PAG Extension Questions and Answers | Latest Version | 2024/2025 | Already Passed

PAG Extension Questions and Answers | Latest Version | 2024/2025 | Already Passed **What is the purpose of mitosis for a living organism?** Mitosis serves for growth and tissue repair, as well as for asexual reproduction. **What are the key visible features of each stage of mitosis?** Prophase - chromosomes become visible Metaphase - chromosomes align along the cell's equator Anaphase - chromatids separate and move to opposite poles Telophase - two nuclei become visible as the cell prepares to split. **Why is it incorrect to describe cells in interphase as "resting" after active cell division?** Interphase is a period of activity where cells perform functions like DNA checking, protein synthesis, respiration, and mRNA synthesis. **Why is a sample from the roots of Allium spp. ideal for studying mitosis?** Root cells are actively dividing, providing a variety of mitotic stages for observation. **In your specimen, which stage of the cell cycle predominates and why?** Interphase predominates because cells spend the majority of their time in this stage, preparing for division. **Could you use your own blood for this practical, and what precautions would be necessary?** Yes, precautions include ensuring sterile handling to prevent infection (ethanol swabbing, sterile dressing), and preventing contamination of others. **Estimate the concentration of erythrocytes in a blood sample and discuss uncertainties and improvements.** An estimate might be around 5 billion erythrocytes per cm3. Accuracy could improve with a haemocytometer, considering factors like droplet volume and smearing thickness. **What is the volume of a spherical erythrocyte assuming a calculated diameter of 7 μm, and is this likely an over- or under-estimate?** Volume would be approximately 180 μm3, but due to their biconcave shape, this estimate likely overestimates the true volume. **What are the functions of different cell types in a blood sample?** Erythrocytes carry oxygen and carbon dioxide, thrombocytes aid in blood clotting, lymphocytes and neutrophils provide specific and non-specific immunity, eosinophils respond to inflammation and parasites, and basophils aid in inflammatory responses. **Calculate how many times thicker the right ventricle is compared to the right atrium.** The right ventricle is significantly thicker than the right atrium due to its role in pumping blood to the lungs. **Calculate how many times thicker the left ventricle is compared to the right ventricle.** The left ventricle is thicker than the right ventricle to generate higher pressure for systemic circulation. **Why are ventricles thicker than atria, and why is the left ventricle thicker than the right?** Atria have thinner walls as they pump blood into the ventricles below. The left ventricle needs greater thickness to pump blood throughout the entire systemic circulation, whereas the right ventricle only pumps blood