Biology of Plants
Evolution of female reproductive coverings. In this course we have traced this evolution from isogamete, to anisogamete, to egg, to egg in oogonium, to egg in archegonium as we went from algae through bryophytes and ferns. It is a pathway of coverage in which the female reproductive structures that once were free-living swimming forms have evolved into sessile forms contained in layers of coverage. Tell what layers are added in each step in evolution...5 points.
Selaginella added the: megaspore wall
Gymnosperms added the: megasporangium = nucellus and integument
Angiosperms added the: ovary wall and receptacle
Evolution of megagametophytes. Describe what has been lost from the megagametophyte during evolution of the three heterosporous life histories. You do not need to mention anything but the gametophyte itself. Starting with a moss female gametophyte: thallus, rhizoid, "stem", "leaf", archegonium, egg, tell what has been lost at each step in evolution (write each word only once among the blanks below). 4 points.
Here diagram the mature megagametophyte of an angiosperm, showing all of its cells. Next to each named cell, write the ultimate fate of that cell. 12 points.
Selaginella lost the: "stem" and "leaf"
Gymnosperms lost the: rhizoid
Angiosperms lost the: archegonium
Diagram: Name of cell(s): What they do or become:
Evolution of microgametophytes. Describe what has been lost from the microgametophyte during evolution of the three heterosporous life histories as you did with a previous question. Starting with a moss male gametophyte: thallus, rhizoid, "stem", "leaf", antheridium, motile sperm, tell what has been lost at each step in evolution (write each word only once among the blanks below). 5 points.
Selaginella lost the: "stem" and "leaf", and rhizoid
Gymnosperms lost the: antheridium
Angiosperms lost the: motility of sperm
Here diagram the mature microgametophyte of an angiosperm, showing all of its cells. Next to each named cell, write the ultimate fate of that cell. 6 points.
Diagram: Name of cell(s): What they do or become:
|Name the process of placing this microgametophyte
in/on a female structure in both gymnosperms and angiosperms.
|What is the ultimate placement of the microgametophyte in gymnosperms?||micropyle|
|What is the ultimate placement of the microgametophyte in angiosperms?||stigma|
What protects the microgametophyte against desiccation|
(drying out) during its travel toward the female structures?
|What is unique about the syngamy event in angiosperms?||double|
What cell and tissue results from syngamy that was not|
seen in either gymnosperms or Selaginella syngamy events?
|What is the ploidy of this unique cell and tissue?||1N 2N 3N 4N|
Label this longitudinal section of a flower. 16 points
The flower above is: epigynous perigynous hypogynous
The ovary above is: superior inferior
The pistil shown above is: simple compound
In the following table, compare the structure and organization of primitive and advanced flowers. 20 points
|Features||Primitive Flower||Advanced Flower|
|leaf number||many parts||fewer parts|
|axis length||elongate axis||short axis|
|pollinator||beetle pollinated||bee, wind pollinated|
|ovary position||superior ovary||inferior ovary|
|flower size||large flowers||tiny flowers|
|flower groups||single flowers||gathered into head|
|division of labor||all flowers same||division of labor|
You have learned about extensive free-nuclear stages in both Pine and Angiosperms. 4 points.
What has to happen for a cell to become free-nuclear? mitosis without cytokinesis
What is the major free-nuclear stage in Pine? megagametophyte
What is the major free-nuclear stage in Angiosperms? endosperm
Make a diagram of the two kinds of seeds. Label completely! 14 points.
|Gymnosperm seed||Angiosperm seed|
|You are on a tropical safari and you find a fruit in the jungle. The spherical object is completely solid, though it looks like it is made of many sections. The fruit appears to be soft and juicy. On the surface you find each section of the fruit has a little ring of five tiny green leaf-like structures. In the center of each ring of leaf-like structures are some dried up threads with a swollen bag-like end. In the middle of these is a very tiny scar. You try to cut through the fruit, but each section of it has a very hard object inside. You pull out one of the hard objects, crack it open, and find a seed inside. To get a good cross-section of this soft fruit with hard objects inside, you freeze it and then slice it on a power saw. When you look at the cross section, you see a central area that is solid and fibrous and the sections of the fruit radiate out from this in all directions. Each section of the fruit appears to consist of two soft layers surrounding the hard object. A native tells you that this tree had clusters of beautiful yellow flowers just a few months ago. Classify the fruit you have found using the three classification schemes used in lab.||
Description: (fleshy, dry, etc. be specific)
|The gymno- part of gymnosperm means||naked|
|What structure in a pine is specifically "gymno-"?||ovule|
|The -sperm part of gymnosperm refers to||seed|
|Which gymnosperm sporophyte most closely resembles the ferns?||Cycadophyta|
|In many gymnosperms, the male and female|
structures are on separate plants. This condition is known as
|What structure of the female Ginkgo tree makes it stink?||integument of ovule|
|What type of shoot has leaves held singly in Ginkgo?||long short|
|What is the name for the endosporic microgametophyte in pine?||pollen|
|What tissue must be penetrated to deliver sperm in pines?||nucellus|
|What process takes place in the first spring of an ovulate pine cone?||pollination|
|What process takes place in the second spring of an ovulate pine cone?||syngamy|
|What process takes place in the third spring of an ovulate pine cone?||seed dispersal|
|Which type of pine cone is simple?||microsporangiate megasporangiate|
|What structure makes a pine cone compound?||bract|
|What structure distinguishes the Gnetophytes from the lower gymnosperms?||vessels|
|The stamen of a flower is equivalent to a pine||microsporophyll|
Heterosporous Life Cycle Diagram. Turn this page sideways and arrange the 20 labels provided to you on this page to demonstrate your understanding of the heterosporous life cycle in angiosperms. Note: you should know that the labels cannot be repositioned! Once stuck down, you are stuck with their position! So plan carefully! 20 points.
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