AP Biology : Understanding Cell Types

Study concepts, example questions & explanations for AP Biology

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Example Questions

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Example Question #11 : Immune System

Which leukocyte releases histamine in order to dilate blood vessels and increase blood flow to infected areas?

Possible Answers:

Plasma cells

Neutrophils

Eosinophils

Basophils

Correct answer:

Basophils

Explanation:

Basophils are the least common leukocyte found in the body, but play a key role in the inflammatory response. They contain histamine, which is a potent vasodilator. Upon release, histamine will increase blood flow to infected areas. Mast cells are another immune cell that is involved in histamine release, but are generally localized to various regions of the body rather than found in circulation.

Basophils, mast cells, eosinophils, and neutrophils are all considered granulocytes and are essential cells in the innate immune response. Plasma cells are differentiated B-lymphocytes that are responsible for mass-producing antibodies to a specific antigen.

Example Question #1 : Understanding Cell Types

Which of the following is not a characteristic of B-cell receptors?

Possible Answers:

Upon further maturation, the B-cell receptor can become a secreted molecule

They consist of two polypeptide chains

They have transmembrane domains that anchor into the B-cell plasma membrane

They consist of two identical heavy chains and two identical light chains

Correct answer:

They consist of two polypeptide chains

Explanation:

Each B-cell receptor is a Y-shape molecule that, upon maturation, can become a secretory form (an antibody). Each receptor is comprised of four polypeptide chains: two identical heavy chains and two identical light chains. The four chains are linked together by disulfide bridges. Both heavy and light chains consist of constant regions, as well as variable regions. The variable regions of each chain provide the specificity for antigen binding, which generates a signaling cascade within the B-cell.

Example Question #2 : Understanding Cell Types

In what way do eosinophils differ from other innate immune system cells?

Possible Answers:

They have low phagocytic activity

They detect and eliminate infected host cells

They secrete antibodies

They produce anti-inflammatory cytokines

Correct answer:

They have low phagocytic activity

Explanation:

The granulocytes are responsible for numerous functions of innate immunity, from secreting histamine, to phagocytosis, to anti-inflammatory processes. These cells are the basophils, neutrophils, eosinophils, macrophages (monocytes), and mast cells.

Eosinophils have a more limited role in innate defense than the other granulocytes. They possess only low phagocytic activity, however, they are more specialized to respond to multi-cellular pathogens, such as parasitic worms. Rather than phagocytosing an invading organism, eosinophils function by releasing an arsenal of destructive enzymes and free radicals to ward off the organism. The other granulocytes are specialized for phagocytosis of bacteria, viruses, and cellular debris.

Example Question #3 : Understanding Cell Types

Embryonic stem cells can go on to form any of the three germ layers (endoderm, mesoderm and ectoderm). How can they be defined? 

Possible Answers:

None of the other answers

Pluripotent

Totipotent

Multipotent

Progenitor cells

Correct answer:

Pluripotent

Explanation:

The ability to form any of the three germ layers is known as pluripotency. Totipotent cells, such as the zygote, are able to form an entire organism, multipotent cells are able to form any cell within the same germ layer lineage, and progenitor cells are cells closer to differentiation, often found in adult organisms. 

Example Question #4 : Understanding Cell Types

What type of cell creates free antibodies that then circulate in the bloodstream?

Possible Answers:

Cytotoxic T-cells

Plasma cells

Memory B-cells

Monocytes

Helper T-cells

Correct answer:

Plasma cells

Explanation:

Humoral, or B-cell, immunity is associated with the formation of antibodies. Plasma cells are B-lymphocytes that have been differentiated with the help of a helper T-cell. They release antibodies, which are created to respond to a specific pathogen in the body.

Cytotoxic T-cells are also activates by help T-cells, but are involved in cell-mediated immunity rather than humoral immunity. They target infected cells based on antibody tagging. Monocytes are a part of the innate immune response and are not involved in antibody interactions. They primarily differentiate into macrophages, which engage in phagocytosis of pathogens.

Example Question #5 : Understanding Cell Types

Which of the following cells is exclusive to the adaptive immune system?

Possible Answers:

Macrophages

Neutrophils

Dendritic cells

B-cells

Mast cells

Correct answer:

B-cells

Explanation:

The adaptive immune system primarily relies on the function of B-cells and T-cells. T-cells help recognize antigens to which the body has been previously exposed and stimulate B-cell to release antibodies to combat that specific antigen.

Upon initial antigen exposure, all other cell types listed (which help comprise the innate immune system) kick in.

Example Question #6 : Understanding Cell Types

Which immune cells primarily contribute to allergic reactions?

Possible Answers:

T-cells

B-cells

Phagocytes

Dendritic cells

Mast cells

Correct answer:

Mast cells

Explanation:

Mast cells contains secretory granules, rich in histamine and other hormonal mediators, that promote inflammation and other allergy symptoms in response to antigen exposure.

Example Question #7 : Understanding Cell Types

Which immune cells contribute most to the humoral immune response?

Possible Answers:

Phagocytes

Helper T cells

Basophils

Natural killer T cells

B cells

Correct answer:

B cells

Explanation:

The humoral response refers to the antiquated term "humors", meaning body fluids, as used in ancient and medieval medicine. In response to antigen exposure, B-cells release antibodies into the extracellular fluid and throughout the body, thus eliciting a "humoral response."

Although helper T-cells are responsible for activating B-cells, the humoral response is limited to B-cells because they are the ones releasing products into the body fluids.

Example Question #8 : Understanding Cell Types

Metastasis is __________.

Possible Answers:

the spread of the cells produced during mitosis

the spread of the cells produced during meiosis

the asexual reproduction of cells

the spread of cancer cells beyond their site of origin

Correct answer:

the spread of cancer cells beyond their site of origin

Explanation:

Metastasis is the proliferation of cancer cells into new tissues. Cancer usually metastasizes through the circulatory or lymphatic systems, and the cancerous cells take residence in other, seemingly unrelated parts of the body.

Example Question #9 : Understanding Cell Types

Long-lived B cells that circulate the body and respond to subsequent infections are called __________.

Possible Answers:

Macrophages

Plasma cells

IgG

Immunoglobulins

Memory cells

Correct answer:

Memory cells

Explanation:

Memory B cells circulate the body and are ready to respond to subsequent infections while plasma cells generate many antibodies to a current infect. "Immunoglobulins" refers to both the B cell receptor and to the excreted form of these proteins (known as antibodies). IgG is a class of immunoglobulins (along with IgA, IgE, IgD, and IgM). Finally, macrophages are cells that engulf non-self (and often antibody-bound) cells and communicate with T cells to promote B cell proliferation.

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