What is true about the heterozygous sickle-cell (HbA HbS) condition? 1. sickle-cell anemia is not expressed
2. sickle-cell anemia is expressed under conditions of oxygen deficiency
3. sickle-cell anemia is apparent in men
4. none of the above

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.

Describe the relationship and movement between temperature and density in a convection cell. make sure you identify the direction of travel

Which of the following is not a type of epithelial cell