<span>Lungs take in air, and diffuse (absorb) air into the capillaries of the blood. However, this process is two steps, one for inhalation and one for exhalation. Diffusion takes place in both processes, and serves different purposes. One is to absorb oxygen, the other is to rid co2.</span>
4. A section of DNA that codes for a specific trait.
Answer:
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Cyanobacteria, also known as blue-green algae, are found in vast quantities in fresh and salt water. Cyanobacteria are able to conduct photosynthesis. By utilising energy from the sun, they produce carbohydrates from water and carbon dioxide. As a byproduct, they produce oxygen. So cyanobacteria provided oxygen to the atmosphere that allowed other lifeforms to develop.
