The Precambrian time refers to the time 4.5 billion to 542 millions year ago. This period is characterized by having reduced atmosphere and included reduced compounds. Scientists believed that atmosphere at that time was devoid of free oxygen and CO2 was present in excess. Before the complex life evolved on the Earth, the Precambrian Earth's ocean contained dissolved carbon dioxide.
Answer:
Which statement is true about biodiversity?
Human activity can improve, maintain, or hurt biodiversity
Explanation:
Biodiversity entails having different varieties of organism spread all over every habitat across the globe. Human activities could help biodiversity as well as reduce it drastically
Answer:
The cell membrane holds the cell's internal contents from its environment.
The cell membrane is comprised of two layers of fat.
The cytoplasm is a liquid in which the various organelles of the cell are suspended.
The cytoplasm keeps organelles in place. It also allows different materials to flow from one organelle to another.
The nucleus of a cell contains genetic material. DNA, RNA and mitochondria replicate in the nucleus. The nucleus also produces and replicates proteins, and sends the proteins to other parts of the cell.
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B) Embryonic stem cell research requires the use of human embryos. Its an unethical dilemma.
