A biologist records observations of two neurones connected to the spinal cord.
| Neurone | Position of cell body | Fibres connected to the cell body |
|---|---|---|
| J | In a swelling just outside the spinal cord, part way along and to one side of the main fibre | One long dendron extends away from the spinal cord and a shorter axon enters the spinal cord |
| K | Inside the spinal cord, at one end of the neurone | Many short dendrites and one long axon that leaves the spinal cord |
The labels identifying neurones J and K have been lost.
Describe how the structural evidence can be used to identify each neurone.
An impulse travels through two sections of a nervous pathway.
| Section | Distance (m\text{m}m) | Impulse speed (m/s\text{m/s}m/s) |
|---|---|---|
| Sensory neurone | 0.84 | 70 |
| Motor neurone | 0.96 | 60 |
Calculate the total time taken for the impulse to travel through both sections.
Use the equation: time === distance ÷ \div\,÷ speed
Give your answer in ms\text{ms}ms.
A person prepares to jump vertically. Motor impulses leave the CNS at the same time for the left and right calf muscles. Both muscles begin to contract as soon as an impulse reaches them.
| Motor neurone | Myelin sheath | Time for impulse to reach muscle (ms\text{ms}ms) |
|---|---|---|
| Left calf | Complete | 12 |
| Right calf | A long section is missing | 44 |
Suggest how the difference in the myelin sheath will affect the person's take-off. Use the data in your answer.
135 exam-style questions on OCR GCSE Biology 3.1 Coordination and control – the nervous system, covering 3.1.1 Structure of the nervous system, 3.1.2 Coordinated response, 3.1.3 The reflex arc, 3.1.4 Structure of the eye, 3.1.5 Defects of the eye, 3.1.6 Structure and function of the brain, 3.1.7 Difficulties of investigating brain function, and 3.1.8 Limitations in treating nervous system damage. Each one has a worked solution and a mark scheme showing where the marks go.