Possible Homeostasis Free Response

1.Homeostasis in multicellular organisms is achieved mainly through cell-to-cell communication. This process almost always involves a signal transduction pathway.

(a)What is a signal transduction pathway?

(b)List and describe the three stages involved in this cell signaling process.

(c)Describe the role does the secondary messenger cyclic AMP (cAMP) plays in the process.

2.A major theme in AP Biology this year is “form fits function.” Choose three body systems involved withthe external/internal exchange of materials and describe, in detail, how the each is adapted to fulfilling this vitallife function necessary for the survival multicellular organism.

3.Describe negative and positive feedback loops, and discuss how feedback mechanisms regulate each of the following:

(a)Ovulation in a non-pregnant human female.

(b)Blood glucose levels in humans.

(c)Body temperature in humans

4.Describe the structure of a mammalian respiratory system. Include in your discussion –

(a)the mechanisms of inspiration and expiration.

(b)a description of the control centers in the brain that regulate the rate and depth of breathing.

(c)the exchange of oxygen and carbon dioxide in skeletal muscle cells.

(d)a detailed description of the transport of these gases in the blood.

5.Homeostatic maintenance of optimal blood glucose levels has been intensively studied in organisms.In normal metabolism, the glucose concentration of the blood tends to remain constant(within a range of 80 to 120 milligrams per deciliter = dynamic equilibrium). Discuss the role of each of the following organs play in maintaining this homeostatic condition:

(a)the pancreas

(b)the liver

(c)the kidneys

(Be sure to describe any and all feedback mechanisms and hormones involved.)

6.The blood, lymph, and other internal fluids have often been referred to as the “internal environment” of the body. Many parts of the body, especially the kidneys, are involved in maintaining the constancy of this internal environment. Discuss how the kidneys help to maintain the constancy of the internal environment in regards to water, salt (Na+) and glucose.

(Be sure to include the processes of filtration, reabsorption, secretion in your answer.)

7.The maintenance of a stable internal environment is vital to an organism’s survival. For complex,

multicellular organisms such as humans, homeostasis is achieved through cell-to-cell communication.

Describe THREE specific examples of cell-to-cell communication utilized in the immune system with a focus on each of the following:

(a)naming thetype of cell(s) involved.

(b)the type of “message” that is passed from cell to cell.

(c)(the stimulus that causes and)the response that results from this type of communication.

8.Describe the following mechanisms of response to a pathogen (disease-causingmicroorganism) by the human body.

(a)The reactions of the body leading to inflammation of a wound infected by bacteria.

(b)The antigen-antibody response to this pathogen.

9.Describe the sequence of events responsible for:

(a)the creation and propagation of an action potential (nerve impulse) along a neuron.

(b) the transmission of this action potential across a synapse to another neuron.