Communication: neuronal and hormonal
In order for plants and animals to survive they must react to changes in their external (and internal) environment. Mechanisms are in place to detect changes and bring about responses through communication systems. Whilst animals have both neuronal and hormonal communication mechanisms, plants only have hormone like substances.
Students are often asked to compare the similarities and differences between neuronal and hormonal communication. Obviously this topic links closely with homeostasis and many resources listed in that topic will also be of value here.
Students at A level are required to have a detailed understanding of the structure and function of the mammalian nervous system. Students must appreciate the basic concept that a nerve impulse is specific to a target cell only because it releases a chemical messenger directly onto it, producing a response that is usually rapid, short-lived and localised. Students should also understand how electrical impulses are transmitted along the cell surface membrane, what is meant by resting potential and the sequence of events during an action potential. Some specifications require students to explain the effects of certain drugs on nerve impulses.
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Tropisms and Hormones *suitable for home teaching*
This short (three minute) video provides a basic introduction to plant hormones and tropisms. It would be suitable to show at the start of the lesson, with questions added in by the teacher to move the level of understanding from anything that was covered at Key Stage Four to the required level of detail needed at A level.
This video could be used as an introduction to a practical session to investigate the effect of auxin in plants - see the protocol included in this list.
Cell Signalling *suitable for home teaching*
This resource can be used in a number of ways. Firstly the content is appropriate for A level in highlighting the way in which hormones communicate with target cells. Activity sheet one covers this process, providing some challenging questions. Answers are provided, so students could self assess or peer assess their responses.
Activity two continues to explore the process of cell signalling and provides an opportunity for students to carry out some self directed/independent study researching the links provided. This activity is provided to model the way in which scientists would use secondary research.
The third part of the activity then uses this topic to consider the setting up of investigations, looking in detail at hypothesis, variables and reliability. This activity links to the provided video. This would be a good activity for A level students, particularly as a revision exercise. Many exam questions require students to consider factors such as variables and reliability in a given investigation.
Quick Reactions *suitable for home teaching*
This Catalyst article provides a good summary of neuronal transmission covering neurones, reflexes, synapses and receptors. The context for this information is how quickly the system is able to react to messages sent from the central nervous system.
This article could be used in a variety of ways. It could simply be a piece of reading for homework, or students could be asked to write a similar article on the endocrine system, highlighting differences and similarities.
The article notes how in certain diseases malfunction of the nervous system is seen, such as in Alzheimer’s syndrome, where the normal mechanism involved in releasing neurotransmitter stays open, flooding the neurone with calcium ions. Students could be asked to research another disease/disorder where neuronal function is in some way impaired, they could then present a summary of this to the class.
Listening to a Locust Brain
In this short, (three minute) video from the Royal Institute, scientists at Newcastle University demonstrate how they have been able to listen in to the activity of a locust neuron.
The information provided in the video is interesting and relevant to the topic, but there isn't much detail presented. It would be possible to use this video on its own as a quick starter/introduction to a lesson. There are questions that could be added either during the video or at the end, to challenge thinking and promote understanding about the propagation of the nerve impulse.
