My understanding of how dendritic cells, macrophages, and B cells interact with helper T cells is dendritic cells present antigens to helper T cells after bringing them from other environments, macrophages present antigens to memory helper T cells for acquired immunity, and B cells present antigens to helper T cells. I am trying to understand the difference in the roles of dendritic cells and B cells. Do dendritic cells present antigens to both memory helper and helper T cells while B cells only present them to helper T cells?

Why do leaves change color in the fall? green pigments break down and no longer mask the color of chlorophyll. chlorophyll breaks down and no longer masks the colors of other pigments. red- and yellow-colored pigments grow and mask green-colored chlorophyll. green-colored chlorophyll breaks down and turns red and yellow.

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.

To store strawberries in sugar syrup, lucy placed them in a jar and covered them with sugar but did not add any water. do you think syrup will be formed? justify. a. no. since water is not added, there cannot be any syrup formation. b. no. the higher concentration of sugar on the outside will cause the water from the sugar to diffuse in the strawberry cells causing them to swell without formation of any syrup. c. yes. the higher concentration of sugar on the outside will cause the water from the strawberry to diffuse out resulting in syrup formation. d. yes. the sugar will melt over time and form the syrup.