A scientist investigates a substance, X, produced by gland G. Equal volumes of blood are collected just before the blood enters G and just after the blood leaves G. Plasma is separated from each blood sample. Equal volumes of each plasma sample are then added to cells from organs P and Q.
The scientist also removes X from some plasma collected after the blood leaves G. The cells are not connected to gland G by neurones.
| plasma added to cells | mean activity of cells from organ P / arbitrary units | mean activity of cells from organ Q / arbitrary units |
|---|---|---|
| collected before blood enters G | 4.0 | 6.0 |
| collected after blood leaves G | 12.0 | 6.0 |
| collected after blood leaves G, with X removed | 4.0 | 6.0 |
Explain what the results show about gland G, substance X and organs P and Q.
89 exam-style questions on Edexcel GCSE Biology 7.1 Hormones and coordination, covering 7.1.1 Endocrine glands and hormone transport, 7.1.2 Adrenalin and fight or flight, and 7.1.3 Thyroxine and negative feedback. Each one has a worked solution and a mark scheme showing where the marks go.