Why do phospholipids form a bilayer in water? The phosphate portions repel each other. The hydrophilic and hydrophobic parts attract each other. The phosphate portions attract water, and the lipid portions repel water. The lipid portions attract water, and the phosphate portions repel water.

The phosphate portions attract water, and the lipid portions repel water.

Explanation:

Lipids are hydrophobic, while phosphates are hydrophilic. The lipid tails of phospholipids repel water and attract other lipid tails, so they are always on the inside of the bilayer, keeping them away from the water. The phosphate portions attract water, so they face the outside of the bilayer.

The phosphate portions attract water, and the lipid portions repel water.

Explanation:

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.

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.