Q.Find out how much cellulose is made by all the plants in the biosphere and compare it with how much of paper is manufactured by man and hence what is the consumption of plant material by man annually. What a loss of vegetation!

This is an investigation you carry out with reference figures rather than a question with a single fixed number, so the real value lies in the comparison and the conclusion it leads to.

• Cellulose is the material of plant cell walls; every plant across the entire biosphere is continuously building cellulose, so the total amount made by all the world's plants is enormous — a truly vast, planet-wide quantity.
• Paper is essentially cellulose, made from plant pulp and fibre such as cotton. The amount of paper manufactured by people, though large in human terms, is only a small fraction of all the cellulose the plant kingdom produces.
• Because paper and other plant products come from cutting and processing vegetation, this human use represents a steady annual consumption of plant material. …

This is a find-out activity, so its purpose is to make you weigh two quantities against each other and draw the conclusion, rather than to memorise a single figure. To do it well you gather reference data for two things and compare them.

Cellulose made by plants. Cellulose is the substance of plant cell walls — it is what gives plants their structural framework, and it is present in every plant. Since plants cover the land and seas of the whole biosphere and are constantly growing, the total cellulose they produce is staggeringly large. This is the natural, renewable output of the plant kingdom, generated on a scale that dwarfs almost anything humans manufacture.

Paper made by people. Paper is, in essence, cellulose. It is produced from plant pulp and from fibres such as cotton, which are themselves cellulose. Humans manufacture a great deal of paper, and while that is a large amount by our standards, it is only a fraction of the total cellulose that plants create. …

Method: Reasoning from Scale Comparisons to a Conclusion

This is a "find out" activity built around comparing two very different scales of quantity, so the approach is not to memorise a single number but to reason about relative MAGNITUDE and then draw the intended conclusion from that comparison.

Start from what you know for certain: cellulose is the structural material of every plant cell wall, and since plants cover the biosphere and are constantly growing, the TOTAL cellulose produced worldwide is on a scale far larger than anything a single industry could match. Paper, in turn, is essentially processed cellulose (from wood pulp or fibres like cotton), so the amount of paper manufactured by humans is a meaningful but much SMALLER slice of that total natural production. Framing the comparison this way — huge natural production vs. smaller human extraction — is what lets you reach the intended conclusion without needing an exact figure for either quantity. …