Chapter 2

Question 1

chromosome

Answer 1

one of 46 rodlike molecules that contain 23 pairs of DNA found in every body cell and collectively contain all of the genes

Question 2

DNA

Answer 2

deoxyribonucleic acid; the chemical structure, shaped like a twisted ladder, that contains all of the genes

Question 3

mitosis

Answer 3

the process of cell duplication in which DNA is replicated and the resulting cell is genetically identical to the original

Question 4

meiosis

Answer 4

the process by which a gamete (sperm/ova) is formed, containing one-half of the cell’s chromosomes

Question 5

zygote

Answer 5

a fertilized ovum

Question 6

dizygotic twin

Answer 6

fraternal twin; occurs when two ova are released and each are fertilized by a different sperm; the resulting offspring share 50% of their genetic material

Question 7

monozygotic twin

Answer 7

identical twin; occurs when the zygote splits apart early in development; the resulting offspring share 100% of their genetic material

Question 8

homozygous

Answer 8

refers to a chromosomal pair consisting of two identical alleles

Question 9

heterozygous

Answer 9

refers to a chromosomal pair consisting of two different alleles

Question 10

dominant-recessive inheritance

Answer 10

a form of genetic inheritance in which the phenotype reflects only the dominant allele of a heterozygous pair

Question 11

incomplete dominance

Answer 11

a genetic inheritance pattern in which both genes are expressed in the phenotype

Question 12

sickle cell trait

Answer 12

a recessive trait, more often affecting African Americans that Caucasians or Asian Americans, that causes red blood cells to become crescent or sickle shaped, resulting in difficulty distributing oxygen throughout the circulatory system

Question 13

polygenic inheritance

Answer 13

occurs when a trait is a function of the interaction of many genes, such as with height, intelligence, and temperament

Question 14

genomic imprinting

Answer 14

the instance when the expression of a gene is determined by whether it is inherited from the mother or father

Question 15

phenylketonuria (PKU)

Answer 15

a recessive disorder that prevents the body from producing an enzyme that breaks down phenylalanine (an amino acid) from proteins, that, without treatment, leads to buildup that damages the central nervous system

Question 16

fragile X syndrome

Answer 16

an example of a dominant-recessive disorder carried on the X chromosome

Question 17

down syndrome

Answer 17

also known as trisomy 21; a condition in which a third, extra chromosome appears at the 21st site; down syndrome is associated with distinctive physical characteristics accompanied by developmental disability

Question 18

mutation

Answer 18

a sudden permanent change in the structure of genes

Question 19

genotype

Answer 19

an individual’s collection of genes that contain instructions for all physical and psychological characteristics, including hair, eye color, personality, health, and behavior

Question 20

phenotype

Answer 20

the observable physical or behavioral characteristics of a person

Question 21

behavioral genetics

Answer 21

the field of study that examines how genes and environment combine to influence the diversity of human traits, abilities, and behaviors

Question 22

heritability

Answer 22

a measure of the extent to which variation of a certain trait can be traced to genes

Question 23

gene-environment interactions

Answer 23

refers to the dynamic interplay between our genes and our environment in determining our characteristics, behavior, physical, cognitive, and social development as well as health

Question 24

range of reaction

Answer 24

the concept that a genetic trait may be expressed in a wide range of phenotypes dependent on environmental opportunities and constraints

Question 25

canalization

Answer 25

the tendency for a trait that is biologically programmed to be restricted to only a few outcomes

Question 26

gene-environment correlation

Answer 26

the idea that many of an individual's traits are supported by his or her genes and environment; there are three types of correlations - active, passive, and reactive

Question 27

niche-picking

Answer 27

an active gene-environment correlation in which individuals seek out experiences and environments that complement their genetic tendencies

Question 28

epigenetic framework

Answer 28

a perspective stating that development results form reciprocal interactions between genetics and the environment such that the expression of genetic inheritance is influenced by environmental forces

Question 29

ovum

Answer 29

the female reproductive cell or egg cell

Question 30

germinal period

Answer 30

also referred to as the period of the zygote; refers to the first two weeks after conception

Question 31

cell differentiation

Answer 31

begins roughly 72 hours after fertilization when the organism consists of about 16 to 32 cells

Question 32

blastocyst

Answer 32

a thin-walled, fluid-filled sphere containing an inner mass of cells from which the embryo will develop; is implanted into the uterine wall during the germinal period

Question 33

embryo

Answer 33

prenatal organism between about 2 and 8 weeks after conception; a period of major structural development

Question 34

implantation

Answer 34

the process by which the blastocyst becomes attached to the uterine wall, completed by about 10 days after fertilization

Question 35

placenta

Answer 35

the principal organ of exchange between the mother and the developing organism, enabling the exchange of nutrients, oxygen, and wastes via the umbilical cord

Question 36

embryonic period

Answer 36

occurs about 2 to 8 weeks after conception, in which rapid structural development takes place

Question 37

neural tube

Answer 37

forms during the third week after conception and will develop into the central nervous system (brain and spinal cord)

Question 38

indifferent gonad

Answer 38

a gonad in an embryo that has not yet differentiated into testes or ovaries

Question 39

lanugo

Answer 39

a fine, down-like hair that covers the fetus's body

Question 40

vernix caseosa

Answer 40

greasy material that protects the fetal skin from abrasions, chapping, and hardening that can occur from exposure to amniotic fluid

Question 41

cesarean section

Answer 41

surgical procedure that removes the fetus from the uterus through the abdomen

Question 42

Apgar scale

Answer 42

a quick overall assessment of a baby's immediate health at birth, including appearance, pulse, grimace, activity, and respiration

Question 43

preterm

Answer 43

a birth that occurs 35 or fewer weeks after conception

Question 44

small for date

Answer 44

describes an infant who is full term but who has significantly lower weight that expected for the gestational age

Question 45

low birthweight

Answer 45

classifies infants who weigh less than 5.5 pounds at birth

Question 46

kangaroo care

Answer 46

an intervention for low-birthweight babies in which the infant is placed vertically against the parent's chest, under the shirt, providing skin-to-skin contact

Question 47

teratogen

Answer 47

an environmental factor that causes damage to prenatal development

Question 48

feteal alcohol syndrome

Answer 48

the most severe form of fetal alcohol spectrum disorder accompanying heavy prenatal exposure to alcohol, including a distinct pattern of facial characteristics, growth deficiencies, and deficits in intellectual development

Question 49

fetal alcohol spectrum disorders

Answer 49

the continuum of physical, mental, and behavioral outcomes caused by prenatal exposure to alcohol

Question 50

spina bifida

Answer 50

a neural tube that results in spinal nerves growing outside of the vertebrae, often resulting in paralysis and developmental disability

Question 51

anencephaly

Answer 51

a neural tube defect that results in the failure of all or part of the brain to develop, resulting in death prior to or shortly after birth