Lab Topic 27

Angiosperm Reproduction, Germination and Development

 

 

Sexual and Asexual Reproduction

 

 

Strawberry plant: What evidence so you see that either sexual and/or asexual reproduction has occurred?
Stawberry stolen: Is this evidence of asexual or sexual reproduction?

 

Flower Structure
Gladiolus Flowers
Gladiolus flower
Is this flower perfect or imperfect?
How many stamens are found in this flower?
 Close-up of Gladiolus floral parts
Point to the structure in which the males  gametophyte develops. 
 Stigma of Gladiolus
What is the purpose of the stigma? 
Where is the style in this photo? 
 Close-up of stigma tip in Gladiolus
Why is the stigma tip moist and sticky? 
 
 
Longitudinal section of Gladiolus ovary
  • What is the name given to the small white structures

  • What will the small white structures develop into?
    Is the male gametophyte or the female gametophyte produced in these structures?
    How do the sperm get from the stigma tip to the egg in the ovule? 
    Cross section of Gladiolus ovary
    Is this a monocot or a dicot flower?
    Point to the ovules, ovary, carpels, and locules. 
    The ovarian wall will develop into what structure when mature? 

     

    Dicot Flowers

    Can you think of a reason why these flowers are so highly colored?

     

    Daffodil Flowers
    Is this flower perfect or imperfect?
    Is this a monocot plant or a dicot plant?
    Is this an example of a complete or an incomplete flower? What are the globular, whitish structures in this photo? 
    Will they develop into fruits or seeds? 

     
    Tulip Flowers
    Is this flower perfect or imperfect? 
    Is this flower a monocot or a dicot? 
    Are the anthers in this photo mature or immature? 
    How many cells are in a mature pollen grain? 

     
    Oat Flowers
    Do grasses produce flowers?
    Why aren't these flowers of grasses colorful and odorous?
    Point to the stigmas and anthers in the above photo of an oat flower. 
    Where would the ovary be located? 
    How does cross pollination occur in grasses? 
    Why are grass flowers not highly colored? 

     
    Wheat Flowers
    Point to the anthers in the above photo. 

    Diagram and name the floral parts of a monocot flower such as a gladiola.
    In order for a flower to be considered complete what must be present?
    What determines if a flower is considered incomplete?
    Define a perfect flower in botanical terms.
    Most grasses have flowers arranged in clusters. What term is used to describe this flower arrangement?
    Is the pistil (stamen)  sporophyte or gametophyte tissue?

     

    Gametogenesis in Flowering Plants
    Pollen Formation

    Cross section of an anther
    What are the small circular structures contained in the microsporangium or pollen sacs?
    What is the name of the flower structure that pollen development takes place in?
    Name the layer that provides the developing pollen with nutrition.
    Microsporocytes caught in Prophase I of meiosis 
    What are the red structures in the cells? 
    How many pollen grains will be produced by each of these cells? 
    What genetic recombination event is happening here? 
    Are these cells from the sporophyte or gametophyte generation? 

    Tetrads of pollen grains
    What type of cell division produced these cells? 
    Are these cells haploid or diploid? 
    Is this a mature anther or a developing anther ? What do you think these structures are? What key features did you use to identify them?  Germinating pollen grain.
    On what structure does the pollen grain nomally rest as it develops a pollen tube?
    Is this pollen tube a sporophyte or gametophyte?
    How many sperms will be transferred by one pollen tube?
    What are you looking at here?

    In flowering plants the female (male) gametophyte is what?
    Microsporangia are the male or female reproductive organs?
    Megasporangia are the male or female reproductive organs?
    In a mature pollen grain, two nuclei are produced by mitosis. What are they called and what do they produce

     

    Egg Formation

     

     

    How many carpels does this flower have? 
    Point to the ovules. 
    What happens in the ovules that is significant to plant reproduction? 

    How many carpels do you see?

    Point to the megaspore mother cell in the above photos.
    Does it first divide by mitosis or meiosis? 
  • Slide of lilium ovary
    •  The two polar nuclei fuse with a sperm to produce what?
    • What is the name of this cell?
    • What is the name this area?
    • What is the name of this structure? What does it contain? What is the name of the progenitor cell of the contents of this structure?
    • What is the structure indicated and what does it develop into?


     
    Embryo Development


    Are these photos of monocot or dicot embryos?
    Point to the cotyledons and radical in these photos. Where is the seed coat?
    What does the seed coat develop from?
    What is the function of the cotyledons?

     
    Seeds
       

    Seeds (corn or lima bean)

     

    Fruits

    Possible fruit questions

  • How many carpels does this fruit have?
  • What do ovules develop into in the fruit?
  • What is the name of this layer?
  • Why do many types of fruit contain seeds with very hard seed coats?
  • What is the structure indicated by the pointer?
  • What does the structure indicated by the pointer develop from?
  • Are all fruits edible?
  • What does the flesh of an edible fruit develop from?
  • A seed is a mature __________ and a fruit is a mature ____________?
  •  


     

    Investigating the Effects of Hormones on Plant Development

     
    Rosette Mutants
    General and comparative questions
    Compare the major features of monocot and dicot flowers
    How is sexual reproduction in flowering plants  adapted to the terrestrial environment?
    How are gametophytes formed, gametes produced in flowering plants?
    Describe the difference between pollination and fertilization?
    Outline the steps in endosperm development.
    Describe embryonic development in a dicot seed.
    Why do seeds have lots of starch and oil? Why do we eat seeds like wheat, corns, nuts?
    A seed has been described as a mature ovule. How can this be true? Explain.
    Why are flower petals colored? Are all flowers colorful?
    What could prevent self fertilization and genetic inbreeding in perfect flowers (Fig. 38.5 and 38.6 in the Campbell text)?
    How might hybridization between species be prevented (pollinator specificity)?
    How do flowering plants protect gametes and embryos?
    Describe how fruits are adaptations to promote seed dispersal. For example, why are some fruits sweet and colorful?
    Make a list of several foods commnly called vegetables that are actually fruits.
    The pistil is described as the female part of a plant and the stamens as the male. Criticize this statement by describibg where sperm and eggs are actually produced.
    What advantage is it to the plant to undergo asexual reproduction?
    What is the principle advantage of sexual reproduction?
    True or False: Pollenation and fertilization are the same. Explain your answer

    Credits

    Photos by Maria Oehler and Warren Dolphin
    Layout by Warren Dolphin and Mark A. Mangum