At the moment, I'm doing about the carbon cycle.
Part of our homework is to say how does the biomass change.
I wasn't sure what he meant by that, I tried looking on the internet for help but I've had no luck.
Can someone please explain to me what he means by 'How does the Biomass change?'
Thanks? Xx :)

The biomass. All organic matter. Living and nonliving.

A simple carbon cycle.

Plants take carbon dioxide from the air, fix it into sugars and use it to build plant matter. ( some carbon dioxide is returned to the air from plant cellular respiration ) Animals, herbivores, eat those plants, break down those sugars into the energy/body mass they need, while predators eat some of those animals and synthesize their needs from the herbivores. Carbon dioxide is returned to the atmosphere through cellular respiration from all these animals.

All animals die and decomposers, bacteria and fungi, decompose carbon compounds from the carcases and also return some carbon dioxide to the air through cellular respiration.

A quick glance at wikipedia 'biomass' is a good start for how it changes, mostly by humans.
But all you have to do is think about how humans change what grows on the earth, and that's changing the biomass. We farm crops instead of picking berries and wild plants, and eat them, feed them to farm animals which we eat, or turn them into fuels. We turn our waste (including our excrement, which came from the biomass we ate) into energy. We cut down trees and burn them.

We take oil, an ancient algae/plankton product (so part plant, part animal), out of the ground and burn it. Natural gas is essentially methane, a gas made from microorganisms, and it's not clear whether plants make methane, but I would call it part of the biomass anyway. Oil and gas aren't really considered biomass, but we are working on ways to produce methane from rotting garbage, and from algae on waste, etc, to make burnable fuel, so I would include it in the discussion.

Where does it all go? Back to the earth? A lot of it goes up in smoke and gasses. So it's not like a natural cycle anymore, where plants lived, died, decomposed, and started anew. We have far fewer crops than occurred naturally, and we also genetically engineer crops. So nothing is the same.

Keep going... you can go on for pages.