The action is Fixed Action Pattern. It is a highly typecasted sequence of behaviors that, once begun, is usually carried to completion. It is triggered by a sign stimulus. The egg outside the nest is the stimulus.b <span>It is performed virtually the same by all regardless of environmental conditions. </span> Even if the egg is removed or slips away, she completes the behavior by returning an "imaginary" egg to the nest.
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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).
An embolus <span>occurs when a clot breaks free from an artery wall and travels through the circulatory system until it lodges in a small artery and suddenly shuts off blood flow to the tissues.</span>
The answer is B i answered this already