Sexual reproduction. Sexual reproduction is more much complex than asexual reproduction. It requires the production of sex cells, or gametes , which have half the number of chromosomes of all other cells in the organism. ... Once the gametes are made in the male and female, they must meet with one another to form offspring
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The little blue-gray critters that live under rocks and logs and roll into a ball when disturbed go by many names
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The little blue-gray critters that live under rocks and logs and roll into a ball when disturbed go by many names: roly-poly bugs, pillbugs, woodlice, tiggy-hogs, parson-pigs and their scientific name, Armadillidium vulgare. Contrary to popular belief, roly-polies are not even technically bugs. But they do play an important role in ecosystems
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3. liquid waste me directly into the ground water
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Aquifer is a layer of water which is present inside the soil at a certain depth. There are certain areas where water is added to the aquifer and maintain the water level. These aquifers were polluted if liquid waste is dumped in these aquifer recharge areas and when this water is extracted through wells so health of both plants and animals are adversely affected. So for that reason liquid waste should not be dumped in recharge areas of aquifer.
The traits an organism displays are ultimately determined by the genes it inherited from its parents, in other words by its genotype. Animals have two copies of all their chromosomes, one from each parent
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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.
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