It expanded slowly - False
It gradually warmed - False
Stars and galaxies formed - True
Atoms such as hydrogen and helium formed - True
It was no bigger than the head of a pin before it exploded - True
Answer: C. Homologous chromosomes are separated in meiosis but not in mitosis.
Explanation: There are two main types of division that take place in eukaryotic cells, mitosis, and meiosis. Mitosis is the type of division that is used for growth, repair, and replacement of tissues. Therefore it is not necessary that the cells have different chromosome numbers or are varied genetically in the daughter cells in the case of mitosis.
Meiosis is the division that takes place to form the gametes for sexual reproduction. It is important in the first stages of meiosis I, to introduce variation and to halve the chromosome number.
Chromosomes numbers are halved (from 46 to 23) during meiosis I because the gametes (sperm and egg) come together and fuse during fertilization to form a zygote. When this fusion occurs (23 from the zygote and 23 from the egg), the chromosome number needs to be returned to that of the parent cell (46).
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Genetic variation is introduced during synapsis which only occurs in meiosis, not mitosis. Homologs exchange genetic information during crossing over of synapsis. Entire chromosomes also separate during meiosis I.
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At the end of meiosis, four genetically unique cells are produced with half the number of chromosomes as the parent cell (23 cromosomes) . After the process of mitosis is completed, two cells genetically identical to each pther are produced and have the same number of chromosomes as the parent cell (46 cromosomes).
Genetic variation is actually important because of changing environmental conditions.
The correct answer is letter (<span>C) The polar air mass moves south to replace the rising maritime tropical air mass.</span> These air masses are bringing cold air to warmer areas most especially during the winter and cool. These air masses are stable and usually does not form much cloud. While the Continental Polar air move down south, across the warmer land, the lower part of the air mass is modified and thus few clouds are formed.
Answer: 20 amino acids
Explanation: The 20 amino acids that are found within proteins convey a vast array of chemical versatility. The precise amino acid content, and the sequence of those amino acids, of a specific protein, is determined by the sequence of the bases in the gene that encodes that protein.
Meiosis: cell division into four daughter cells (each has half the number of chromosome of the parent cell)
mitosis: cell division that results in two daughter cells (each has the same number and type of chromosomes as the parent cell)
