Cells -> Tissues -> Organs -> Organs systems -> Organisms
They contain symbiotic bacteria called rhizobia within nodules in their root systems, producing nitrogen compounds that help the plant to grow and compete with other plants. When the plant dies, the fixed nitrogen is released, making it available to other plants; this helps to fertilize the soil.
Before puberty, children do have an estrogen level in their body. This is only truly noticeable around the time of puberty. It's always there, but not hyperactive until puberty.
Louder, because the sound would have a stronger pitch for the ear it is closer to
A neuron (also known as nerve cell) is an electrically excitable cell that takes up, processes and transmits information through electrical and chemical signals. It is one of the basic elements of the nervous system. In order that a human being can react to his environment, neurons transport stimuli.
