Answer:
The correct answer will be option-neural tube, hindbrain, metencephalon,
Explanation:
The development of the brain during the embryogenesis takes place by the formation of a neural tube or the predecessor of the central nervous system.
The neural tube arises from the ectoderm layer of the gastrula where the anterior portion of the neural tube forms the brain.
The neural tube development results in the formation of three sacs filled vesicles in which the fist vesicle forms the forebrain, second forms the midbrain and the third vesicle forms the hindbrain.
Later development process divides the hindbrain into two new portions called metencephalon and myelencephalon where the metencephalon forms the cerebellum portion of the brain.
Thus, the selected order is the correct order.
Answer:
Option B
Explanation:
Water soluble hormones associate with the G protein of cAMP. This G protein is intra-cellular i.e found inside the cell.
However in case of lipid derived hormones, the hormone has to diffuse through the cell across the plasma membrane to bind to DNA or the intra-cellular receptors.This regulates the gene transcription and induces protein production that affects the cell functioning for a long time.
Hence, option B is correct
b. the first stage because it could never be in the secound stage
Within a gymnosperm megasporangium, the following developmental sequences that are correct, assuming fertilization occurs is: megaspore, female gametophyte, egg cell, sporophyte embryo. The last Option (Option D) is correct.
In gymnosperm megasporangium, the meiotic division produces four haploid megaspores from a single cell, three of which generally degenerate. The female gametophyte is formed by mitosis from the surviving megaspore.
Prior to fertilization, the male mature gametophyte needs to be transferred to the female gametophyte for fertilization to take place.
When the nuclei of the sperm encounter the nucleus of the egg cell in gymnosperms, it fuses with the egg nucleus to produce a diploid zygote.
Mitosis occurs in the fertilized egg to initiate the growth of a new sporophyte generation (the multicellular embryo of the seed.)
Therefore, we can conclude that we've understood the mechanism of developmental sequence in the gymnosperm megasporangium.
Learn more about the gymnosperm here:
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