Question 1

Which of the following best describes the maternal-to-zygotic transition (MZT) during early embryonic development in mammals?

Accepted Answer

MZT is the process where the embryo switches from relying on maternal mRNAs and proteins to activating its own genome, typically occurring at the 2-cell stage in mice and 4-8 cell stage in bovines.

Question 2

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

Accepted Answer

Ectoderm

Question 3

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

Accepted Answer

Homeosis

Question 4

Which of the following mechanisms is NOT a form of epigenetic regulation?

Accepted Answer

Point mutation in the coding region of a gene

Question 5

Which statement about pluripotent stem cells is correct?

Accepted Answer

They can differentiate into any cell type of the three germ layers but cannot form extraembryonic tissues like the placenta.

Question 6

During the maternal-to-zygotic transition, which enzyme is primarily responsible for maintaining methylation at imprinted germ cell differentiated methylated regions (gDMRs)?

Accepted Answer

DNMT1

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 direct application of induced pluripotent stem cells (iPSCs) in medicine?

Accepted Answer

Generating patient-specific cells for regenerative therapy to avoid immune rejection.

Question 9

Which class of genes is responsible for establishing the anterior-posterior axis in Drosophila embryos by forming protein gradients?

Accepted Answer

Maternal-effect genes

Question 10

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

Accepted Answer

The cell is reprogrammed to a pluripotent state, becoming an induced pluripotent stem cell (iPSC).

Question 11

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 corresponds to their spatial and temporal expression along the anterior-posterior axis.

Question 12

Which process describes the inheritance of fate-specifying molecules by daughter cells during development?

Accepted Answer

Asymmetric cell division

Question 13

Which of the following is a consequence of a loss-of-function mutation in the Ultrabithorax (Ubx) gene in Drosophila?

Accepted Answer

Transformation of the third thoracic segment (T3) into a second thoracic segment (T2), resulting in a four-winged fly.

Question 14

Which of the following best describes the difference between orthologs and paralogs in Hox gene clusters?

Accepted Answer

Orthologs are genes in different species derived from a common ancestor, while paralogs are genes duplicated within a species.

Question 15

Which of the following is a key feature of gene regulation that allows different cell types (e.g., skin, liver, brain) to express different sets of genes?

Accepted Answer

The presence of specific transcription factors, activators, or repressors in each cell type.

Question 16

Which of the following statements about DNA methylation during early embryogenesis is correct?

Accepted Answer

Global DNA methylation is erased after fertilization, except for imprinted regions, and is re-established after implantation.

Question 17

Which of the following is a real-world application of bioinformatics in genetics?

Accepted Answer

Identifying disease-associated genetic variants using databases like GenBank and Ensembl.

Question 18

Which of the following best describes the role of transcription factors in stem cell biology?

Accepted Answer

They regulate self-renewal and lineage-specific differentiation by controlling gene expression.

Question 19

Which of the following is a consequence of deleting all paralogs of Hox10 genes in mice?

Accepted Answer

Lumbar and sacral vertebrae develop ribs, resembling thoracic vertebrae.

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

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