A student writes: “Homeostasis stops all changes. Only the brain controls it. Muscles and glands detect every stimulus.”
Evaluate this description of homeostasis. Explain how automatic control systems actually work.
[6 marks]AQA GCSE Combined Science June 2023 Biology Paper 2H
5 questions on this paper's topics
27:001 of 5
After rainfall, water enters soil and is taken up by trees. On a sunny day the air above the woodland contains more water vapour.
.1
Explain how water moves from the soil to the atmosphere through the trees.
[2 marks].2
Describe two later processes that return this water to land as part of the cycle.
[2 marks]A clinic considers transferring two embryos instead of one. Two-embryo transfer may increase pregnancy probability per transfer, but also increases the chance of multiple pregnancy.
Evaluate the use of two-embryo transfer. Include scientific, practical and ethical considerations.
[6 marks]A chart shows an XX egg-producing parent and an XY sperm-producing parent. A student says that the egg determines whether the child is XX or XY.
.1
Explain why the student’s statement does not follow the chromosome model.
[2 marks].2
Explain why an earlier XY child does not make an XX child more likely next time.
[2 marks]A genetically engineered crop produces a protein harmful to one insect pest. Small field trials report less insect damage, but did not measure other insect populations.
.1
Explain how genetic engineering can produce the new crop characteristic.
[2 marks].2
Evaluate whether the trial establishes that large-scale use has no ecological disadvantages.
[3 marks]