▶️ Answer/Explanation
Solution
(a)(i) Stem cells are required in the lining of the small intestine because:
- They continuously replace old, worn-out, or dead cells that are damaged by food movement and digestive processes.
- They maintain the pool of stem cells through self-renewal while also producing differentiated cells through division.
- The intestinal lining has a high turnover rate, requiring constant cell replacement to maintain its function.
- They ensure genetically identical cells are produced to maintain consistent tissue function.
(a)(ii) Anaphase.
Explanation: This is the stage where sister chromatids separate and move to opposite poles of the cell.
(a)(iii) Cytokinesis.
Explanation: This is the final stage of the cell cycle where the cytoplasm divides to form two separate daughter cells.
(b) The role of centromeres in the cell cycle:
- They hold sister chromatids together after DNA replication during S phase.
- They serve as attachment points for spindle fibers during mitosis, allowing proper chromosome alignment and separation.
- They divide during anaphase, enabling the separation of sister chromatids into daughter chromosomes.
- This ensures accurate distribution of genetic material to daughter cells.
(c) Specialized cell functions and structural adaptations:
