Photosynthesis is the act of a producer creating its own food by taking in carbon-dioxide and sunlight, producing sugar which the plant eats. Whilst the plant is creating its food, it also produces oxygen which we breathe in. We breathe out carbon-dioxide which the plant takes in and starts the cycle again.
A biotic factor is anything that is living in an environment. Examples: Jungle tree, ape, cocoa, boa constrictor, leopard etc.
An ecosystem is a group of non-living and living creatures such as animals plants and weather that creates an ecosystem. Animals, plants. and weather (etc.) all help each other by producing climates, oxygen, or death for one another. Death helps animals and plants by controlling the number of animals by not letting the over populate. Such as predators hunting other animals. Weather makes the place a livable area or deadly one. Plants provide food and oxygen.
Weather is what is happening in the air, temperature, and wind (etc.) all at the same moment. Everything in the atmosphere happening all at the same moment which causes the temperature to change and some other things like that.
A delta is a land form created by sediment carried by a river flowing into an ocean, which creates the delta. Deltas usually are formed near oceans.