1. A.1 Neural Development

2. Understandings:
The neural tube of embryonic chordates is formed by in-folding of ectoderm followed by elongation of the tube.
Neurons are initially produced by differentiation in the neural tube
Immature neurons migrate to a final location
An axon grows from each immature neuron in response to chemical stimuli
Some axons extend beyond the neural tube to reach other parts of the body
A developing neuron forms multiple synapses
Synapses that are nut used do not persist
Neural pruning involves the loss of unused neurons
The plasticity of the nervous system allows it to change
Application
Incomplete closure of the embryonic neural tube can cause spina bifida
Events such as strokes may promote reorganization of brain function
Skill
Annotation of a diagram of embryonic tissues of Xenopus, used as an animal model, during neurulation

3. Xenopus – frog embryonic tissue

5. Field of Study
Characteristics needed for model
Suitable species
Genetics
Large numbers and short generation times
Fruit fly
Baker’s yeast
Nematode worm
Developmental Biology
Robust embryos that are easily manipulated
Chicken
African clawed frog (Xenopus)
Genomic studies, such as genes that cause diseases
60% of human genetic diseases studied have a counterpart in the fruit fly and nematode
Nematode
Comparative genomics
The mouse genome is similarly organized to the human genome
Mouse