<span>Sedimentation - uses solutions of lower specific gravity than the organisms, which concentrated in the sediment. This technique is recommended for general diagnostic laboratories because it is easy to perform and less prone to technical errors.
Flotation - this technique uses solutions of higher specific gravity than the parasitic organisms so the organisms float and the debris sinks producing a cleaner material while the disadvantage is that walls of cysts and eggs collapse that may blocking its identification.<span>
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Answer:
Molecular genetic approaches to the study of plant metabolism can be traced back to the isolation of the first cDNA encoding a plant enzyme (Bedbrook et al., 1980), the use of the Agrobacterium Ti plasmid to introduce foreign DNA into plant cells (Hernalsteens et al., 1980) and the establishment of routine plant transformation systems (Bevan, 1984; Horsch et al., 1985). It became possible to express foreign genes in plants and potentially to overexpress plant genes using cDNAs linked to strong promoters, with the aim of modifying metabolism. However, the discovery of the antisense phenomenon of plant gene silencing (van der Krol et al., 1988; Smith et al., 1988), and subsequently co‐suppression (Napoli et al., 1990; van der Krol et al., 1990), provided the most powerful and widely‐used methods for investigating the roles of specific enzymes in metabolism and plant growth. The antisense or co‐supression of gene expression, collectively known as post‐transcriptional gene silencing (PTGS), has been particularly versatile and powerful in studies of plant metabolism. With such molecular tools in place, plant metabolism became accessible to investigation and manipulation through genetic modification and dramatic progress was made in subsequent years (Stitt and Sonnewald, 1995; Herbers and Sonnewald, 1996), particularly in studies of solanaceous species (Frommer and Sonnewald, 1995).
Regulation of opening and closing of stomata
<u>Question</u>:
Which value is being measured in the columns labeled "Fraction remaining” and "Percentage remaining”?
-
years of decay
- quantity of energy
- number of stable atoms
- amount of material that has not decayed
<u>Answer</u>:
"Amount of material that has not decayed" being measured in the columns labelled "Fraction remaining” and "Percentage remaining”
<u>Explanation</u>:
The table shown below having explains about the half life , the amount of sample in both fraction and percentage. The first column named half life elapsed tells us the the number of half life that that is completed. Half life is the time taken for an element to reduce or decay into half of its initial amount.
The fraction remaining column gives the amount of sample that is left behind after the half life particular number of half life has completed. similarly the percentage remaining column gives the amount of sample in percentage. For example, the 5th row tells us that after 4 half life is over 
of the sample remained. In percentage it is 6.25%
