Ch 22

What is a morphogen? a) a protein that varies in concentration along a gradient and brings about different developmental responses based on its concentration b) a protein that causes selective apoptosis of cells in the early Drosophila embryo c) a protein that controls chromatin remodeling during Drosophila embryogenesis d) an mRNA that affects the morphology (shape) of cells in an early Drosophila embryo e) an mRNA that varies in concentration along a gradient and brings about different developmental responses based on its concentration

a) a protein that varies in concentration along a gradient and brings about different developmental responses based on its concentration

Most T-cell receptors are composed of one _____ and one _____ polypeptide chain held together by _____ bonds. a) alpha; beta; disulfide b) alpha; lambda; phosphodiester c) alpha; beta; covalent d) lambda; kappa; covalent

a) alpha; beta; disulfide

Cloning in plants and animals demonstrates that a) cells retain their nuclear genome during development. b) cytoplasmic inheritance does not occur in plants. c) plant cloning is more challenging than animal cloning. d) genes are lost during development. e) cells remain totipotent during development.

a) cells retain their nuclear genome during development.

Which types of genes do not regulate development in Drosophila? a) dextro‑sinestral genes b) all of these genes regulate development in Drosophila c) segmentation genes d) homeotic genes e) egg‑polarity genes

a) dextro‑sinestral genes

Which class of segmentation gene would potentially have the most devastating effect on segment development when mutated? a) gap genes b) homeotic genes c) pair-rule genes d) egg-polarity genes

a) gap genes

Anterior-posterior development in Drosophila is regulated by a) mRNA that is deposited at one end of the egg. b) a protein that is deposited at one end of the egg. c) a protein produced by the early embryo. d) an interfering RNA that is deposited at one end of the egg. e) a chromatin-remodeling complex that is deposited at one end of the egg.

a) mRNA that is deposited at one end of the egg.

Class A genes are active in which parts of the flower? a) sepals and petals b) carpels and stamens c) sepals only d) petals only

a) sepals and petals

To function, T cell receptors must simultaneously bind a foreign antigen and a(n) _____ a) plasma cell b) MHC antigen c) antibody d) B cell

b) MHC antigen

The cascade of protein cleavage that leads to the termination of the cell is stimulated by: a) RNase b) caspases c) DNase d) procaspases

b) caspases

What would you expect in a cell with low nuclear concentrations of the Dorsal protein? a) transcription of the toll gene b) transcription of the decapentaplegic gene c) transcription of the twist gene d) development of ventral tissues

b) transcription of the decapentaplegic gene

A self-initiated program that leads to highly organized cell death is called _____. a) necrosis b) embryogenesis c) apoptosis d) autophagy

c) apoptosis

One early (and incorrect) concept of the genetic control of development was that a) cells do not start out totipotent. b) most of development was not specified in the genome. c) development consists of cells losing genes, specifying their identity with the remaining genes. d) different cell types inherit distinct genomes.

c) development consists of cells losing genes, specifying their identity with the remaining genes.

Which is an important group of homeobox genes in animals? a) box genes b) gap genes c) hox genes d) APETALA1 genes

c) hox genes

Major histocompatibility complex (MHC) proteins do not a) associate with peptide fragments. b) mediate transplant rejection. c) interact directly with B‑cell receptors. e) interact directly with T‑cell receptors.

c) interact directly with B‑cell receptors.

Which genes control the establishment of identity for each segment? a) egg-polarity genes b) morphogen genes c) segmentation genes d) homeotic genes

d) homeotic genes

Which statements about apoptosis, or programmed cell death, is incorrect? a) it is controlled by genes that can be activated in most cells b) it can be inactivated in some cancers c) it is a normal part of development d) it results in the spillage of cell contents e) it is distinct from necrosis

d) it results in the spillage of cell contents

Which of the statements are accurate about cell determination in animals? ( More than one) a) all cells become irreversibly committed to specific fates b) chromosomal rearrangements are usually involved c) it begins with the zygote (i.e., one‑cell embryo) d) regulation of transcription can be involved e) cells lose totipotency

d) regulation of transcription can be involved e) cells lose totipotency

What do egg‑polarity genes in Drosophila specify? a) the left-right axis b) the anterior-posterior axis c) the anterior-posterior, dorsal-ventral, and left-right axes d) the dorsal-ventral axis e) both the anterior-posterior and dorsal-ventral axes

e) both the anterior-posterior and dorsal-ventral axes