When observed from Earth, the wavelengths of light emitted by a star are shifted toward the red end of the
electromagnetic spectrum. Why does this redshift occur?

The redshift occurs because the starts are moving away from the earth.

Explanation:

Every object emits wavelength from its body. When it comes to universe there are some visible light emitted by the stars and other objects in galaxy.

If a star is moving towards the sun then it emits a shorter wavelength compared to the source which is at rest. This is blue in color called as blue shift.

But when it comes to stars they move away from the earth and hence emits longer wavelength called as red shift.

As the object it at rest it more towards the blue side and when the objects starts moving it starts moving towards the red side in the visible spectrum.

So, when the starts moves away from the earth it forms a Redshift.

c. magnitude and direction

bacteria that live on the ocean floor are sustained by phytoplankton. phytoplankton, microscopic marine photosynthetic organisms, have a vastly significant role to play not only in the marine food web of which they’re part of, but also on a more global scale. despite their infinitely small size in comparison to other marine organisms, these tiny creatures occupy an immensely important ecological niche: they are the foundation of the marine food web, and as primary producers, play key roles in supporting all other organisms in the marine environment, as well as in the regulation of the earth’s climate through the sequestration of carbon, oxygen production, and other related processes. phytoplankton account for roughly half of all global primary productivity; therefore, their significance extends far beyond the marine environment alone. there is an intriguing sense of irony in the realization that these tiny living beings that often live out their existence unnoticed and undetected by the rest of the world, have such a far-reaching impact on the lives of virtually all other living organisms on the planet, particularly on those in the marine environment. the world that we have become accustomed to has been and is continuously shaped by the workings of these miniscule yet vital “plants of the sea”.

hope this !