Chapter 16

Morphogenesis occurs through the multistep process of (a) differentiation (b) determination (c) pattern formation (d) totipotency (e) selection

The cloning experiments carried out on frogs demonstrated that (a) all differentiated frog cells are totipotent (b) some differentiated frog cells are totipotent (c) all nuclei from differentiated frog cells are totipotent (d) some nuclei from differentiated frog cells are totipotent (e) the mechanism of cell differentiation always requires the loss of certain genes

Drosophila is a particularly good model for developmental studies because (a) a large number of developmental mutants are available (b) it has a fixed number of somatic cells in the adult (c) its embryos are transparent (d) it is a vertebrate (e) all of the preceding

The anterior-posterior axis of a Drosophila embryo is first established by certain (a) homeotic genes (b) maternal effect genes (c) segmentation genes (d) chronogenes (e) pair-rule genes

You discover a new Drosophila mutant in which mouthparts appear where the antennae are normally found. You predict that the mutated gene is most likely a (a) homeotic gene (b) gap gene (c) pairrule gene (d) maternal effect gene e) segment polarity gene

Most segmentation genes code for (a) transfer RNAs (b) enzymes (c) transcription factors (d) histones (e) transport proteins

The developmental pattern of \(C\). elegans is said to be mosaic because (a) development is controlled by gradients of morphogens (b) part of the embryo fails to develop if a founder cell is destroyed (c) some individuals are self- fertilizing hermaphrodites (d) all development is controlled by maternal effect genes (e) apoptosis never occurs

Which of the following illustrates the regulative nature of early mouse development? (a) the mouse embryo is free-living prior to implantation in the uterus (b) it is possible to produce a transgenic mouse \((\mathrm{c})\) it is possible to produce a mouse in which a specific gene has been knocked out (d) genes related to Drosophila homeotic genes have been identified in mice (e) a chimeric mouse can be produced by fusing two mouse embryos

When the human gene that codes for insulin is introduced into fertilized mouse eggs that are subsequently allowed to develop, the insulin gene is correctly expressed in the mouse's pancreatic cells. This indicates that (a) the gene that codes for insulin is analogous to the homeotic genes of Drosophila (b) the signals for tissue-specific gene expression are highly conserved through evolution (c) like humans, the mouse has polytene chromosomes (d) unlike the rigid developmental pattern of \(C\). elegans, the development of mice and humans is highly regulative (e) genomic rearrangements have occurred in the mouse embryo

Arabidopsis is useful as a model organism for the study of plant development because (a) it is of great economic importance (b) it has large polytene chromosomes (c) many developmental mutants have been isolated (d) it contains a large amount of DNA per cell (e) it has a rigid developmental pattern

According to the ABC model of floral organ development in Arabidopsis, the A gene is needed to specify sepals, the A and B genes to specify petals, the \(\mathrm{B}\) and \(\mathrm{C}\) genes to specify stamens, and the C gene to specify the pistil. If a mutation occurs in one of the B genes, rendering it inactive, the resulting flowers will consist of (a) sepals, petals, stamens, and pistils, (b) sepals, stamens, and pistils (c) petals, stamens, and pistils (d) sepals and pistils (e) petals and stamens

Pluripotent stem cells (a) lose genetic material during development (b) give rise to many, but not all, types of cells in an organism (c) organize into recognizable structures through pattern formation (d) cannot grow in tissue culture (e) have been used to clone a sheep and several other mammals

The genetic material for Dolly, the first cloned sheep, was a nucleus from (a) an early sheep embryo (b) cultured cancer cells (c) intestinal epithelial cells (d) a mouse-sheep chimera (e) a cultured mammary gland cell

Genomic rearrangement is an exception to the principle of (a) nuclear equivalence (b) pattern formation (c) morphogenesis (d) differential gene expression (e) mosaic development

Which of the following statements about cancer is false? (a) Oncogenes arise from mutations in proto-oncogenes. (b) Tumor suppressor genes normally interact with growth-inhibiting factors to block cell division (c) More than 100 oncogenes and 15 tumor suppressor genes have been identified (d) Oncogenes were first discovered in mouse models for cancer (e) The development of cancer is usually a multistep process involving both oncogenes and mutated tumor suppressor genes

Proto-oncogenes code for (a) morphogens (b) antibodies for immune responses (c) growth factor receptors and other components of the growth control cascade (d) enzymes such as reverse transcriptase (e) proteins such as chorion protein