Below is a microarray analysis of gene expression among developmentally significant catego...

Below is a microarray analysis of gene expression among developmentally significant categories (tissues and organs) in the model organism Arabidopsis thaliana (Schmid et al., 2005). Relative gene activities are presented on the ordinate, while several tissue types are presented on the abscissa.

(a) Are gene-expression patterns reasonably compatible with expectations?

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(b) The general developmental program of plants contrasts with that of animals in that plants develop continuously, with new organs being added throughout their life span. How much does such a developmental program help explain the expression of photosynthetic genes in flowers and seeds?

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(c) Typically, single or small numbers of genes are studied to determine their impact on development. Here, genome-wide analysis reveals output from general classes containing many genes. How might such a global approach further our understanding of the role of genes in development?