CHAPTER 3 Forming a New Life: Summary and Key Terms

Question 1

the union of an ovum and a sperm

Answer 1

Fertilization

Question 2

Multiple births can occur either by the fertilization of ___ ___ (or one ovum that has split) or by the splitting of ___ _______ _____.

Answer 2

two ova ; one fertilized ovum

Multiple births can occur either by the fertilization of two ova (or one ovum that has split) or by the splitting of one fertilized ovum.

Higher multiple births result from either one of these processes or a combination of the two.

Question 3

They have different genetic makeups and may be of different sexes

Answer 3

Dizygotic (fraternal) twins

Question 4

They typically have much the same genetic makeup, they may differ in temperament or other respects

Answer 4

monozygotic (identical) twins

Question 5

Fertilization results in the formation of a one-celled ______, which then duplicates itself by cell division.

Answer 5

zygote

Question 6

The basic functional units of heredity are the genes, which are made of?

Answer 6

deoxyribonucleic acid (DNA)

Question 7

DNA carries the _________________ that governs the development of cell functions.

Answer 7

biochemical instructions, or genetic code

Question 8

Each gene is located by
function in a definite position on a particular \_\_\_\_\_\_\_\_\_.

Answer 8

chromosome

Question 9

The complete sequence of genes in the human body is called?

Answer 9

the human genome

Question 10

At conception, each normal human being receives

__ chromosomes from the mother and __ from the father.

Answer 10

23

These form 23 pairs of chromosomes

Question 11

22 pairs of ________ band 1 pair of ___ ________

Answer 11

autosomes ; sex chromosomes

22 pairs of autosomes and 1 pair of sex chromosomes

Question 12

XX

Answer 12

Female

Question 13

XY

Answer 13

Male

Question 14

The simplest patterns of genetic transmission

Answer 14

dominant and recessive inheritance

Question 15

When a pair of alleles are the same, a person is ___________ for the trait

Answer 15

same pair of alleles = homozygous

Question 16

When a pair of alleles are different, a person is ___________ for the trait

Answer 16

different pair of alleles = eterozygous

Question 17

Most normal human characteristics are the result of?

Answer 17

polygenic or multifactorial transmission

Question 18

For most monozygotic twins, each child inherits a unique ________.

Answer 18

genotype

Question 19

It explains why a person’s phenotype does not always express the underlying genotype.

Answer 19

Dominant inheritance and multifactorial transmission

Question 20

The _______ _______ controls the functions of particular genes; it can be affected by environmental factors.

Answer 20

epigenetic framework

Question 21

Birth defects and diseases may result from?

Answer 21

simple dominant, recessive, or sex-linked inheritance, from mutations, or from genome imprinting

Question 22

It can cause birth defects.

Answer 22

Chromosomal abnormalities

Question 23

Through this, prospective parents can receive information about the mathematical odds of bearing children with certain defects.

Answer 23

genetic counseling

Question 24

It involves risks as well as benefits.

Answer 24

Genetic testing

Question 25

Research in ______ _______ is based on the assumption that the relative influences of heredity and environment within a population can be measured statistically.

Answer 25

behavioral genetics

If heredity is an important influence on a trait, genetically closer persons will be more similar in that trait.

Question 26

Family studies, adoption studies, and studies of twins enable researchers to measure the _______ of specific traits.

Answer 26

heritability

Question 27

These concepts describe ways in which

heredity and environment work together.

Answer 27

reaction range, canalization, genotype environment interaction, genotype environment correlation (or covariance), and niche-picking

Question 28

Siblings tend to be more different than alike in intelligence and personality. According to some behavioral geneticists,
heredity accounts for most of the similarity, and _______ ________ _____ account for most of the difference.

Answer 28

nonshared environmental effects

Question 29

The aspects of personality that are influenced by both heredity and environment.

Answer 29

Obesity, longevity, intelligence, temperament, and other aspects of personality

Question 30

a highly heritable neurological disorder that also is environmentally influenced

Answer 30

Schizophrenia

Question 31

occurs in three stages of gestation

Answer 31

Prenatal development

Question 32

the three stages of gestation

Answer 32

the germinal, embryonic, and fetal stages

Question 33

Severely defective embryos often are __________ ______ during the first trimester of pregnancy.

Answer 33

spontaneously aborted / spontaneous abortion

Question 34

As fetuses grow, they move ____, but ____ vigorously.

Answer 34

less ; more

As fetuses grow, they move less, but more vigorously.

Question 35

Swallowing ______ ____, which contains substances from the mother’s body, stimulates taste and smell.

Answer 35

amniotic fluid

Fetuses seem able to hear, exercise sensory discrimination, learn, and remember.

Question 36

The developing organism can be greatly affected by its?

Answer 36

prenatal environment

Question 37

The likelihood of a birth defect may depend on the timing and intensity of an ?

Answer 37

environmental event and its interaction with genetic factors

Question 38

Important environmental influences involving the mother include?

Answer 38

nutrition, smoking, intake of alcohol or other drugs, transmission of maternal illnesses or infections, maternal stress, anxiety, or depression, maternal age and physical activity, and external environmental hazards, such as chemicals and radiation

Question 39

It also may affect the father’s sperm.

Answer 39

External influences