1. The cell membrane is , which means that some substances can pass through it but others can't. 2. In diffusion, molecules move from an area of concentration to an area of concentration.
3. Two ways of moving things into and out of cells that do NOT need energy are and . Moving materials through a cell membrane without using energy is called transportation.
4. List two ways that the cell moves things by active transport.
a. Active transport requires energy from the cell.
b.

estuaries are the partially enclosed coastal bodies of brackish water formed at the mouth of sea where river meets an ocean. it is a transition zone between river and sea water so estuaries are influenced to both marine environment such as tides, waves and to riverine such as flow of fresh water and sediments. the mixing of sea and fresh water provide high level of nutrients, making estuaries a high product habitats.

many estuaries suffers degradation from a variety of human activities like erosion from deforestation, overgrazing, overfishing, drainage and eutrophication.

so from the above statement answers will be

1. false as estuaries are formed due to both brackish and freshwater.

2.true, due to high productivity estuaries are breeding ground for many marine species.

3. direct and indirect activities of man that contribute to pollution and deposition of sediments.