Unit 4 (CH 14)

Question 1

____ (different versions of a specific gene) can be dominant or recessive.

Answer 1

Alleles

Question 2

____ Allele: exerts its effects whenever present (symbol = uppercase letter).

Answer 2

Dominant

Question 3

_____ Allele: has no effect if a dominant allele is present (symbol = lower-case letter).

Answer 3

Recessive

Question 4

An allele that exerts its effects whenever it is present is:

Answer 4

Dominant

Question 5

the genetic composition of alleles in an individual (written as a pair of letters).

Answer 5

Genotype

Question 6

2 identical alleles for the same gene (1) YY or 2) yy)

Answer 6

Homozygous

Question 7

2 different alleles for the same gene (3 Yy).

Answer 7

Hetrozygous

Question 8

the physically expressed trait that results from the genotype (ex. yellow/green peas).

Answer 8

Phenotype

Question 9

If the two alleles for a particular gene are identical, the gene pair is:

Answer 9

homozygous

Question 10

If an individual is homozygous for a particular trait:

Answer 10

Each parent contributed the same allele for that trait.

Question 11

Mendel’s pea plants can have yellow peas or green peas. Mendel found the yellow pea color allele to be dominant over the green pea color allele. What does this mean?
a) The yellow allele masks the effects of the green allele in an individual heterozygous for pea color.
b) Both individuals who are heterozygous and homozygous dominant for pea color will have yellow peas.
c) Only individuals who are homozygous recessive for pea color will have green peas.
d) The green pea color allele can be found in some individuals but not expressed.
e) All of the above.

Answer 11

all the above

Question 12

A diagram showing the possible genotypes & phenotypes of offspring for a specific trait.

Answer 12

Punnett squares

Question 13

Punnett squares represent _____(gamete formation) & _____ (gamete fusion). Shows the probabilities that offspring will inherit a trait.

Answer 13

Punnett squares represent meiosis (gamete formation) & fertilization (gamete fusion).

Question 14

Shows the probabilities that offspring will inherit a trait.

Answer 14

Punnett Square

Question 15

*Each square represents an equally probable genotype & phenotype that one single offspring can inherit.
*Each fertilization event producing an offspring is independent (1 fertilization event does not impact another).

Answer 15

Punnett Square

Question 16

Mendel found that green pea pod color (y) was recessive to yellow pea pod color (Y). For the cross Yy × yy, what percentage of offspring are expected to be yellow?

Answer 16

c) 50%.

Explanation:

The genotypes of the parents are Yy × yy.

Possible gametes: Y and y from Yy, y from yy.

Punnett square results:

    Yy, Yy, yy, yy.

Question 17

A female dog with black fur (Ff) mates with a male dog that also has black fur (Ff). Determine the possible genotypes and phenotypes of their puppies using a Punnett Square. Black fur (F) is dominant to grey fur (f).

Answer 17

a) # of possible Genotypes:
FF: 25%
Ff: 50%
ff: 25%

b) % of possible Phenotypes:
Black fur: 75%
Grey fur: 25%

Question 18

Mendel used two types of fertilization (gamete fusion) in his experiments, using either self or cross parent organisms.

Answer 18

Self-Fertilization: apply pollen from a male organ to a female organ on the same plant.

Cross-Fertilization: cross pollen from a male organ to a female organ on different plants.

Question 19

apply pollen from a male organ to a female organ on the same plant.

Answer 19

Self-Fertilization

Question 20

cross pollen from a male organ to a female organ on different plants.

Answer 20

Cross-fertilization

Question 21

self-fertilization produces offspring with identical phenotypes as the parent.

Answer 21

True-Breeding (Homozygous)

Question 22

self-fertilization produces offspring with varied phenotypes.

Answer 22

Hybrid (Heterozygous)

Question 23

are heterozygous for one specific trait/gene.

Answer 23

monohybrids

Question 24

Mendel discovered dominant & recessive traits when he cross-fertilized yellow & green pea plants.
When analyzing offspring, Mendel always found yellow peas (yellow = _____ trait).

Answer 24

dominant

Question 25

Mendel crossed a pea plant with yellow peas with a pea plant with green peas. All of the offspring created from this cross have yellow peas. What must be true about the parent plants of this cross for this to occur? a) The parent with green peas was heterozygous for pea color. b) The parent with green peas was homozygous recessive for pea color. c) The parent with yellow peas was heterozygous for pea color. d) The parent with yellow peas was homozygous dominant for pea color.

Answer 25

e) A and C. The parent with green peas was homozygous recessive for pea color. The parent with yellow peas was heterozygous for pea color.

Question 26

You cross a pea plant with yellow peas (Yy) and a pea plant with green peas. How many unique genotypes are possible for pea color in the offspring? How many unique phenotypes are possible for pea color in the offspring?

Answer 26

3 unique genotypes; 2 unique phenotypes.

Question 27

_____ Generation: the original (parent) set of individual plants that are mated.

Answer 27

Parental (P)

Question 28

First ___ Generation (__): the offspring of the P generation (filial = “children”).

Answer 28

First Filial Generation (F1): the offspring of the P generation (filial = “children”).

Question 29

____ ____ Generation (__): the offspring of the F1 generation plants.

Answer 29

Second Filial Generation (F2): the offspring of the F1 generation plants.

Question 30

In the study of genetics, the offspring of the parental generation is referred to as the:

Answer 30

F1 generation

Question 31

Through his research with pea plants, Gregor Mendel proposed 2 fundamental laws of genetics:

Answer 31

1. Law of Segregation 2. Law of Independent Assortment

Question 32

During gamete formation, 2 alleles of the same gene separate & end up in different gametes.

Answer 32

Law of Segregation

Question 33

During gamete formation, gametes are haploid & only receive one copy of a gene/allele.

Answer 33

Law of Segregation

Question 34

According to Mendel's Law of Segregation, which of the following is a true statement? a) Each gamete receives both of the parent’s alleles for each gene. b) Dominant alleles segregate into gametes more frequently than recessive alleles. c) Alleles segregate into different gametes with equal frequency. d) Recessive alleles segregate into gametes more frequently than dominant alleles

Answer 34

c) Alleles segregate into different gametes with equal frequency.

Question 35

Mendel's law of independent assortment has its basis in which of the following events of meiosis I? a) Synapsis of homologous chromosomes. b) Crossing over of homologous pairs of chromosomes. c) Alignment of pairs of homologous chromosomes along the middle of the cell. d) The division of cells during cytokinesis.

Answer 35

c) Alignment of pairs of homologous chromosomes along the middle of the cell.

Question 36

During Metaphase I, _______ pairs align randomly along the metaphase plate. This random alignment leads to the independent assortment of alleles for different genes during Anaphase I.

Answer 36

homologous chromosome

Question 37

Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?

Answer 37

d) Anaphase I of meiosis.

Question 38

During _____ of meiosis, homologous chromosomes are pulled apart to opposite sides of the cell, leading to the segregation of alleles for each gene.

Answer 38

Anaphase I

Question 39

allele segregation of one gene does not affect the segregation of another gene.

Answer 39

Law of Independent Assortment

Question 40

Independent assortment, homologous chromosomes randomly align on the metaphase I plate during ______

Answer 40

meiosis

Question 41

Cross-fertilization between two heterozygous organisms.

Answer 41

Monohybrid cross

Question 42

_____: Organisms that are heterozygous for one specific gene.

Answer 42

Monohybrids

Question 43

____ Ratio: The ratio of different genotypes observed in the offspring. **The characteristic ____ ratio from a monohybrid cross is 1:2:1.

Answer 43

Genotypic Ratio: The ratio of different genotypes observed in the offspring. **The characteristic genotypic ratio from a monohybrid cross is 1:2:1.

Question 44

_____ Ratio: The ratio of different phenotypes observed in the offspring. **The characteristic _____ ratio from a monohybrid cross is 3:1.

Answer 44

Phenotypic Ratio: The ratio of different phenotypes observed in the offspring. **The characteristic phenotypic ratio from a monohybrid cross is 3:1.

Question 45

T is the dominant allele for plant height, resulting in tall plants. t is the recessive allele for plant height, resulting in short plants. A monohybrid cross of two heterozygous (Tt) parents results in offspring having a tall plant to short plant ratio of:

Answer 45

3:1.

Question 46

What is the genotypic ratio of offspring created from a cross of two heterozygous parents for a single gene?

Answer 46

1:2:1

Question 47

In a single gene cross between a homozygous dominant parent and a homozygous recessive parent, which generation is always completely heterozygous?

Answer 47

F1 generation

Question 48

_____ _____ genotype is identified by cross-fertilization with a homozygous recessive genotype.

Answer 48

Mystery parent’s

Question 49

Which of the following single-gene crosses would always result in all offspring with the dominant phenotype?

Answer 49

TT x tt.

Question 50

A single gene test cross is conducted to determine the genotype of a pea plant that shows the dominant phenotype for height (T = tall, t = short). If all offspring of the cross show the dominant phenotype, then the genotype of the unknown parent is:

Answer 50

TT

Question 51

You want to determine the pea color genotype of a pea plant with yellow peas. You conduct a test cross with your mystery pea plant. The test cross results in 50% of the offspring possessing yellow peas and 50% of the offspring possessing green peas. What is the genotype for pea color of the mystery parent?

Answer 51

Yy

Question 52

Organism that is heterozygous for two specific genes (ex. RrYy).

Answer 52

Dihybrid

Question 53

_____ :Cross-fertilization between two heterozygous organisms. The characteristic phenotypic ratio from a ______ is: 9:3:3:1.

Answer 53

Dihybrid cross

Question 54

A _____ cross involves organisms that are heterozygous for two characters that are being studied, and a ____ cross involves organisms that are heterozygous for only one character being studied.

Answer 54

A dihybrid cross involves organisms that are heterozygous for two characters that are being studied, and a monohybrid cross involves organisms that are heterozygous for only one character being studied.

Question 55

_______ show a blended phenotype that is an intermediate of the phenotypes from the two alleles. (incomplete dominance)

Answer 55

Heterozygotes

Question 56

where neither allele is completely dominant, and the result is a mix (e.g., red flower × white flower → pink flower).

Answer 56

Incomplete dominance

Question 57

Codominance: _______ codominantly express both phenotypes from each allele in “patches”.

Answer 57

Heterozygotes

Question 58

for example, a white cow crossed with a red cow resulting in a roan cow (with both red and white hairs visible).

Answer 58

codominance

Question 59

When crossing two true-breeding plants (one red, one white) results in pink offspring, this indicates ____ dominance. In this case, the red allele doesn't completely mask the white allele, so the heterozygous F1 offspring show a blend — pink.

Answer 59

incomplete