Test Crosses and Probability

Test Cross breeding an individual whose phenotype is known but whose genotype is unknown to an individual with a homozygous recessive genotype can be used to determine the first individual’s genotype

Test Cross Example A purple-flowered plant is crossed with a white-flowered plant. Some of the plants in the next generation produce purple flowers and some produce white flowers. What is the genotype of the purple-flowered plant?

A purple-flowered plant is crossed with a white-flowered plant A purple-flowered plant is crossed with a white-flowered plant. Some of the plants in the next generation produce purple flowers and some produce white flowers. What is the genotype of the purple-flowered plant? Identification of Alleles P = purple p = white Parent Genotype Identification Purple parent: P? White parent: pp

A purple-flowered plant is crossed with a white-flowered plant A purple-flowered plant is crossed with a white-flowered plant. Some of the plants in the next generation produce purple flowers and some produce white flowers. What is the genotype of the purple-flowered plant? Punnett Square P ? p p

A purple-flowered plant is crossed with a white-flowered plant A purple-flowered plant is crossed with a white-flowered plant. Some of the plants in the next generation produce purple flowers and some produce white flowers. What is the genotype of the purple-flowered plant? Punnett Square P ? Pp p p

A purple-flowered plant is crossed with a white-flowered plant A purple-flowered plant is crossed with a white-flowered plant. Some of the plants in the next generation produce purple flowers and some produce white flowers. What is the genotype of the purple-flowered plant? Punnett Square P ? Pp p p p

A purple-flowered plant is crossed with a white-flowered plant A purple-flowered plant is crossed with a white-flowered plant. Some of the plants in the next generation produce purple flowers and some produce white flowers. What is the genotype of the purple-flowered plant? Punnett Square P ? Pp p p p

A purple-flowered plant is crossed with a white-flowered plant A purple-flowered plant is crossed with a white-flowered plant. Some of the plants in the next generation produce purple flowers and some produce white flowers. What is the genotype of the purple-flowered plant? Punnett Square P ? Pp p p p

Genotype of Purple Parent A purple-flowered plant is crossed with a white-flowered plant. Some of the plants in the next generation produce purple flowers and some produce white flowers. What is the genotype of the purple-flowered plant? Genotype of Purple Parent

A purple-flowered plant is crossed with a white-flowered plant A purple-flowered plant is crossed with a white-flowered plant. Some of the plants in the next generation produce purple flowers and some produce white flowers. What is the genotype of the purple-flowered plant? Punnett Square P ? Pp p p p

Test Cross Example Punnett Square Pp pp p p

Genotype of Purple Parent Pp Heterozygous A purple-flowered plant is crossed with a white-flowered plant. Some of the plants in the next generation produce purple flowers and some produce white flowers. What is the genotype of the purple-flowered plant? Genotype of Purple Parent Pp Heterozygous

total # of possible outcomes Probability the likelihood (“chance” or “odds”) that a specific event will occur can be expressed as words, percents, or fractions the chance of flipping a heads on a coin is: 1/2 Probability = # of one kind of outcome total # of possible outcomes

Probability Example Two heterozygous purple-flowered plants are crossed. What is the probability that they will have a white-flowered offspring?

Two heterozygous purple-flowered plants are crossed Two heterozygous purple-flowered plants are crossed. What is the probability that they will have a white-flowered offspring? Identification of Alleles P = purple p = white Parent Genotype Identification Heterozygous parent 1: Pp Heterozygous parent 2: Pp

Two heterozygous purple-flowered plants are crossed Two heterozygous purple-flowered plants are crossed. What is the probability that they will have a white-flowered offspring? Punnett Square P p P p

Two heterozygous purple-flowered plants are crossed Two heterozygous purple-flowered plants are crossed. What is the probability that they will have a white-flowered offspring? Punnett Square P p PP P p

Two heterozygous purple-flowered plants are crossed Two heterozygous purple-flowered plants are crossed. What is the probability that they will have a white-flowered offspring? Punnett Square P p PP Pp P p

Two heterozygous purple-flowered plants are crossed Two heterozygous purple-flowered plants are crossed. What is the probability that they will have a white-flowered offspring? Punnett Square P p PP Pp P p

Two heterozygous purple-flowered plants are crossed Two heterozygous purple-flowered plants are crossed. What is the probability that they will have a white-flowered offspring? Punnett Square P p PP Pp pp P p

Probability of White Offspring Two heterozygous purple-flowered plants are crossed. What is the probability that they will have a white-flowered offspring? Probability of White Offspring

Two heterozygous purple-flowered plants are crossed Two heterozygous purple-flowered plants are crossed. What is the probability that they will have a white-flowered offspring? Punnett Square P p PP Pp pp P p

Probability of White Offspring 1/4 Two heterozygous purple-flowered plants are crossed. What is the probability that they will have a white-flowered offspring? Probability of White Offspring 1/4

Multiple Events Probability calculate the probability of two or more things happening in a row by multiplying the probability of each event occurring on its own Probability of flipping a heads:

Multiple Events Probability calculate the probability of two or more things happening in a row by multiplying the probability of each event occurring on its own Probability of flipping a heads: 1/2 Probability of flipping a tails:

Multiple Events Probability calculate the probability of two or more things happening in a row by multiplying the probability of each event occurring on its own Probability of flipping a heads: 1/2 Probability of flipping a tails: 1/2 Probability of flipping a heads and then a tails:

Multiple Events Probability calculate the probability of two or more things happening in a row by multiplying the probability of each event occurring on its own Probability of flipping a heads: 1/2 Probability of flipping a tails: 1/2 Probability of flipping a heads and then a tails: 1/2 * 1/2 = 1/4

Two heterozygous purple-flowered plants are crossed Two heterozygous purple-flowered plants are crossed. What is the probability that they produce a white-flowered offspring and then produce a purple-flowered offspring? Identification of Alleles P = purple p = white Parent Genotype Identification Heterozygous parent 1: Pp Heterozygous parent 2: Pp

Two heterozygous purple-flowered plants are crossed Two heterozygous purple-flowered plants are crossed. What is the probability that they produce a white-flowered offspring and then produce a purple-flowered offspring? Punnett Square P p PP Pp pp P p

Multiple Events Probability Example White Flower Probability

Two heterozygous purple-flowered plants are crossed Two heterozygous purple-flowered plants are crossed. What is the probability that they produce a white-flowered offspring and then produce a purple-flowered offspring? Punnett Square P p PP Pp pp P p

Multiple Events Probability Example White Flower Probability Purple 1 4

Two heterozygous purple-flowered plants are crossed Two heterozygous purple-flowered plants are crossed. What is the probability that they produce a white-flowered offspring and then produce a purple-flowered offspring? Punnett Square P p PP Pp pp P p

Multiple Events Probability Example White Flower Probability Purple Probability of Getting BOTH 1 3 4

Multiple Events Probability Example White Flower Probability Purple Probability of Getting BOTH 1 * 3 = 4

Multiple Events Probability Example White Flower Probability Purple Probability of Getting BOTH 1 * 3 = 4 16

In garden peas, long stems (L) are dominant and short stems (l) are recessive. A long plant is crossed with a short plant. This is a test cross to determine the genotype of the long plant. If all of the offspring produced in this test cross are also long plants, what was the genotype of the parental long stem plant? Identification of Alleles L = long stems l = short stems Parent Genotype Identification Long stem parent: L? Short stem parent: ll

In garden peas, long stems (L) are dominant and short stems (l) are recessive. A long plant is crossed with a short plant. This is a test cross to determine the genotype of the long plant. If all of the offspring produced in this test cross are also long plants, what was the genotype of the parental long stem plant? Punnett Square L ? l l

In garden peas, long stems (L) are dominant and short stems (l) are recessive. A long plant is crossed with a short plant. This is a test cross to determine the genotype of the long plant. If all of the offspring produced in this test cross are also long plants, what was the genotype of the parental long stem plant? Punnett Square L ? Ll l l

In garden peas, long stems (L) are dominant and short stems (l) are recessive. A long plant is crossed with a short plant. This is a test cross to determine the genotype of the long plant. If all of the offspring produced in this test cross are also long plants, what was the genotype of the parental long stem plant? Punnett Square L ? Ll l l l

In garden peas, long stems (L) are dominant and short stems (l) are recessive. A long plant is crossed with a short plant. This is a test cross to determine the genotype of the long plant. If all of the offspring produced in this test cross are also long plants, what was the genotype of the parental long stem plant? Punnett Square L ? Ll l l l

In garden peas, long stems (L) are dominant and short stems (l) are recessive. A long plant is crossed with a short plant. This is a test cross to determine the genotype of the long plant. If all of the offspring produced in this test cross are also long plants, what was the genotype of the parental long stem plant? Punnett Square L ? Ll l l l

Long stem Plant Genotype In garden peas, long stems (L) are dominant and short stems (l) are recessive. A long plant is crossed with a short plant. This is a test cross to determine the genotype of the long plant. If all of the offspring produced in this test cross are also long plants, what was the genotype of the parental long stem plant? Long stem Plant Genotype

In garden peas, long stems (L) are dominant and short stems (l) are recessive. A long plant is crossed with a short plant. This is a test cross to determine the genotype of the long plant. If all of the offspring produced in this test cross are also long plants, what was the genotype of the parental long stem plant? Punnett Square L ? Ll l l l

In garden peas, long stems (L) are dominant and short stems (l) are recessive. A long plant is crossed with a short plant. This is a test cross to determine the genotype of the long plant. If all of the offspring produced in this test cross are also long plants, what was the genotype of the parental long stem plant? Punnett Square L ? Ll l l

In garden peas, long stems (L) are dominant and short stems (l) are recessive. A long plant is crossed with a short plant. This is a test cross to determine the genotype of the long plant. If all of the offspring produced in this test cross are also long plants, what was the genotype of the parental long stem plant? Punnett Square L L Ll l l

Long stem Plant Genotype LL Homozygous dominant In garden peas, long stems (L) are dominant and short stems (l) are recessive. A long plant is crossed with a short plant. This is a test cross to determine the genotype of the long plant. If all of the offspring produced in this test cross are also long plants, what was the genotype of the parental long stem plant? Long stem Plant Genotype LL Homozygous dominant

If a heterozygous long stem plant (L) is crossed with a homozygous recessive short stem plant (l), what is the probability that their offspring will be short stemmed? You may report your answer in a fraction or a percent. Identification of Alleles L = long stems l = short stems Parent Genotype Identification Ll ll

If a heterozygous long stem plant (L) is crossed with a homozygous recessive short stem plant (l), what is the probability that their offspring will be short stemmed? You may report your answer in a fraction or a percent. Punnett Square L l l l

If a heterozygous long stem plant (L) is crossed with a homozygous recessive short stem plant (l), what is the probability that their offspring will be short stemmed? You may report your answer in a fraction or a percent. Punnett Square L l Ll l l

If a heterozygous long stem plant (L) is crossed with a homozygous recessive short stem plant (l), what is the probability that their offspring will be short stemmed? You may report your answer in a fraction or a percent. Punnett Square L l Ll ll l l

If a heterozygous long stem plant (L) is crossed with a homozygous recessive short stem plant (l), what is the probability that their offspring will be short stemmed? You may report your answer in a fraction or a percent. Punnett Square L l Ll ll l l

If a heterozygous long stem plant (L) is crossed with a homozygous recessive short stem plant (l), what is the probability that their offspring will be short stemmed? You may report your answer in a fraction or a percent. Punnett Square L l Ll ll l l

Short Stemmed Offspring Probability If a heterozygous long stem plant (L) is crossed with a homozygous recessive short stem plant (l), what is the probability that their offspring will be short stemmed? You may report your answer in a fraction or a percent. Short Stemmed Offspring Probability

If a heterozygous long stem plant (L) is crossed with a homozygous recessive short stem plant (l), what is the probability that their offspring will be short stemmed? You may report your answer in a fraction or a percent. Punnett Square L l Ll ll l l

Short Stemmed Offspring Probability 2/4 If a heterozygous long stem plant (L) is crossed with a homozygous recessive short stem plant (l), what is the probability that their offspring will be short stemmed? You may report your answer in a fraction or a percent. Short Stemmed Offspring Probability 2/4

Simplify fractions if possible.

Short Stemmed Offspring Probability 2/4 If a heterozygous long stem plant (L) is crossed with a homozygous recessive short stem plant (l), what is the probability that their offspring will be short stemmed? You may report your answer in a fraction or a percent. Short Stemmed Offspring Probability 2/4

Short Stemmed Offspring Probability 2/4 1/2 or 50% If a heterozygous long stem plant (L) is crossed with a homozygous recessive short stem plant (l), what is the probability that their offspring will be short stemmed? You may report your answer in a fraction or a percent. Short Stemmed Offspring Probability 2/4 1/2 or 50%

In garden peas, inflated (I) pods are dominant to constricted pods (i) In garden peas, inflated (I) pods are dominant to constricted pods (i). A plant that has inflated pods is crossed with a plant that has constricted pods in a test cross. If all of the offspring produced from this cross have inflated pods, what was the genotype of the parental plant with inflated pods? Identification of Alleles I = inflated pods i = constricted pods Parent Genotype Identification Inflated parent: I? Constricted parent: ii

In garden peas, inflated (I) pods are dominant to constricted pods (i) In garden peas, inflated (I) pods are dominant to constricted pods (i). A plant that has inflated pods is crossed with a plant that has constricted pods in a test cross. If all of the offspring produced from this cross have inflated pods, what was the genotype of the parental plant with inflated pods? Punnett Square I ? i i

In garden peas, inflated (I) pods are dominant to constricted pods (i) In garden peas, inflated (I) pods are dominant to constricted pods (i). A plant that has inflated pods is crossed with a plant that has constricted pods in a test cross. If all of the offspring produced from this cross have inflated pods, what was the genotype of the parental plant with inflated pods? Punnett Square I ? Ii i i

In garden peas, inflated (I) pods are dominant to constricted pods (i) In garden peas, inflated (I) pods are dominant to constricted pods (i). A plant that has inflated pods is crossed with a plant that has constricted pods in a test cross. If all of the offspring produced from this cross have inflated pods, what was the genotype of the parental plant with inflated pods? Punnett Square I ? Ii i i

In garden peas, inflated (I) pods are dominant to constricted pods (i) In garden peas, inflated (I) pods are dominant to constricted pods (i). A plant that has inflated pods is crossed with a plant that has constricted pods in a test cross. If all of the offspring produced from this cross have inflated pods, what was the genotype of the parental plant with inflated pods? Punnett Square I ? Ii i i i

In garden peas, inflated (I) pods are dominant to constricted pods (i) In garden peas, inflated (I) pods are dominant to constricted pods (i). A plant that has inflated pods is crossed with a plant that has constricted pods in a test cross. If all of the offspring produced from this cross have inflated pods, what was the genotype of the parental plant with inflated pods? Punnett Square I ? Ii i i i

In garden peas, inflated (I) pods are dominant to constricted pods (i) In garden peas, inflated (I) pods are dominant to constricted pods (i). A plant that has inflated pods is crossed with a plant that has constricted pods in a test cross. If all of the offspring produced from this cross have inflated pods, what was the genotype of the parental plant with inflated pods? Punnett Square I ? Ii i i i

Inflated Pods Parent Genotype In garden peas, inflated (I) pods are dominant to constricted pods (i). A plant that has inflated pods is crossed with a plant that has constricted pods in a test cross. If all of the offspring produced from this cross have inflated pods, what was the genotype of the parental plant with inflated pods? Inflated Pods Parent Genotype

In garden peas, inflated (I) pods are dominant to constricted pods (i) In garden peas, inflated (I) pods are dominant to constricted pods (i). A plant that has inflated pods is crossed with a plant that has constricted pods in a test cross. If all of the offspring produced from this cross have inflated pods, what was the genotype of the parental plant with inflated pods? Punnett Square I ? Ii i i i

In garden peas, inflated (I) pods are dominant to constricted pods (i) In garden peas, inflated (I) pods are dominant to constricted pods (i). A plant that has inflated pods is crossed with a plant that has constricted pods in a test cross. If all of the offspring produced from this cross have inflated pods, what was the genotype of the parental plant with inflated pods? Punnett Square I ? Ii i i

In garden peas, inflated (I) pods are dominant to constricted pods (i) In garden peas, inflated (I) pods are dominant to constricted pods (i). A plant that has inflated pods is crossed with a plant that has constricted pods in a test cross. If all of the offspring produced from this cross have inflated pods, what was the genotype of the parental plant with inflated pods? Punnett Square I I Ii i i

Inflated Pods Parent Genotype II Homozygous dominant In garden peas, inflated (I) pods are dominant to constricted pods (i). A plant that has inflated pods is crossed with a plant that has constricted pods in a test cross. If all of the offspring produced from this cross have inflated pods, what was the genotype of the parental plant with inflated pods? Inflated Pods Parent Genotype II Homozygous dominant

Identification of Alleles Parent Genotype Identification In garden peas, axial flowers are dominant and terminal flowers are recessive. In a cross between two homozygous plants, one that has axial flowers and one that has terminal flowers, what will be the probability that they produce an axial offspring then a terminal offspring? Identification of Alleles Parent Genotype Identification

The Work of Gregor Mendel (a little background information…) Holt Biology, pg. 163

In garden peas, axial flowers are dominant and terminal flowers are recessive. In a cross between two homozygous plants, one that has axial flowers and one that has terminal flowers, what will be the probability that they produce an axial offspring then a terminal offspring? Identification of Alleles A = axial flowers a = terminal flowers Parent Genotype Identification AA aa

In garden peas, axial flowers are dominant and terminal flowers are recessive. In a cross between two homozygous plants, one that has axial flowers and one that has terminal flowers, what will be the probability that they produce an axial offspring then a terminal offspring? Punnett Square A A a a

In garden peas, axial flowers are dominant and terminal flowers are recessive. In a cross between two homozygous plants, one that has axial flowers and one that has terminal flowers, what will be the probability that they produce an axial offspring then a terminal offspring? Punnett Square A A Aa a a

In garden peas, axial flowers are dominant and terminal flowers are recessive. In a cross between two homozygous plants, one that has axial flowers and one that has terminal flowers, what will be the probability that they produce an axial offspring then a terminal offspring? Probability of Producing an Axial Offspring followed by a Terminal Offspring

Multiple Events Probability Example Axial Flower Probability Terminal Probability of Getting BOTH 4

Multiple Events Probability Example Axial Flower Probability Terminal Probability of Getting BOTH 4 * =

Multiple Events Probability Example Axial Flower Probability Terminal Probability of Getting BOTH 4 * = 16

Simplify fractions if possible.

In garden peas, axial flowers are dominant and terminal flowers are recessive. In a cross between two homozygous plants, one that has axial flowers and one that has terminal flowers, what will be the probability that they produce an axial offspring then a terminal offspring? Probability of Producing an Axial Offspring followed by a Terminal Offspring 0