Answer:
D
Explanation:
The presence of homeotic genes shows that all of the listed organisms (mice, flies, humans etc) all evolved from a common ancestor.
(A) is wrong as the evidence of the same gene existing in vastly different species shows the evolutionary relationship between these organisms.
(B) is wrong as there is insufficient evidence to prove that flies are the precessor of humans. We do know that flies and humans have evolved from a common ancestor though.
(C) is non-conclusive as the passage said nothing about the gene allowing the species to have a higher chance of surviving and reproducing. Hence, an errornous claim.
(D) is the correct answer as from a common ancestor, all of the listed organisms undergo and accumulates mutation, undergoes selective pressures that resulted in divergent evolution (aka branching evolution that results in many noval species forming) after millions of years.
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.
There are
39
chromosomes in their haploid cells.
Explanation:
During meiosis I, the
78
chromosomes in a diploid cell line up at the equator of the cell. Note that the chromosomes have already replicated.
The position of the diver is described as "below a certain point"; therefore, the reference point must be above the diver. For a diver in the middle of his dive, the bottom of the pool, the other swimmers and the far side of the swimming pool are likely to be below the diver, or at level with the diver at most. Out of the options, the only point of reference that is likely to be above the diver is B. the diving board.
There you go! I hope it helped you :)
