Answer:
Explanation:
Meiosis is a form of cell division that occurs in the sex cells of organisms. It ensures the reduction of a diploid cell to an haploid cell to allow for the formation of a diploid zygote after fertilization (contribution of both parents haploid sex cells to give a diploid zygote). Thus, this process is very essential and important.
The reduction is accomplished by 2 divisions after the duplication of chromosomes
- first division: separation of homologous pairs of chromosomes (this reduces the total in half)
- second division: separation of sister chromatids of a chromosome.
The rearrangement in meiosis occurs by crossing over/genetic recombination.
This is the exchange of genetic material between homologous pairs of chromosome bringing about a rearrangement and genetic variation
An example of a chromosomal abnormality that arises as a result of defects in this process is the Down Syndrome which is caused by a nondisjunction of the chromosomes 21 pair in a sex cell.
This condition produces offsprings that have some characteristic facial features, short stature etc
Answer:
A planet's atmospheric conditions influence its ability to retain heat, so that the location of the habitable zone is also specific to each type of planet.
Explanation:
Answer:
The phylum platyhelminthes includes the organism like flatworms, earth worm and many other species. They play a major role in the marine, terrestrial and freshwater ecosystem. It contains a variety of nutrient sources.
Explanation:
They are of great importance from the times when there were no other organism.
Answer:
plants For example, phototropism is the plant's response to stimulus, i.e. sunlight. A plant hormone “auxin” keeps the plant's direction towards the sun by activating the growth in a particular part of a stem. Similarly, gravitropism in plants responds to the stimulus, i.e. gravity
Explanation:
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