Transgenic plants Essay Example | Topics and Well Written Essays - 750 words

Transgenic plants - Essay Example ique was to create disease resistant specie by making forced hybridization between distinct plant species through in-vitro technique such as protoplast fission or embryo rescue (Wikipedia, 2009). In the process of transgenic plants development, DNA plays the most vital role. The genetic information remains encoded in DNA through certain specific sequence of four bases (adenine, cytosine, guanine, and thymine). The whole process can be well expressed with the help of the diagram given below: Hence, from the diagram it is clear that at first the DNA gets converted to mRNA through transcription and then by the process of translation it gets converted into protein. This protein acts as a bio-catalyst and can accelerate other biochemical reactions or it can turn to storage unit of a cell and contribute in formation of a trait of the plant. As discussed above, transgenic plant is the product of DNA transfer and hence, there are two main methods of transforming plants cell and tissues. It can be performed either by â€Å"Gene Gun† method, which is more common in monocot species, or through â€Å"Agrobacterium† method, that has been successfully used in the dicot species. (Department of Soil and Crop Sciences, 2004). The traditional process of transgenic plant development is still controversial as evidences indicate that this technique was in use from many years for developing different variety of food crop which were resistant to many devastating diseases. In 1930, a variety of wheat called â€Å"Hope† was developed by E. S. McFadden which was resistant to â€Å"rusts†. It was found that natural movement of genes commonly occurs due to transposons and retrotransposons (mobile genetic elements). They assist in natural translocation of the genes in the genome and thus, lead to the formation of a new species. This is a natural process for formation of transgenic plants and these natural mobile genetic elements have been used by many researchers in their laboratory work

QUANTITATIVE RESEARCH METHODS-SEEN EXAM Coursework

QUANTITATIVE RESEARCH METHODS-SEEN EXAM - Coursework Example 2. By using or combining several time series of cross section observations, panel data provide â€Å"more informative data, more variability, less collinearity among variables, more degrees of freedom and efficiency† as per Baltagi’s discussion (1995, p. 3-6). 3. Panel data are able to study better the dynamics of change because the panel data technique is able to cover repeated cross section of observation across time. Thus, panel data is believed to more appropriate than either of the two methods (cross section and time series analysis) in the study of situations like successive waves of minimum wage increases across localities and local minimum wages and over time 4. Panel data can detect and measure effects better than what purely time series and cross-section data can do. 5. Panel data are able to study complicated behavioural models like economies of scale and technical change---better than what pure time series and pure cross-section analysis can do. For example, panel data can study the interaction of the variables involved over time, which cannot be done by pure time series data. 6. By covering more units over time, panel data can minimize the biases that may result as data are aggregated. In 1995, Baltagi pointed out that time series and cross-section studies were not controlling for heterogeneity and run the risk of obtaining biased results (p. 3). For example, Baltagi (1995, p. 3) cited for example that consumption of cigarettes is often modelled as a function of lagged consumption, price, and income but the specification of the same function can vary across countries, state, and time. Baltagi 1995, p. 4) added that panel data are able to control for location specific and time invariant variables while a time-series study or a cross-section study cannot at that time. As panel data can cover heterogeneity, Baltagi (1995, p. 4), not accounting for country heterogeneity can cause serious specification error. In addition, Baltagi (1995, p. 4) said that panel data are able to study the dynamics of adjustment. Meanwhile, Verbeek (2008, p. 655) said that the main advantage of panel data over either time series or cross-section analysis is that through panel data, economists are able to specify more complicated and realistic models than a single time series or cross-section data can do. (b) Explain the intuition behind the fixed effect model (FEM) and describe the least square dummy variable (LSDV) and the time demeaned approaches to estimating a FEM. [30 Marks] Verbeek (2008, p. 359) defined the fixed effects model as simply a regression model in which the intercept terms vary over the individual units. Gujarati (2004, p. 642) pointed out that the main intuition behind the fixed effect model or FEM is that although the intercept may differ across individual elements, each specific intercept does not change over time or is time invariant. The methods for estimating the fixed effects model (FEM) are the least square dummy variable (LSDV) and the time demeaned approaches towards estimating the FEM. In the LSDV method, the main instruments for capturing the fixed effects are dummy variables. The time demeaned variable approach to FEM modelling, reconstruct the basic model yit = ? + ?xit + uit as departures of a variable from its mean over time or yit - i ?(xit - i ) + ( uit - )i) where the values with bars denote the time mean of the said variable (Brooks