Sarah performs an experiment to determine the effect of nitrogen on plants. she studies the effect of nitrogen on the growth of the root hair, height of the plants, and nodule formation. which factor is an independent variable? a) amount of nitrogen b) growth of root hair c) nodule formation d) height of the plants

When Sarah performed this experiment, she changed the levels of nitrogen in order to observe the changes in the morphological features of the plant.
All of the characteristics of the plant that she observed were dependent on multiple different things, but the level of nitrogen was an independent variable that she was changing at her will. 

Aliving thing consumes berries on a yree

No that answer is wrong. you have written the function of mitochondria in chloroplast and function of chloroplast in mitochondria.