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5.6 Neurulation — Test 1
Q1. In primary neurulation, the neural tube forms by:✓ Folding of the neural plate and its separation from the surface ectoderm
Q2. In secondary neurulation, the neural tube forms by:✓ Mesenchyme cells coalescing into a solid cord that then hollows
Q3. In mammals, secondary neurulation begins at the level of the:✓ Sacral (caudal) vertebrae
Q4. Failure of the neural tube to close at the anterior end results in:✓ Anencephaly
Q5. Sonic hedgehog, secreted by the notochord, induces which structure in the overlying neural plate?✓ The floor plate (medial hinge point)
Q6. In neural-tube dorsal-ventral patterning, high levels of BMP specify cells to become:✓ Epidermis (and dorsal neural fates)
Q7. The neural crest, which forms peripheral neurons, melanocytes and facial cartilage, arises from the:✓ Edges of the neural plate (dorsal neural tube)
Q8. Fusion of precursor cells (myoblasts) is essential in the development of:✓ Skeletal muscle
Q9. The first organ system to begin functioning during vertebrate organogenesis is the:✓ Cardiovascular system
Q10. Lateral inhibition, which makes two distinct cell types emerge from a uniform population, requires:✓ Direct cell-cell contact and reciprocal Notch-Delta signalling
Q11. Which is NOT true of lateral inhibition?✓ It results from a long-range diffusible morphogen
Q12. In neural induction generally, ectoderm becomes neural when BMP signalling is:✓ Inhibited
Q13. The medial hinge point of the folding neural plate forms above the:✓ Notochord (induced by its Shh)
Q14. The first sign of primary neurulation is the formation of the:✓ Neural plate (a thickening of dorsal ectoderm)
Q15. As the neural plate folds, its raised edges are called the:✓ Neural folds
Q16. Neural tube closure begins in the middle of the body and proceeds toward both ends, like a:✓ Zipper closing in two directions
Q17. Failure of the posterior neuropore to close results in:✓ Spina bifida
5.6 Neurulation — Test 2
Q18. Maternal folic acid (folate) supplementation reduces the risk of:✓ Neural tube defects
Q19. Neural crest cells are sometimes called the 'fourth germ layer' because they:✓ Migrate widely and form an extraordinary range of derivatives
Q20. Which of the following is a derivative of the neural crest?✓ Melanocytes (pigment cells)
Q21. In the neural tube, Sonic hedgehog from the floor plate and BMP from the roof plate set up:✓ Opposing gradients that pattern dorsal-ventral neuron types
Q22. Motor neurons are specified in the ____ part of the neural tube, where Shh is high.✓ Ventral
Q23. The notochord is essential in neurulation because it:✓ Secretes Shh to induce the floor plate and pattern the ventral tube
Q24. During neuronal differentiation, lateral inhibition (Notch-Delta) ensures that:✓ Only some cells in a field become neurons, spacing them out
Q25. A neuron extends a long process toward its target guided by a motile tip called the:✓ Growth cone
Q26. Axon guidance molecules such as netrins and semaphorins act by:✓ Attracting or repelling the growth cone to steer the axon
Q27. Neurons that fail to make functional connections during development are often removed by:✓ Programmed cell death (apoptosis)
Q28. Nerve growth factor (NGF) is an example of a neurotrophin, which:✓ Promotes the survival of specific neurons
Q29. The brain develops from the ____ region of the neural tube.✓ Anterior
Q30. The anterior neural tube first forms three primary brain vesicles, which are the:✓ Prosencephalon, mesencephalon and rhombencephalon
Q31. Hox genes pattern the hindbrain into segments called:✓ Rhombomeres
Q32. Compared with primary neurulation, secondary neurulation is the main mode for forming the:✓ Caudal (tail/sacral) spinal cord
Q33. Overall, neurulation and neural patterning illustrate how the nervous system is built by combining:✓ Morphogenetic movements with signalling gradients (Shh, BMP)