckle away from its companion guard cell, this increases the stoma between the two cells.
What three cues contribute to stomatal opening at dawn?
Sunlight = stimulates guard cells to accumulate potassium

Low Level of Carbon Dioxide

Internal timing mechanism
Phloem transports...
Sugars
The main function of phloem is to...
transport the products of photosynthesis
Sugary solution that moves freely from one cell to the next, may contain inorganic ions, amino acids, and hormones, its main solute is usually the disaccharide sucrose, produces maple syrup, moves throughout the plant in various directions
Phloem Sap
Plant organ that is a net producer of sugar, by photosynthesis or by breakdown of starch. Leaves are the primary sources of this in most mature plants.
Sugar Source
Organ that is a net consumer or storer of sugar. Includes growing roots, buds, stems, and fruits .
Sugar Sink
Storage Organ
Tuber or Bulb
What causes phloem sap to flow from a sugar source to a sugar sink?
Pressure Flow Mechanism
1. Sugar is loaded into a phloem tube by active transport. Sugar loading at the source end raises the solute concentration inside the phloem tube.

2. High solute concentration draws water into the tube by osmosis. The inward flow of water raises the water pressure at the source end of the tube. At the sugar sink, both sugar and water leave the phloem tube

3. Sugar departs from the phloem

4. water exits via osmosis
Pressure Flow Mechanism
Plant health is dependent upon...
a complete diet of essential inorganic nutrients
Essential Element
If a plant must obtain it to complete its life cycle, to grow from a seed and produce another generation of seeds
Macronutrients
Carbon, Oxygen, hydrogen, nitrogen, sulfur, phosphorous, potassium, calcium, magnesium
Important in the formation of cell walls, and combines with certain proteins to form a glue that holds plant cells together in tissues, helps maintain the structure of cell membranes and helps regulate their selective permeability
Calcium
Crucial as a cofactor required for the activity of several enzymes, main solute for osmotic regulation in plants
Potassium
Component of chlorophyll and thus essential for photosynthesis, also a cofactor for several enzymes
Magnesium
Micronutrients
Chlorine, iron, manganese, boron, zinc, copper, nickel, molybdenum
Compounds given to plants to promote growth. Two basic types, organic and inorganic
Fertilizer
Soil-like mixture of decomposed organic matter
Compost
Fertile soil supports...
Plant growth
Subject to extensive weathering (freezing, drying, erosion), mixture of rock particles of various sizes,living organisms, and humus, rich in organic materials and most important for plant growth.
Topsoil
Humus
Remains of partially decayed organic material
Mechanism by which root hairs take up certain positively charged ions (cation). Inorganic cations like calcium, potassium, and magnesium adhere by electrical attraction to the negatively charged surfaces of soil particles.
Cation Exchange
System embracing a variety of farming methods that are conservation-minded, environmentally safe, and profitable.
Sustainable Agriculture
Most plants depend on bacteria to supply...
Nitrogen
Nitrogen Fixation
Metabolic process of converting atmospheric nitrogen to ammonia
Fungus Root, increase surface area for water and uptake of minerals, secrete growth factors, and antibiotics
Mycorrhiza
Nodules
Swellings that grow on roots of plants
FUNCTION: Stimulate stem elongation, affect root growth, diffrentiation, branching, development of fruit, apical dominance, phototropism, gravitropism (response to gravity)

PRODUCED OR FOUND IN:

Meristems of apical buds, young leaves, embryos within seeds
Auxins
FUNCTION:
Affect root growth and diffrentiation, stimulate cell division and growth, stimulate germination, delay aging

PRODUCED OR FOUND IN:
Made in roots and transported to other organs
Cytokinins
FUNCTION:
Promote seed germination, bud development, stem elongation, and leaf growth, stimulate flowering and fruit development, affect root growth and diffrentiation

PRODUCED OR FOUND IN:
Meristems of apical buds and roots, young leaves, embryos
Gibberellins
FUNCTION:
Inhibits growth, closes stomata during water stress, helps maintain dormancy

PRODUCED OR FOUND IN:
Leaves, stems, roots, green fruits
Abscisic Acid (ABA)
FUNCTION:
Promotes fruit ripening, opposes some auxin effects, promotes or inhibits growth and development of roots, leaves and flowers depending on species

PRODUCED OR FOUND IN:
Ripening fruits, nodes of stems, aging leaves and flowers
Ethylene
Tropisms
Directed growth responses that cause parts of a plant to grow upward (a positive tropism) or away from a stimulus (a negative tropism)
How do plants respond to light?
Through phototropism, using a greater rate of cell elongation on the darker side of the stem, when illuminated auxin will move across the tip from the bright to the dark side
How do plants respond to gravity?
Through gravitropism, a higher auxin concentration on the lower side of a root inhibits cell elongation, while cells on the upper side continue to elongate causing the root to curve downward
How do plants respond to touch?
Through thigmotropism, plants respond to touch by coiling around the object or to fold together as is true with the mimosa pudica.
Innate biological cycle of about 24 hours, persists even when an organism is sheltered from environmental cues
Circadian Rhythm
Internal timekeepers, continues to mark time in the absence of environmental cues but requires daily signals from the environment to remained tuned to a period of 24 hours, light/dark of the day helps with this
Biological Clock
The environmental stimulus plants most often use to detect the time of year, the relative lengths of day and night
Photoperiod
Generally flower in late summer, fall, or winter, when light periods shorten, some are pointsettias
Short-day Plants
Spinach, lettuce, iris, and many cereal grains, flower in late spring or early symmer when light periods lengthen, spinach for example flowers only when daylight is at least 14 hours
Long-day Plants
Will not flower until it is exposed to a dark period of 14 hours and will not flower even if this is interrupted by a flash of light
Short-day Plants
Flowering occurs when the night length is shorter than a critical length of 10 hours, too long of a dark interval will not produce flowers, flash of light at night can induce flowering
Long-day plants
Proteins with a light-absorbing component
Phytochromes