Homeostasis and coordination

25 Which endocrine gland produces follicle-stimulating hormone? A adrenal gland B ovary C pancreas D pituitary gland

20 What is the effect of regular excessive consumption of alcohol? A acts as a stimulant making the person more alert B increases the risk of liver damage C decreases the time taken to respond to a stimulus D makes the person less likely to be aggressive

25 Which event happens when the blood glucose concentration rises? A Less adrenaline is released. B Less insulin is released. C More adrenaline is released. D More insulin is released.

26 What is not an example of homeostasis involving a negative feedback mechanism? A maintaining the core body temperature at around 36.5 °C B releasing adrenaline from the adrenal glands when frightened C releasing glucose from liver cells into the blood after missing a meal D releasing insulin from the pancreas after eating a meal

© UCLES 2025 5090/12/O/N/25 [Turn over 36 Some stages in the production of human insulin are listed. 1 Genetically modified E. coli bacteria are grown in large fermenters. 2 The gene for human insulin is inserted into the DNA of an E. coli bacterium. 3 The gene for human insulin is obtained from human pancreas cells. 4 Human insulin is extracted and purified. What is the correct sequence of these stages? A 3  1  2  4 B 4  3  2  1 C 3  2  4  1 D 3  2  1  4 14

5090/21/O/N/25 © UCLES 2025 2 Fig. 2.1 shows a section through the human eye. K J M L N Fig. 2.1 (a) (i) Identify the letter on Fig. 2.1 that has been used to label the part of the eye that: contains circular and radial muscles ...................................... has the highest concentration of light receptors. ...................................... [2] (ii) On Fig. 2.1, draw and label: • the lens • the suspensory ligaments. [2] (iii) Explain the function of the suspensory ligaments. ...........................................................................................................

5090/21/O/N/25 © UCLES 2025 8 Fig. 8.1 shows a synapse between a sensory neurone and a relay neurone. The sensory neurone receives information from a pain receptor. sensory neurone relay neurone Fig. 8.1 (a) Explain how impulses in the sensory neurone can stimulate the relay neurone. ................................................................................................................................................... ................................................................................................................................................... ...................