<span>I believe it is light, but this is kind of a confusing question. Technically there is a independent and dependent variable in the question. The variable being manipulated is light, and the earthwork activity depends on the light. </span>
Petiole, hopefully this helps you
the three kinds of nitrogenous wastes based on the energy required to synthesize them are arranged; Ammonia < urea < uric acid.
Nitrogenous wastes are the nitrogen compounds that organisms use to get rid of excess nitrogen. Ammonia, urea, and uric acid are the most common nitrogenous wastes that animals excrete. Protein metabolism generates all of these nitrogenous wastes.
Ammonia is the most toxic of these nitrogenous wastes, and it is the most common but requires the least energy. Urea is more harmful than uric acid, but it is less harmful than ammonia, reducing the amount of energy required to synthesize it. Uric acid is the least harmful, a non-poisonous particle with four nitrogen molecules. This is useful for birds and reptiles that lay hard eggs because it eliminates the most nitrogen, uses the least amount of water, and is not toxic. It also takes the most energy input.
Know more about urea here: brainly.com/question/14453829
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they are so unique and seen often
Answer : The Aerobic exercise improves the oxygen purifying capacity of lungs. So, one can breathe in more oxygen through inhalation and then more oxygen is transferred to muscles in the body, also carbon dioxide is given actively out of the body through exhalation. All these gives body more energy to perform daily tasks and stay fit and healthy.