Q: Answer the following question given this paragraph: Lymphocytes: B Cells, T Cells, Plasma Cells, and Natural Killer Cells As stated above, lymphocytes are the primary cells of adaptive immune responses (Table 21.1). The two basic types of lymphocytes, B cells and T cells, are identical morphologically with a large central nucleus surrounded by a thin layer of cytoplasm. They are distinguished from each other by their surface protein markers as well as by the molecules they secrete. While B cells mature in red bone marrow and T cells mature in the thymus, they both initially develop from bone marrow. T cells migrate from bone marrow to the thymus gland where they further mature. B cells and T cells are found in many parts of the body, circulating in the bloodstream and lymph, and residing in secondary lymphoid organs, including the spleen and lymph nodes, which will be described later in this section. The human body contains approximately 10 12 lymphocytes. Q: What are the primary cells of adaptive immune response? A: | OPTIONS:
- erythrocytes
- red blood cells
- white blood cells
- lymphocytes
A: lymphocytes

Q: Answer the following question given this paragraph: Electric charge is a physical property of particles or objects that causes them to attract or repel each other without touching. All electric charge is based on the protons and electrons in atoms. A proton has a positive electric charge, and an electron has a negative electric charge (see Figure below ). Q: What kind of charge does a proton have? A: | OPTIONS:
- ionic
- constant
- negative
- positive
A: positive

Q: Answer the following question given this paragraph: For most women, menstrual cycles continue until their mid- or late- forties. Then women go through menopause , a period during which their menstrual cycles slow down and eventually stop, generally by their early fifties. After menopause, women can no longer reproduce naturally because their ovaries no longer produce eggs. Q: What's the term for the period during which women's ovaries stop producing eggs? A: | OPTIONS:
- puberty
- maturity
- adolescence
- menopause
A: menopause

Q: Answer the following question given this paragraph: Eukaryotic cells also contain other organelles besides the nucleus. An organelle is a structure within the cytoplasm that performs a specific job in the cell. Organelles called mitochondria, for example, provide energy to the cell, and organelles called vacuoles store substances in the cell. Organelles allow eukaryotic cells to carry out more functions than prokaryotic cells can. This allows eukaryotic cells to have greater cell specificity than prokaryotic cells. Ribosomes, the organelle where proteins are made, are the only organelles in prokaryotic cells. Q: What is the term for a structure within the cytoplasm that performs a specific job in the cell? A: | OPTIONS:
- vacuole
- nucleolus
- molecule
- organelle
A: organelle