Summary
Read the full abstract on PubMed
Political upheaval in Nicaragua leaves scientists under siege
Contact us if these videos are not relevant.
Contact us if these videos are not relevant.
Contact us if these videos are not relevant.
Contact us if these videos are not relevant.
Related Concept Videos
9.7K
The nature of leaving groups strongly influences the outcome of a nucleophilic substitution reaction.
In general, in a nucleophilic substitution reaction, a nucleophile displaces a functional group, called the leaving group, from the substrate to give a substituted product. A leaving group departs the substrate molecule through heterolytic cleavage, taking the pair of electrons with it to become a relatively stable weak base in the form of an anion or a neutral molecule.
In a...
64.4K
The primary organs of vascular plants are roots, stems, and leaves, but these structures can be highly variable, adapted for the specific needs and environment of different plant species.
Roots
While roots are most often found underground, this is not universally the case. Aerial roots are any roots that emerge aboveground. Epiphytic plants, such as orchids, can live their entire lives without touching soil. Other types of aerial roots, such as those of the strangler fig or banyan, germinate...
13.8K
Behavior is a product of both the situation (e.g., cultural influences, social roles, and the presence of bystanders) and of the person (e.g., personality characteristics). Subfields of psychology tend to focus on one influence or behavior over others. Situationism is the view that our behavior and actions are determined by our immediate environment and surroundings. In contrast, dispositionism holds that our behavior is determined by internal factors (Heider, 1958).
21.8K
Crop cultivation has a long history in human civilization, with records showing the cultivation of cereal plants beginning at around 8000 BC. This early plant breeding was developed primarily to provide a steady supply of food.
As humans' understanding of genetics advanced, improved crop varieties could be achieved more quickly. Artificial selection could be more directed, and crop varieties enhanced for favorable traits more quickly to produce better, more robust, or more palatable...
49.5K
Plants grow throughout their lives; this is called indeterminate growth, and it distinguishes plants from most animals. Although certain parts of plants stop growing (e.g., leaves and flowers), others grow continuously—like roots and stems.
Indeterminate growth in plants is enabled by meristems, tissues containing undifferentiated cells—called meristematic cells. When meristematic cells divide, some daughter cells remain in the meristem, ensuring a steady supply of undifferentiated...
265.4K
The scientific method is a detailed, empirical problem-solving process used by biologists and other scientists. This iterative approach involves formulating a question based on observation, developing a testable potential explanation for the observation (called a hypothesis), making and testing predictions based on the hypothesis, and using the findings to create new hypotheses and predictions.
Generally, predictions are tested using carefully-designed experiments. Based on the outcome of these...