Question 1

Animal species exhibit an enormous diversity of genetic information contained in nuclear DNA. This may be reflected in very different genome sizes. One might predict that animals with more complex structures might show greater numbers of different types of mRNAs during development. Scientists investigating this possibility were surprised to find that similar numbers of genes were transcribed at a particular time in development among species whose genomes differed greatly in size. How can this result be interpreted?

Accepted Answer

A)  Some species retain large amounts of DNA that are never used. 
B)  The number of genes transcribed at any one time is tightly regulated and independent of genome size. 
C)  Nuclear DNA complexity is unrelated to the complexity of mRNAs transcribed during development. 
D)  Genome size has nothing to do with the physical complexity of the species.

Question 2

Scientists have found that the lifetimes of mRNAs coding for pair- rule regulatory elements in Drosophila embryos may be measured in minutes. What does this suggest about the overall developmental plan of an animal body?

Accepted Answer

A)  Timing of pair- rule sequence determination is not as important as spatial signaling. 
B)  Each segment specified by pair- rule mRNAs is completely determined in the embryo in a very short time. 
C)  Building an animal body requires a sequence of steps; each of these steps is precisely timed. 
D)  mRNAs in general have short lifetimes; this is not a surprising finding.

Question 3

The protein of the bicoid gene in Drosophila determines

Accepted Answer

A)  the medial- lateral axis of the embryo. 
B)  the anterior- posterior axis of the embryo. 
C)  the number of segments in the embryo. 
D)  the ventral- lateral axis of the embryo.

Question 4

Suppose there was a mutation in the segment- polarity genes of Drosophila. What do you suppose might be the outcome?

Accepted Answer

A)  Antennae will appear in a different part of their usual segment. 
B)  Legs will appear in the place of antennae. 
C)  Every other segment of the embryo will be missing. 
D)  Several segments of the embryo will be missing.

Question 5

Many different lineages of animals share similar pattern- formation gene complexes. The study of how these shared complexes function in evolution is termed

Accepted Answer

A)  regulatory evolution. 
B)  convergent evolution. 
C)  conservative evolution. 
D)  evo- devo evolutionary developmental biology).

Question 6

What types of changes in the regulation of development can lead to evolutionarily significant morphological changes?

Accepted Answer

A)  Changes in when developmental genes are expressed. 
B)  Changes in where developmental genes are expressed. 
C)  Changes in development are not evolutionarily significant. 
D)  Both A and B are evolutionarily significant.

Question 7

Even though plant and animal development processes share a number of features, there are some differences between the two groups of organisms. Which of the following is NOT a shared characteristic of plant and animal development?

Accepted Answer

A)  Cell types, once determined, generally cannot change their differentiated characteristics. 
B)  Orientation of cells and tissues is critical for proper development. 
C)  Differentiation of cells is directed and maintained by cascades of signals. 
D)  Gene expression in developing embryonic tissues is closely regulated.

Question 8

Cellular differentiation is usually produced by

Accepted Answer

A)  morphogenesis. 
B)  differences in DNA sequences. 
C)  differences in gene expression. 
D)  differences in gene copy numbers.

Question 9

Suppose you found several Drosophila mutants that possessed additional legs growing out of the head segments. The probable mutation would be found in

Accepted Answer

A)  homeotic genes. 
B)  gap genes. 
C)  pair- rule genes. 
D)  segment- polarity genes.

Question 10

The Bicoid gene product is normally localized to the anterior end of the embryo. If large amounts of the product were injected into the posterior end as well, which of the following would occur?

Accepted Answer

A)  Anterior structures would form in both ends of the embryo. 
B)  The embryo would probably show no anterior development and die. 
C)  The embryo would grow extra wings and legs. 
D)  The embryo would develop normally. 
E)  The embryo would grow to an unusually large size.

Question 11

Which of the following human cells contains the gene for alcohol dehydrogenase, a liver enzyme that processes alcohol?

Accepted Answer

A)  sperm and egg cells 
B)  liver cells 
C)  heart cells 
D)  Only the cells in A and B contain the gene for this enzyme. 
E)  All of the cells in A, B, and C contain the gene for this enzyme.

Question 12

Which of the following is not an example of the process of apoptosis during organ and tissue development?

Accepted Answer

A)  Lou Gehrig's disease 
B)  leaves falling off trees in the fall 
C)  petals falling off flowers after pollination 
D)  death of cells between the toes in chicken embryos

Question 13

What is common to gap genes, segment- polarity genes, and homeotic genes?

Accepted Answer

A)  They are unique to Drosophila embryos. 
B)  They act independently of one another. 
C)  They can be activated at any time during development. 
D)  They code for transcription regulatory factors.

Question 14

Undifferentiated cells that continue to proliferate throughout an individual's life are referred to by what terms in plants and animals respectively?

Accepted Answer

A)  stem cells and stem cells 
B)  meristems and stem cells 
C)  meristems and meristems 
D)  stem cells and meristems

Question 15

In combination, what do the products of gap genes, pair- rule genes, and segmentation polarity genes of fruit flies do?

Accepted Answer

A)  They direct cell movements during differentiation. 
B)  They trigger the reorganization of the larval body into an adult body. 
C)  They define the segmented body plan of the embryo. 
D)  They set up the back- to- belly axis of the larval body.

Question 16

Evolutionary theory has until recently stressed genetic mutations that alter protein amino acid sequences as the major source of variation that leads to speciation. Evo- devo evolutionary developmental biology) offers a different understanding of the role of genetic change in evolution. Which of the following statements best summarizes this understanding?

Accepted Answer

A)  Changes in cell-cell interactions in a parent's body can lead to phenotypic change in offspring. 
B)  Similar genes are found in most developing animal bodies; changes in the times and places they are expressed can lead to phenotypic variation. 
C)  Genetic mutations are not as important in evolutionary change as the environment in which the organism develops. 
D)  Greater numbers of genes, rather than the ways in which they are regulated, lead to the development of more complex animals over time.

Question 17

During development, what a cell differentiates into depends in part on its location along three body axes. Which axis runs towards the organism's belly?

Accepted Answer

A)  ventral 
B)  dorsal 
C)  posterior 
D)  anterior

Question 18

Gene expression in developing organisms is regulated on several different levels. In many developing animals, regulation of gene expression is influenced by the action of Hox genes. Which of the following regulatory elements are produced by many Hox genes?

Accepted Answer

A)  transcriptional factors 
B)  signals from maternal cytoplasm, such as bicoid 
C)  mRNA processing factors 
D)  cell surface molecules for cell- cell interactions

Question 19

What does the term "genetic equivalence" refer to?

Accepted Answer

A)  Plant cells can differentiate into animal cells and vice versa. 
B)  Differentiated cells of a plant contain the same genes as other cells in the same plant. 
C)  During development, sending and receiving of signals via cell- cell interactions makes the cells involved more equal. 
D)  Differentiated animal cells can share gene products with each other, resulting in a balance of products among the cells.

Exam 21: Gene Structure and Development