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Following a body injury, bone marrow stem cells move to the site of damage and undergo cell differentiation - AQA - A-Level Biology - Question 4 - 2023 - Paper 3
Question 4
Following a body injury, bone marrow stem cells move to the site of damage and undergo cell differentiation. Figure 5 shows how this differentiation occurs. 1. Sug... show full transcript
Worked Solution & Example Answer:Following a body injury, bone marrow stem cells move to the site of damage and undergo cell differentiation - AQA - A-Level Biology - Question 4 - 2023 - Paper 3
Step 1
Step 2
Using all of the information, suggest explanations for the results for the Control group.
Answer
In the Control group, cardiomyocytes (cardiac muscle cells) have not been replaced. This could be due to several reasons: firstly, the infarcted tissue is not repaired or replaced. Additionally, if the contraction of the ventricle is weak, there may be a small number of cardiomyocytes, which would lead to impaired heart function. Lastly, if the ventricular pressure is low, this could indicate that cardiomyocytes are damaged or dead.
Step 3
Using all of the information, suggest explanations for the results for the c-KIT- group.
Answer
In the c-KIT- group, the result is higher than the Control group, indicating that some stem cells must have been able to differentiate. This means that some cardiomyocytes have been repaired or the infarcted tissues have been regenerated. However, the increase is less than in the c-KIT+ group, suggesting that SCF may not be the only factor responsible for differentiation. Something else must be able to activate the signaling in those c-KIT- cells.
Step 4
Assuming that mean ventricular blood pressure is directly proportional to the number of cardiomyocytes, calculate the percentage of infarcted tissue that was made up of new cardiomyocytes in the c-KIT- group.
Answer
If the c-KIT+ group showed that 68% of the infarcted tissue was made up of new cardiomyocytes, the calculation for the c-KIT- group would yield approximately 34% of new cardiomyocytes based on the proportional relationship.
Step 5
Suggest how production of Connexin-43 could give the result seen in the c-KIT+ group.
Answer
Connexin-43 allows electrical impulses to pass between cardiomyocytes, promoting coordinated contraction of the heart muscle, which could lead to improved healing and functionality of the infarcted tissue.
Step 6
Suggest how production of GATA-4 could give the result seen in the c-KIT+ group.
Answer
GATA-4 acts as a transcription factor that stimulates the expression of genes involved in actin and myosin production. This could lead to the formation of more actinomyosin bridges in new cardiomyocytes, enhancing contractile function and contributing to the recovery of the heart tissue.