Explain how visual stimuli is relayed to the brain and how it is processed there.

The optic nerve, leading from the eyeball, allows information that we see to travel to the optic chiasm. This is the point at which axons from the inside half of each eye cross over and project to the opposite half of the brain. The purpose of the optic chiasm is to ensure that visual signals go to both hemispheres of brain. The majority of neural signals are sent to the thalamus for processing and are then distributed into areas of the occipital lobe. The neural signals are then received by the visual cortex (the ultimate destination for visual input), which is located at the occipital lobe. There, feature detectors assist us in interpreting what it is we are actually seeing as they respond to specific features of the object before us. These specific cells will fire as we encounter various shapes or movements.  

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.