if a human needs to eat about 10000kj per day estimate the mass of phtoplankton that would be required to meet their daily energy requirements based on this value what proportion of her own body weight in phytoplankton would a 60kg woman need to eat oer the course of a year if this were her only source of energy

You need to know how much energy per unit mass is in phytoplankton. Last I knew, it's something around 6000 kj/kg, but you may have a more accurate number.

Anyway, assuming my number is accurate that means a human would have to eat about 1.7 kg of phytoplankton per day. (I got that number by taking 10000/6000).

I wonder why this question keeps coming... (rolleyes)

https://www.askmehelpdesk.com/chemistry/number-moles-oxygen-produced-consumed-experiment-557075.html

There was one more in Other Science I think but I can't find it, same question...

Oh, here it is, in 'Energy' instead.

https://www.askmehelpdesk.com/energy/converting-gpp-g-m-energy-kj-557249.html

And if you read the last post of that second thread, it says "this is a question taken directly from the Open University S104 'Exploring Science' Tutor Marked Assignment 05. If you are having problems you should speak to your tutor because getting the answers from anyone else is considered cheating. I think you will find that the OU anti-plagiarism software is set to scan for questions/answers on sites like this, and you may get yourself in trouble. Be very careful."

Yes exactly, meaning that there are still people who can't get this question solved, even with solutions over the forum, and despite knowing the gravity of their acts...