1. Organisms tend to resemble each other during the embryonic stage of development. This is because during this stage, all vertebrate embryos have certain common structures or features that are shared by their ancestors. These structures are known as homologous structures.
For example, in the given image, the embryos of different vertebrates have similar structures such as a notochord, pharyngeal pouches, and a dorsal nerve cord. The notochord is a long, rod-like structure that provides support to the developing embryo, and eventually gives rise to the backbone in vertebrates. The pharyngeal pouches are a series of paired pouches that form in the pharyngeal region of the developing embryo. These pouches give rise to various structures such as gills, ear bones, and parts of the throat and neck. The dorsal nerve cord is a hollow tube that runs along the back of the developing embryo, and eventually gives rise to the spinal cord and brain.
2. These structures are similar in different vertebrate embryos because they have a common ancestry and evolved from a common ancestor. However, as the embryos continue to develop, they begin to acquire unique features and characteristics that distinguish them from one another.
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Answer:
1. Organisms tend to resemble each other during the embryonic stage of development. This is because during this stage, all vertebrate embryos have certain common structures or features that are shared by their ancestors. These structures are known as homologous structures.
For example, in the given image, the embryos of different vertebrates have similar structures such as a notochord, pharyngeal pouches, and a dorsal nerve cord. The notochord is a long, rod-like structure that provides support to the developing embryo, and eventually gives rise to the backbone in vertebrates. The pharyngeal pouches are a series of paired pouches that form in the pharyngeal region of the developing embryo. These pouches give rise to various structures such as gills, ear bones, and parts of the throat and neck. The dorsal nerve cord is a hollow tube that runs along the back of the developing embryo, and eventually gives rise to the spinal cord and brain.
2. These structures are similar in different vertebrate embryos because they have a common ancestry and evolved from a common ancestor. However, as the embryos continue to develop, they begin to acquire unique features and characteristics that distinguish them from one another.