The <u><em>correct answer</em></u> is:
He needs to select a more representative sample.
Explanation:
Choosing students from the basketball team for the sample he uses on a study of heart rates and exercise will be a biased sample. This is because students on the basketball team are potentially healthier than other students, which means that exercise will not have a large an effect on their heart rate as it would if they were not as healthy and not as physically fit.
In order to reduce the amount of bias, he should choose students from different groups throughout the school.
Answer:
They may change due to environmental changes. for example, if a cactus suddenly experiences a drought, it may change to become better at holding water than before. if it suddenly experiences large amounts of rainfall, it may change to release more water, etc.
Answer: Of all the branches of complex animals, sponges are the only group lacking TRUE TISSUE.
Explanation:
The role is that it helps you with the urinal system and makes the things in your body go out of the body. (hopes it at least helped a little! (=^T^=)