Lesson 3: Punnett Squares

Question 1

Who is known as the Father of Modern Genetics?

Answer 1

Gregor Mendel

Question 2

Where did Gregor Mendel conduct his experiments on pea plants?

Answer 2

In his monastery’s garden

Question 3

How many independent traits did Mendel study in pea plants?

Answer 3

Seven

Question 4

What fundamental concepts did Mendel’s experiments establish?

Answer 4

The basis for heredity and inheritance

Question 5

What type of reproduction did Mendel focus on?

Answer 5

Sexual reproduction

Question 6

What is asexual reproduction?

Answer 6

Asexual reproduction is when offspring are created from only one parent. Offspring are exact copies of that parent.

Question 7

Give two examples of organisms that reproduce asexually.

Answer 7

Bacteria and some plants

Question 8

What is sexual reproduction?

Answer 8

Sexual reproduction is the process of combining the genetic information of two individuals to create a new individual.

Question 9

Give two examples of organisms that reproduce sexually.

Answer 9

Humans and horses

Question 10

According to Mendel, how does each offspring inherit its genetic makeup?

Answer 10

Each offspring gets half of its genetic makeup from each parent.

Question 11

What are the individual genetic units that offspring inherit from their parents called?

Answer 11

Alleles

Question 12

How many alleles does an individual have for each trait?

Answer 12

Two

Question 13

How does sexual reproduction determine an offspring’s alleles?

Answer 13

Each parent gives one allele to the offspring.

Question 14

What are dominant alleles?

Answer 14

Dominant alleles are expressed in the offspring and are represented by capital letters (e.g., E for brown eyes).

Question 15

What are recessive alleles?

Answer 15

Recessive alleles are present but not expressed unless paired with another recessive allele (e.g., e for blue eyes).

Question 16

If an offspring receives an E (brown eyes) from one parent and an e (blue eyes) from the other, what will its eye color be?

Answer 16

Brown, because the dominant E allele is expressed.

Question 17

The genetic makeup of an individual organism.

Answer 17

Genotype

Question 18

A set of observable characteristics of an individual.

Answer 18

Phenotype

Question 19

If an individual has the genotype Ee for eye color, what is its phenotype?

Answer 19

Brown eyes

Question 20

What determines an individual’s phenotype?

Answer 20

Its genotype

Question 21

What is a Punnett Square used for?

Answer 21

To determine the probability that offspring will express a certain genotype.

Question 22

What information does a Punnett Square require?

Answer 22

The genotype of the parents.

Question 23

What does it mean if an organism is homozygous for a trait?

Answer 23

It has two identical alleles for a trait (e.g., AA or aa).

Question 24

What does it mean if an organism is heterozygous for a trait?

Answer 24

It has one dominant allele and one recessive allele (e.g., Aa).

Question 25

What are the three possible genotypes in a Punnett Square?

Answer 25

1. Homozygous Dominant (AA) 2. Homozygous Recessive (aa) 3. Heterozygous (Aa)

Question 26

If both parents are heterozygous (Aa), what percentage of offspring will be homozygous dominant (AA)?

Answer 26

25%

Question 27

If both parents are heterozygous (Aa), what percentage of offspring will be homozygous recessive (aa)?

Answer 27

25%

Question 28

If both parents are heterozygous (Aa), what percentage of offspring will be heterozygous (Aa)?

Answer 28

50%

Question 29

What should the total percentage of all possible offspring genotypes in a Punnett Square always add up to?

Answer 29

100%

Question 32

Two inherited alleles together form an organism's this.

Answer 32

GENOTYPE

Question 33

An organism's physical appearance for a given characteristic.

Answer 33

PHENOTYPE

Question 34

An inherited trait that results from the expression of the dominant allele over the recessive allele.

Answer 34

DOMINANT TRAITS

Question 35

Once you have filled in the Punnett square with the genotypes you must determine the ______?

Answer 35

phenotypes

Question 36

If a _____ trait is in the square, the dominant gene will show up in the phenotype.

Answer 36

dominant

Question 37

The only way a recessive trait shows up in the phenotype is if there are ____ recessive traits.

Answer 37

two

Question 38

A genotype with two dominant or two recessive alleles.

Answer 38

HOMOZYGOUS RR rr

Question 39

A genotype with one dominant and one recessive allele.

Answer 39

HETEROZYGOUS Rr

Question 40

This is used to organize all the possible combinations of offspring from particular parents.

Answer 40

PUNNETT SQUARES