Which of the following statements about pattern formation are true? (4)
1 Cells receive molecular signals that communicate their position in relation to other cells.
2 Homeotic genes code for transcription factors that control the development of segment-specific body parts.
3 The process of pattern formation involves segmentation of the body but does not involve the development of segment-specific body parts.
4 Homeotic genes establish major body axes.
5 Pattern formation begins in adult animals.
6 Positional information controls pattern formation.
7 Differential gene expression affects the developmental process in animals