AP Bio Review sheet for the Life Cycle of Plants
Name _________________________________________________
AP Bio Review for Sexual Life Cycle for Plants and Animals
This worksheet is designed to familiarize you with the fundamental differences between the life cycles of a) vertebrates (you - as a reference), b) early land plants (e.g. mosses as an example of a phylum with easily distinguishable alternating generations), and c) seed plants). The main goal of this review is for you to learn and understand what the term “alternation of generations” means, to be able to identify haploid and diploid generations in seed plants, to be familiar with the terms “ sporophyte” and “gametophyte” and to have an understanding of the principle of “double fertilization” in angiosperms. Please use chapters 13, 31, 38 of your Campbell Biology textbook for assistance and/or see me for help.
A [pic]
B [pic]
Answer the following questions: (see Figures A and B above and your textbook for help)
1. What does the term “ploidy” refer to?
2. What is the ploidy of the gametes of a normally diploid organism?
3. Which biological process is required for a cell to go from diploid to haploid state?
4. What is the function of haploid cells in humans?
5. What other functions can haploid cells have in fungi, algae, and plants?
Over evolutionary time, different phyla have developed different strategies of reproduction, each changing the way the two alternating generations contribute to development. Figure C shows these differences for bryophytes (mosses), pteridophtes (ferns) and angiosperms (seed plants).
C [pic]
D [pic]
Figures from ch 30 of: Campbell and Reece (2002): Biology, 6th edition, Benjamin Cummings, San Francisco
Figure D reviews the life cycle of angiosperms and shows where “double fertilization”, which is unique to angiosperms, occurs. (In simplified terms, angiosperms are all “flowers” and trees that you see around you, except for needle trees (conifers), ginkgos, and cycads, which collectively are called gymnosperms.)
Double fertilization refers to the fact that each pollen contains 2 sperm. Both sperm fertilize nuclei in the female gametophyte. During fertilization, sperm #1 fuses with the egg (one of the seven cells) to form the zygote/embryo, sperm #2 fuses with the two nuclei in the central cell to form the “endosperm”, which becomes a nutritive tissue used to nurture the embryo in the seed.
Answer the following questions:
1. Label the parts of the complete flower below
[pic]
2. What does the sporophyte of an angiosperm plant consist of? (Use general terms for plant parts/organs).
3. Which part of the plant is the male gametophyte? _______ Female? _______
4. Define “microsporogenesis” and “megasporogenesis”. In what portion(s) of the flower does each of these processes occur? What is the end product of each process?
5. What is the ploidy of the male and female gametophyte?
6. By which process (meiosis or mitosis) are the sperm cells in the male gametophyte of an angiosperm formed?
7. What is pollination? How does it differ from fertilization?
8. What is the ploidy of the embryo?
9. What is the ploidy of the endosperm? Why?
10. Why don’t humans undergo alteration of generations? Is one generation more prevalent than the other? Which one? Explain.
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