This worksheet covers the fundamental concepts of cell division, including mitosis and meiosis. It's designed for students to test their understanding of the processes, stages, and significance of these crucial biological events. The answer key is provided at the end for self-assessment.
Section 1: Mitosis
Instructions: Answer the following questions about mitosis.
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What is the primary purpose of mitosis? a) Sexual reproduction b) Growth and repair of cells c) Genetic variation d) Production of gametes
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List the four main phases of mitosis in the correct order.
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Describe the key events that occur during each phase you listed in question 2. Be specific and include descriptions of chromosome behavior.
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What is cytokinesis, and how does it differ in plant and animal cells?
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Explain the significance of checkpoints in the cell cycle. What are the potential consequences of checkpoint failure?
Section 2: Meiosis
Instructions: Answer the following questions about meiosis.
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What is the primary purpose of meiosis? a) Asexual reproduction b) Growth and repair of somatic cells c) Production of gametes (sex cells) d) Maintaining the same number of chromosomes in daughter cells
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How many daughter cells are produced by meiosis, and how many chromosomes do they contain compared to the parent cell?
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What are the two main stages of meiosis, and how do they differ?
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Explain the importance of crossing over during meiosis I. What is its effect on genetic diversity?
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Compare and contrast mitosis and meiosis. Use a table to organize your answer.
Section 3: Problem Solving
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A cell with 24 chromosomes undergoes mitosis. How many chromosomes will each daughter cell have?
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A cell with 46 chromosomes undergoes meiosis. How many chromosomes will each daughter cell have?
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Explain why errors in meiosis can lead to genetic disorders.
Answer Key
Section 1: Mitosis
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b) Growth and repair of cells
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Prophase, Metaphase, Anaphase, Telophase (Note: Some sources may include prometaphase as a separate phase)
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Prophase: Chromosomes condense and become visible, the nuclear envelope breaks down, and the mitotic spindle begins to form. Metaphase: Chromosomes line up along the metaphase plate (the equator of the cell). Anaphase: Sister chromatids separate and move to opposite poles of the cell. Telophase: Chromosomes arrive at the poles, the nuclear envelope reforms, and the chromosomes decondense.
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Cytokinesis is the division of the cytoplasm, resulting in two separate daughter cells. In animal cells, a cleavage furrow forms, pinching the cell in two. In plant cells, a cell plate forms between the two nuclei, eventually developing into a new cell wall.
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Checkpoints are control mechanisms that ensure the cell cycle proceeds correctly. They monitor DNA replication, chromosome alignment, and other critical events. Checkpoint failure can lead to uncontrolled cell division, potentially resulting in cancer or other genetic abnormalities.
Section 2: Meiosis
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c) Production of gametes (sex cells)
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Four daughter cells are produced, each containing half the number of chromosomes as the parent cell (haploid).
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Meiosis I and Meiosis II. Meiosis I separates homologous chromosomes, reducing the chromosome number by half. Meiosis II separates sister chromatids, similar to mitosis.
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Crossing over is the exchange of genetic material between homologous chromosomes. It increases genetic variation by creating new combinations of alleles on chromosomes.
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Feature Mitosis Meiosis Purpose Growth, repair Gamete production Number of Divisions One Two Number of Daughter Cells Two Four Chromosome Number Same as parent cell (diploid) Half the parent cell (haploid) Genetic Variation No significant variation Significant variation due to crossing over
Section 3: Problem Solving
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24 chromosomes
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23 chromosomes
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Errors in meiosis, such as nondisjunction (failure of chromosomes to separate properly), can result in gametes with an abnormal number of chromosomes. Fertilization of these gametes can lead to genetic disorders like Down syndrome (trisomy 21).
This worksheet provides a solid foundation for understanding cell division. Remember to consult your textbook and other resources for a more comprehensive understanding.
