Which statement about embryonic development is true?
A) Determination is the process by which blastomeres differentiate into specific cell types.
B) Preimplantation genetic diagnosis is possible in humans because they have regulative development.
C) In Drosophila, pole cells are the last cells to become determined.
D) Determination occurs later in species with mosaic development than in species with regulative development.
E) If the cells of a roundworm embryo in the two-cell stage are separated, each will develop into a complete animal.

Question

Quizplus · Accepted Answer

Preimplantation genetic diagnosis relies on the ability to remove one or a few cells from an early embryo without affecting its development. Regulative development (seen in animals such as sea urchins) allows for this, as each cell has the potential to develop into a complete organism until a certain point in development. In contrast, mosaic development (seen in animals such as nematodes) does not allow for this, as cells become determined to a specific fate early in development.

Answer: A
 Determination is the process by which cells become committed to a specific fate or differentiation pathway. This occurs in the early stages of embryonic development, typically after several rounds of cell division. In animals with regulative development, determination occurs later in development, while in animals with mosaic development, determination occurs earlier.

Answer: E
 Embryos of certain species have the ability to develop into complete organisms even if their cells are separated at an early stage. This is called totipotency and is seen in species such as roundworms. In contrast, cells of embryos from species with more advanced development (such as humans) are less able to form a complete organism if separated.

Which Statement About Embryonic Development Is True