CH 11 & 12 AP BIO

)Which of the following is a type of signaling in which a cell secretes a signal molecule that affects distant cells? A) paracrine signaling B) endocrine signaling C) synaptic signaling D) autocrine signaling

B

)Cells from advanced malignant tumors often have very abnormal chromosomes and an abnormal number of chromosomes. What might explain the association between malignant tumors and chromosomal abnormalities? A) Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities. B) Transformation introduces new chromosomes into cells. C) Cancer cells are no longer anchorage-dependent. D) Cancer cells are no longer density-dependent.

A

)Use the data in the accompanying table to answer the question. 68) Minutes Spent in Cell Cycle Phases Cell Type G1S G2 M Beta 18 24 12 16 Delta 100 1 0 0 Gamma 18 48 14 20 The data in the table were obtained from a study of the length of time spent in each phase of the cell cycle by cells of three eukaryotic organisms designated beta, delta, and gamma. What is the best explanation for the data associated with delta cells? A) Delta cells are in the G0 phase. B) Delta cells contain no RNA. C) Delta cells contain no DNA. D) Delta cells divide in the G1 phase.

A

)When the body's blood glucose level rises, the pancreas secretes insulin and, as a result, the blood glucose level declines. When the blood glucose level is low, the pancreas secretes glucagon and, as a result, the blood glucose level rises. Such regulation of the blood glucose level is the result of ________. A) negative feedback B) positive feedback C) protein-protein interactions D) catalytic feedback

A

)Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because they ________. A) are species specific B) amplify the original signal many times C) counter the harmful effects of phosphatases D) always lead to the same cellular response

B

50)Use the figure to answer the question below. graph of 2 cycles In the figure, G1 is represented by which numbered part(s) of the cycle? A) II B) I and V C) III D) IV 8

B

7)Early observations of a cultured cell line indicated that the cells did not exhibit either 7) density-dependent inhibition or anchorage dependence. What do these observations suggest about this cell line? A) The cells have nonfunctional MPF. B) The cells show characteristics of tumors. C) The cells are unable to form spindle microtubules. D) The cells follow an altered series of cell cycle phases.

B

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogen and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects? A) Each cell responds in the same way when steroids bind to the cell surface. B) Estrogen binds to specific receptors inside many kinds of cells, each with different responses. C) Estrogen is produced in very large concentration by nearly every tissue of the body. D) Estrogen is kept away from the surface of any cells, not able to bind it at the surface.

B

Consider this pathway: 8) epinephrine G protein-coupled receptor G protein adenylyl cyclase cAMP protein kinse A The second messenger in this pathway is ________. A) adenylyl cyclase B) cAMP C) G protein D) G protein-coupled receptor

B

Eukaryotic chromosomes are composed of which of the following macromolecules? 14) A) DNA and RNA B) DNA and proteins C) DNA only D) DNA and phospholipids

B

G1 is associated with which of the following cellular events? ) A) break down of the nuclear membrane B) normal growth and cell function C) the beginning of mitosis D) DNA replication

B

If a cell at metaphase of mitosis contains 20 sister chromatids, how many chromosomes will be present in a G1 cell? A) 40 B) 10 C) 20 D) 5 11

B

Metaphase is characterized by ________. 22) A) separation of sister chromatids B) alignment of chromosomes on the equator of the cell C) separation of the centromeres D) cytokinesis

B

Put the steps of the process of signal transduction in the order they occur. 23) 1. A conformational change in the signal-receptor complex activates an enzyme. 2. Protein kinases are activated. 3. A signal molecule binds to a receptor. 4. Target proteins are phosphorylated. 5. Second messenger molecules are released. A) 1, 2, 3, 4, 5 B) 3, 1, 5, 2, 4 C) 3, 1, 2, 4, 5 D) 1, 2, 5, 3, 4

B

The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called 60) A) binary fission. B) cytokinesis. C) mitosis. D) telophase.

B

The process by which the information in a gene directs the synthesis of a protein is called ________. 46) A) replication B) gene expression C) post translation modification D) cloning

B

3)If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system? A) It would not be able to activate G proteins on the cytoplasmic side of the plasma membrane. B)It would use ATP instead of GTP to activate G proteins on the cytoplasmic side of the plasma membrane. C)It would be able to carry out reception and transduction but would not be able to respond to a signal. D) It would not be able to activate receptor tyrosine kinases.

A

A benign tumor differs from a malignant tumor in that a benign tumor 67) A) does not metastasize. B) spreads from the original site. C) is cancerous. D) never causes health problems.

A

Besides the ability of some cancer cells to over proliferate, which of the following situations might logically result in a tumor? A) lack of appropriate cell death B) failure of cells to enter S phase C) inability to form spindles D) changes in the order of cell cycle stages

A

DNA plus its associated proteins is called a ________. 17) A) chromatin B) gene C) centromere D) genome

A

Dead or damaged cells are replaced by the process of ________. 18) A) mitosis B) fertilization C) binary fission D) meiosis

A

In yeast signal transduction, a yeast cell releases a mating factor, which ________. A) binds to receptors on the membranes of other types of yeast cells B) passes through the membranes of neighboring cells, binds to DNA, and initiates transcription C)diffuses through the membranes of distant cells, causing them to produce factors that initiate long-distance migrations D) acts back on the same cell that secreted the mating factor, changing its development

A

Most homeostasis depends on A) negative feedback control. B) predictable environmental conditions. C) hormonal regulation. D) positive feedback control.

A

One difference between cancer cells and normal cells is that cancer cells 9) A) continue to divide even when they are tightly packed together. B) are unable to synthesize DNA. C) are arrested at the S phase of the cell cycle. D) cannot function properly because they are affected by density-dependent inhibition.

A

Protein kinase is an enzyme that functions in which of the following ways? 53) A) activates or inactivates other proteins by adding a phosphate group to them B) activates a G protein C) as a second messenger molecule D) as a receptor for various signal molecules

A

What is a primary function of transcription factors? 28) A) They control gene expression. B) They regulate the release of calcium from the endoplasmic reticulum. C) They convert ATP into cAMP. D) They regulate the synthesis of DNA in response to a signal.

A

When animal cells are grown in a petri dish, they typically stop dividing once they have formed a single, unbroken layer on the bottom of the dish. This arrest of division is an example of A) density-dependent inhibition. B) growth factor desensitization. C) cell constraint. D) cell division repression.

A

Which of the following is a type of local signaling in which a cell secretes a signal molecule that 25) affects neighboring cells? A) paracrine signaling B) hormonal signaling C) autocrine signaling D) synaptic signaling

A

Why do neurons and some other specialized cells divide infrequently? 52) A) They have entered into G0. B) They no longer produce MPF. C) They can no longer degrade cyclins. D) They no longer have active nuclei.

A

)A signal transmitted via phosphorylation of a series of proteins is generally associated with which of the following events? A) activation of a ligand-gated ion channel B) conformational changes to each protein in the series C) binding of a hormone to an intracellular receptor D) production of ATP in the process of signal transduction

B

)In the cells of many eukaryotic species, the nuclear envelope has to disappear to permit which of 11) the following events in the cell cycle? A) separation of the centrosomes B) attachment of microtubules to kinetochores C) DNA synthesis D) condensation of the chromosomes

B

The receptors for steroid hormones are located inside the cell instead of the membrane surface like 30) most other signal receptors. How do steroids gain access to their receptors? A)Steroid hormone receptors undergo conformational changes that relocate them on the membrane surface. B)Steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell membrane. C)Steroid hormones first bind to a steroid activator and this complex is transported across the cell membrane by a steroid transport protein. D) Both steroid hormones and their receptors are produced by the same cells.

B

Use the figure to answer the question below. (Pic of cells in mitosis (PMAT)) The unlettered circle at the top of the figure shows a diploid nucleus with four chromosomes that have not yet replicated. There are two pairs of homologous chromosomes, one long and the other short. One haploid set is black, and the other is gray. The circles labeled A to E show various combinations of these chromosomes What is the correct chromosomal condition at prophase of mitosis? A) C B) B C) D D) E.

B

Use the figure to answer the question below. 21) In the figure, which number represents DNA synthesis? A) I B) II C) III D) IV

B

Which of the following statements regarding sexual and asexual reproduction is true? A) Cell division only occurs after sexual reproduction. B) Sexual reproduction is more likely to increase genetic variation than is asexual reproduction. C) Sexual reproduction typically includes the development of unfertilized eggs. D) Only offspring from asexual reproduction inherit traits from two parents.

B

the body's automatic tendency to maintain a constant and optimal internal environment is termed as ________. A) static equilibrium B) homeostasis C) balanced equilibrium D) physiological chance

B

) In what way do kinetochore microtubules facilitate the process of splitting the centromeres? 13) A) They slide past each other like actin microfilaments. B) They phosphorylate the centromere, thereby changing its conformation. C) They create tension by pulling toward opposite poles.D) They use motor proteins to hydrolyze the centromere at specific arginine residues.

C

)Use the figure to answer the question below. graph 1st n 2nd cycle In the figure, at which of the numbered regions would you expect to find cells at metaphase? A) II only B) IV only C) III only D) II and IV

C

)Which of the following is a feature of plant cell division that distinguishes it from animal cell 12) division? A) production of four (rather than two) new cells per mitotic division B) formation of a cleavage furrow C) formation of a cell plate D) lack of cytokinesis

C

After reading the paragraph below, answer the questions that follow. Under normal conditions, blood sugar levels are controlled within a narrow range by negative feedback. Two hormones are involved in maintaining blood sugar levels at the set point (about 90 mg of glucose/100 mL of blood). When blood sugar levels rise above the set point, the hormone insulin signals the liver to absorb the excess sugar. When blood sugar levels drop below the set point, the hormone glucagon signals the liver to release its stored glucose to the bloodstream. In juvenile onset diabetes, the body doesn't produce enough insulin and insulin supplements are required. 75)Based on your understanding of homeostasis, for negative feedback control of blood glucose levels

C

After reading the paragraph below, answer the questions that follow. Under normal conditions, blood sugar levels are controlled within a narrow range by negative feedback. Two hormones are involved in maintaining blood sugar levels at the set point (about 90 mg of glucose/100 mL of blood). When blood sugar levels rise above the set point, the hormone insulin signals the liver to absorb the excess sugar. When blood sugar levels drop below the set point, the hormone glucagon signals the liver to release its stored glucose to the bloodstream. In juvenile onset diabetes, the body doesn't produce enough insulin and insulin supplements are required. 74)If you hadn't eaten for several hours, which hormone would be responsible for returning your glucose levels to the set point? A) insulin B) pancreas C) glucagon D) liver

C

During which phase of mitosis does the nuclear envelope re-form? 31) A) prophase B) metaphase C) telophase D) anaphase

C

Not all intercellular signals require transduction. Which one of the following signals would be 26) processed without transduction? A) a signal that is weakly bound to a nucleotide B) a signal that binds to the extracellular matrix C) a lipid-soluble signal D) a signal that binds to a receptor in the cell membrane

C

Positive feedback has occurred when A)a decrease in blood sugar increases the secretion of a hormone that converts glycogen to glucose. B)a decrease in blood calcium increases the amount of the hormone that releases calcium from bone.

C

The genetic material is duplicated during 10) A) G2. B) G1. C) the S phase. D) the mitotic phase.

C

The mitotic spindle fibers play a critical role in which of the following processes? 15) A) dissolving the nuclear membrane B) triggering the compaction and condensation of chromosomes C) separation of sister chromatids D) splitting of the cell (cytokinesis) following mitosis

C

The primary function of G proteins in signal transduction is 69) A) phosphorylating relay molecules in the pathway. B) converting ATP to cATP to amplify the signal. C) transducing the signal from an activated receptor to the next protein in the pathway. D) binding extracellular signal molecules to activate the pathway.

C

Use the figure to answer the question below. (Pic of cells in mitosis (PMAT)) The unlettered circle at the top of the figure shows a diploid nucleus with four chromosomes that have not yet replicated. There are two pairs of homologous chromosomes, one long and the other short. One haploid set is black, and the other is gray. The circles labeled A to E show various combinations of these chromosomes. What is the correct chromosomal condition for one daughter nucleus at telophase of mitosis? A) D B) B C) E D) C

C

Use the following figure to answer the question. (pic of receptor and ligand) Which of the following types of signaling is represented in the figure? A) paracrine B) autocrine C) synaptic D) hormonal

C

What is the most likely mechanism by which testosterone functions inside a cell? 32) A) It coordinates a phosphorylation cascade that reduces spermatogenesis. B) It acts as a signal receptor that activates tyrosine kinases. C)It binds with a receptor protein that enters the nucleus and activates expression of specific genes. D) It acts as a steroid signal receptor that activates ion channel proteins in the plasma membrane.

C

When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway? A) transducer B) response molecule C) signal molecule D) relay molecule

C

When one cell goes through cell division, it produces ________. 49) A) four identical cells B) two different cells C) two identical cells D) four different cells

C

Which of the following does not occur during mitosis? A) separation of sister chromatids B) condensation of the chromosomes C) replication of the DNA D) spindle formation

C

Which of the following provides the best evidence that cell-signaling pathways evolved early in the history of life? A) Most signals in all types of cells are received by cell surface receptors. B) Cell-signaling pathways are seen in "primitive" cells such as bacteria and yeast. C) Signal transduction molecules identified in distantly related organisms are similar. D) Bacteria and yeast cells signal each other in a process called quorum sensing.

C

)Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. Which of the following conditions is required for the target organ to respond to a particular hormone? A)Cells in the target organ must modify their plasma membranes to allow the hormone to enter the cytoplasm. B)The target organ must have the opposite mating type of the organ that produced the hormone. C) The target organ must be the same as the organ that produced the hormone. D) The target organ must have receptors that recognize and bind the hormone molecule.

D

1) Different body cells can respond differently to the same hormones because 1) A)the hormone is chemically altered in different ways as it travels through the circulatory system. B) each cell converts that hormone to a different metabolite. C) different target cells have different sets of genes. D)target cells responses are determined by the components of their signal transduction pathways. E)the circulatory system regulates responses to hormones by routing the hormones to specific targets.

D

2)Cells that are infected, damaged, or have reached the end of their functional life span often 2) undergo "programmed cell death." This controlled cell suicide is called apoptosis. Select the appropriate description of this event on a cell's life cycle. A)Apoptosis is regulated by cell surface receptors that signal when a cell has reached its density-dependent limits. B)During apoptosis, dying cells leak out their contents, including digestive enzymes that also destroy healthy cells. C)Each cell organelle has protein signals that initiate the breakdown of the organelle's components, which leads to cell death. D)During apoptosis, cellular agents chop up the DNA and fragment the organelles and other cytoplasmic components of a cell.

D

33) Which of the following events occurs during interphase of the cell cycle? 33) A) spindle formation B) separation of the spindle poles C) condensation of the chromosomes D) replication of the DNA

D

At which phase of the cell cycle do centrioles begin to move apart in animal cells? 42) A) metaphase B) anaphase C) telophase D) prophase

D

Density-dependent inhibition is explained by which of the following processes? 51) A)As cells become more numerous, the protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor. B)As cells become more numerous, the level of waste products increases, which slows metabolism and inhibits growth. C)As cells become more numerous, they begin to squeeze against each other, restricting their size. D)As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells, and they signal each other to stop dividing.

D

Eukaryotic cells spend most of their cell cycle in which phase? 24) A) telophase B) prophase C) metaphase D) interphase

D

For a chemotherapeutic drug to be useful for treating cancer cells, which of the following characteristics is most desirable? A) It specifically inhibits cells entering G0. B) It does not interfere with metabolically active cells. C) It is safe enough to prevent all apoptosis. D) It specifically inhibits rapidly dividing cells.

D

In a diploid cell with 5 chromosome pairs (2n = 10), how many centromeres will be found in a nucleus at G2 of the cell division cycle? A) 20 B) 5 C) 40 D) 10

D

In a diploid cell with 5 chromosome pairs (2n = 10), how many sister chromatids will be found in a 58) nucleus at prophase of mitosis? A) 5 B) 10 C) 40 D) 20

D

Particular receptor tyrosine kinases (RTKs) that promote excessive cell division are found at high 19) levels in various cancer cells. HER2 is an RTK that is present at excessively high levels in some breast cancer cells. Herceptin is a protein that binds to HER2 and inhibits cell division. Herceptin may be an effective treatment for breast cancer treatment under which of the following conditions? A) If the patient has excessive levels of other RTKs in cancer cells. B) If the patient's genome codes for the HER2. C) If injection of HER2 in the patient's cancer cells stimulates cell division. D) If the patient's cancer cells have excessive levels of HER2.

D

Prior to mitosis, each chromosome of a eukaryotic cell consists of a pair of identical structures called A) sister chromosomes. B) nucleoli. C) chromatin. D) sister chromatids.

D

The creation of genetically identical offspring by a single parent, without the participation of sperm and egg, is called A) sexual reproduction. B) spontaneous generation. C) regeneration. D) asexual reproduction.

D

What are scaffolding proteins? 20) A) proteins that enter the nucleus of a cell to regulate transcription B)microtubule arrays that allow lipid-soluble hormones to get from the cell membrane to the nuclear pores C)relay proteins that orient receptors and their ligands in appropriate directions to facilitate complex formation D) large molecules to which several relay proteins attach to facilitate cascade effects 3

D

What does it mean to say that a signal is transduced? A) The signal enters the cell directly and binds to a receptor inside. B) The signal is amplified, such that even one signal molecule evokes a large response. C) The signal triggers a sequence of phosphorylation events inside the cell. D)The physical form of the signal changes as it passes from the cell membrane to the ultimate intracellular target.

D

What role do phosphatases play in signal transduction pathways? 27) A)They transfer a phosphate group from one protein in the pathway to the next molecule in the series. B) They amplify the second messenger cAMP. C) They activate protein kinases by phosphorylation. D) They inactivate protein kinases to turn off signal transduction.

D

What two components constitute an active MPF? 29) A) cyclin and tubulin B) ATP synthetase and a protease C) a growth factor and mitotic factor D) cyclin and a cyclin-dependent kinase

D

Which of the following is most likely to be responsible if, when your blood sugar level rises, the 16) level of sugar goes back down? A) type II diabetes B) the use of the sugar for energy by your cells C) a homeostatic mechanism based on positive feedback D) a homeostatic mechanism based on negative feedback

D

Which of the following is the correct sequence of events during mitosis? A)Nuclear membrane forms, chromosomes line up, chromosomes split, nuclear membrane dissolves B)Chromosomes split, nuclear membrane dissolves, nuclear membrane forms, chromosomes line up C)Chromosomes line up, nuclear membrane forms, nuclear membrane dissolves, chromosomes split D)Nuclear membrane dissolves, chromosomes line up, chromosomes split, nuclear membrane forms

D

Which of the following statements about a G protein signaling pathway is true? A) G protein bound to GDP is in its active state. B) Hydrolysis of bound GTP by a G protein activates the G protein. C) A G protein-coupled receptor bound to GTP is in its active state. D) A G protein bound to GTP is in its active state.

D

Why does testosterone, a lipid-soluble signaling molecule that crosses the membranes of all cells, affect only target cells? A)Only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor. B) Only target cells retain the appropriate genes regulated by testosterone. C)Only target cells possess the cytosolic enzymes that transduce the signal from testosterone to adenylyl cyclase. D) Intracellular receptors for testosterone are present only in target cells.

D