Exam 4_Practice Test

What is fertilization in embryonic development?

The union of male (sperm) and female (egg) gametes to form a diploid zygote.

What happens during cleavage?

Rapid series of mitotic divisions without overall growth, forming a multicellular embryo called a blastula.

What is gastrulation?

The rearrangement of blastula cells into a three-layered structure (gastrula) with ectoderm, mesoderm, and endoderm layers.

Define organogenesis.

The formation and development of organs from the germ layers.

What is determination in developmental biology?

A process by which a cell becomes committed to a specific developmental fate.

What is differentiation?

The process in which a cell undergoes changes to become a specialized cell type.

What does morphogenesis refer to?

The biological process that causes an organism to develop its shape through coordinated cell growth, migration, and death.

Name a common morphogen factor and its role.

Bicoid: a protein that acts as a morphogen influencing anterior development in Drosophila.

What are totipotent cells?

Cells that can develop into any cell type, including the placenta.

What are pluripotent cells?

Cells that can give rise to all cell types of the body but not extra-embryonic tissues.

Define multipotent cells.

Cells that can give rise to multiple, but limited, cell types.

What are unipotent cells?

Cells that can produce only one cell type, their own.

What is polarity in development?

The establishment of spatial differences in the shape, structure, and function of cells and embryos.

How is polarity established in amphibians?

Through cortical rotation after fertilization.

What role does Bicoid play in Drosophila development?

Acts as a transcription factor that activates head-specific genes and represses posterior genes.

How does Nanos function in Drosophila?

By inhibiting translation of hunchback mRNA, allowing abdominal development.

Define morphogen.

A signaling molecule that induces different cell fates at different concentrations.

What is a transcription factor?

Proteins that bind to DNA to regulate gene expression.

What are gap genes?

Genes that define broad regions of the embryo.

What are Hox genes?

A subset of homeotic genes that determine the identity of body segments along the anterior-posterior axis.

What is the function of Ubx in Drosophila?

Prevents the formation of wings in the third thoracic segment.

What does Sonic Hedgehog (Shh) do?

Involved in patterning the neural tube, limbs, and somites.

What is induction in developmental biology?

A process where one group of cells influences the developmental fate of nearby cells.

What do segment identity genes specify?

They specify segment identity across the animal kingdom.

How is differential gene expression initiated?

Through morphogen gradients, localized cytoplasmic determinants, and cell signaling pathways.

What is the significance of cytoplasmic determinants?

They lead to different gene expression profiles and developmental fates.

What does the ectoderm develop into?

Epidermis, nervous system, and sensory organs.

What does the mesoderm develop into?

Muscle, skeleton, circulatory system, and kidneys.

What does the endoderm develop into?

Lining of the digestive tract, liver, pancreas, and lungs.

What differentiates protostomes from deuterostomes?

Protostomes have mouth forming first; deuterostomes have anus forming first.

What are three features of cnidarians?

Radial symmetry, mesoglea, and a nerve net.

What is the notochord?

A flexible rod providing support, aiding in the development of the vertebral column.

What are two key features of echinoderms?

Water vascular system and tube feet.

What is the difference between homeotherms and poikilotherms?

Homeotherms maintain a constant body temperature; poikilotherms vary with the environment.

What is a regulator in metabolic needs?

An organism that actively maintains internal conditions despite external changes.

What is one characteristic of mammals?

The presence of hair/fur and mammary glands.

What is negative feedback in homeostasis?

A mechanism to maintain homeostasis by reducing the effect of a stimulus.

What is positive feedback?

Reinforces the stimulus, leading to an even greater response.

What is the difference between open and closed circulatory systems?

Open systems have hemolymph bathing organs directly; closed systems have blood confined to vessels.

What does Fick's Law optimize?

Gas exchange through increased surface area and reduced diffusion distance.

What is a tracheal system?

A system where air-filled tubes transport oxygen directly to tissues.

What are the functions of the amniotic egg membranes?

Amnion protects embryo, chorion is for gas exchange, allantois stores waste, yolk sac provides nutrients.