Biology Developmental Biology & Embryology Flashcards

What is the primary function of the amnion in amniotic vertebrates?

Answer: It encloses the embryo in a fluid-filled cavity that cushions it from mechanical shock and prevents desiccation

The amnion forms a fluid-filled (amniotic fluid) compartment around the embryo, providing physical protection from shock and maintaining a moist environment—an adaptation critical for terrestrial reproduction.

The trophoblast cells of the blastocyst are primarily responsible for:

Answer: Implanting into the uterine wall and forming the fetal contribution to the placenta

Trophoblast cells form the outer layer of the blastocyst, invade the uterine endometrium during implantation, and give rise to the chorion and fetal side of the placenta.

What is cellular determination in developmental biology?

Answer: The irreversible commitment of a cell to a particular developmental fate, maintained even if the cell is transplanted to a new location

Determination refers to the irreversible commitment of a cell to a specific developmental pathway; once determined, a cell differentiates along that pathway regardless of its new environment, distinguishing it from earlier, reversible specification.

Which description best defines stem cells in a developmental biology context?

Answer: Undifferentiated cells with the capacity for self-renewal and the ability to differentiate into one or more specialized cell types

Stem cells are defined by two key properties: self-renewal (the ability to divide and produce more stem cells) and potency (the ability to differentiate into specialized cell types), making them fundamental to development and tissue maintenance.

What is hemimetabolism (incomplete metamorphosis) in insects?

Answer: A life cycle consisting of egg, nymph, and adult stages in which the nymph gradually resembles a wingless adult

Hemimetabolism (incomplete metamorphosis) proceeds through three stages—egg, nymph, and adult—where the nymph resembles a miniature wingless adult and undergoes gradual change, unlike holometabolism which includes a pupal stage.

What is the primary developmental significance of the notochord in vertebrate embryos?

Answer: It provides axial structural support and secretes signals that induce the overlying ectoderm to form the neural plate and tube

The notochord is a transient mesodermal rod that defines the body axis, provides structural support, and critically releases Sonic Hedgehog (Shh) and other signals that induce neural tube formation and pattern the surrounding tissues.

What is totipotency in the context of cell development?

Answer: The capacity of a single cell to give rise to every cell type in the organism, including both embryonic tissues and extraembryonic structures such as the placenta

Totipotency is the highest level of developmental potential; a totipotent cell can form a complete organism including all extraembryonic tissues—only the zygote and the earliest blastomeres (up to the 4-cell stage in mammals) are truly totipotent.