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Questions and Answers
What is the defining characteristic of diploid cells in humans?
What is the defining characteristic of diploid cells in humans?
Which of the following statements correctly describes polyploidy?
Which of the following statements correctly describes polyploidy?
In the lifecycle terms, which category does most animal species fall under?
In the lifecycle terms, which category does most animal species fall under?
What differentiates haploid organisms from diploid organisms?
What differentiates haploid organisms from diploid organisms?
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What describes the term 'trisomy' in relation to chromosome conditions?
What describes the term 'trisomy' in relation to chromosome conditions?
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What is the ploidy level of a human zygote?
What is the ploidy level of a human zygote?
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How many pairs of autosomes do dogs have?
How many pairs of autosomes do dogs have?
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Which statement accurately distinguishes sex chromosomes in humans?
Which statement accurately distinguishes sex chromosomes in humans?
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What defines homologous chromosomes?
What defines homologous chromosomes?
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How many distinct types of chromosomes are present in a haploid cell with n=6?
How many distinct types of chromosomes are present in a haploid cell with n=6?
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What is the total number of chromosomes for a species with a haploid number of n=23?
What is the total number of chromosomes for a species with a haploid number of n=23?
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Which characteristic differentiates the sex chromosomes X and Y in humans?
Which characteristic differentiates the sex chromosomes X and Y in humans?
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What is the significance of homologous chromosomes during cell division?
What is the significance of homologous chromosomes during cell division?
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During which phase does DNA synthesis occur?
During which phase does DNA synthesis occur?
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What is the main purpose of the G2 phase?
What is the main purpose of the G2 phase?
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Which process immediately follows mitosis in the cell cycle?
Which process immediately follows mitosis in the cell cycle?
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What is the function of DNA polymerase during DNA replication?
What is the function of DNA polymerase during DNA replication?
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What occurs primarily during the S phase of the cell cycle?
What occurs primarily during the S phase of the cell cycle?
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Which statement correctly describes the G0 phase?
Which statement correctly describes the G0 phase?
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What happens to the DNA during cell division?
What happens to the DNA during cell division?
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Which of the following is not a phase of the cell cycle?
Which of the following is not a phase of the cell cycle?
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What is the primary outcome of meiosis for daughter cells?
What is the primary outcome of meiosis for daughter cells?
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Which statement correctly describes the function of cytokinesis?
Which statement correctly describes the function of cytokinesis?
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Which of the following is NOT a function of cell division in multicellular organisms?
Which of the following is NOT a function of cell division in multicellular organisms?
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How does cell division differ in single-celled organisms compared to multicellular organisms?
How does cell division differ in single-celled organisms compared to multicellular organisms?
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In the context of cell types produced, which statement is true regarding mitosis?
In the context of cell types produced, which statement is true regarding mitosis?
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What distinguishes genetic material division in both mitosis and meiosis?
What distinguishes genetic material division in both mitosis and meiosis?
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Which type of reproduction is associated with single-celled organisms?
Which type of reproduction is associated with single-celled organisms?
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What role does cellular division play in multicellular organisms beyond reproduction?
What role does cellular division play in multicellular organisms beyond reproduction?
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Study Notes
DNA and Chromosomes
- DNA is condensed to form chromosomes.
- Chromosome number varies among species.
- Humans have 46 chromosomes (23 pairs).
- Dogs have 78 chromosomes (39 pairs).
- Humans have 22 autosome pairs (non-sex chromosomes) and 1 sex chromosome pair (XX or XY).
- Dogs have 38 autosome pairs (non-sex chromosomes) and 1 sex chromosome pair (XX or XY).
- In species with two chromosome pairs, the two that make up the pair are called homologs (homologous chromosomes).
- Homology is similarity due to common ancestry.
- Autosomes have nearly identical sizes and genetic compositions.
- Sex chromosomes (X and Y) are very different in size and composition, they’re not considered homologous chromosomes.
- One autosome homolog is inherited from the mother and the other from the father.
Ploidy Levels
- Haploid (n): single set of chromosomes.
- Human gametes are haploid.
- Diploid (2n): two sets of chromosomes.
- Humans are diploid.
- Polyploid (3n+): more than two sets of chromosomes.
- Polyploidy is lethal in humans.
Cell Division: Mitosis and Meiosis
- Cell division replicates genetic material, divides it evenly, and forms two daughter cells.
- Cell division happens in both prokaryotes and eukaryotes.
- There are two types of cell division:
- Mitosis: creates somatic cells (all body cells besides gametes), produces genetically identical daughter cells.
- Meiosis: creates gametes, reduces genetic material by half in daughter cells.
- Both forms of cell division are accompanied by cytokinesis, dividing the cytoplasm into two daughter cells.
Cell Division Functions
- Cell division allows for:
- Asexual reproduction in single-celled organisms.
- Growth, reproduction, repair, and asexual reproduction in multicellular organisms.
The Cell Cycle
- The cell cycle has four main phases:
- G1 (first gap): cell grows and duplicates cellular contents (excluding chromosomes).
- S (synthesis): replication of chromosomes.
- G2 (second gap): cell synthesizes proteins needed for mitosis and cytokinesis, spindle fibers form.
- M (mitosis): division of the nucleus, separation of sister chromatids occurs.
- Cytokinesis occurs after mitosis, dividing the cytoplasm into two daughter cells.
DNA Replication
- DNA replication happens during the S phase of the cell cycle.
- DNA Polymerase helps in replication.
Conclusion
- DNA is duplicated and divided evenly between parent and daughter cells during cell division.
- Mitosis and meiosis are distinct processes that lead to different outcomes.
- The cell cycle is a tightly regulated process ensuring precise duplication of DNA.
- DNA replication is a complex process crucial for the transmission of genetic information.
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Description
This quiz covers key concepts about DNA and chromosomes, including their structure and function in different species. Explore the variations in chromosome numbers and the significance of homologous chromosomes. Additionally, understand the different ploidy levels and their implications for organisms such as humans and dogs.
