A student says: "DNA is copied after mitosis because daughter cells only need half the genetic information at first."
.1
Explain why this account is incorrect.
[3 marks].2
Explain why mitosis is useful in healing a skin wound.
[2 marks]Edexcel GCSE Combined Science November 2021 Biology Paper 1H
5 questions on this paper's topics
25:001 of 5
Plant tissue gains 4% mass at 0.20 mol/dm³ sugar and loses 4% at 0.40 mol/dm³. Assume a linear relationship between these points.
.1
Estimate the concentration giving zero net mass change.
[2 marks].2
Explain what zero net change means and how to improve the estimate.
[2 marks]Equal masses of fat are mixed with equal lipase concentrations at 37 °C. A has large droplets at pH 3; B has large droplets at pH 8; C has small droplets at pH 8. This lipase works best near pH 8.
.1
Explain why B should digest fat faster than A.
[2 marks].2
Explain why C should be faster than B and relate this to bile.
[2 marks]A virus damages immune cells. Patients later get frequent infections from other pathogens. Long illness prevents some patients from working or meeting friends.
.1
Explain why other infections become more frequent.
[2 marks].2
Suggest two links between long illness and poorer mental health.
[2 marks]A clinic diagnoses gonorrhoea in a patient with pain on urination. An initial antibiotic fails; tests identify a resistant bacterial strain.
.1
Explain why an antibiotic can be appropriate for gonorrhoea but this antibiotic failed.
[2 marks].2
Explain how a barrier method reduces transmission and why pain relief alone does not prevent spread.
[2 marks]