Why are the lungs made up of these progressively smaller tubes and then millions of tiny alveoli rather than each lung just being a large empty sack?

For each of the following, decide whether the statement describes photosynthesis, cellular respiration, or both. releases energy in the form of atp. stores energy in glucose molecules. performed by producers. performed by consumers.

What best explains the inability for life to exist in earth early atmosphere

Which statements best describe the differences or similarities between a comparative investigation and an experimental investigation? check all that apply. experimental investigations are best for showing cause-and-effect relationships, while comparative investigations do not necessarily show this type of relationship. comparative investigations are often impractical and unrealistic, while experimental investigations are the most practical and realistic kinds of investigations. comparative investigations allow for the use of a wide range of variables but do not have a control group, while experimental investigations involve variables that can be controlled. both experimental investigations and comparative investigations are designed to answer scientific questions. both experimental investigations and comparative investigations focus on making observations rather than collecting new data.