Bio

Which of the following is associated with secondary messengers in a cell?

examples include Ca+ ions and cAMP, amplify signals within a cell, found in cells from all kingdoms of life

Antigens are:

foreign molecules that trigger an immune response

Which signaling molecule would most easily pass through the membrane into the cell's interior?

Small, hydrophobic

At what point on the graph shown is an action potential triggered (when is a neuron fired)?

-55

The point on the graph where K+ is diffusing out of the cell is ________ and results in ___________ of the neuron.

4; repolarization

These enzymes remove phosphates from kinases and act an an "off" switch in signaling pathways

?

Which of the following is an example of intraspecies cell signaling?

Quarom sensing, pheromones, yeast mating factors

The drug 5-fluorouracil inhibits thymine production in eukaryotic cells. Which of the following cell cycle stages will be most directly affected by 5-fluorouracil?

S phase (thymine is a nucleotide found in DNA. Cell would not be able to replicate DNA during S phase of Interphase)

The diagram shown illustrates feedback control as exerted by the hormone thyroxine. Following surgical removal of the thyroid gland, the level of TSH in the blood will increase. Which of the following best explains this increase?

A decrease in thyroxine levels means a loss of inhibition to the hypothalamus and anterior pituitary, leading to increased TSH secretion

The mechanism of action of many common medications involves interfering with the normal pathways that cells use to respond to hormone signals. Which of the following best describes a drug interaction that directly interferes with a signal transduction pathway?

A medication enters the target cell and inhibits an enzyme that normally synthesizes a second messenger. (Second messengers are involved in signal transduction pathways, and if the second messenger is not present, the pathway is blocked)

Which of the following statements are true for all ligands?

Binding to a receptor causes a conformation change

Which of the following is not an example of a positive feedback system?

Blood glucose regulation

Which of the following is NOT a characteristic of a reflex arc?

Bypasses the brain to trigger a response

Scientists compared the chemical structure of several molecules that various bacterial species use for quorum sensing. Quorum sensing is an ability some bacteria have to detect the number of related cells nearby (see image) 1Which of the following research questions would best guide an investigation of the link between the structure of the signaling molecules and the evolution of quorum sensing?

Did these species evolve from a common ancestor that used a similar signaling molecule?

Which of the following best describes the role of mitosis in the cell cycle?

Distributing replicated chromosomes to daughter nuclei

Ethylene is an organic compound produced by ripening fruits. In a controlled experiment, researchers found that ethylene gas stimulated the ripening process in newly harvested fruits. Which of the following describes the most likely connection between natural ethylene production and fruit ripening?

Ethylene gas is a chemical signal through which ripening fruits trigger the ripening process in other fruits.

G proteins function as signal transmitters in coordination with G protein-coupled receptors. They are active when bound to which of the following chemical energy carriers?

GTP

Most cells that have become transformed into cancer cells have which of the following characteristics when compared to normal, healthy cells?

Higher rates of mitosis

Cortisol is a hormone produced in response to stress, including starvation, in humans. Which of the following is most likely an immediate effect of a starvation-induced increase in cortisol secretion?

Increased mobilization of fatty acids from fat cells (break down stored fat for energy in the stressed state)

Vertebrate immune responses involve communication over short and long distances. Which of the following statements best helps explain how cell surface proteins, such as MHC proteins and T cell receptors, mediate cell communication over short distances?

The proteins interact directly with proteins on the surfaces of other cells

What is the main purpose of glycoproteins on the cell surface?

They are involved in cell-to-cell recognition

The term steroid describes both hormones produced by the body and artificially produced medications that duplicate the action for the naturally occurring steroids. All of the following describe steroid hormones EXCEPT

They bind with receptor proteins in the plasma membrane to trigger cellular responses.

What is the expected percent change in the DNA content of a typical eukaryotic cell as it progresses through the cell cycle from the start of the G1 phase to the end of the G2 phase?

amount of DNA doubles (during S phase, DNA is replicated along with organelles in cell)

A common feature of action potentials is that they

are triggered by a diffusion of Na+, followed by a diffusion of K+

Promotes tissue growth in plants; stimulates physical response to phototropism and gravitropism

auxins

An immune response to a specific antigen generates the production of which type of cell, which will launch an attack the next time the antigen infects the body?

memory cells

Growth factors released by a cell cause nearby cell to grow. This is an example of:

paracrine signaling (taking place in local area and not in a nerve cell so that rules out choices b and c)

Plant cells use these channels to send signals between adjacent cells.

plasmodesmata

Insulin, epinephrine, testosterone, follicle stimulating hormone, and estrogen are all capable of triggering the flow of communication in a signal transduction pathway. Which of the following terms best describes such molecules?

steroid hormone

As represented by letter C in the image, this is the second step of a signaling pathway:

transduction pathway