Some bacteria are helpful because they help us breathe by producing

Bacteria such as Porphyromonas gingivalis, Treponema denticola and Prevotella intermedia can help people produce breath.

Explanation:

1)

i))the process of preparing food by green plants in the presence of sunlight is called photosynthesis.

ii) leaf is the site for photosynthesis.

iii) it takes place as,

6h2o+6co2=c6h12o6+602

a compound light microscope is used to magnify objects in steps.  

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