What is the objective of keys and kingdoms? answer if u know this no links please

Which class of molecules contains the amino group, nh2 (a) sugars (b) water (c) proteins (d) hydrocarbons

Sydney drew a flow chart to illustrate the nitrogen cycle.which labels best complete the flow chart? x: producers undergo photosynthesis.y: nitrogen compounds are released into the air.x: nitrogen compounds are released into the air.y: producers undergo photosynthesis.x: free nitrogen is in the atmosphere.y: producers absorb nitrogen compounds through their roots.x: producers absorb nitrogen compounds through their roots.y: free nitrogen is in the atmosphere.

The activity of the modern sample is 1.10 bq . how long does that measurement take?