Answer:
Small and tube shaped, water enters the sponge through dermal pores and flows into the atrium. Choanocyte flagella create the current to expel it through a single osculum. Note that water enters the sponge through a modified cell known as a porocyte.
Explanation:
Hope this helped, Have a Wonderful Day!!
Both answers C and D are correct, however, answer D makes more sense.
Answer:
The C. elegans embryo is a powerful model system for studying the mechanics of metazoan cell division. Its primary advantage is that the architecture of the syncytial gonad makes it possible to use RNAi to generate oocytes whose cytoplasm is reproducibly (typically >95%) depleted of targeted essential gene products via a process that does not depend exclusively on intrinsic protein turnover. The depleted oocytes can then be analyzed as they attempt their first mitotic division following fertilization. Here we outline the characteristics that contribute to the usefulness of the C. elegans embryo for cell division studies. We provide a timeline for the first embryonic mitosis and highlight some of its key features. We also summarize some of the recent discoveries made using this system, particularly in the areas of nuclear envelope assembly/ dissassembly, centrosome dynamics, formation of the mitotic spindle, kinetochore assembly, chromosome segregation, and cytokinesis.
1. The C. elegans embryo as a system to study cell division
The C. elegans embryo is a powerful model system for studying the mechanics of metazoan cell division. Its primary advantage is that the syncytial gonad makes it possible to use RNA interference (RNAi) to generate oocytes whose cytoplasm is reproducibly (>95%) depleted of targeted essential gene products. Introduction of dsRNA rapidly catalyzes the destruction of the corresponding mRNA in many different systems. However, depletion of pre-existing protein is generally a slow process that depends on the half-life of the targeted protein. In contrast, in the C. elegans gonad, the protein present when the dsRNA is introduced is depleted by the continual packaging of maternal cytoplasm into oocytes (Figure 1). Since depletion relies on the rate of embryo production instead of protein half-life, the kinetics tend to be similar for different targets. By 36-48 hours after introduction of the dsRNA, newly formed oocytes are typically >95% depleted of the target protein.
Explanation:
Answer:
convergent evolution.
Explanation:
When organisms of distantly related species or groups are found in similar environmental conditions, they develop some similar features which are otherwise not present in their ancestral species. This is called convergent evolution. Convergent evolution also results in the development of similar traits in the distantly related organisms that are found in distantly located geographical regions having similar environmental conditions. Therefore, the presence of the same features in rodents and flying squirrels represent convergent evolution.
