Ch 4.1 Key Terms

Question 1

altruistic behavior

Answer 1

an action that benefits someone other than the actor

Question 2

artificial selection

Answer 2

a process of selecting plants/animals for desired traits

Question 3

chromosomes

Answer 3

strands of genes

Question 4

autosomal genes

Answer 4

all chromosomes other than X and Y

Question 5

dizygotic (“from two eggs”) twins

Answer 5

fraternal (nonidentical) twins derived from two eggs DNA. See Deoxyribonucleic acid (DNA)

Question 6

deoxyribonucleic acid (DNA)

Answer 6

double-stranded molecule that is part of the chromosomes

Question 7

epigenetics

Answer 7

a field that deals with changes in gene expression without modification of the DNA sequence

Question 8

dominant gene

Answer 8

gene that shows a strong effect in either the homozygous or heterozygous condition

Question 9

evolution

Answer 9

a change over generations in the frequencies of various genes in a population

Question 10

evolutionary psychology

Answer 10

field that deals with how behaviors evolved

Question 11

fitness

Answer 11

the spreading of genes; number of copies of one’s genes that endure in later generations

Question 12

genes

Answer 12

units of heredity that maintain their structural identity from one generation to another Genetics. See also Heritability

Question 13

group selection

Answer 13

evolutionary selection favoring a gene because of its benefits to a group

Question 14

heritability

Answer 14

estimate of the degree to which variation in a characteristic depends on genetic variations in a given population

Question 15

heterozygous

Answer 15

having two unlike genes for a given trait

Question 16

histones

Answer 16

proteins that bind DNA into a shape that resembles a string wound around a ball

Question 17

homozygous

Answer 17

having two identical genes for a given characteristic

Question 18

kin selection

Answer 18

selection for a gene that benefits the individual’s relatives

Question 19

Lamarckian evolution

Answer 19

discredited hypothesis that the use or disuse of some body part will increase or decrease its size in the next generation, known as “inheritance of acquired characteristics”

Question 20

monozygotic (“from one egg”) twins

Answer 20

twins derived from one egg

Question 21

mutation

Answer 21

a heritable change in a DNA molecule

Question 22

phenylketonuria

Answer 22

a genetic inability to metabolize the amino acid phenylalanine

Question 23

recessive gene

Answer 23

one that shows effects only in the homozygous condition

Question 24

reciprocal altruism

Answer 24

helping others who may be helpful in return

Question 25

ribonucleic acid (RNA)

Answer 25

a single-strand chemical coded by DNA

Question 26

sex-limited genes

Answer 26

genes that are present in both sexes but that exert their effects primarily in one sex because of activation by androgens or estrogens

Question 27

sex-linked genes

Answer 27

genes on either the X or the Y chromosome