Biology Vocab Unit 7

Question 1

Homologous chromosomes

Answer 1

chromosomes that have the same length, appearance, and copies of genes, although the alleles may differ

Question 2

autosomes

Answer 2

chromosome that contains genes for characteristics not directly related to the sex of the organism

Question 3

sex chromosome

Answer 3

chromosome that directly controls the development of sexual characteristics

Question 4

gamete

Answer 4

sex cell; an egg or a sperm cell

Question 5

meiosis

Answer 5

form of nuclear division that divides a diploid cell into haploid cells; important in forming gametes for sexual reproduction

Question 6

chromatid

Answer 6

one half of a duplicated chromosome

Question 7

genetic variation

Answer 7

differences in physical traits of an individual from the group to which it belongs

Question 8

independent assortment

Answer 8

Mendel’s second law, stating that allele pairs separate from one another during gamete formation

Question 9

crossing over

Answer 9

exchange of chromosome segments between homologous chromosomes during meiosis

Question 10

trait

Answer 10

characteristic that is inherited

Question 11

genetic cross

Answer 11

mating of two organisms

Question 12

gene

Answer 12

specific region of DNA that codes for a particular protein

Question 13

allele

Answer 13

any of the alternative forms of a gene that occurs at a specific place on a chromosome

Question 14

homozygous

Answer 14

characteristic of having two of the same alleles at the same locus of sister chromatids

Question 15

heterozygous

Answer 15

characteristic of having two different alleles that appear at the same locus of sister chromatids

Question 16

genotype

Answer 16

collection of all of an organism’s genetic information that codes for traits

Question 17

Phenotype

Answer 17

collection of all of an organism’s physical characteristics

Question 18

dominant

Answer 18

allele that is expressed when two different alleles are present in an organism’s genotype

Question 19

recessive

Answer 19

allele that is not expressed unless two copies are present in an organism’s genotype

Question 20

incomplete dominance

Answer 20

heterozygous phenotype that is a blend of the two homozygous phenotypes

Question 21

codominance

Answer 21

heterozygous genotype that equally expresses the traits from both alleles

Question 22

polygenic trait

Answer 22

trait that is produced by two or more genes

Question 23

epistasis

Answer 23

the interaction of genes that are not alleles, in particular the suppression of the effect of one such gene by another

Question 24

Punnett square

Answer 24

model for predicting all possible genotypes resulting from a cross, or mating

Question 25

probability

Answer 25

likelihood that a particular event will happen

Question 26

monohybrid cross

Answer 26

cross, or mating, between organisms that involves only one pair of contrasting traits

Question 27

testcross

Answer 27

cross between an organism with an unknown genotype and an organism with a recessive phenotype

Question 28

dihybrid cross

Answer 28

cross, or mating, between organisms involving two pairs of contrasting traits

Question 29

sex-linked gene

Answer 29

gene that is located on a sex chromosome