Answer 1

Positive effects of tides are as follows :

1. With the high tides, fish move into the creeks and this helps fishing activity.
2. The tides clear the waste and hence the coasts become clean.
3. Due to tides, ports do not get filled with sediments.
4. Ships can move up to the ports during high tide.
5. During high tide, sea water can be stored in salt pans from which salt can be obtained.
6. The tidal force can be used to generate electricity.
7. The tides help in maintaining the mangroves and the coastal biodiversity. (B)

 Negative effect of the tide is as follows: 
A lack of an understanding of the timings of high tide and low tide may cause accidents to swimmers entering the sea.