Question

The preformationism hypothesis suggested that inside the egg or sperm is a tiny adult called a homunculus. It was hypothesized that the homunculus simply enlarged during development. Select the evidence that disproves the early heredity hypothesis of preformationism. - Zygotically expressed genes regulate development in a sequential manner. - A fruit fly forms from an early embryo that lacks distinct anterior and posterior regions. - Maternal-effect genes can affect embryonic development. - Genes expressed in the developing embryo interact with each other. - Maternal-effect genes do not affect embryonic development.

Answer 1

Evidence against preformationism includes the role of zygotically expressed and maternal-effect genes in regulating sequential and complex embryonic development, as well as the interaction of genes during the processes of body axes formation and organogenesis.

Step-by-step explanation:

The hypothesis of preformationism, which suggested the presence of a miniature adult or homunculus within the sperm or egg that would simply grow during development, is disproven by various pieces of evidence that emphasize the complexity and sequential nature of embryonic development. One of the key pieces of evidence against preformationism includes the zygotically expressed genes that regulate development in a sequential manner. Another important aspect is the influence of maternal-effect genes on embryonic development, which can determine the outcome of the embryo before zygotic genes start being expressed.

The discovery that genes expressed in the developing embryo interact with each other in a highly intricate and organized manner also refutes preformationism. The fact that specific genes are activated at certain times during development and can cause cells to differentiate into various types translates into complex development far beyond the concept of a preformed homunculus. Furthermore, experiments with model organisms such as the fruit fly (Drosophila) have shown that embryonic development involves the formation of body axes and organogenesis, guided by the expression of certain genes, rather than the expansion of a preformed structure.

Answer 2

The evidence that disproves the early heredity hypothesis of preformationism includes zygotically expressed genes, fruit fly development, and maternal-effect genes.

Step-by-step explanation:

The evidence that disproves the early heredity hypothesis of preformationism includes:

1. Zygotically expressed genes regulate development in a sequential manner. This means that genes are activated at specific times during development, which contradicts the idea of a fully formed adult in the egg or sperm.
2. A fruit fly forms from an early embryo that lacks distinct anterior and posterior regions. This shows that development occurs gradually and is not predetermined by a preformed adult.
3. Maternal-effect genes can affect embryonic development. These genes are expressed in the mother and influence the development of the embryo, which suggests that development is not solely determined by the genes within the egg or sperm.