A person touches a hot object and their hand moves away without them thinking. Describe the path taken by the nerve impulse in this reflex action.
Show mark scheme
- impulse travels along the sensory neurone (from the receptor) to the CNS / spinal cord (1)
- impulse crosses a synapse to the relay neurone (1)
- impulse passes (across another synapse) to the motor neurone (1)
- motor neurone carries the impulse to the effector / muscle, which contracts (1)
- Max 3
A student measured her reaction time five times using a computer test. The results were 0.26 s, 0.24 s, 0.31 s, 0.27 s and 0.28 s. Calculate her mean reaction time.
Show mark scheme
- 0.26 + 0.24 + 0.31 + 0.27 + 0.28 = 1.36 (1)
- 1.36 ÷ 5 = 0.27 s (1) allow 0.272 s
- allow 1 mark for dividing their total by 5 if the addition is wrong
Describe how you could investigate the effect of a distraction, such as music, on a person’s reaction time using a ruler.
Show mark scheme
- partner holds ruler vertically and drops it without warning; the person catches it and the distance is read from the ruler (1)
- repeat with and without the distraction (1)
- control variables stated, such as the same person, the same hand and the same drop height (1)
- repeat several times and calculate a mean (for each condition) (1)
- allow: a shorter distance means a faster reaction
The cerebral cortex, the cerebellum and the medulla are regions of the brain. Describe one function of each region.
Show mark scheme
- cerebral cortex: consciousness / intelligence / memory / language (1)
- cerebellum: coordinates muscular activity / balance (1)
- medulla: controls unconscious activities, such as heart rate or breathing (1)
Explain why it is difficult to investigate brain function and to treat brain disorders.
Show mark scheme
- the brain is very complex / made of billions of interconnected neurones with different regions (1)
- the brain is delicate, so investigation or treatment can damage it (1)
A person walks from a bright room into a dim room. What happens in their eye so that they can see better?
- The ciliary muscles contract
- The pupil becomes wider
- The lens becomes thinner
- The pupil becomes narrower
Show mark scheme
Answer: B B: the iris makes the pupil wider so more light enters the eye (1)
Explain how the eye focuses on a near object.
Show mark scheme
- ciliary muscles contract (1)
- suspensory ligaments loosen (1)
- lens becomes thicker (1)
- so refracts the light rays more strongly / light focuses on the retina (1)
- Max 3
A person with myopia (short sightedness) cannot see distant objects clearly. Explain how a spectacle lens can correct this.
Show mark scheme
- in myopia, light rays from distant objects focus in front of the retina (1)
- a concave lens is used (1)
- it refracts / spreads the light rays so that they focus on the retina (1)
A person walks outside on a very cold day and their body temperature begins to fall. Explain how their body responses raise body temperature.
Show mark scheme
- blood vessels constrict / vasoconstriction (1)
- so less blood flows near the skin surface and less energy is transferred to the surroundings (1)
- sweating stops, so less energy is transferred by evaporation (1)
- skeletal muscles contract rapidly / shiver (1)
- respiration in the muscles releases energy, which warms the body (1)
- Max 4