Developmental Biology Exam 1. Real Exam Questions and Correct Verified Answers 2024-2025., Exams of Biology

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Developmental Biology Exam 1. Real Exam

Questions and Correct Verified Answers 2024-

2025. Graded A

Analogous structures - ANSThose whose similarity comes from their performing a similar function rather than their arising from a common ancestor Animal hemisphere - ANSUpper half of the egg Blastocoel - ANSThe fluid-filled cavity within the blastula Blastomeres - ANSAny of the cells resulting from the cleavage of a fertilized ovum during early embryonic development that together form the blast Blastopore - ANSThe invagination point where gastrulation begins. For deuterostomes= anus and protostomes= mouth This is the dimple that becomes a ring through which cells migrate. Those inside will become the mesoderm Blastula - ANSEarly-stage embryo consisting of a sphere of cells surrounding an inner fluid-filled cavity, the blastocoel Cadherin - ANS...

Cell lineage - ANSSeries of cell types stating from an undifferentiated, pluripotent stem cell through stages of increasing differentiation, to the terminally differentiated cell type Centrolecithal - ANSIncomplete cleavage. (yolk in center of egg) Superficial - most insects Chimeric embryos - ANSEmbryos made from tissues of more than one genetic source, useful to trace cell lineages by fate maps Cleavage - ANSSeries of rapid mitotic divisions following fertilization, cytoplasm of zygote divided into smaller cells (blastomeres), and by the end formation of the blastula Convergent extension or Intercalation - ANSCells intercalate to narrow the tissue and at the same time move it forward. Mechanism for elongation Delamination - ANSSplitting or migration of one sheet into two sheets Ectoderm - ANSGenerates outer layer of embryo, produces epidermis of the skin, forms the brain and nervous system Embryogenesis - ANSCollective name for the stages of development between fertilization and hatching

Endoderm - ANSBecomes innermost layer of the embryo, produces epithelium of digestive tube and its associated organs (including the lungs) Epiboly - ANSThe expansion of one cell sheet over other cells Epithelial cells - ANSOne of two major types of cells in the embryo, are tightly connected to one another in sheets or tubes Fate map - ANSDiagram mapping larval or adult structures onto the region of the embryo from which they arose Fertilization - ANSFusion of gametes which stimulates development and initiates a new individual Gametogenesis - ANSDevelopment of gametes, usually not complete until the organism is physically mature Gastrula - ANSThe stage of the embryo following gastrulation in which the three germ layers are formed Gastrulation - ANSStage where blastomeres undergo dramatic movements and change their positions relative to one another, results in formation of three germ layers Holoblastic cleavage - ANSComplete cleavage.

First cleavage always occurs along the vegetal-animal axis of the egg, the second cleavage is perpendicular to the first. Two types: Isolecithal (small yolk distribution) and Mesolecithal (moderate yolk distribution)

1. Radial- echinoderms
2. Spiral - flatworms
3. Bilateral- tunicates
4. Rotational- mammals Homologous structures - ANSOrgans whose underlying similarity arises from their being derived from a common ancestral structure How does the embryo achieve rapid divisions without growth? - ANSThe cleavage cell cycle lacks G1 and G2 phases Ingression - ANSMigration of individuals cells into the embryo Inner cell mass - ANSGive rise to the embryo and some extraembryonic structures Invagination - ANSThe infolding of a portion of the outer layer of a blastula in the formation of a gastrula Involution - ANSInturning of cell sheet over the basal surface of an outer layer. Isolecithal cleavage - ANSComplete cleavage. (small amount of evenly distributed yolk)

1. Radial- echinoderms
2. Spiral - flatworms
3. Bilateral- tunicates
4. Rotational- mammals Meroblastic cleavage - ANSIncomplete cleavage. In the presence of a large amount of yolk in the fertilized egg cell, the cell can undergo partial, or meroblastic, cleavage. Two major types of meroblastic cleavage are discoidal and superficial. Mesenchymal cells - ANSOne of two major types of cells in the embryo, are unconnected to one another and operate as independent units Mesoderm - ANSGenerates blood, heart, kidney, gonads, bones,muscles, and connective tissues Mesolecithal cleavage - ANSComplete cleavage. (moderate vegetal yolk disposition) Radial- amphibians Neural tube - ANSEmbryonic precursor to central nervous system, i.e. the brain and spinal chord Neurula - ANSThe embryo while the neural tube is forming

Notochord - ANSMesodermal rod in the most dorsal portion of the embryo, important role in inducing and patterning the nervous system Organogenesis - ANSGerm layers interact with one another and rearrange themselves to produce tissues and organs Stages of embryogenesis - ANSFertilization, cleavage, gastrulation, organogenesis, metamorphosis, and gametogenesis Teloecithal cleavage - ANSIncomplete cleavage. (dense yolk throughout most of the cell) Bilateral- cephalopod Discodial- fish Trophoblast cells - ANSGive rise to the chorion - part of the placenta Vegetal hemisphere - ANSBottom portion of the egg which contains the yolk What are the molecular machines that divide cells? - ANSMitosis: karyokinesis (nuclear division) Cytogenesis ( cytoplasmic division) What causes the different cleavage patterns observed? - ANSCleavage patterns are influenced by the amount and distribution of yolk and by cytoplasmic factors

What is the function of the blastocoel? - ANSPrevents contact between vegetal and animal cells and provides space for gastrulation movements What regulates the end of cleavage? - ANSMid-blastula transition is the point when zygomatic genomes are activated Zygote - ANSFertilized egg, a single cell which divides mitotically to produce all the cells of the body