Explain the objectives of introductions and conclusions

What will be an ideal response?

The objectives of an introduction are arousing the attention of the audience, winning the goodwill and respect of your listeners, setting a tone and direction for the substance of your speech, and providing a preview.
The arousal of attention and goodwill of the audience prepares the audience to listen and lays a foundation for the central idea of the speech. The preview of the speech gives the audience an indication of the direction of the speech. The preview provides the audience with the central idea of the speech.
The objectives of the conclusion are to round off the message of the speech and complete the relationship you've constructed with the audience. The speaker should summarize the main points or ideas. In addition to reinforcing the ideas presented in the speech, the speaker should leave the audience in the proper mood.