HWrkSht 3_6
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1. Complete the table below by describing how each of the neurones carry electrical impulses. The first one has been done for you.
2. What is a synapse?
3. What type of molecule is released when a nerve impulse arrives at the end of a neurone?
4. In your jotter draw and label a diagram of a synapse.
5. What is a reflex action, and what advantage does a reflex response represent for an organism?
6. Why is a reflex action so rapid?
7. Examine the diagram of a reflex arc below.
The stage of the reflex arc are numbered on the diagram. Use the numbers to match each of the statements to identify each stage of the reflex arc.
a) Damaging or threatening stimulus is detected by sensory receptor (e.g pain receptor in skin).
b) Impulse sent along relay nerve cell in spinal cord.
c) Impulse sent along sensory nerve into spinal cord.
d) Response made by effector organ (e.g. muscle or gland).
e) Impulse sent along motor nerve cell out of spinal cord.
8.
The contraceptive pill contains hormones and its use has resulted in small quantities of these hormones reaching our fresh water supplies. The effect of these hormones on the heart rate of water fleas was investigated. Water fleas were placed into solutions of different hormone concentration and their heart rates were measured.
a) In your jotter plot a line graph to show the effect of the hormone on the heart rate of the water fleas.
b) Describe the effect of increasing hormone concentration on the heart rate of water fleas.
c) It has been suggested that the presence of this hormone in drinking water may have an effect on the heart rate of humans.
State whether you agree or disagree with this suggestion and give a reason to support your choice.
d) An improvement to this experiment would be to set up a control to count the heart rate of water fleas placed in water without the hormone.
State the purpose of this control.
