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Notes by Sir Hadi
📌 Introduction to Cell Cycle:
The cell cycle is the sequence of events that a cell goes through as it grows and divides. It includes periods of growth, DNA replication, and cell division.
It ensures that cells grow properly, replicate their DNA, and divide into two identical daughter cells.
🔄 Main Phases of the Cell Cycle:
1- Interphase:
Longest phase
Cell grows, performs its functions, and prepares for division
2-Mitotic Phase (M phase):
Includes mitosis and cytokinesis
Actual division of the cell takes place here
✂️ Mitosis – Definition and Stages
Mitosis is the type of cell division in which a parent cell divides to form two identical daughter cells, each having the same number of chromosomes as the parent.
🔁 Meiosis – Definition
Meiosis is a type of cell division that reduces the chromosome number by half, producing four non-identical daughter cells (gametes: s***m or egg), each with half the chromosomes of the parent cell.
❓ Conceptual MCQs
1. In which phase does DNA replication occur?
A) G1
B) G2
C) S
D) M
✔️ Correct Answer: C) S
2. Mitosis results in:
A) Four identical cells
B) Two identical cells
C) Four different cells
D) One large cell
✔️ Correct Answer: B) Two identical cells
3. What happens during metaphase?
A) Chromosomes disappear
B) Chromosomes line up in the center
C) DNA is copied
D) Cell grows
✔️ Correct Answer: B) Chromosomes line up in the center
4. Meiosis is important for:
A) Growth
B) Repair
C) Formation of gametes
D) Asexual reproduction
✔️ Correct Answer: C) Formation of gametes
5. In which stage of mitosis do chromatids move to opposite poles?
A) Prophase
B) Metaphase
C) Anaphase
D) Telophase
✔️ Correct Answer: C) Anaphase
✍️ Short Questions
1-What is the cell cycle?
2-Define mitosis.
3-Define meiosis.
4-Name the three phases of interphase.
5-What happens in the S phase?
6-What is cytokinesis?
7-Why is mitosis important?
8-How is meiosis different from mitosis?
9-Name the four main stages of mitosis.
10-In which type of cells does meiosis occur?....................................................................................................................................................
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