As electrons are passed through the system of electron carriers associated with photosystem ii, they lose energy. what happens to this energy?

a) it excites electrons of the reaction center of photosystem i.
b) it is lost as heat.
c) it is used to establish and maintain a proton gradient.
d) it is used to phosphorylate nad+ to nadph, the molecule that accepts electrons from photosystem i.

Option C) It is used to establish and maintain a proton gradient

Explanation:

Once light photons excite photosystem II, electrons of the main central chlorophyl  are ejected to reach another energy level.  One different molecule accepts those electrons, and they are delivered to a redox chain (also called respiratory chain). Passing across this chain, protons are pumped to the other side of the membrane of chloroplasts, or equivalent, and a proton gradient is produced.  This gradient will allow ATP production. This is energy to be used in the Calvin cycle.

Finally those electrons will arrive to the photosystem I, where Option D occurs, that is NAD+ will be phosphorylated to NADPH, that represents reducing power for the Calvin cycle

is this a psat question, if so do not cheat try your best.

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.