AP Bio Chapter 21 Key Terms

Question 1

apical meristem

Answer 1

Embryonic plant tissue in the tips of roots and in the buds of shoots that supplies cells for the plant to grow in length.

Question 2

apoptosis

Answer 2

The changes that occur within a cell as it undergoes programmed cell death, which is brought about by signals that trigger the activation of a cascade of suicide proteins in the cell destined to die.

Question 3

cell differentiation

Answer 3

The structural and functional divergence of cells as they become specialized during a multicellular organism’s development; dependent on the control of gene expression.

Question 4

cell lineage

Answer 4

The ancestry of a cell.

Question 5

chimera

Answer 5

An ogranism with a mixture of genetically different cells.

Question 6

clone

Answer 6

(1) A lineage of genetically identical individuals or cells. (2) In popular usage, a single individual organism that is genetically identical to another individual. (3) As a verb, to make one or more genetic replicas of an individual or cell. See also gene cloning.

Question 7

cloning

Answer 7

Using a somatic cell from a multicellular organism to make one or more genetically identical individuals.

Question 8

cytoplasmic determinants

Answer 8

The maternal substances in the egg that influence the course of early development by regulating the expression of genes that affect the developmental fate of cells.

Question 9

determination

Answer 9

The progressive restriction of developmental potential, causing the possible fate of each cell to become more limited as the embryo develops.

Question 10

egg-polarity gene

Answer 10

Another name for a maternal effect gene, a gene that helps control the orientation (polarity) of the egg.

Question 11

embryonic lethal

Answer 11

A mutation with a phenotype leading to death at the embryo or larval stage.

Question 12

homeobox

Answer 12

A 180-nucleotide sequence within homeotic genes and some other developmental genes that is widely conserved in animals. Related sequences occur in plants and prokaryotes.

Question 13

homeotic gene

Answer 13

Any of the genes that control the overall body plan of animals and plants by controlling the developmental fate of groups of cells.

Question 14

induction

Answer 14

The ability of one group of embryonic cells to influence the development of another.

Question 15

maternal effect gene

Answer 15

A gene that, when mutant in the mother, results in a mutant phenotype in the offspring, regardless of the genotype.

Question 16

model organism

Answer 16

An organism chosen to study broad biological principles.

Question 17

morphogen

Answer 17

A substance, such as Bicoid protein, that provides positional information in the form of a concentration gradient along an embryonic axis.

Question 18

morphogenesis

Answer 18

The development of body shape and organization.

Question 19

organ identity genes

Answer 19

Plant homeotic genes that use positional information to determine which emerging leaves develop into which types of floral organs.

Question 20

pattern formation

Answer 20

The ordering of cells into specific three-dimensional structures, an essential part of shaping an organism and its individual parts during development.

Question 21

pluripotent

Answer 21

Describing a stem cell, from an embryo or adult organism, that can give rise to multiple but not all differentiated cell types.

Question 22

positional information

Answer 22

Signals to which genes regulating development respond, indicating a cell’s location relative to other cells in an embryonic structure.

Question 23

segmentation gene

Answer 23

A gene of the embryo that directs the actual formation of segments after the embryo’s axes are defined.

Question 24

stem cell

Answer 24

Any relatively unspecialized cell that can divide during a single division into one identical daughter cell and one more specialized daughter cell, which can undergo further differentiation.

Question 25

totipotent

Answer 25

Describing a cell that can give rise to all parts of an organism.