Heredity Review

​Heredity Review

Meiosis, Mendel, and Punnett Squares​

​Meiosis and Genetic Variation

​Sources of Genetic Variation:

• crossing over - exchange of genetic information

• independent assortment of chromosomes

• segregation of alleles​

• random fertilization​

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Happens in Prophase I of Meiosis. Exchange of genetic information between homologous chromosomes.

​​Crossing Over

Different genes independently separate from one another when reproductive cells are formed.

Independent Assortment

Two alleles coding for the same trait separate during gamete formation.

Segregation of Alleles

Multiple Choice

Which best describes the process shown?

• nondisjunction
• mitosis
• independent assortment
• crossing over

Multiple Choice

One gene for the type of earlobes a person will have will be in each gamete.

• Law of Dominance

• Law of Independent Assortment

• Law of Segregation

Multiple Choice

Which of Mendel's laws states that alleles are separated during meiosis?

• Law of Dominance

• Law of Segregation

• Law of Independent Assortment

Multiple Choice

Which of Mendel's laws states that alleles are distributed to gametes independent of one another?

• Law of Dominance

• Law of Segregation

• Law of Independent Assortment

Multiple Choice

How does meiosis provide genetic variation?

• Random DNA in the sperm cells

• Random DNA in the egg cells

• Random sperm fertilizes a random egg

• All the above

Multiple Choice

Which two processes are sources of genetic variation?

• Meiosis and Mitosis

• Meiosis and Fertilization

• Interphase and Mitosis

• Prophase and Metaphase

Multiple Choice

The diagram represents a cell. The letters in the diagram represent alleles for two different traits. Which of the following shows all of the possible allele combinations expected in gametes produced by this cell?

Multiple Choice

Two chromosome pairs from a diploid organism are shown. Assuming meiosis and fertilization occur normally, which of the following pairs of alleles can an offspring receive from this parent?

• A and f

• A and A

• A and a

• F and F

​Haploid cells produced during meiosis. The sperm and egg cells.

​Gametes

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​Variations of a gene

​​Alleles

​Chromosome pairs 1 - 22 Receive one from biological mother and one from biological father

​​Autosomes

​Twenty-third pair of chromosomes - determines genetic sex

​​Sex Chromosomes

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​The allele that always shows up in the phenotype when in the genotype

​Dominant

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​The allele that is hidden by the dominant allele; must have two copies in genotype to show up in the phenotype

​​Recessive

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​The alleles that an organism has. The genes. The genetic makeup of an organism. The DNA

​​Genotype

​The expression of the trait. The physical features of the organism.

​​Phenotype

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Multiple Choice

If Purple Flowers (P) are dominant over white flowers (p), what would the phenotype be for a Pp genotype?

• Purple flowers

• White flowers

• Not enough information

Multiple Choice

Alternative forms of a gene are called

• Alleles

• Homozygous

• DNA

• Genetics

Multiple Choice

_____ is the genetic makeup of an organism.

• phenotype

• genotype

​Cross involving only one trait. Alleles are dominant or recessive.

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​​Monohybrid Cross

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​Cross involving two traits.

Alleles are dominant or recessive​

​​Dihybrid Cross

​One allele is not completely dominant over the other.

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RR - Red

rr - White

Rr - pink​

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​​Incomplete Dominance

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​Both alleles are dominant. ​

Both show up in the phenotype equally​

​BB - black

WW - white

BW - black & white spotted​

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​​Codominance

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​Cross involving two traits.

Alleles are dominant or recessive​

​​Multiple Alleles

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Multiple Choice

Some flowers are controlled by codominance. Red flowers (RR), white flowers (WW) and Speckled flowers (RW).

Cross a red flower with a speckled flower. What is the phenotypic ratio?

• 2 red, 2 speckled

• 2 red, 2 blue

• 2 blue, 2 speckled

Multiple Choice

Codominance occurs in calico cats, which allows for the Black and Tan colors to show. What percentage of the offspring represented in this P square will be calico (black and tan spotted)?

• 25%

• 50%

• 75%

• 100%

Multiple Choice

Brown fur and short coat are both dominant traits in guinea pigs. If the phenotype for both parents is dominant, how can their offspring have white fur and long coats?

• Both parents are homozygous for brown fur

• Both parents are homozygous for long coats

• The offspring inherited one recessive allele from each parent

• The offspring inherited one dominant gene from each parent

Multiple Choice

What are the possible genotypes for this cross?

• TT=25% Tt=50% tt=25%

• All will be tall

• Tt=100%

• TT=75% tt=25%

Multiple Choice

What is the genotype that should be in the blank square?

• yyRr

• YYRR

• yyrr

• YrYr

Multiple Choice

Parent 1 is heterozygous for both pea color and shape. Parent 2 is heterozygous for both pea color and shape.

How many offspring will be Wrinkled & Yellow?

• 4

• 3

• 1

• 9

Multiple Choice

Vasilli has type A blood and his mother has type O blood. Misha is homozygous for type B blood. What is the probability that they will have a child with type A blood?

• 0%

• 25%

• 50%

• 75%

Genetic tools that help to trace traits or genetic disorders in families

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​Pedigrees

Multiple Choice

What type of inheritance is shown in this pedigree?

• X-linked dominant

• X-linked recessive

• Autosomal dominant

• Autosomal recessive