<span>B. A prokaryotic cell does not have nucleus and the other one does. The most defining characteristic of eukaryotic cells is their true nucleus. Prokaryotes lack true nucleus</span> and membrane bound organelles.
Answer:
One of the major goals of environmental science is to understand and to solve environmental problems. In order to accomplish this goal, scientists study two main types of interactions between humans and their environment. One area of focus is on how we use natural resources, such as water and plants.
Explanation:
Environmental science is important because it enables you to understand how these relationships work. For example, humans breathe out carbon dioxide, which plants need for photosynthesis. Plants, on the other hand, produce and release oxygen to the atmosphere, which humans need for respiration.
Answer:
Helper T cells are arguably the most important cells in adaptive immunity, as they are required for almost all adaptive immune responses. They not only help activate B cells to secrete antibodies and macrophages to destroy ingested microbes, but they also help activate cytotoxic T cells to kill infected target cells.
Explanation:
Helper T cells become activated when they are presented with peptide antigens by MHC class II molecules, which are expressed on the surface of antigen-presenting cells (APCs). Once activated, they divide rapidly and secrete cytokines that regulate or assist the immune response.
Answer: Of all the branches of complex animals, sponges are the only group lacking TRUE TISSUE.
Explanation:
