Chapter 13 - Meiosis & Sexual Life Cycles

Chapter 13 - Meiosis & Sexual Life Cycles - AP Biology...

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AP Biology ROOSEVELT HIGH SCHOOL Dr. Block Chapter 13 Meiosis and Sexual Life Cycles Lecture Outline Overview Living organisms are distinguished by their ability to reproduce their own kind. Offspring resemble their parents more than they do less closely related individuals of the same species. The transmission of traits from one generation to the next is called heredity or inheritance. However, offspring differ somewhat from parents and siblings, demonstrating variation. Farmers have bred plants and animals for desired traits for thousands of years, but the mechanisms of heredity and variation eluded biologists until the development of genetics in the 20th century. Genetics is the scientific study of heredity and variation. Student Misconceptions 1. The majority of your students will have some level of confusion about the¤structures and processes of meiosis. And, of course, students who misunderstand meiosis often have difficulty with genetics as well. Most students have studied meiosis in high school. As a result, students are not fully attentive when they encounter the topic again in a first-year class. However, it is likely that they didn't “get it” the first time and that unresolved misunderstandings will continue. Think carefully about how to engage students in this important topic. Rather than asking students the questions they expect—c ompare and contrast meiosis and mitosis; describe the events of prophase I— give them problems that require them to reason about the process of meiosis. State specific combinations of alleles in daughter cells and ask students to explain the steps that would produce each combination. Such questions will be more likely to reveal misunderstandings, both to students themselves and to their instructors. 2. Many students have fundamental misunderstandings about chromosomes and their structure and behavior during meiosis. It is very common for students to be confused about ploidy and chromosome structure. Some students are uncertain about the significance of the centromere. a. Many students think that chromosomes with a single unreplicated chromatid are characteristic of haploid cells and that replicated chromosomes with two chromatids are characteristic of diploid cells. b. Some students think that chromosomes consisting of two chromatids are formed not by replication, but when a maternal chromatid and a paternal chromatid come together during fertilization and join at the centromere. c. Some students do not realize that sister chromatids are joined at the centromere. These students will draw sister chromatids as independent entities throughout meiosis I. d. Other students think that all four chromatids of a tetrad are joined by a single centromere during prophase I. How can an instructor address these fundamental misunderstandings? Clearly distinguish between the concepts
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This note was uploaded on 12/13/2010 for the course ACT 101 taught by Professor Jenkins during the Spring '10 term at Alabama State University.

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Chapter 13 - Meiosis & Sexual Life Cycles - AP Biology...

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