Chapter 2: Genetics, prenatal development, and birth

Question 1

zygote

Answer 1

the new cell formed by the process of fertilization

Question 2

genes

Answer 2

the basic unit of genetic information

Question 3

DNA molecules

Answer 3

the substance that genes are composed of that determines the nature of every cell in the body and how it will function

Question 4

chromosomes

Answer 4

rod-shaped portions of DNA that are organized in 23 pairs

Question 5

monozygotic twins

Answer 5

twins who are gentically identical

Question 6

dizygotic twins

Answer 6

twins who are produced when two separate ova are fertilized by two separate sperm at roughly the same time

Question 7

dominant trait

Answer 7

the one trait that is expressed when two competing traits are present

Question 8

recessive trait

Answer 8

a trait within an organism that is present but is not expressed

Question 9

genotype

Answer 9

the underlying combination of genetic material present (but not outwardly visible in an organism)

Question 10

phenotype

Answer 10

an observable trait; the trait that actually is seen

Question 11

homozygous

Answer 11

inheriting from parents similar genes for a given trait

Question 12

heterozygous

Answer 12

inheriting from parents different forms of a gene for a given trait

Question 13

polygenetic inheritance

Answer 13

inheritance in which a combination of multiple gene pairs is responsible for the productive of a particular trait

Question 14

X-linked genes

Answer 14

genes that are considered recessive and located only on the X chromosomes

Question 15

behavioral genetics

Answer 15

the study of the effects of heredity on behavior

Question 16

down syndrome

Answer 16

a disorder produced by the presence of an extra chromosome on the 21st pair; once referred to as mongolism

Question 17

fragile X syndrome

Answer 17

a disorder produced by injury to a gene on the X chromosome, producing mild to moderate mental retardation

Question 18

sickle-cell anemia

Answer 18

a blood disorder that gets its name from the shape of the red blood cells in those who have it

Question 19

Tay-Sachs disease

Answer 19

a disorder that produces blindness and muscles degeneration prior to death; there is no treatment

Question 20

Klinefelter’s syndrome

Answer 20

a disorder resulting from the presence of an extra X chromosome that produces underdeveloped genitals, extreme height, and enlarged breasts

Question 21

genetic counseling

Answer 21

the discipline that focuses on helping people deal with issues relating to inherited disorders

Question 22

ultrasound sonography

Answer 22

a process in which high-frequency sound waves scan the mother’s womb to produce and image of the unborn baby, whose size and shape can then be assessed

Question 23

chronic villus sampling (CVS)

Answer 23

a test used to find genetic defects that involves taking samples of hairlike material that surrounds the embryo

Question 24

amniocentesis

Answer 24

the process of identifying genetic defects by examining a small sample of fetal cells drawn by a needle inserted into the amniotic fluid surrounding the unborn fetus

Question 25

temperament

Answer 25

patterns of arousal and emotionality that represent consistent and enduring characteristics in an individual

Question 26

multifactorial transmission

Answer 26

the determination of traits by a combination of both genetic and environmental factors in which a genotype provides a range within which a phenotype may be expressed

Question 27

fertilization

Answer 27

the process by which a sperm and an ovum-the male and female gametes, respectively- join to form a single new cell

Question 28

germinal stage

Answer 28

the first- and shortest- stage of the prenatal period, which takes place during the first two weeks following conception

Question 29

placenta

Answer 29

a conduit between the mother and fetus, providing nourishment and oxygen via the umbilical cord

Question 30

embryonic stage

Answer 30

the period from two to eight weeks following fertilization during which significant growth occurs in the major organs and body systems

Question 31

fetal stage

Answer 31

the stage that begins at about eight weeks after conception and continues until birth

Question 32

fetus

Answer 32

a developing child, from eight weeks after conception until birth

Question 33

infertility

Answer 33

the inability to conceive after 12 to 18 months of trying to become pregnant

Question 34

artificial insemination

Answer 34

a process of fertilization in which a man’s sperm is placed directly into a woman’s vagina by a physician

Question 35

in vitro fertilization (IVF)

Answer 35

a procedure in which a woman’s ova are removed from her ovaries and a man’s sperm are used to fertilize the ova in a laboratory

Question 36

teratogen

Answer 36

an environmental agent such as a drug, chemical, virus, or other factor that produces a birth defect

Question 37

fetal alcohol syndrome (FAS)

Answer 37

a disorder caused by the pregnant mother consuming substantial quantities of alcohol during pregnancy, potentially resulting in mental retardation and delayed growth in the child

Question 38

fetal alcohol effects (FAE)

Answer 38

a condition in which children display some, although not all, of the problems of fetal alcohol syndrome due to the mother’s consumption of alcohol during pregnancy

Question 39

episiotomy

Answer 39

an incision sometimes made to increase the size of the opening of the vagina to allow the baby to pass

Question 40

preterm infants

Answer 40

infants who are born prior to 38 weeks after conception (aka premature infants)

Question 41

low-birthweight infants

Answer 41

infants who weigh less than 2,500 grams (5 1/2 pounds) at birth

Question 42

small-for-gestational-age infants

Answer 42

infants who, because of delayed fetal growth, weigh 90% (or less) of the average weight of infants of the same gestational age

Question 43

postmature infants

Answer 43

infants still unborn 2 weeks after the mother’s due date

Question 44

very-low-birthweight infants

Answer 44

infants who weigh less than 1,250 grams (2.25 pounds) or, regardless of weight, have been in the womb less than 30 weeks

Question 45

cesarean delivery

Answer 45

a birth in which the baby is surgically removed from the uterus rather time known as a c-section

Question 46

fetal monitor

Answer 46

a device that measures the baby’s heartbeat during labor

Question 47

stillbirth

Answer 47

the delivery of a child who is not alive, occurring in less than 1 delivery in 100

Question 48

infant mortality

Answer 48

death within the first year of life