Question 1: Define stem cells and explain their primary characteristic that distinguishes them from specialised cells.

Answer: Stem cells are undifferentiated cells capable of dividing and renewing themselves, with the primary characteristic of being able to differentiate into specialised cell types.

Question 1: Describe the process by which embryonic stem cells differentiate into specialised cells.

Answer: Embryonic stem cells differentiate through gene expression changes triggered by signals in the environment, leading to activation of specific genes that produce proteins necessary for specialised cell functions.

Question 2: Explain why adult stem cells are considered more limited in their differentiation capacity compared to embryonic stem cells.

Answer: Adult stem cells are more limited because they typically can only differentiate into cell types of their tissue of origin, whereas embryonic stem cells can become any cell type.

Question 1: A study reports that 75% of successful bone marrow transplants involve stem cells. In a sample of 120 transplants, how many were successful using stem cells? Show your calculation and state the units.

Answer: Number of successful transplants = 75% of 120 = 0.75 × 120 = 90 transplants.

Question 2: Interpret what the high success rate of stem cell use in bone marrow transplants suggests about their potential in medicine.

Answer: The high success rate indicates that stem cells are effective in restoring damaged tissue, highlight their potential in regenerative medicine, and suggest that stem cell therapy can be a reliable treatment for certain conditions.

Question 1: Outline a basic experimental design to test the ability of adult stem cells to differentiate into nerve cells in vitro. Include variables and safety precautions.

Answer: The experiment involves isolating adult stem cells from tissue, culturing them in a medium with nerve growth factors, and observing differentiation over time. Variables include the type of growth factors (independent variable) and cell differentiation (dependent variable). Controls should include cultures without growth factors. Safety precautions include using sterile techniques, wearing protective equipment, and proper disposal of biological waste.

Question 1: Explain the ethical issues associated with the use of embryonic stem cells in medical research. (6 marks)

Answer: Ethical issues include the moral status of the embryo, as harvesting embryonic stem cells involves destroying the embryo. There are concerns about consent and the potential for misuse or exploitation. Alternatives like adult stem cells are considered more ethically acceptable, but may be less versatile than embryonic stem cells.

Question 1: Describe how stem cell research is contributing to the development of treatments for degenerative diseases such as Parkinson’s disease.

Answer: Stem cell research aims to generate dopamine-producing nerve cells to replace damaged cells in Parkinson’s disease, potentially restoring function and reducing symptoms.