a) Make a gain-of-function mutation in an inhibitor or an inducer of the pathway
ID: 34020 • Letter: A
Question
a) Make a gain-of-function mutation in an inhibitor or an inducer of the pathway
b) Make a loss-of-function mutation in an inducer of the pathway or make a gain-of-function in an inhibitor of the pathway
c) Make a loss-of-function mutation in an inhibitor or an inducer of the pathway
2) A cell-autonomous mutation:
a. Affects every cell in the body
b. Only affects cells that do not have the mutation in a mosaic analysis
c. Is not necessary for cell function
d. Only affects equivalence groups
3) Which are examples of lateral inhibition
a. Delta signaling through Notch (nerve formation in Drosophila)
b. Boss signaling through Sevenless (eye formation in Drosophila)
c. APX-1 signaling through GLP-1 (pharynx formation in C. elegans)
d. Lin-3 signaling through let-23 (vulva formation in C. elegans)
4) What is a competence group?
a. A group of cells capable of differentiating into the same cell type if they get the right signal.
b. A group of cells resistant to apoptosis.
c. A group of cells capable of forming mesoderm, ectoderm or endoderm.
d. A group of cells that will differentiate into the same type of cell.
5) Bicoid and hunchback up regulated even-skipped, while Kruppel and giant down regulated even-skipped. Under what conditions will even-skipped be expressed.
a. Kruppel levels high, giant levels low, bicoid levels low, hunchback levels low
b. Kruppel levels moderate, giant levels hig, bicoid levels low, hunchback levels moderate
c. Kruppel levels moderate, giant levels low, bicoid levels moderate, hunchback levels high
d. Kruppel levels low, giant levels high, bicoid levels moderate, hunchback levels low
e. Kruppel levels high, giant levels moderate, bicoid levels low hunchback levels moderate
6) ___________ are specialized protein complexes that create an aqueous pore between the cytoplasms of two adjacent cells.
a. Hormones
b. Receptors
c. Gap junctions
d. Ion channels
In the above diagram, P5p, P6p and P7p (and their descendents) will become vulva cells and P3p, P4p and P8p will become hypodermal cells.
7) What will be the fate of these cells if the AC cell is moved so it is closest to P3p?
A) P3p will give rise to the primary vulva cells, P4p and P5p will become secondary vulva cells and P6p, P7p and P8p will become hypodermal cells.
B) P3p will give rise to the primary vulva cells, P4p will become secondary vulva cells and P5p, P6p, P7p and P8p will become hypodermal cells
C) P3p will give rise to the primary vulva cells, and the rest will become hypodermal cells
D) All the cells will die
E) All the cells will become hypodermal cells.
8) What will be the fate of the cells if the Anchor cell is not producing lin-3?
A) All the cells will die.
B) All the cells become primary vulva cells
C) The cells will alternate vulva, hypodermal, vulva, hypodermal.
D) All the cells will become hypodermal cells.
E) There will be no affect, P5p, P6p and P7p (and their descendents) will become vulva cells and P3p, P4p and P8p will become hypodermal cells.
9) Drosophila mutations such as bcd, if homozygous in the mother, produce offspring with lethal defects, no matter what the genotype of the offspring. For some other genes, the mutant phenotype can be "rescued" by introducing a wild-type allele. Why the difference?
A) Non-rescuable mutations are of paternal origin.
B) Rescuable mutations act as dominants.
C) bcd is a maternal effect mutation.
D) Rescue requires recombination between the maternal and introduced alleles.
E) bcd is a Hox gene.
10) If a female is heterozygous mutant for a maternal effect gene and is mated to a male who is homozyous, what will be the phenotype of her offspring?
a. Half will display the mutant phenotype, half will display the normal phenotype
b. All will be normal
c. All will be mutant
d. All will die
11) What is a morphogen?
a. A substance whose presence in differing concentrations directs different developmental fates
b. A substance that binds the DNA to turn on or off gene expression
c. A substance that binds to the Ribosome to prevent translation
d. A substance that is necessary for RNA interference
12) If dzy is a strict maternal-effect lethal mutation, all the embryos produced by a dzy/dzy hermaphrodite mated with a +/+ male will die.
a. True
b. False
13) Mutations which alter time of expression of a gene are:
a. Holocentric
b. Heterochronic
c. trans-splicing
d. free duplication
e. RNA-mediated interference
14) In a hypothetical developmental cascade, A suppresses B, B activates C, C represses D, and D represses E. Which of the following statements is true?
a. A is off, B is on, C is on, D is off, E is on
b. A is on B is on, C is on, D is off, E is on
c. A is on, B is off, C is off, D is on, E is off
d. A is off, B is on, C is on, D is off, E is on
e. A is on, B is off, C is off, D is on, E is on
15) chromosome which does not undergo recombination by virtue of its physical map exemplifies a:
a. morphogen
b. homeodomain
c. balancer
d. homeobox
e. nonautonomous trait
16) A protein sequence which confers binding to segment-specific regulatory sequences within genes is a:
a. Morphogen
b. Balancer
c. Homeobox
d. nonautonomous trait
17) A substance that defines different cell fates in a concentration-dependent manner is a:
a. Morphogen
b. Homeodomain
c. Balancer
d. Homeobox
e. nonautonomous trait
18) Order the following classes of genes according to their hierarchy of function in early embryogenesis: A. pair rule genes, B. homeotic genes, C. gap genes, D. segment polarity genes, E. maternal genes
a. CDABE
b. ECDAB
c. BCADE
d. ACBED
e. DEABC
19) The distribution of hunchback mRNA in the oocyte immediately prior to fertilization is a gradient from anterior (highest) to posterior (lowest).
a. True
b. False
20) Signal transduction must take over for transmission of regulatory gradients after development of the embryonic _________.
a. P elements
b. ineage compartment
c. imaginal discs
d. syncitial blastoderm
e. cellular blastoderm
21) A gap gene mutation might cause which of the following defects in the embryonic body plan?
a. Every other segment would be missing, resulting in T1, T3, A2, A4, etc. but no T2, A1, A3, and so on.
b. Segments A2 through A6 would be missing, but the rest of the pattern is essentially normal.
c. No segmentation would be evident.
d. Patterning within each segment would be abnormal, causing for example denticle belts to form across the entire segment.
e. The identity of one or more segments would be transformed to that of a different segment, such that the T3 leg would transformed to a T2 leg.
22) Gap genes directly regulate pair-rule genes.
a. True
b. False
23) Which of these would be an example of a homeotic phenotype?
a. The wings are shrunken and useless.
b. The eyes of the fly are brown instead of the normal red.
c. The first abdominal segment has legs
d. All of these.
e. None of these.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Anchor cell A Somatic gonad P7p P8p VPCs P3p Hypoder Vulva-forming cells Key: LET-23 receptor at cell surface (c) Extracellular P SH2 SEM-5 341 (active) MAP kinase GAP GDP GTP MPK-1 Intracellular (inactive) s LIN-1 -25, LIN-3Explanation / Answer
1. The correct option is (C) Make a loss-of-function mutation in an inhibitor or an inducer of the pathway.
2. The correct option is (C) Is not necessary for cell function.
3. The correct option is (a) Delta signaling through Notch (nerve formation in Drosophila)
4. The correct option is (a) A group of cells capable of differentiating into the same cell type if they get the right signal.
5. The correct option is (c) Kruppel levels moderate, giant levels low, bicoid levels moderate, hunchback levels high
6. The correct option is (c) Gap junctions
7. Diagram is invisible
8. The correct option is (C) The cells will alternate vulva, hypodermal, vulva, hypodermal.
9. The correct option is (C) bcd is a maternal effect mutation.
10. The correct option is (c) All will be mutant
11. The correct option is (a) A substance whose presence in differing concentrations directs different developmental fates
12. The given statement is false.
13. The correct option is (b) Heterochronic mutations.
14. The correct option is (c) A is on, B is off, C is off, D is on, E is off
15. The correct option is (c) balancer.
16. The correct option is (c) Homeobox
17. The correct option is (a) morphogen.
18. The correct option is (b) ECDAB
19. The correct option is (a) false.
20. The correct option is (d) syncitial blastoderm
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