Which three organ systems work together to take in oxygen and other nutrients and deliver them to an animal's body cells?
A. Digestive, because it breaks down the nutrients in food into
substances that can be used by cells
B. Respiratory, because it takes in gases from the external
environment
I c. Circulatory, because blood absorbs nutrients and carries them to
other cells
OD. Nervous, because it controls the body functions and responses to
stimuli

The diagram illustrates the activity of vesicles during a cellular process.

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.

Which of the following statements about protists are true? a.they are typically found in moist environments. b.they are all unicellular. c.they have a nucleus. d.they are all multicellular.