An organism must regulate the concentration of solutes in its body fluids, called osmolarity. An extreme change in osmolarity will alter the diffusion of water through cell membranes, potentially disrupting the functions of cells.  In a healthy human, a homeostatic system ensures that the osmolarity of blood stays within a certain range. When the osmolarity increases, nerve cells in the hypothalamus detect the diffusion of water through channel proteins in their membranes (osmosis). These channels activate a signaling pathway that causes a nerve cell to secrete a hormone called vasopressin. A molecule of vasopressin can bind to receptors in the membranes of kidney cells, causing the kidneys to excrete less water as urine. Over time, the osmolarity of blood returns back to its expected range.  Alcohol inhibits the release of vasopressin by nerve cells. Typically, a person who has not consumed alcohol has a concentration of vasopressin between 0.5 pg ml-1 and 2 pg ml-1, but a person who has ingested alcohol has a much lower concentration of vasopressin.  The figure shows a path model of the homeostatic system that regulates the osmolarity of blood. This model also describes the effect of alcohol on the concentration of vasopressin in blood. The regulated variable is represented by a dashed box. Other variables are represented by a solid black box. An arrow connecting one box to another indicates a relationship between two variables. The value above each arrow indicates the slope of the linear relationship between the variables connected by the arrow.  Which concentration of alcohol in the blood would cause the osmolarity of the blood to increase by 11 mmol L-1?

The figure shows four containers of the same size. The purple dots represent molecules within each container.  The temperature in each container is identical. In which container would you expect to observe the most number of interactions between molecules?   

An organism must regulate the concentration of solutes in its body fluids, called osmolarity. An extreme change in osmolarity will alter the diffusion of water through cell membranes, potentially disrupting the functions of cells.  In a healthy human, a homeostatic system ensures that the osmolarity of blood stays within a certain range. When the osmolarity increases, nerve cells in the hypothalamus detect the diffusion of water through channel proteins in their membranes (osmosis). These channels activate a signaling pathway that causes a nerve cell to secrete a hormone called vasopressin. A molecule of vasopressin can bind to receptors in the membranes of kidney cells, causing the kidneys to excrete less water as urine. Over time, the osmolarity of blood returns back to its expected range.  The figure shows a path model of the homeostatic system that regulates the osmolarity of blood. This regulated variable is represented by a dashed box. Other variables are represented by a solid black box. An arrow connecting one box to another indicates a relationship between two variables. The value above each arrow indicates the slope of the linear relationship between the variables connected by the arrow. If the rate at which the kidneys excrete water decreases by 3.45 mL min-1, how would the osmolarity of blood change? The osmolarity would _______.

True or false? The value of π (pi) is a variable.

An enzyme called phosphofructokinase binds a substrate called fructose-6-phosphate (F6P) and catalyzes a reaction to form a product. The activity of this enzyme depends on the presence of a molecule called adenosine triphosphate, or ATP.  The figure shows the relationship between the concentration of F6P and the activity of enzymes, in either the presence or absence of ATP. The activity of enzymes was measured as the rate at which products were formed (also called the rate of reaction). ATP likely binds to ________ of the enzyme.

Thyroxine (T4) is a hormone that certain animals use to regulate the activity of cells. The production of T4 depends on the concentrations of two other hormones: thyrotropin releasing hormone (TRH) and thyroid stimulating hormone (TSH).  TRH comes from a part of the brain called the hypothalamus. This hormone can bind to receptors in another part of the brain, called the pituitary gland. Upon binding to a receptor, TRH activates a signaling pathway that causes a cell to release TSH.  The figure shows the signaling pathway that controls the production of T4. TSH binds to receptors in the thyroid gland, causing cells of this gland to produce T4. The production of T4 depends on an enzyme called thyroid peroxidase (TPO), which creates T4 by adding an iodide ion (I-) to a molecule.  A nonpolar structure enables T4 to diffuse through the phospholipid bilayer of any cell, including cells of the hypothalamus and the pituitary gland, where T4 inhibits the release of TRH and TSH, respectively. Choose the word or phrase that accurately completes the following sentence. When TSH binds to a receptor, the concentration of cAMP in a cell should ______.

The figure shows an artificial cell suspended in a solution of water. The membrane consists of a phospholipid bilayer without transport proteins. The concentrations of glucose molecules inside of the cell and outside of the cell are provided. Which two claims are accurate?

A biologist wanted to know the number of insects that occur in a square meter of land. They counted insects on 20 plots, each having an area of 1 m2. The following set of numbers represents the number of insects on these plots:  Number of insects = [150, 150, 162, 168, 171, 171, 182, 184, 188, 199, 199, 199, 220, 220, 228, 228, 232, 244, 253, 253] Use this sample to answer the following question.   What is the frequency of the value 253?

A company that makes athletic shoes wanted to design a running shoe for female marathon runners. To inform the design of this shoe, the company measured the body mass of 200 marathon runners. The plot shows the frequency distribution of body mass, as measured in kilograms (kg).    Which value is closest to the minimum of body mass?

Vocabulario. Definiciones. Read the definitions and select the word that is being described. (8×1.5=12) Palabras: aceite –  cuchara – cuchillo – desayuno – dulce – ensalada – pan – sal  1. Es lo primero que comes por la mañana. 2. Se usa para freír la comida, por ejemplo, las papas fritas. 3. Es un utensilio que usas para cortar la comida. 4. Es un condimento blanco. 5. Las fresas saben a esto. 6. Usas esto para tomar la sopa o comer cereales. 7. Es necesario para preparar un sándwich. 8. Es un plato que puede contener lechuga, tomate, cebolla y zanahoria.