Educational biology worksheet covering cell cycle and DNA replication topics.
A worksheet titled "Cell Cycle, DNA Replication, Transcription & Translation Worksheet" for Chapter 10, featuring questions about cell division, DNA replication, and related biological processes.
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You've uploaded a worksheet titled “Cell Cycle, DNA Replication, Transcription & Translation Worksheet”, specifically focusing on Chapter 10: The Cell Cycle. Since I can’t see the image directly (as per your note), I’m working from the text you provided — which appears to be the worksheet itself with numbered questions and some answers already filled in.
I’ll go through each question, provide the correct answer, and explain the reasoning behind it. Some answers are already partially filled — I’ll verify or complete them as needed.
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Answer: Mitosis
Explanation:
Mitosis is the phase of the cell cycle where the nucleus divides, resulting in two genetically identical daughter nuclei. This is followed by cytokinesis (division of the cytoplasm), which completes the formation of two separate daughter cells. While “cell division” is a broader term, the specific process that splits the *nucleus* into two is mitosis.
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Answer: Histones
Explanation:
DNA in eukaryotic cells is wrapped around histone proteins to form nucleosomes, which are the basic units of chromatin. This packaging allows meters of DNA to fit inside the tiny nucleus and also helps regulate gene expression.
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Answer: Interphase
Explanation:
The cell cycle consists of interphase (G1, S, G2) and the mitotic phase (M). Interphase accounts for about 90% of the cell cycle — this is when the cell grows, carries out metabolic activities, and replicates its DNA in preparation for division.
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Answer: Chromosomes
Explanation:
Before mitosis begins, during the S phase of interphase, the cell duplicates its chromosomes. Each chromosome becomes composed of two identical sister chromatids joined at the centromere. This ensures each daughter cell receives a full set of chromosomes.
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Answer: Mitosis, Cytokinesis, (and sometimes listed as) Karyokinesis
*(Note: Most textbooks list Mitosis and Cytokinesis as the two main parts of M phase. Sometimes “Karyokinesis” — nuclear division — is used synonymously with mitosis.)*
Best Answer: Mitosis, Cytokinesis
Explanation:
- Mitosis = division of the nucleus
- Cytokinesis = division of the cytoplasm
Together, they make up the M (mitotic) phase. Some curricula may break mitosis down further into prophase, metaphase, anaphase, telophase — but those are *stages within mitosis*, not separate phases of the M phase.
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Answer: G2 phase
*(Wait — actually, correction needed!)*
Correct Answer: S phase *(or sometimes G2, depending on source — but S phase is more accurate)*
Better Explanation:
Centrosome duplication begins in S phase and is completed by G2 phase. Centrioles (found in animal cells) duplicate during S phase along with DNA replication. So while some sources say G2, the initiation and majority of duplication occurs in S phase.
✔ Final Answer: S phase
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Answer: S phase
Explanation:
S stands for “Synthesis.” During this phase, DNA replication occurs — each chromosome is duplicated to produce two sister chromatids.
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Answer: DNA
Explanation:
Thanks to DNA replication in S phase and precise segregation during mitosis, each daughter cell gets an identical copy of the parent cell’s genetic material — its DNA.
---
Answer: Genetic diversity
Explanation:
Sexual reproduction combines genetic material from two parents, leading to offspring with unique combinations of genes. This increases genetic variation in a population, which enhances adaptability and survival in changing environments — a key advantage over asexual reproduction, which produces clones.
---
Answer: Chromosome
Explanation:
In prophase, chromatin condenses into tightly coiled structures called chromosomes, making them visible under a light microscope. Each chromosome consists of two sister chromatids.
---
*(Since no image is available, I’ll assume it’s showing a cell in mitosis with centrosomes/centrioles visible.)*
Answer:
Picture shows: Animal cell in mitosis (likely prophase or metaphase)
Role of centrosomes: Organize microtubules to form the mitotic spindle, which separates chromosomes.
Order during mitosis:
- Prophase: Centrosomes move to opposite poles of the cell.
- Metaphase: Spindle fibers attach to kinetochores; centrosomes anchor spindle poles.
- Anaphase/Telophase: Centrosomes remain at poles until cytokinesis.
Explanation:
Centrosomes act as microtubule-organizing centers. In animal cells, they contain centrioles and help form the spindle apparatus critical for chromosome separation.
---
Answer: 46
Explanation:
Human somatic (body) cells are diploid — they have 23 pairs of chromosomes, totaling 46. Gametes (sperm and egg) have 23 chromosomes (haploid).
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Answer: 23
Explanation:
Gametes are haploid cells formed by meiosis. They carry half the number of chromosomes so that when fertilization occurs, the zygote will have the correct diploid number (46).
---
Answer: Prophase
Explanation:
During prophase of mitosis, the nuclear envelope breaks down, allowing spindle fibers to access the chromosomes. The nucleolus also disappears.
---
Answer: Chromatin
Explanation:
In telophase, chromosomes decondense back into long, thin strands of chromatin. The nuclear envelope reforms around each set of chromosomes, and nucleoli reappear.
---
Answer: Prophase, Metaphase, Anaphase
*(Sometimes Telophase is included, but chromosomes begin to uncoil and become less visible then.)*
Best Answer: Prophase, Metaphase, Anaphase
Explanation:
Chromosomes are most condensed and visible during these stages. By telophase, they start to decondense into chromatin and become less distinct under a microscope.
---
## 📝 Summary of Final Answers:
1. Mitosis
2. Histones
3. Interphase
4. Chromosomes
5. Mitosis, Cytokinesis
6. S phase
7. S phase
8. DNA
9. Genetic diversity
10. Chromosome
11. (Assumed) Animal cell in mitosis; Centrosomes organize spindle fibers; appear in Prophase → Metaphase → Anaphase
12. 46
13. 23
14. Prophase
15. Chromatin
16. Prophase, Metaphase, Anaphase
---
Let me know if you’d like this formatted as a printable answer key or need diagrams/explanations for any specific part!
I’ll go through each question, provide the correct answer, and explain the reasoning behind it. Some answers are already partially filled — I’ll verify or complete them as needed.
---
✔ 1. The process by which a cell splits into two daughter cells is called ________.
Answer: Mitosis
Explanation:
Mitosis is the phase of the cell cycle where the nucleus divides, resulting in two genetically identical daughter nuclei. This is followed by cytokinesis (division of the cytoplasm), which completes the formation of two separate daughter cells. While “cell division” is a broader term, the specific process that splits the *nucleus* into two is mitosis.
---
✔ 2. DNA wraps itself around proteins called ________, which aid in the tight packing of DNA into chromosomes.
Answer: Histones
Explanation:
DNA in eukaryotic cells is wrapped around histone proteins to form nucleosomes, which are the basic units of chromatin. This packaging allows meters of DNA to fit inside the tiny nucleus and also helps regulate gene expression.
---
✔ 3. Cells spend most of their time in what phase? ________
Answer: Interphase
Explanation:
The cell cycle consists of interphase (G1, S, G2) and the mitotic phase (M). Interphase accounts for about 90% of the cell cycle — this is when the cell grows, carries out metabolic activities, and replicates its DNA in preparation for division.
---
✔ 4. During cell division, ________ are duplicated before cell division so that each new daughter cell has a complete set.
Answer: Chromosomes
Explanation:
Before mitosis begins, during the S phase of interphase, the cell duplicates its chromosomes. Each chromosome becomes composed of two identical sister chromatids joined at the centromere. This ensures each daughter cell receives a full set of chromosomes.
---
✔ 5. The M phase of the cell cycle includes: ________, ________, and ________.
Answer: Mitosis, Cytokinesis, (and sometimes listed as) Karyokinesis
*(Note: Most textbooks list Mitosis and Cytokinesis as the two main parts of M phase. Sometimes “Karyokinesis” — nuclear division — is used synonymously with mitosis.)*
Best Answer: Mitosis, Cytokinesis
Explanation:
- Mitosis = division of the nucleus
- Cytokinesis = division of the cytoplasm
Together, they make up the M (mitotic) phase. Some curricula may break mitosis down further into prophase, metaphase, anaphase, telophase — but those are *stages within mitosis*, not separate phases of the M phase.
---
✔ 6. The centrioles and centrosomes are produced and duplicate during: ________
Answer: G2 phase
*(Wait — actually, correction needed!)*
Correct Answer: S phase *(or sometimes G2, depending on source — but S phase is more accurate)*
Better Explanation:
Centrosome duplication begins in S phase and is completed by G2 phase. Centrioles (found in animal cells) duplicate during S phase along with DNA replication. So while some sources say G2, the initiation and majority of duplication occurs in S phase.
✔ Final Answer: S phase
---
✔ 7. During which stage of interphase is the cell’s chromosomes copied? ________
Answer: S phase
Explanation:
S stands for “Synthesis.” During this phase, DNA replication occurs — each chromosome is duplicated to produce two sister chromatids.
---
✔ 8. When a cell divides each daughter cell receives one copy of the parent cell’s ________.
Answer: DNA
Explanation:
Thanks to DNA replication in S phase and precise segregation during mitosis, each daughter cell gets an identical copy of the parent cell’s genetic material — its DNA.
---
✔ 9. Explain one advantage of sexual reproduction over asexual reproduction.
Answer: Genetic diversity
Explanation:
Sexual reproduction combines genetic material from two parents, leading to offspring with unique combinations of genes. This increases genetic variation in a population, which enhances adaptability and survival in changing environments — a key advantage over asexual reproduction, which produces clones.
---
✔ 10. During prophase, DNA coils up and becomes a visible ________.
Answer: Chromosome
Explanation:
In prophase, chromatin condenses into tightly coiled structures called chromosomes, making them visible under a light microscope. Each chromosome consists of two sister chromatids.
---
✔ 11. The picture on the right shows a ________. What role do centrosomes play in mitosis? ________. Make specific references to order in which the centrosomes appear during mitosis.
*(Since no image is available, I’ll assume it’s showing a cell in mitosis with centrosomes/centrioles visible.)*
Answer:
Picture shows: Animal cell in mitosis (likely prophase or metaphase)
Role of centrosomes: Organize microtubules to form the mitotic spindle, which separates chromosomes.
Order during mitosis:
- Prophase: Centrosomes move to opposite poles of the cell.
- Metaphase: Spindle fibers attach to kinetochores; centrosomes anchor spindle poles.
- Anaphase/Telophase: Centrosomes remain at poles until cytokinesis.
Explanation:
Centrosomes act as microtubule-organizing centers. In animal cells, they contain centrioles and help form the spindle apparatus critical for chromosome separation.
---
✔ 12. Normal humans have a total of ________ chromosomes.
Answer: 46
Explanation:
Human somatic (body) cells are diploid — they have 23 pairs of chromosomes, totaling 46. Gametes (sperm and egg) have 23 chromosomes (haploid).
---
✔ 13. Human gametes have a total of ________ chromosomes.
Answer: 23
Explanation:
Gametes are haploid cells formed by meiosis. They carry half the number of chromosomes so that when fertilization occurs, the zygote will have the correct diploid number (46).
---
✔ 14. During ________ phase, the nuclear envelope begins to disappear.
Answer: Prophase
Explanation:
During prophase of mitosis, the nuclear envelope breaks down, allowing spindle fibers to access the chromosomes. The nucleolus also disappears.
---
✔ 15. During telophase, chromosomes uncoil to become ________.
Answer: Chromatin
Explanation:
In telophase, chromosomes decondense back into long, thin strands of chromatin. The nuclear envelope reforms around each set of chromosomes, and nucleoli reappear.
---
✔ 16. During which 3 phases are chromosomes visible? ________, ________, ________
Answer: Prophase, Metaphase, Anaphase
*(Sometimes Telophase is included, but chromosomes begin to uncoil and become less visible then.)*
Best Answer: Prophase, Metaphase, Anaphase
Explanation:
Chromosomes are most condensed and visible during these stages. By telophase, they start to decondense into chromatin and become less distinct under a microscope.
---
## 📝 Summary of Final Answers:
1. Mitosis
2. Histones
3. Interphase
4. Chromosomes
5. Mitosis, Cytokinesis
6. S phase
7. S phase
8. DNA
9. Genetic diversity
10. Chromosome
11. (Assumed) Animal cell in mitosis; Centrosomes organize spindle fibers; appear in Prophase → Metaphase → Anaphase
12. 46
13. 23
14. Prophase
15. Chromatin
16. Prophase, Metaphase, Anaphase
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Let me know if you’d like this formatted as a printable answer key or need diagrams/explanations for any specific part!
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