Answer:
The brain and the spinal cord are wrapped in three protective layers of tissue called the meninges. The cerebral spinal fluid goes between these layers to provide more cushion and protection. It nourishes and protects the nerve tissues of the brain and spinal cord. It also acts as a shock absorber, considering humans move a lot and fall.
A virus.
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The process of sexual reproduction involves two parents, each contributing one gamete. Gametes are produced
by a process called meiosis, which starts by the duplication of the
chromosomes, followed by two rounds of cell divisions and halving of the
chromosome number. Gametes have half the chromosome number of other
adult
cells of an organism.
A key feature of meiosis is the exchange of chromosome pieces which occurs in the first division of this process, called recombination or
crossing over. Recombination is a very important source of genetic
variation between individuals of sexually reproducing species, and the
driving force for the process of natural selection.
Answer:a. mitosis
Explanation: mitosis is a type of cell division found in somatic cells.
The daughter cells contains the same number of chromosomes as the parent cell.
Mitosis involves four stages namely;prophase, metaphase, anaphase,telophase.
There is also an interphase,of normal functioning of the cells.
Mitosis is important in asexual reproduction , regeneration and replacement of lost cells.
It also causes growth in organisms.
Unlike meiosis , crossing over does not occur in mitosis thus there is no variation in daughter cells
Answer:
the grand canyon is older than the rocks in its wall hope it helps