Master GCSE Biology

MS1.

- A stimulus is a change in the internal or external environment that triggers a response from an organism. (1)

MS2.

- A receptor has a specific shape that binds to a specific stimulus (1)

- When the stimulus binds, it causes a change in the shape of the receptor (1)

- This change in shape triggers a signal transduction pathway, which leads to a response in the organism. (1)

MS3.

- Neurons are specialised cells that transmit signals over long distances (1)

- In a reflex arc, a sensory neuron receives a stimulus from a receptor (1)

- The sensory neuron sends a signal to an interneuron in the central nervous system (1)

- The interneuron then sends a signal to an effector, such as a muscle or gland, which produces a response. (1)

MS4.

- Insulin (1)

MS5.

- Auxins are plant hormones that regulate growth and development (1)

- They help plants to respond to stimuli such as light, gravity, and touch (1)

- For example, auxins cause plants to grow towards light and to develop roots away from gravity. (1)

MS6.

- Body temperature is detected by receptors in the skin and the hypothalamus in the brain (1)

- When body temperature rises, the hypothalamus triggers the release of hormones such as adrenaline (1)

- Adrenaline increases sweating and causes blood vessels near the skin to dilate, which helps to dissipate heat (1)

- When body temperature falls, the hypothalamus triggers the release of hormones such as thyroxine, which increases metabolism and heat production. (1)

MS7.

- Pituitary gland (1)

MS8.

- Glucagon is produced by the pancreas when blood glucose levels are low (1)

- Glucagon stimulates the liver to break down glycogen into glucose, which raises blood glucose levels (1)

- Insulin is produced by the pancreas when blood glucose levels are high (1)

- Insulin stimulates cells to take up glucose from the blood, which lowers blood glucose levels. (1)

MS9.

- Gibberellins are plant hormones that promote cell elongation and growth (1)

- They are involved in a variety of processes, including seed germination, stem elongation, and fruit development (1)

- For example, gibberellins cause plants to produce longer stems and larger fruits. (1)

MS10.

- Dendrite (1)