Bio 156 - Human Biology Chapter 20

Front 1

when two copies of each gene in a diploid organism separate from each other during meiosis in germ cells resulting in each gamete containing only one copy of each gene

Back 1

segregation

Front 2

Parent generation of a cross is designated by a

Back 2

P

Front 3

Offspring of a monohybrid cross are called the

Back 3

first filial generation (F1)

Front 4

tool used by genetic counselors to predict the outcome of mating

Back 4

Punnett square

Front 5

number between 0 and 1 that expresses the likelihood of a particular event

Back 5

probablility

Front 6

simple way to determine a genotype of a nonhuman organism working backward from the phonotypes of offspring to help identify the genotype of a parent

Back 6

testcross

Front 7

monk who hypothesized in the 1850's that factors from each parent were the units of heredity

Back 7

Gregor Mendel

Front 8

rule stating that alleles for different traits are sorted into gametes independently of one another

Back 8

independent assortment

Front 9

cross in which two traits are studied

Back 9

dihybrid cross

Front 10

when there are two contrasting alleles of each gene, one dominant and on recessive (parents have different combinations of alleles)

Back 10

simple dominance

Front 11

inheritance principle of independent assortment

Back 11

either copy of a gene may end up in a particular gamete

Front 12

A gene is ____ when its instructions are carried out and the cell makes the protein

Back 12

Expressed

Front 13

expression of the gene at just a sinl=gle location on a chromosome may affect two or more traits in positive or negative ways

Back 13

pleiotropy

Front 14

when both alleles are expressed in a heterozygote

Back 14

codominance

Front 15

a gene that has three or more alleles

Back 15

multiple allele system

Front 16

the probability that someone who inherits an allele will have the phonotype associated with it

Back 16

penetrance

Front 17

condition in which someone has extra fingers or toes

Back 17

polydactyly

Front 18

condition caused by the abnormal attachment of muscles to bones of the little finger

Back 18

campodactyly

Front 19

when an allele can produce a range of phenotypes its expression is said to be _____

Back 19

variable

Front 20

result from the combined expression of several genes

Back 20

polygenic traits

Front 21

members show a range of continuous, rather than incremental differences in a trait

Back 21

continuous variatrion

Front 22

field of study aimed to pinpoint genetic variatrions that influence how individuals respond to medications

Back 22

pharmacogenetics

Front 23

Define difference between gene and allele

Back 23

genes are the specific units on a specific location on a chromosome and are passed to offspring, alleles are copies of each gene

Front 24

Define difference between dominant and recessive alleles

Back 24

an allele is dominant when its effect on a trait masks that of any recessive allele paired with it

Front 25

Define difference between homozygote and heterozygote

Back 25

a homozygote is someone who has two identical alleles for a trait and a heterozygote is someone who has 2 different alleles for a trait

Front 26

Define difference between genotype and phenotype

Back 26

genotype refers to the particular alleles an individual has, phenotype refers to the actual observable trait an individual has

Front 27

Does segregation occur during mitosis or meiosis?

Back 27

meiosis

Front 28

Distinguish between monohybrid and dihybrid crosses.

Back 28

a monohybrid cross is a cross between parents with different versions of a single trait, a dihybrid cross is a cross between parents who show different versions of two traits

Front 29

why is a testcross useful in genetic analysis?

Back 29

allows researchers to work backward from the phenotypes of offspring to determine the genotype of a parent

Front 30

Does independent assortment occur during mitosis or during meiosis?

Back 30

meiosis

Front 31

Alleles are_______
A. alternate forms of a gene
B. different molecular forms of a chromosome
C. always homozygous
D. always heterozygous

Back 31

A

Front 32

A heterozygote has _____
A. only one of the various forms of a gene.
B. a pair of identical alleles
C. a pair of contrasting alleles
D. a haploid condition in genetic terms

Back 32

C

Front 33

The observable traits of an organism are its_____
A phenotype
B. pedigree
C. genotype
D. multiple allele system

Back 33

A

Front 34

Offspring of a monohybrid cross AAxaa are _____.
A. all AA
B. all aa
C. all Aa
D 1.2 AA and 1/2 aa
E. none of the above

Back 34

C

Front 35

Second-generation offspring from a cross between two homozygotes are the ______.
A. F1 generation
B. F2 generation
C. hybrid generation
D. none of the above

Back 35

B

Front 36

Assuming complete dominance, offspring of the cross Az x Aa will show a phenotypic ratio of _____.
A. 1:2:1
B. 1:1:1
C. 9:1
D. 3:1

Back 36

D

Front 37

Which statement best fits the principle of segregation?
A. units of heredity are transmitted to offspring.
B. Two genes of a pair separate from each other during meiosis.
C. Members of a population become segretated.
D. A segregating pair of genes is sorted out into gametes independently of how gene pairs located on other chromosomes are sorted out.

Back 37

B

Front 38

Dihybrid crosses of heterozygous individuals (AaBbxAaBb) lead to F2 offspring with phenotypic ratios close to ______.
A. 1:2:1
B. 1:1:1:1
C. 3:1
D. 9:3:3:1

Back 38

D