11.1 Embryonic development Flashcards
A zygote is a ….
Multicellular organism (diploid cell resulting from union of 2 haploid gametes - 1st cell of next generation)
An embryo is a…
Young anima or plant while still contained in protective structure (seed coat, egg shell, uterus)
Two major processes occurring during embryonic development?
- Cleavage: first cell divisions in the embryo (forming many cells from one cell)
- Gastrulation: in-folding, invagination (forms embryonic tissue layers from first layers of cells)
In Gastrula, the layers of embryonic cells are formed. They are called…
Germ layers
Different part of germ layers?
- Ectoderm (epidermis, nervous system)
- Endoderm (lining of digestive and respiratory system)
- Mesoderm (most internal organs: muscles, skeletal system, heart, stomach)
Organisms with 2 germs layers are?
Diploblastic (ectoderm + endoderm)
Organisms with 3 germ layers are?
Triploblastic
What is called the digestive space (gut cavity) during the gastrula?
Archenteron
What is called the mouth or anus during gastrula?
Blastopore
Tissues enable …., while gut enables ….
- Complex body organization
- Extracellular digestion
Types of symmetry?
- Asymmetrical (no axis devides body into equal halves - some sponges)
- Radially symmetrical (equal halves from many angles - cnidarians)
- Bilaterally symmetrical (single axis, midsagittal plane)
Development of a digestive tract enables?
- Specialization of gut regions
- Sequential food processing
- Continuous operation
Two ways to develop digestive tract?
- Protostomes (first mouth: blastopore is the mouth, the second opening is the anus)
- Deuterostomes (second mouth: blastospore is anus, second opening is mouth)
Three different plans with respect to body cavities
- Acoelomate
- Pseudocoelomate
- Coelomate
Acoelomate
No body cavity (solid except digestive space)
