Plant Science 102

Study Guide Section #2

2007

  1. Why would you want to know what controls the growth and development of plants?
  • To manipulate plant growth, and predict production.
  • To optimize nutrient and agronomic practice to maximize crop productivity and end use quality.
  • To allow plant breeders to genetically modify plants to increase productivity or quality.
  • To determine the effects of pests and diseases on plant growth and hence develop natural resistance.
  • To determine aspects of a plants growth to discover ways to kill them(herbicides).
  1. What does a plant have to do to survive?
  • Plants need to produce energy from the sun through photosynthesis.
  • Uptake water and nutrients from the roots.
  • In take CO2and H2O and exhale O2
  • Must have the ability to reproduce either sexually or A-sexually (i.e. clonally).
  • Must be able (at least in part) to have some defense against pests and other stress factors.
  1. Identify the following plant cell components are briefy indicate their function.
  • Cell wall: provides protection and structure.
  • Plasma membrane: controls movement of minerals, metabolites and water into and out of the cell.
  • Chloroplast: site of photosynthesis, starch biosynthesis and starch accumulation.
  • Golgi apparatus: site of synthesis of polysaccharides such as hemicellulose needed for cell walls.
  • Mitochondria: site of all biochemical reactions of respiration.
  • Endoplasmic reticulum: site of protein synthesis.
  • Vacuole: site for storage of proteins.
  • Nucleus : site of the majority of the genetic information (DNA) and is the site of transcription.
  1. Identify the plant part in the diagram shown below.

  1. Which plant cells can differenciate into different cell types?
  • Meristem cells
  1. What is the major function of the following cell types?

(a)Parenchyma cells

  • Make up the majority of the fruit and vegetables we eat.
  • In leaves they function in photosynthesis (mesophyll), while in stems and roots they function in starch, sugar and oil storage.
  • Adjacent to the xylem or phloem sieve they act as transfer cells.

(b)Collenchyma cells

  • They are elongated with much thicker cell walls.
  • Just underneath the epidermis and provide mechanical support

(c)Sclerenchyma cells

  • These cells also have a supportive role, but these cells are actually dead cells and have very thick cell walls with lignin.
  • They form fibers that protect the phloem in the stem.
  1. Meristematic cells in plants differentiate into three tissue types. Label the three tissue types on the stem cross section shown below.

  1. What is the major function of Vascular tissues?
  • The major function of phloem is to transport sugars and amino acids throughout the plant: from leaves to roots, and to developing fruit and seed; and from senescing to growing.
  • The major function of xylem is to transport water and minerals from the root to the shoot.
  1. What is the major function of stometes?
  • Stomates are small holes or pores in leaves and stems that regulate gas exchange.
  1. What are the tree primary regions of root development?
  • At the root tip ia a region of cell division (apical meristem), moving up the root is then a region of cell elongation, followed by a region of cell maturation.
  1. What is the difference between cells that result from mitosis compared to cells that result from meiosis?
  • Mitosis starts with a diploid somatic cell and results in two diploid somatic cells.
  • Meiosis starts with a diploid sex cell and results in four haploid cells.
  1. What is the function of a seed endosperm?
  • The cells in the endosperm will divide to produce cells that will store energy for the seed to utilize when it germinates.
  1. Crop plant species can generally be categorized into self-pollinators or out-pollinators. What are the major characteristics of each pollinator type.
  • Self-pollinating crop species are:
  • Tolerant to inbreeding
  • Few deleterious recessive alleles
  • “Closed” flowers
  • Little heterosis
  • Out-pollinating crop species are:
  • Intolerant to inbreeding;
  • Have many deleterious recessive alleles which results in inbreeding depression when plants become homozygous.
  • Have flower morphology that promotes cross pollination (i.e. monacious, diacious, or self-incompatible).
  • Have high heterosis (hybrid vigor).
  1. What is the difference between a homozygous locus compared to a heterozygous locus.
  • A homozygous locus has identical copies of both alleles (i.e. AA or aa), whereas a heterozygous locus had different alleles (i.e. Aa or aA).
  1. Label the following part on the flow diagram below.

  1. List three reasons for treating seeds.
  • To enhance germination (including seed priming)
  • To apply fungicides, or insecticides or nutrients.
  • To increase the size of small seed for better seed placement (i.e. pelletization).
  1. List two methods of A-sexual (clonal) propagation in crop plants.
  • Budding and grafting onto various root stocks:
  • Rosaceous top fruits, citrus, avocado, grape.
  • Leafy cuttings:
  • Pineapple, strawberry.
  • Leafless cuttings:
  • Sugar cane.
  • Tubers, bulb, etc.:
  • Potato, various bulb flowers, sweet potato.
  1. What is the major characteristic of the following plant growth hormones?
  • Auxins
  • Stimulates cell elongation.
  • Mediates the tropistic response of bending in response to gravity and light.
  • Stimulates cell division in combination with cytokinins in tissue culture.
  • Cytokinin
  • Are generally found in higher concentrations in meristematic regions and growing tissues.
  • They are believed to be synthesized in the roots and translocated via the xylem to shoots.
  • Stimulates cell division.
  • Giberellic acid
  • Stimulate stem elongation by stimulating cell division and elongation.
  • Stimulates bolting/flowering in response to long days.
  • Breaks seed dormancy in some plants which require stratification or light to induce germination.
  • Abscicic acid
  • Stimulates the closure of stomata (i.e. water stress brings about an increase in absicic acid causeing stomates to close and hence reduce water loss through transperation).
  • Ethylene
  • Stimulates the release of dormancy.
  • Stimulates shoot and root growth and differentiation.
  1. The ratio of auxin to cytokinin in a tissue dictates growth of axillary meristems. Circle the ratio which is most likely to cause the meristem to under go cell division and start to grow.

(a)High auxin / Low cytokinins

(b)Low auxin / High cytokinins

  1. Which synthetic plant growth hormone is used as a herbicide? Is this herbicide a giberellin, auxin or cytokinin?
  • 2,4-D or 2,4-Dichlorophenoxyacetic acid
  • It is an auxin.
  1. What range of light energy is not generally absorbed by atmospheric gases?
  • Between 400 and 700 um.
  1. The visible light spectrum is also called what?
  • Photosynthetic active radiation
  1. Light intensity is one important factor of photosynthetic efficiency. What causes increased and decreased light intensity?
  • Increased light intensity is cause by the 23½o tilt of the earth. This causes suns light to go through more atmosphere the further away from the earths equator.
  1. Why is there greater light intensity in Idaho during the summer months compared to the winter months?
  • The 23½o tilt of the earth results in Idaho being physically closer to the sun in the summer months compared to the winter months. In addition, in the summer the angle of Idaho in relation to the sun means that the sun energy passes through less atmospheric gases. The reverse would be true in the winter months.
  1. Which wavelengths of light energy (red, blue or green) are least absorbed into plant leaves for use in photosynthesis? What is the major result of this?
  • Red and blue light is absorbed more than green light which is reflected off leaf surfaces resulting is the green color of our plants.
  1. What is the major result of photomorphism in plants?
  • Photomorphism in plants causes a plant to increase stem growth as a result of competition from neighboring plants.
  1. If the ratio of red light to far-red light is low in a plant the plant is experiencing high or low competition from a neighboring plant?
  • High competition.
  1. List two things in a plant that might be affected by day-lengh?
  • Flowering
  • Bud dormancy
  • Formation of vegetables or storage organs.
  1. In regard to plant flowering, describe the difference between long-day plants and short-day plants?
  • Long-day plants require short nights in order to flower.
  • Short-day plants require long nights to flower.
  1. What is a plants critical day length?
  • The critical day length of a plant determines the minimum (or maximum) night period necessart to initiate flowering.
  1. List the two major atmospheric gases.
  • Nitrogen (N2)
  • Oxygen (O2)
  1. What is generally believed to be the major cause of global warming?
  • Increased burning of fossil fuels that result in higher concentrations of carbon monoxide and carbon dioxide in the earths atmosphere.
  1. Approximatly what proportion of a plants weight is accounted for by water?
  • ~90%
  1. Delete the least appropriate word from the following sentences. Bob the pine tree had to stratify/vernilize seeds from pine trees in order to get uniform germinantion. However, his sister Betty, was more interested in stratification/vernilization treatments to get her winter wheat to flower.
  1. In photosyetem I, two water molecules are convereted into what?
  • One oxygen molecule, three positively charged hydrogen atoms and four electrons.
  1. What is the function of Rubisco in the Calvin Cycle of photosynthesis?
  • Rubisco can either catalyze carbon dioxide and a 5 carbon molecule into two 3 carbon molecules or it can catalyze oxygen and a 5 carbon molecule into a two carbon molecule and one three carboln molecule.
  1. Complete the photosynthesis equation below:

6CO2 + 12H2O = C6H12O6 + 6H2O + 6O2

  1. Label the components of the photosynthesis diagram below.

  1. What are the three primary soil types?
  • Sand
  • Clay
  • Silt
  1. Soil that is saturated with water and with very little air is said to be what?
  • Waterlogged
  1. Soil which has the correct mix of water and air is said to be what?
  • At field capacity
  1. What types of soil would most likely have the particle size shown below
  • 2 to 0.02 mm in diameter = sand
  • 0.02 to 0.002 mm in diameter = silt
  • Smaller than 0.002 mm in diameter = clay
  1. What causes soil compaction?
  • Use of heavy farm machinery and inappropriate cultivation.
  1. List four macro plant nutrients.
  • Calcium
  • Potassium
  • Magnesium
  • Nitrogen
  • Sulfur
  • Phosphorous
  1. Label the diagram below with appropriate water potential that will result in water movement from the soil to the plant leaves.

  1. List four micro plant nutrients.
  • Boron
  • Iron
  • Copper
  • Nickel
  • Chlorine
  • Zinc
  • Manganese
  1. List the major importance of the following plant nutrients.
  • Nitrogen
  • Stimulates leaf and stem growth
  • Potasium
  • Promotes general plant vigor, disease resistance, and sturdy plant growth.
  • Phosphorous
  • Important for good seed germinantion and early root development.
  • Calcium
  • Important ingredient in plant cell walls.
  1. If a plant nutrient is mobile within a plant, would deficiency of the nutrient be noted first in old leaves or young leaves?
  • Old leaves.
  1. List two plant nutrients that are mobine in plants and two that are impbile in plants.
  • Mobile = Nitrogen, magnesium, potassium, sulphur
  • Imobile = Zinc, calcium, boron, phosphorus, iron
  1. What two factors can influence nutrient uptake in plants.
  • Soil temperature
  • Soil Ph