<span>The models have their own purpose, which is to gain a better understanding of the world. Therefore the statement is true.
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Mammalian fertilization comprises sperm migration through the female reproductive tract, biochemical and morphological changes to sperm, and sperm-egg interaction in the oviduct. Recent gene knockout approaches in mice have revealed that many factors previously considered important for fertilization are largely dispensable, or if they are essential, they have an unexpected function. These results indicate that what has been observed in in vitro fertilization (IVF) differs significantly from what occurs during “physiological” fertilization. This Review focuses on the advantages of studying fertilization using gene-manipulated animals and highlights an emerging molecular mechanism of mammalian fertilization.
Answer: B
Explanation: Most mammals have only one pair of sex chromosomes in each cell. Males have only one Y chromosome and one X chromosome, while females have two X chromosomes. In Mammals, the Y chromosome contains a gene, SRY, which triggers embryonic development in a male.
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