The correct answer is the trophoblast forms two distinct layers.
Under usual conditions, fertilization takes place in one of the fallopian tubes, then the fertilized egg starts to produce its path towards the uterus. By about the fifth day of conception, the embryo ultimately reaches the uterus and gets the implant in the uterine lining or endometrium.
During week II of implantation, the trophoblast layer gets involved by combining with the uterine wall, and during this time the layer of trophoblast differentiates and proliferates into two different layers, that is, cytotrophoblast and syncytiotrophoblast.
Answer:
B
Explanation:
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The seven levels of classification are Kingdom, Phylum, Class, Order, Family, Genus, and Species.
A trait is a characteristic, such as color or size, that is inherited by an offspring from its parents. The genes that control a trait come in pairs, one gene from each parent. We represent these gene pairs by writing a combination of two letters. For example, if one parent contributes a gene for blue eyes (c), and other parent contributes a gene for brown eyes(C), then we write the offspring’s eye color trait as Cc. This combination, of the two genes that determine the trait, is called a genotype. If gene pair contains a dominant allele, the the offspring will show this dominant trait