Based on fossil evidence, about how long ago did the first single-celled life form appear on Earth? 130 million years ago 1.5 billion years ago 2.5 billion years ago 4.1 billion years ago

How does human environment effect the biosphere

Which are evidence of seafloor spreading? check all that apply. molten material magnetic stripes continent material drilled core samples ocean water samples

What is the function of the root cap? a. extra-absorbent cells in the root cap absorb more water and nutrients b. protect the meristematic area of the stem c. contains sensors for sunlight d. increases surface area of the root