Question

Zebrafish (Danio rerio) are especially useful in the study of early development because their embryos ______________.

(a) are exceptionally large.
(b) develop slowly.
(c) are transparent.
(d) are pigmented.8

Answer 1

Zebrafish are useful for studying early development due to their transparent embryos, which allows for direct observation of developmental processes.

Step-by-step explanation:

Zebrafish (Danio rerio) are particularly useful in the study of early development because their embryos are transparent. This transparency allows scientists to easily observe and study developmental processes as they occur. Unlike the African clawed frog, Xenopus laevis, which has large embryos that are easy to study but are not transparent, the clear embryos of zebrafish facilitate real-time observation of organogenesis and other developmental phenomena.

The use of zebrafish complements studies in other model organisms such as Drosophila (fruit flies), Caenorhabditis elegans (nematodes), and sea urchins, each providing unique insights into early developmental stages. These models are invaluable for understanding fundamental biological processes and have relevant implications when studying human biology, due to the conservation of key developmental genes across species.

Answer 2

Zebrafish embryos are particularly useful for early developmental studies due to their transparency, which enables direct observation of developing organs and tissues, aiding in our understanding of organogenesis and gene expression. Option c is the correct answer.

Step-by-step explanation:

Zebrafish (Danio rerio) are especially useful in the study of early development because their embryos are transparent. Unlike other model organisms used in developmental biology, such as Xenopus laevis which has large embryos, or Drosophila and Caenorhabditis elegans that are studied for their segmentation in the body and cell lineage, zebrafish embryos offer the advantage of transparency. This transparency allows researchers to observe the processes of development in real time without invasive procedures, providing a window into understanding how organs and tissues develop.

Furthermore, this transparency is a key reason why changes in genes important to embryonic development have been relatively minor across different taxa - any significant mutation can be catastrophic due to the fragile nature of early embryos. Additionally, embryonic transparency, as seen in sea urchins, is an asset because it enables the assessment of development at a molecular level. In conclusion, this characteristic facilitates detailed studies of organogenesis and gene expression without the obstruction of pigmentation or the need for transparency-inducing techniques.

The correct option for why zebrafish are useful in early developmental studies is (c) are transparent.