Genetics Unit Test Vocabulary

Question 1

genetics

Answer 1

the science of heredity and of the mechanisms by which traits are passed from parents to offspring

Question 2

heredity

Answer 2

the passing of genetic traits from parent to offspring

Question 3

trait

Answer 3

a genetically determined characteristic

Question 4

pollination

Answer 4

the transfer of pollen from the male reproductive structures (the anthers) to the tip of a female reproductive structure (the pistil) of a flower in angiosperms or to the ovule in gymnosperms

Question 5

self-pollination

Answer 5

the transfer of pollen grains from an anther to the stigma of the same flower or to the stigma of another flower on the same plant

Question 6

cross-pollination

Answer 6

a reproductive process in which pollen from one plant is transferred to the stigma of another plant

Question 7

true-breeding

Answer 7

describes organisms or genotypes that are homozygous for a specific trait and thus always produce offspring that have the same phenotype for that trait

Question 8

P generation

Answer 8

parental generation, the first two individuals that mate in a genetic cross

Question 9

F1 generation

Answer 9

the first generation of offspring obtained from an experimental cross of two organisms

Question 10

F2 generation

Answer 10

the second generation of offspring, obtained from an experimental cross of two organisms; the offspring of the F1 generation

Question 11

dominant

Answer 11

in genetics, describes an allele that is fully expressed whenever the allele is present in an individual

Question 12

recessive

Answer 12

in genetics, describes an allele that is expressed only when no dominant allele is present in an individual

Question 13

law of segregation

Answer 13

states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete

Question 14

law of independent assortment

Answer 14

the law that states that genes separate independently of one another in meiosis

Question 15

allele

Answer 15

one of the alternative forms of a gene that governs a characteristic, such as hair color

Question 16

genotype

Answer 16

the entire genetic makeup of an organism; also the combination of genes for one or more specific traits

Question 17

phenotype

Answer 17

an organism’s appearance or other detectable characteristic that results from the organism’s genotype and the environment

Question 18

homozygous

Answer 18

describes an individual that has identical alleles for a trait on both homologous chromosomes

Question 19

heterozygous

Answer 19

describes an individual that has two different alleles for a trait

Question 20

probability

Answer 20

the likelihood that a possible future event will occur in any given instance of the event

Question 21

monohybrid cross

Answer 21

a cross between individuals that involves one pair of contrasting traits

Question 22

Punnett square

Answer 22

a graphic used to predict the results of a genetic cross

Question 23

genotypic ratio

Answer 23

the ratio of the genotypes that appear in offspring

Question 24

phenotypic ratio

Answer 24

the ratio of phenotypes produced by a cross

Question 25

test cross

Answer 25

the crossing of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype

Question 26

complete dominance

Answer 26

a relationship in which one allele is completely dominant over another

Question 27

incomplete dominance

Answer 27

a condition in which a trait in an individual is intermediate between the phenotype of the individual’s two parents because the dominant allele is unable to express itself fully

Question 28

codominance

Answer 28

a condition in which both alleles for a gene are fully expressed

Question 29

dihybrid cross

Answer 29

a cross between individuals that have different alleles for the same gene

Question 30

sex chromosome

Answer 30

one of the pair of chromosomes that determine the sex of an individual

Question 31

autosome

Answer 31

any chromosome that is not a sex chromosome

Question 32

sex-linked trait

Answer 32

a trait that is determined by a gene found on one of the sex chromosomes, such as the X chromosome or the Y chromosome in humans

Question 33

linked gene

Answer 33

one of a pair of genes that tend to be inherited together

Question 34

chromosome map

Answer 34

a diagram of gene positions on a chromosome

Question 35

map unit

Answer 35

in chromosome mapping, an increment of 1 percent in the frequency of crossing-over

Question 36

germ-cell mutation

Answer 36

mutation that occurs in an organism’s gametes

Question 37

somatic-cell mutation

Answer 37

a mutation that occurs in a body cell

Question 38

lethal mutation

Answer 38

a gene or chromosomal mutation that influences the development of an organism in such a way that the organism cannot survive

Question 39

pedigree

Answer 39

a diagram that shows the occurrence of a genetic trait in several generations of a family

Question 40

carrier

Answer 40

in biology, an individual who has one copy of a recessive autosomal allele that causes disease in the homozygous condition

Question 41

genetic disorder

Answer 41

an inherited disease or disorder that is caused by a mutation in a gene or by a chromosomal defect

Question 42

multiple alleles

Answer 42

more than two alleles (versions of the gene) for a genetic trait