Plant Science Exam 2

  1. Parenchyma
    Thin wall, living, storage, wound healing and regeneration
  2. what are the least specialized cells?
  3. These cells have a lot of intercellular space, are usually stuffed with plastids and are found in the pith of shoots, storage tissue of fruits, seeds and roots and the mesophyll of leaves
  4. cells that can perform a wide variety of functions, including photosynthesis
  5. Collenchyma
    thickening walls, living, support
  6. Where is collenchyma found?
    near the surface of the cortex in stems, along the veins of leaves, petiole (stalk) of leaves
  7. cells starting to develop a secondary cell wall
  8. these cells can revert to a parenchyma state
  9. These cells are found most often in areas that are growing rapidly and need to be strengthened
  10. celery strands
  11. Two types of sclerenchyma?
    • Fibers (needle-shaped, mechanical strength for stems, high load-bearing capacity)
    • and Sclereids (variable in shape, can be grouped in bundles, single cells or small groups of cells within parenchyma tissues)
  12. Where can sclereid tissue be found?
    • Pears
    • Hard outer shell of seeds and nuts
    • Stones of drupes
  13. These have the thickest cell walls
  14. when the apical meristem is removed from a shoot, what happens?

    B. axillary or lateral buds will grow
  15. The hollow stem of a grass plant is called

    C. culm
  16. Stem that holds a corn ear
  17. It supports and arranges leaves to intercept light, supports flowers and fruits, transports water and nutrients, stores plant food, helps with plant propogation and photosynthesis (succulents)
  18. what plant hormone is involved in apical dominance?
  19. shoot
    stem plus leaves and other structures
  20. stalk
    solid stem of grass
  21. examples of a woody stem
    walnut tree
  22. example of a herbaceous stem
  23. what do grass plants have instead of petioles?
  24. what are the axillary branches called on grass plants?
  25. To produce certified disease-free plants, which portion of a plant is typically propogated via tissue culture?

    C. apical meristem
  26. This type of plastid stores starch

    A. amyloplast
  27. These living cells have sieve tube elements and companion cells, while they do not have vacuoles or nuclei

    B. phloem
  28. T/F Stems have vascular bundles of xylem and phloem for water and carbohydrate transport
  29. Is xylem living at maturity?
    No, it loses cytoplasm at maturity so it's a non-living tissue
  30. Features of a monocot stem
    • epidermis
    • parenchyma inside
    • scattered vascular bundles
    • no cambium
    • vascular bundles surrounded by sclerenchyma or other thick-walled cells
  31. Features of a dicot stem
    • epidermis
    • cortex in woody dicots is between epidermis and ring of vascular bundles
    • vascular bundles in circle (circle grows together with age in woody stme)
    • vascular cambium
    • pith in center of stem for food storage
  32. T/F Dicot stems have pith in the center for food storage
  33. T/F Grasses usually have compound leaves
  34. T/F Excess nitrogen can cause weaker plant stems
  35. T/F Grasses have intercalary meristems, while dicot plants do not
  36. T/F The stem that holds an ear of corn is known as a cob
    False (it's a shank)
  37. Lodging is the ability of a plant to produce tiny plants at the margins of their leaves - T/F
  38. Low light intensity promotes
    • etiolation
    • longer internodes, less lignin (strong fiber in cell walls), lodging
  39. Plants transport photosynthates from leaves to sites of active growth, called

    A. sinks
  40. A leaf scar is where

    E. none of the above is true
  41. lodging
    • affects leaf orientation
    • reduces light interception for photosynthesis
    • crops difficult to mechanically harvest
  42. what causes lodging?
    shading, excess nitrogen, excessive soil water, diseases, insect damage
  43. a leaf scar is
     the mark left on a twig where the leaf petiole was attached
  44. the main site of photosynthesis
    • leaves
    • also responsible for transpiration, respiration, carb storage and transport and gas exchange
  45. monocot leaves
    • blade or lamina
    • sheath
    • collar (where sheath and blade join)
    • parallel veins
  46. dicot leaves - two types?
    • simple (one blade per leaf)
    • compound (two or more leaflets or blades per leaf)
  47. where are leaves attached?
  48. where the petiole of leaf attaches to the stem
    leaf axil
  49. types of veins
    • net
    • pinnate (feather-like)
    • palmate (finger/hand-like)
  50. Radicle
    • first root from a seed
    • develops into primary root
  51. If the primary root continues to grow and develop, what type of root does it become?
    tap root
  52. advantages of taproot system?
    • can grow deeply into soil
    • some are harvested for food
  53. how do you know if you're looking at a cross section of a dicot root?
    it has a cross in the middle
  54. if the primary root doesn't develop much, but there are lots of little roots shooting out, what type of system?
    fibrous root system
  55. advantages of a fibrous root system?
    • more thoroughly distributed and abosorb more water and nutrients within the root zone
    • allows greater contact within the rooting zone (common in grass crops)
  56. Secondary roots
    branch out from first degree roots or arise from plant stem tissue
  57. tertiary roots
    arise from second degree roots
  58. adventitious roots
    • arise from stem or other non-root meristems
    • usually originate at a node
  59. types of adventitious roots
    brace and prop roots
  60. loosely packed parenchyma cells inside the epidermis of a root, which store food and nutrients for the root are called the

    B. cortex
  61. the band of water-proof material that forces water to enter the vascular system via cells outside of it is called

    D. casparian strip
  62. 20-30 percent of photosynthetic energy is spent on what?
    root production
  63. How much of plant mass is apical meristem?
    less than 1%
  64. where do roots come from?
    meristems near the tip of roots
  65. features of a monocot root system?
    • fibrous root system
    • root system develops from adventitious roots
    • scattered vascular system around the perimiter (vascular bundles around the outer part)
  66. features of a dicot root?
    • taproot system
    • 1st degree root persists, produces branches and continues as main root of plant
    • vascular system is a cross in the center of the stele
  67. where is the apical meristem?
    • above the root cap
    • cells divide fairly rapidly here
  68. above the meristem is
    • zone of elongation (1 to 10mm long)
    • this is where new-formed cells take on water and elongate to mature size, its primary function is to increase root length
  69. located above the zone of elongation is
    differentiation zone or zone of maturation
  70. Root hairs develop from where?
    • epidermal cells
    • once epidermal cells cease elongation, they produce tiny extensions into the soil area
    • up to 200 root hairs per mm2 of root
  71. these are essential for rapid absorption of water and nutrients
    root hairs
  72. in typical soil, water is mostly a thin film surrounding every microscopic soil particle. how does it get absorbed?
    • by root hairs
    • water diffuses molecule by molecule, trhough the root hair's cell membrane, toward the main roots and then enters the xylem
  73. Root anatomy: the cortex
    • under the epidermis
    • loosely packed cells, can be several layers thick
    • conduct water and nutrients to vascular bundle
    • stores food and nutrients for the root
  74. Root anatomy: epidermis
    • outermost cells
    • single layer of cells on the root surface
    • absorb water and nutrients
  75. root anatomy: endodermis
    • single layer of cells that separates the vascular bundle from the cortex
    • regulates types of absorbed nutrients allowed to enter vascular cylinder
  76. Two pathways of water in roots
    • symplast (living portion of cells)
    • apoplast (moves between the spaces between the cells)
  77. endodermis barrier is
    casparian strip
  78. T/F A typical tree has hundreds of miles of roots with hundreds of thousands of root tips
  79. T/F Taproots can grow deeper into the soil than fibrous roots, but fibrous roots absorb more water and nutrients than taproots
  80. T/F soughing and root secretions are high energy processes, and a plant uses 2 to 5% of its photosynthetic energy to grow new roots
  81. T/F Cells in a root's zone of elongation are newly-formed cells that take on water and elongate to their mature size
  82. T/F Root hairs are an extension of epidermal cells
  83. T/F Roots are able to detect the presence of water in the soil and grow toward the water
  84. T/F When water enters a root and moves inside a cell, and then travels from cell to cell on its way to the vascular system, this pathway is known as the apoplast
    False (it's the symplast)
  85. Pericycle
    • separates xylem and phloem
    • layer of meristematic cells where branch roots develop
    • vascular cylinder tissue
  86. Stele
    • vascular cylinder tissue, the stele is the root center tissues including the pericycle, phloem and xylem
    • stele diameter is larger in monocots than dicots
  87. vascular system
    • very center of the root
    • made up of phloem and xylem
  88. pith
    found in the center of a monocot
  89. cambium
    • found only in dicots
    • cells can divide to produce 2nd degree growth in perennial plants
  90. 80% of nutrient and water uptake occurs where in the soil?
    the top 18 inches
  91. once water enters the root, it moves through the cortex to where?
    the endodermis, through the endodermis to pericycle and then to the xylem
  92. water has entered the xylem. now what?
    it moves rapidly upward in plant to stems and leaves, carrying nutrients with it
  93. most carbohydrates transported to the root do what?
    • they're used for active root growth, but some crops will sore carbohydrates in their roots for later growth or regrowth
    • stored carbohydrates allow plants to produce new shoot growth
  94. Rhizobium
    • nitrogen-fixing bacteria
    • symbiotic relationship with legumes
    • n-fixing enzyme nitrogenase
    • converts atmospheric n into ammonia
    • gives N to Plant
    • plant gives food to bacteria
  95. Azospirillum
    • Nitrogen-fixing genus of bacteria in many grasses including grain crops
    • bacteria secretes auxins which stimulate growth of root hairs
  96. Frankia
    • Nitrogen
    • Defense
    • Increase number of root hairs
    • mineral and water uptake
    • transport of hormones through roots
  97. mycorrhizae
    • A mycorrhizae is a mutualistic symbiosis between plant and fungus
    • localized in a root in which energy (carbon compounds) move primarily from plant to fungus and inorganic resources (principally phosphate) move from fungus to plant.
  98. root dry weight is usually how much of the total plant dry weight
    1/3 to 1/4
  99. Root surface area
    at least 20 to 30 times greater than leaf and stem surface area
  100. symbiosis
    a mutually beneficial relationship between different species of organisms
  101. The Rhizobium genus of nitrogen-fixing microbes is in this classification
  102. Frankia microbes enter into a mutually beneficial relationship with
    Woody trees and shrubs
  103. flavinoids
    plant secretes, attracts rhizobium
  104. myco refers to
  105. the ideal soil has these characteristics
    • 20-25% air space
    • 25% water
    • 45% minerals
    • 5% organic matter
  106. geotropism
    roots grown downward with gravity
  107. phototropism
    roots grow away from light
  108. thermotropism
    roots grow better in certain temperatures
  109. tropism
    when growth responds to external stimuli
  110. hydrotropism
    roots grow more favorably in moisture environment
  111. T/F Roots can grow only where root pressure is greater than the physical pressures exerted against the roots
  112. T/F Wetter soils warm up more slowly and cool more slowly than drier soils
  113. T/F Dihydrous oxygen should be banned from drinking water
  114. T/F Soil texture is determined by the amount of sand, silt and clay in the ground
  115. T/F Adhesion is the attraction between molecules that are not alike, for example, a clay particle and a water molecule
  116. T/F Field capacity is the water available for plant uptake a short while after a heavy rain or irrigation (after gravitational water is gone)
  117. What percentage of plants are water?
  118. Soil is a water reservoir. Inputs?
    Rain, irrigation
  119. Soil is a water reservoir. Outputs?
    • plant uptake
    • evaporation
    • leaching
  120. adhesion
    attraction between unlike molecules
  121. cohesion
    attraction between like molecules
  122. soil moisture tension
    • soil particles have an attraction on soil water to keep it near particles
    • water also has an attraction for itself
    • water in large pores held with less tension than water in smaller pores (easier for roots to get water from larger pores)
  123. saturation
    all soil pores are filled with water
  124. gravitational water (free water)
    water in saturated soil that will quickly drain once the source of water input is gone
  125. field capacity
    • when gravitational water is gone
    • water held in pore spaces that is available for plant uptake
  126. unavailable water
    as soil dries, it reaches a point where plants can no longer extract water from soil although there is still water tightly held in small pore spaces
  127. wilting point
    name for soil when the remaining water is unavailable for plant uptake
  128. what pulls water through the plant to the highest leaves?
  129. how is the pull of transpiration created?
    when water evaporates from stomata
  130. active transport
    use energy to make protein move or change shape to allow ion inside membrane (takes energy to transport ions)
  131. where is water stored?
  132. turgor pressure
    • high water volume inside cells creates turgor pressure
    • gives plants rigidity
  133. organic matter that has decomposed as far as will happen and is considered a stable product is called

    D. humus
  134. This is the conversion of organic forms of a nutrient to an inorganic form that plants can absorb

    E. mineralization
  135. The A horizon of the soil is

    D. answers a and b are both true
  136. T/F Most of the organic matter is found in the top 2 feet of the soil
    False - it's the top 12 inches
  137. T/F High rainfall increases the rate at which new organic matter is formed and high temperature increases the rate of organic matter decomposition
  138. T/F Litter is crop residue that has not started to decay yet and individual components are still recognizable
  139. T/F The higher a soil's CEC, the harder it is for plant roots to obtain nutrients from the soil
  140. T/F Negatively charged ions are called cations
    False - they're anions
  141. T/F clay and organic matter have a large number of negatively charged sites on their surfaces
  142. List some soil inhabitants that become organic matter
    • roots
    • fungi
    • bacteria
    • microbes
    • worms
    • burrowing animals
  143. Soil structure
    • arrangement of soil particles into stable aggregates or granules
    • natural and cultural factors can improve or reduce structure
    • long-term ways to improve structure (root growth, soil organisms, add OM)
  144. Temporary ways to improve soil structure?
    • wetting and drying
    • freezing and thawing
  145. cultural practices that destroy soil structure
    • excessive tillage
    • tilling when soil is too wet
    • compaction
  146. Coarse textured soils
    have fewere but larger pores that hold less water
  147. fine textured soils
    have more but smaller pores that hold more water
  148. 1 tsp of soil may hold:
    • 3B bacteria
    • 1M fungi
    • 1/4 million more algae
  149. earthworms
    • known as the intestines of the earth
    • they can shift stones 60x their weight
  150. how much of the world's topsoil has been lost to erosion or carried away by water?
  151. Carbon nitrogen ratio recommended for compost?
    • 30:1
    • (carbon is brown, nitrogen is green)
  152. sandy soil
    • well drained
    • easier to till
    • warms quickly
    • low fertility
    • probably need water more
  153. loams
    • balanced mix of sand, silt, clay
    • relatively fertile
  154. clay
    • poor drainage
    • so tightly packed, holds onto water
    • warms slowly
  155. imrove soil structure
    • add compost, organic matter
    • facilitate growth of earth worms
  156. the amount of organic matter in soil depends on
    • precipitation, temperature and cultural practices
    • increased temp increases rate of OM decomp
    • increased rainfall increases rate of OM formed
    • tillage increases decomp
  157. most organic matter is found where?
    top 12 inches
  158. Litter
    Crop residue - can still recognize what it was originally
  159. Duff
    • Partially decomposed
    • can still recognize what it was originally
  160. Humus
    Stable OM, broken down as much as it's going to
  161. Mineralization
    OM can't be taken up by plants, so it's turned into inorganic matter plants can absorb
  162. Soil air is essential for
    • root and microbe growth
    • poor aeration slows microbial decomposition and causes more anaerobic organisms to grow
  163. 2 main factors that affect soil nutrient status and availability of nutrients for plant uptake
    • pH
    • CED (Cation Exchange Capacity)
  164. CEC of a soil determines
    how well it can hold nutrients
  165. Cation nutrients
    • K, Ca, Mg
    • Can be held by soil for plant root uptake
  166. Anion Nutrients
    • Not held by soil and can wash down with gravitational water
    • Nitrates
  167. Soil pH
    • measure of acidity or alkalinity of a soil
    • measures 0-14
  168. Soil pH less than 7
  169. Soil pH greater than 7
  170. Soil pH of 7
  171. Most horticultural crops prefer a pH of
  172. How would you raise pH
    add lime, limestone
  173. How would you lower pH
    add sulfur or peat moss, pine needles, orange peels (maybe)
  174. T/F Soil pH usually goes down over time
    True - alkaline products leach below the root zone
  175. A Horizon
    • Top soil, top layer
    • Highest in OM
    • Main region of plant growth
    • can wash away
    • could be 1", 12-18" ideal, or several feet deep
  176. B Horizon
    • More clay
    • Less OM than A
    • Sometimes called subsoil
    • Can be several feet thick
    • Can be totally exposed
  177. C Horizon
    • between B and bedrock
    • Least amount of chemical changes over time
    • in certain places, including Ozarks, may not have any or have v. little
  178. On average, how often should you test your soil?
    every three years, unless you have a problem or have low CEC soil
  179. salinity
    excessive nutrients
  180. symptoms of salinity?
    • plants wilting even when soil is wet
    • salt crusting on soil surface
  181. halophytes
    • can tolerate increased salt conditions
    • may have roots that exclude uptake, excrete excess salt thru glands, store in vacuoles
  182. Sodic soil
    excess sodium
  183. What are saline soils?

    C. soils with too many soluble salts
  184. What materials may be added to soil to lower its pH?

    E. peat moss and sulfur
  185. A plant will not grow and develop properly if any one nutrient is deficient even if it is a nutrient that the plant needs in very small quantity
    law of the minimum
  186. term used to describe a nutrient deficiency that causes leaves or other plant parts to turn yellow
  187. t/f tilling when the soil is wet can destroy soil surface
  188. t/f if a nutrient is mobile within a plant, deficiency symptoms will first appear on the youngest, newest tissue
  189. list the three macronutrients
    • Potassium
    • Phosphorus
    • Nitrogen
  190. List essential micronutrients
    • B
    • Cl
    • Cu
    • Fe
    • Mn
    • Mo
    • Zn
  191. Atomospheric Nutrients come from the atmosphere. what are these?
    Carbon, Hydrogen and Oxygen
  192. Macronutrients, taken up from the soil
    N, P, K
  193. Macronutrients used in the greatest quantity
    S, Ca, Mg
  194. Chlorosis
  195. interveinal chlorosis
    yellowing of areas between veins on leaves
  196. necrosis
  197. marginal necrosis
    browning of margins of leaves
  198. gypsum
    form of lime, raises pH
  199. Is nitrogen mobile in plants?
  200. Deficiency symptoms of nitrogen
    uniform chlorosis, then necrosis, older leaves first, stunted growth
  201. Nitrogen is a component of
    plant proteins, DNA, enzymes, more
  202. Nitrogen exists as
    • in nature, as gas
    • inorganic compounds NH4 and NO3
    • organic compounds
  203. unavailable forms of nitrogen are made available to plants through a series of chemical reactions called
    the nitrogen cycle
  204. can lightning during thunderstorms add nitrogen
    yes, about 10 pounds per acre per year
  205. luxury consumption
    plants absorb with their roots more of a particular element than they need
  206. the manufacturing of ammonia for fertilizer is known as the
    • haber-Bosch Process
    • converts N2 to NH3
  207. Urea has how much nitrogen
  208. NO4
  209. NO3
  210. Plants take up nitrogen in what form?
    Ammonium (NH4) or Nitrate (NO3)
  211. This element is an essential component of cell walls and has an important role in cell division
  212. Which essential mineral may build up in excessive amounts in the soil if you fertilize often with animal wastes?
  213. A deficiency of this element may result in a purple or reddish color on leaves, especially on the undersides.
  214. What is phosphorus good for?
    • component of ATP, DNA, Cell membranes, proteins, enzymes
    • Required for synthesis of carbohydrates and proteins in the plant
    • concentrated in regions of active plant growth and flowers and fruit
  215. Most of plant P (Phosphorus) is used in what stages of growth?
    the first stage
  216. Is phosphorus (P) mobile or immobile?
  217. deficiency symptoms of phosphorus
    • purplish coloring of older leaves
    • stunted growth
    • poor root growth
  218. what symbiotic relation helps plants take up P (phosphorus) and can be used as part of a fertility program?
    • mycorrhiza
    • can absorb P from soil and carry back to plant in exchange for carbs
  219. T/F If you apply an organic mulch such as wood chips around your plants, you need to add extra nitrogen to the soil so that the microbes and the plants hae adequate nitrogen nutrition
  220. T/F Most plants have a vascular/pipe system to move oxygen from the canopy down to the root system
  221. T/F Mycorrhizae are more likely to be found in heavily-fertilized soils than in soils of moderately good fertility
  222. What is mineralization?
    the conversion of an element from an organic form to an inorganic state as a result of microbial decomposition
  223. In a fertilizer analysis of 6-24-16, the 16 tells you that the fertilizer contains
    16% potassium by weight as K2O
  224. How much nitrogen would be in a 50-lb bag of 5-10-5?
    2.5 pounds
  225. How much potassium would be in a 100-pound of 20-5-10 when the conversion factor to arrive at K = 0.82?
    8.2 pounds
  226. What is the ratio of a bag of 20-10-20 fertilizer?
  227. What is a complete fertilizer?
    only guaranteed to contain N P and K
  228. Potassium (K)
    • highly mobile in plant
    • plants take up more K than N but K is less likely to be deficient
    • Plants may actually take up more K than they need
  229. Is K prone to leaching?
    No - has cation charge which allows it to adsorb to soil particles
  230. Deficiency symptoms of K
    • marginal necrosis of leaves
    • curling leaves
    • weak stems (lodging or falling over of plant parts)
  231. luxury consumption of K can reduce uptake of other essential nutrients, especially
  232. Essential for cell wall formation and cell division
    • calcium
    • it's relatively immobile in soil due to cation charge ++
    • seldom deficient
  233. Iron
    • most commonly deficient of micronutrients
    • immobile
    • deficiency symptom is yello to white interveinal chlorosis on new growth
  234. Soil nutrient balance: inputs
    • fertilization
    • atmopsheric deposition
    • organic residues
  235. Soil nutrient balance: outputs
    • plant removal
    • gaseous loss
    • conversion to unavailable forms
    • Leaching loss
  236. Light: quantity is
    • intensity
    • measured in foot candles (how much light would give off a foot away)
  237. Light quality is
    • wavelengths
    • wavelengths that have the most effect on plant growth are red and blue
  238. blue wavelength
  239. red wavelengths
    promote flowering
  240. photoperiod
    length of light in a 24 hour day
  241. photoperiodism
    response of plants to changes in photoperiod
  242. phytochrome
    • hormone that controls floral initiation
    • occurs in two forms - phytochrome red and phytochrome far red
  243. Forcing
    tricking a plant into doing something at a time earlier that usual
  244. light quality refers to
    light wavelength or color
  245. freezing injury
    • causes formation of razor-sharp ice crystals
    • occurs at temps less than 32 F
    • is a common occurence for crops native to temperate climate
    • the risk of frost is greatest during the hours just before sunlight on a clear spring night
  246. you are growing a variety of chrysanthemum (a short day plant) whose critical photoperiod is 12.5 hours. when would the crop flower?
    when it gets 12.5 hours or more of uniterrupted darkness
  247. which of these adaptations do not help plants tolerate drought?

    A. shallow root systems that are quick to take advantage of any rain or irrigation that seeps into the soil
  248. the pigment that controls flower initiation is called
Card Set
Plant Science Exam 2
Plant Science Exam Two