Cell Biology Answers

At the beginning of cellular respiration, all NAD+ are already reduced. True or false?

What would happen to a cell that lacked p53 ?

64.
Each eukaryotes can regulate gene expression. Determine which of the five mechanisms each example represents. Not all examples will be used.
changes in chromatin structure Activity of transcription apparatus RNA processing RNA interference Initiation of translation
1. the 3 end can be cleaved to produce different transcript lengths before addition of the poly-a-tail. 2. acetylation of histones facilitates transcription. 3. The RISC degrades mRNA complexed with miRNA or siRNA. 4. Transcriptional repressors compete with activators for DNA binding sites. 5. RNA granules control the availability of mRNA for translation. 6. Gene inversion does not cause a loss of genetic information but may affect regulation of the inverted genes.

68. Which of the following factors determine cell fate?
cytoplasmic determinants
genome sequence
signals from neighboring cells
cell location in the embryo

62.
A homeotic gene is a gene that
is responsible for maintaining cellular conditions.
is expressed only in a specific tissue type after development.
assigns tissue identity during development.
is expressed at similar levels in all tissues.
is expressed during development.

63.
All of the cells in the human body contain the same genes. How do cells have different morphologies and functions when they contain the same genetic information?
Different cell types express particular genes at different levels.
Different cell types receive different endocrine signals.
Different cell types obtain different types of nutrients from their surroundings.
Different cell types synthesize proteins at a different rate.

59. Arrange the following steps of the regulation of the trp operon in order of occurrence.
1. Rna polymerase binds to the promoter, allowing transcription of the trp genes to proceed. 2. Enzymes produced from the trp genes catalyze tryptophan production 3. sufficient quantities of tryptophan make further synthesis unnecessary. 4. Tryptophan activates the trp repressor protein. 5. the trp repressor protein binds to the operator. 6. the trp repressor protein blocks RNA polymerase from binding to the promoter.


60.
An operon is a group of genes under the control of a single promoter. Match each type of operon with the descriptions below.
Inducible repressible constitutive
A. under default conditions, transcription is inhibited. b. activating the repressor gene product inhibits transcription. c. the amount of gene product is constant d. Sufficient amounts of the gene product inhibit further transcription

51.
Which of the following are mechanisms by which cells communicate with each other? Check all that apply. More than one
cell junction
translation
pancrine signaling
cell cell recognition

56.
Classify the following statements as describing a protein kinase or a protein phosphatase.
protein kinase protein phosphatase
1. binds adenosine triphosphate 2. transfers a phosphate group to a protein. 3. dephosphorylates a protein 4. releases inorganic phosphate

49.
The cells that make up multicellular organisms send, receive, and respond to a variety of signals. Synaptic signaling is a form of cell-to-cell communication in which…
a cell produces a signal released into the bloodstream to be carried to specific distant organ.
adjacent cells pass molecules from one cell\'s cytoplasm to another through cell junctions.
the same cell that produces a signal also responds to the signal.
a neuron produces a chemical that induces changes in local, nearby, neurons.

50.
Match each description to the appropriate signal transduction stage.
reception transduction response
A. phytochrome receptor is activated by light signal. B, Specific genes are expressed. C. Proteins are activated through phosphorylation cascade. D. Second messenger activates specific protein kinase.

37. The kidney of a given land animal has particularly short loops of Henle. Predict the type of environment in which this animal lives.
desert
wetland
temperate forest
arid mountain range


48. The cells that make up multicellular organims send, receive, and respond to a variety of signals. Which of the following is an example of direct signaling?
During wound healing, platelet cells produce a growth factor that induces nearby cells to divide.
Junctions between adjacent plant cells connect their cytoplasms and allow them to share molecules.
Mutated cancer cells produce as well as respond to growth signals, resulting in tumor growth.
Pancreas cells produce and release insulin into the bloodstream to induce liver cells to uptake and use glucose.

32. Organisms use a variety of excretory systems to filter metabolic wastes out of their body fluid (blood, coelomic fluid, or hemolymph). Match each organism to the type of filtration structure it contains.
Prontonephridia metanephridia malpighian tubules Nephrons
annelids insects humans flatworms arachnids molluscs roitfers birds

36
Match each function to its site of action in the nephron.
glomenulus proximal convoluted tubule descending limb of loop of Henle Distal convoluted tubule ascending limb of loop of Henle collecting duct
1, regulation of NaCl and K in bodily fluids by secreting K and reabsorbing NaCL 2. transport of filrate to renal pelvis. 3. filration of blood plasma 4. reabsorption of water only, increasing solute concentration of filtrate 5. reabsorption of nutrients such as glucose. 6. reabsorption of salt only, during filtrate.

30
Freshwater and marine fish inhabit waters with different osmotic properties, so they regulate osmolarity in different ways. Classify each of the osmoregulation properties as relevant to freshwater fish or marine fish.
1. ingest large amounts of water and salt through mouth. 2. constantly gain water by osmosis. 3. excrete large amounts of water in urine. 4. gain salt ions through gills.
5. constantly lose water by osmosis. 6. excrete large amount of salt in urine. 7. Excrete large amounts of salt through gills. 8. Ingest little to no water by mouth.

31.
What is the primary benefit for an animal to excrete nitrogenous waste as uric acid?
Uric acid requires less energy to synthesize than urea.
Uric acid helps an animal to conserve water.
Uric acid increases efficiency of kidney function.
Uric acid improves gastric absorption of nucleic acids.