chapter 14 Mendel and the gene idea

Question 1

What scientific approach did Mendel use to identify laws of inheritance?

Answer 1

Mendel cross bred peas and tracked characteristics in two distinct forms

Question 2

What are true-breeding varieties?

Answer 2

Varieties that produce offspring of the same variety when self-pollinated

Question 3

What is hybridisation in Mendel’s experiments?

Answer 3

Mating two contrasting true-breeding varieties

Question 4

What does the ‘P’ in P generation stand for?

Answer 4

Parental generation

Question 5

What does the ‘F1’ generation refer to?

Answer 5

Hybrid offspring of the P generation

Question 6

What is the F2 generation?

Answer 6

Offspring resulting from self or cross-pollinating F1 hybrids

Question 7

What is the law of segregation?

Answer 7

The two alleles separate during gamete formation

Question 8

What was the ratio of purple to white flowers in Mendel’s F2 generation?

Answer 8

3 to 1

Question 9

What did Mendel call the purple flower color?

Answer 9

Dominant trait

Question 10

What did Mendel call the white flower color?

Answer 10

Recessive trait

Question 11

What is a ‘heritable factor’ according to Mendel?

Answer 11

What we now call a gene

Question 12

What are alleles?

Answer 12

Alternative versions of a gene

Question 13

What does the law of dominance state?

Answer 13

The dominant allele determines the organism’s appearance

Question 14

What is a Punnett square used for?

Answer 14

To show possible combinations resulting from sperm and egg

Question 15

Define homozygous.

Answer 15

Having 2 identical alleles

Question 16

Define heterozygous.

Answer 16

Having 2 different alleles

Question 17

What is a test cross used for?

Answer 17

To determine if a plant is homozygous dominant or heterozygous

Question 18

What is a monohybrid?

Answer 18

Heterozygous for only one character/gene

Question 19

What does the law of independent assortment state?

Answer 19

Each pair of alleles segregates independently to others

Question 20

What is the phenotypic ratio resulting from crossing F1 dihybrids?

Answer 20

9:3:3:1

Question 21

What is epistasis?

Answer 21

One gene alters the phenotypic expression of another gene

Question 22

What is pleiotropy?

Answer 22

One gene influences multiple, seemingly unrelated phenotypic traits

Question 23

What is multifactorial inheritance?

Answer 23

Genetic and environmental factors collectively influence phenotype

Question 24

What is a recessively inherited disorder?

Answer 24

Exhibited only in individuals homozygous for the allele

Question 25

What is albinism?

Answer 25

A recessive condition characterized by lack of pigmentation

Question 26

What are dominantly inherited disorders?

Answer 26

Disorders caused by rare dominant alleles that arise by mutation

Question 27

What is achondroplasia?

Answer 27

A form of dwarfism caused by a rare dominant allele

Question 28

What is the challenge in studying human genetics?

Answer 28

Generation time is too long and breeding experiments are unacceptable

Question 29

True or False: Carriers of recessive disorders display the disorder.

Answer 29

False

Question 30

Fill in the blank: The four phenotypes of the ABO blood group are determined by three alleles for the enzyme (I) that attaches ______ carbohydrates to red blood cells.

Answer 30

A or B

Question 31

What scientific approach did Mendel use to identify laws of inheritance?

Answer 31

Mendel used carefully designed experiments with garden peas.

Question 32

What types of characteristics did Mendel track in his experiments?

Answer 32

Characteristics that occurred in two distinct forms.

Question 33

What is hybridization in Mendel's experiments?

Answer 33

The process of mating two contrasting, true-breeding varieties.

Question 34

What happens when contrasting true-breeding white and purple flower plants are crossed?

Answer 34

All F1 hybrids were purple.

Question 35

What ratio of purple to white flowers did Mendel observe in the F2 generation?

Answer 35

3 to 1.

Question 36

What did Mendel conclude about the purple flower factor in F1 hybrids?

Answer 36

It was the only factor affecting flower color.

Question 37

What are the terms for the traits Mendel identified in his flower experiments?

Answer 37

Purple flower color is a Dominant trait, white flower color is a Recessive trait.

Question 38

What concept explains that alternative versions of a gene account for variations in inherited characters?

Answer 38

Alleles.

Question 39

How many alleles does an organism inherit for each characteristic?

Answer 39

Two alleles, one from each parent.

Question 40

What is the law of dominance?

Answer 40

The dominant allele determines the organism’s appearance.

Question 41

What tool can show possible combinations resulting from sperm and egg?

Answer 41

Punnett square.

Question 42

What is a test cross used for?

Answer 42

To determine whether an organism is homozygous dominant or heterozygous.

Question 43

What does the law of independent assortment apply to?

Answer 43

Genes on different chromosomes or those far apart on the same chromosome.

Question 44

What is non-mendelian inheritance?

Answer 44

Inheritance patterns that do not follow simple Mendelian genetics.

Question 45

What is complete dominance?

Answer 45

Phenotype of heterozygote and dominant homozygote are identical.

Question 46

What is incomplete dominance?

Answer 46

F1 hybrid phenotype is between the phenotypes of the two parents.

Question 47

What is codominance?

Answer 47

Two dominant alleles affect the phenotype in distinguishable ways.

Question 48

What can cause heterochromia iridium?

Answer 48

Excess or lack of melanin due to genetic mosaicism, chimerism, disease, or injury.

Question 49

What factors influence phenotype?

Answer 49

Both genetic and environmental factors.

Question 50

What is a multifactorial disorder?

Answer 50

A disease with both genetic and environmental components.

Question 51

Why are humans not good subjects for genetic research?

Answer 51

Generation time is too long, parents produce few offspring, breeding experiments are unacceptable.

Question 52

What characterizes recessively inherited disorders?

Answer 52

Exhibited only in individuals homozygous for the allele.

Question 53

What is a carrier in genetics?

Answer 53

A heterozygous individual having the recessive allele but not displaying the disorder.

Question 54

What is achondroplasia?

Answer 54

A form of dwarfism caused by a rare dominant allele.