Question 1

Which of the following best describes the role of maternal-effect genes in Drosophila embryogenesis?

Accepted Answer

They encode morphogens that establish positional gradients in the unfertilized egg, guiding early axis formation.

Question 2

During the maternal-to-zygotic transition (MZT) in mammals, which of the following events occurs?

Accepted Answer

Zygotic genome activation (ZGA) initiates, and control of development shifts from maternal mRNAs to embryonic transcription.

Question 3

Which germ layer gives rise to the central nervous system and epidermis?

Accepted Answer

Ectoderm

Question 4

What is the primary function of DNA methylation during early embryonic development?

Accepted Answer

To regulate gene expression by altering chromatin accessibility, with global demethylation followed by de novo methylation.

Question 5

Which of the following statements about pluripotent stem cells (PSCs) is correct?

Accepted Answer

They are derived from the inner cell mass of the blastocyst and can form all adult cell types but not the placenta.

Question 6

A mutation in a homeotic (Hox) gene in Drosophila causes legs to develop where antennae should be. This is an example of:

Accepted Answer

A gain-of-function mutation causing homeosis.

Question 7

Which of the following best explains how epigenetic reprogramming enables stem cells or differentiated cells to change cell identity?

Accepted Answer

It resets DNA methylation and chromatin state, allowing previously silenced genes to be reactivated.

Question 8

Which of the following is a key difference between totipotent and pluripotent stem cells?

Accepted Answer

Totipotent cells can form both embryonic and extraembryonic tissues, while pluripotent cells can only form embryonic tissues.

Question 9

In the context of gene regulation, what is the role of transcription factors (TFs) in stem cell differentiation?

Accepted Answer

TFs regulate stem cell self-renewal and lineage-specific differentiation by activating or repressing target genes.

Question 10

Which of the following statements about the colinearity rule of Hox gene expression is correct?

Accepted Answer

The physical order of Hox genes on the chromosome matches the spatial and temporal order of their expression along the anterior-posterior axis.

Question 11

A researcher uses CRISPR-dCas9 to activate endogenous OSKM genes in a differentiated cell. What is the expected outcome?

Accepted Answer

The cell will be reprogrammed to an induced pluripotent stem cell (iPSC) state.

Question 12

Which of the following best describes the function of pair-rule genes in Drosophila development?

Accepted Answer

They subdivide the embryo into smaller regions, about two segments wide.

Question 13

Which process is responsible for the erasure and re-establishment of DNA methylation patterns during mammalian development?

Accepted Answer

Epigenetic reprogramming

Question 14

Which of the following is a real-world application of pluripotent stem cells (PSCs)?

Accepted Answer

Regenerative medicine to repair damaged tissues and organs

Question 15

A loss-of-function mutation in the Ultrabithorax (Ubx) gene in Drosophila results in which phenotype?

Accepted Answer

Transformation of thoracic segment 3 (T3) into another thoracic segment 2 (T2), resulting in a four-winged fly.

Question 16

Which of the following statements about evolutionary conservation of developmental mechanisms is correct?

Accepted Answer

Highly conserved regulatory genes, such as Hox genes, control body plan formation across animal taxa.

Question 17

Which of the following best describes the fate of primordial germ cells (PGCs) during mammalian development?

Accepted Answer

They are set aside early and give rise to sperm or eggs.

Question 18

Which of the following is a plausible consequence of a mutation in a pair-rule gene in Drosophila?

Accepted Answer

Loss of every other segment in the embryo.

Question 19

Which of the following statements about gene regulation in different cell types is correct?

Accepted Answer

Gene expression is regulated by the presence of specific transcription factors, activators, and repressors in each cell type.

Developmental Genetics: Gene Regulation, Stem Cells, and Pattern Formation

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