Questions and Answers
Why is it more accurate to call mitosis nuclear replication rather than cellular division?
It is more accurate to call mitosis nuclear replication because the cell doesn't really divide. Mitosis is just the cell's nucleus dividing into 2 separate nuclei, not the cell.
Explain why whitefish blastula and onion root tip are selected for the study of mitosis.
They are selected because whitefish blastula and onion root tip have cells that rapidly divide, making it easier to see the different stages of mitosis under a microscope.
Many of the cells of the root meristem are not undergoing mitosis, rather they are in a stage called ______.
interphase
Based on the interpretations made, interphase appears to be much _____ than mitosis.
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What processes occur in interphase cell prior to the onset of mitosis?
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Once cell division ends, the cells will exit the cell cycle and enter the _____ stage.
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Why is it incorrect to say that these cells are resting?
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If your observations had not been restricted to the area of the root tip that is actively dividing, how would your results have been different?
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What evidence shows that mitosis is a continuous process and not a series of separate events?
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What would happen if the process of mitosis skipped metaphase? Telophase?
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How many chromosomes are in each of the cells that you observed?
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After meiosis, how many chromosomes would be in each sex cell?
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How many chromosomes would be in the zygotes that are produced after sexual reproduction?
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Where does one find cells undergoing meiosis in plants?
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Where does one find cells undergoing meiosis in animals?
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Some tissues in both plants and animals rarely divide once the organism is mature. Where are they found in plants?
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Some tissues in both plants and animals rarely divide once the organism is mature. Where are they found in animals?
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Study Notes
Mitosis Overview
- Mitosis is more accurately termed "nuclear replication" as it involves the division of the nucleus into two nuclei, not the entire cell.
- Whitefish blastula and onion root tip are chosen for study due to their rapidly dividing cells, facilitating observation of mitosis stages.
Interphase
- A significant portion of root meristem cells are in interphase, a stage different from mitosis.
- Interphase is longer compared to mitosis.
- Processes in interphase include:
- G1 Phase: Cell growth, DNA assessment for readiness, organelle, and protein synthesis.
- S Phase: DNA replication occurs, and chromosomes are prepared with chromatids attached.
- G2 Phase: Continued growth and metabolic activity, formation of centrosomes.
Cell Cycle and Metabolic Activity
- Once cell division concludes, cells enter the G0 phase.
- Cells in G0 are not resting; they maintain metabolic activity despite not dividing.
Observations and Results
- Focusing observations only on actively dividing root tips likely leads to fewer interphase cells being counted, affecting mitosis stage percentages.
Continuous Nature of Mitosis
- Mitosis is a continuous cycle where each stage relies on the preceding one, indicating that each phase is interconnected.
Consequences of Skipping Mitosis Stages
- Skipping metaphase may prevent proper chromosome alignment, hindering division.
- Omitting telophase would disrupt the formation of cells, as key structures develop during this phase.
Chromosome Count and Reproduction
- An onion plant begins as a single cell with X chromosomes; daughter cells retain this chromosome count post-mitosis.
- For sexual reproduction, meiosis reduces the chromosome number in sex cells to 1/2 X.
- Zygotes formed post-fertilization would have X chromosomes, equal to the parent cell's count.
Meiosis in Plants and Animals
- Cells undergoing meiosis in plants and animals were not specifically identified but are essential for sexual reproduction.
- In mature plants, tissues that rarely divide include strengthening and fluid connective tissues.
- In mature animals, non-dividing tissues include heart muscle and neurons.
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Description
This quiz focuses on key concepts related to mitosis, specifically in the context of a biology final. It covers the accuracy of the term 'nuclear replication' and the importance of specific organisms in studying mitosis. Test your understanding of these crucial biological processes!