Answer:
Gymnosperms and lower vascular plants have sieve cells as their sieve elements, while sieve tubes are characteristic of flowering plants angiosperms. In gymnosperms, typical companion cells are lacking in the phloem. In gymnosperms, generally the xylem contains only tracheids. Vessels are absent.
Explanation:
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Answer:
Myelination.
Explanation:
Brain acts as one of the most important organ of the body that helps in receiving the stimuli and interpret the information in the form of signal. Two main types of neuron are myelinated neuron and unmyelinated neuron.
The myelinated neuron increases the conductivity of the impulse. The myelinated neurons are much more active than the unmyelinated neuron. In case of the quick thinking and instant actions, the myelinated neurons play an important role.
Thus, the answer is myelination.
MAD (mitotic arrest deficient) are proteins related to spindle cell cycle checkpoint and it is important since they prevent the segregation of sister chromatids until all have bound to the spindle.
The cell cycle ensures the duplication of the genome and its distribution in daughter cells by passing through a coordinated and regulated sequence of events.
A series of checkpoints guarantee the orderly progression of the phases of cell division and the correct distribution of the duplicated genetic material in the daughter cells.
The checkpoints during mitosis are:
- At the end of stage G1 and before S.
- Before anaphase in mitosis.
- DNA damage checkpoints in G1, S or G2.
The checkpoint before anaphase in mitosis guarantees the separation of chromosomes, and operates by activating the Mad2 protein that prevents the degradation of segurin, until the conditions are appropriate.
That is, the Mad2 protein prevents the segregation of sister chromatids until they have all bound to the spindle.
Therefore, we can conclude that MAD (mitotic arrest deficient) are proteins related to spindle cell cycle checkpoint and it is important since they prevent the segregation of sister chromatids until all have bound to the spindle.
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Answer: option C - activating second messengers and stimulating glycogenolysis and gluconeogenesis.
Explanation:
Glucagon is an hormone, produced by the pancreas, that opposes the action of insulin by stimulating the production of SUGAR.
Glucagon is usually released whenever blood glucose levels is detected to be LOW. it works by activating secondary messengers.
