heredity traits 1 classact srs enabled. in this presentation you will: explore how biological traits...
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Heredity Traits 1
ClassAct SRS enabled.
In this presentation you will: explore how biological traits are passed
on from one generation to the next explore the processes of natural selection
and selective breeding
Heredity Traits 1
In this presentation, you will cover all aspects involved in studying genetics.
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You will also learn about the processes of:
Genetics is the scientific study that is concerned with genes, hereditary traits and variation of organisms.
• natural selection
• selective breeding
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I. DNA
A. Every living cell contains DNA.
1. Genes are like the ingredients that are needed to make up each individual recipe.
1. DNA is like a large recipe book that determines all of the characteristics that are specific to individual organisms.
2. Each gene represents a specific protein molecule.
B. Small sections of DNA are called genes.
3. Different types of protein carry out different functions.
A strand of DNA
A gene
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Which of the following statements is correct?
Question
A) An individual's DNA will help determine every one of their characteristics.
B) Small sections of DNA are called genes.
C) DNA is found inside every living cell.
D) All of the above are correct.
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II. Genes
B. This is because you have a unique collection of genes.
A. Nobody on this planet will ever share exactly the same copies of DNA as yourself (unless you have an identical twin).
C. There will be a gene (ingredient) for each characteristic (recipe) you can think of, for example, hair color, eye color or face shape.
Blonde hair Black hair
Gene A / Protein A
Gene B / Protein B
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"A single gene represents a single protein. This specific protein then determines a specific characteristic, such as eye color." Is this statement true?
Answer Yes or No.
Question
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III. Genomes
A. We are complex organisms with large amounts of DNA in each of our cells. To save space inside the cells, DNA is tightly coiled and grouped into 23 pairs of chromosomes. Together these are called our genome.
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6 7 8 9 10
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23
23 chromosome pairs of the human genome
A chromosome
B. Within a species (group of related organisms) each organism has the same number of chromosomes.
D. For example a fruit fly has a genome of 8 chromosomes, whereas a dog has 78 chromosomes.
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C. However, genome size (the number of chromosomes) changes from one species to the next.
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III. Genetic Information – Sexual ReproductionA. You cannot choose the ingredients that make you who you are today.
B. All of your DNA, found in the nucleus of every cell, carries the entire genetic information that is needed to form every one of your characteristics.
C. When organisms sexually reproduce, genetic information is passed down from each biological parent to their offspring.
Motherchromosome pair
Fatherchromosome pair
Child chromosome pair
+
=D. In other words, one DNA chromosome from each pair is inherited from each biological parent and the new pair will not be identical to either parent.
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IV. Genetic Information – Asexual Reproduction
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A. Some individuals produce offspring without the need for a mate, and produce offspring genetically identical to itself. That is, the offspring will contain exactly the same genetic information as the parent.
B. This type of reproduction is known as asexual reproduction.It is most common in plants,for example a strawberry plant that produces runners to make new plants. It does occur in some animals too (for example flatworms).
C. Organisms that are identical to its parent are called clones.
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The entire DNA content of a worm is grouped into six chromosomes. This is called its genome. The worm's genome contains...
Question
A) ...all of its genetic information.
B) ...none of its genetic information.
C) ...half of its genetic information.
D) ...genetic information for itself and another worm.
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V. Hereditary Traits
B. This is because it is never certain which half of each parental chromosome pair will be passed down.
A. Although with sexual reproduction DNA chromosomes are inherited from each biological parent, non-twin siblings (having the same biological parents) never look identical.
C. Characteristics that are passed on from one generation to the next are called hereditary traits. For example, hair color.
Generation 2
Generation 1Mother Father
+
=
Sibling 1 Sibling 2
+
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"Apart from identical twins, siblings do not look identical. This is because it is not certain which half of each parental chromosome pair will be inherited." Is this statement true or false?
Answer True or False.
Question
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VI. Desirable Traits
A. Organisms have certain features, or traits, that make it easier for them to survive in their habitat. It may be a feature that enables them to find food, escape predators or reproduce more successfully. These are desirable or favorable traits.
B. A trait that makes it more difficult for an organism to survive, for example a feature that makes it easier prey, or that reduces an organism's ability to reproduce is called an undesirable or less favorable trait.
C. The genes that control these traits are passed from parent to offspring.
Different forms of the finchfound on the Galapagos Islands
The peppered moth
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D. When pale moths landed on the dark sooty trees, they were eaten by birds more often. The dark moths therefore lived longer and reproduced more, resulting in more dark moths. As a result of natural selection, the darker moths thrived but the pale moths declined.
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VII. Natural Selection
A. Over time desirable traits thrive while undesirable traits decline, due to natural selection.
C. About 100 years ago, city trees in the UK were blackened by soot from coal burning.
B. The peppered moth is a well-known example of this. Peppered moths are either pale speckled or dark brown.
Black moths became nine times as common as brown ones.
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VIII. Selective Breeding
A. Selective breeding is used to ensure plants and animals produce offspring with the most desirable characteristics possible.
1. isolation - a group of organisms is kept separate to prevent any new members, and so new genetic material entering the group.
B. It is achieved using three strategies:
2. artificial selection - breeding is limited to those organisms that display the desirable trait.
3. Inbreeding - breeding between closely-related individuals that have the most desirable traits is encouraged.
Desirable
Less desirable
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IX. Uses of Selective Breeding
A. There are many uses for selective breeding.
B. Farmers use it to improve their products, for example, chickens that produce large numbers of eggs, or grow quickly for meat.
C. Dogs are bred selectively for particular characteristics. For example, to be of a gentle nature to make them good household pets, or to be of an aggressive nature to make them good guard dogs.
D. Plants are also produced using selective breeding methods. For example, to produce the prettiest blooms or disease resistant crops.
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"Natural selection and selective breeding both tend to favor 'desirable' genetic traits." Is this statement true or false?
Answer True or False.
Question
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"Natural selection is a natural process. Selective breeding happens when humans control and direct breeding between plants and animals." Is this statement true?
Answer Yes or No.
Question
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X. Genetic Engineering
B. It firstly involves identifying the gene that controls a particular trait. Genes can then be removed and inserted into chromosomes.
A. Genetic engineering is the process of changing and controlling the genetic make-up of an organism.
C. This process has many uses, including farmers using it to try to produce the biggest and best crops possible.
Gene for height
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In this presentation you will: explore how the characteristics of living things vary explore how characteristics are passed on through generations explore how the environment can affect the characteristics of
living things
ClassAct SRS enabled.
Heredity Traits 1
In this presentation, you will learn about what determines the characteristics of living things.
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You will explore how the characteristics of living things vary, and how characteristic traits are passed on through generations.
You will also see how the environment can affect the characteristic traits of living things.
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I. Variation
A. All living things in the world are different.
B. Some living things are very different to each other, for example a worm and a parrot.
C. Other living things are not so different from each other, for example a black cow and a brown cow.
D. We call these differences variation. You can have variation between different species and within a species.
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What is the term given to the differences in characteristics shown by living things?
Question
A) Variables
B) Variability
C) Variation
D) All of these
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GreenBlue Hazel Brown
Num
ber
of
peo
ple
Eye color
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II. Types of Variation
A. There are two main types of variation within living things:
1. Continuous variation:This is when characteristics can have any value within a certain range. For example, height, intelligence, or leaf surface area.
2. Discontinuous variation:This is when the characteristics only have a few distinct options.For example, eye color, blood group or hair color.
Num
ber
of
peo
ple
150 160 170 180 190 200 Height in cm
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This chart shows the heights of students within a class. What type of variation does it show?
Question
A) Continuous variation
B) Discontinuous variation
Num
ber
of
peo
ple
150 160 170 180 190 200 Height in cm
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III. Genes and Variation
A. The variation between different organisms is partly due to the genes they possess.
B. Genes are responsible for the characteristics of all living things. There are millions of different types of genes.
C. A gene is a set of complex chemical instructions that controls one small detail of how to build a living thing.
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D. Living things inherit genes from their biological parents.
F. You can see how the hair color and features of this kitten are similar to that of its parent.
E. This is why offspring have similar features to their parents.
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A. Genes are contained in the DNA of chromosomes that are found in the nuclei of cells.
IV. Genes and Inheritance
B. Humans have 46 chromosomes. They occur in 23 pairs. One chromosome from each pair comes from each biological parent, so we have two copies of each gene.
C. Tucked away inside your chromosomes is the information that your body uses to make you who you are.
NucleiDNAChromosome
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23
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V. Alleles
A. Some genes have different forms, these are known as alleles.
B. Take hair color as an example. The alleles for red hair are different to the alleles for brown hair, and these are different to the alleles for blond hair.
C. The allele combinations that you possess are responsible for your unique mix of characteristics.
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Chromosomes
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VI. How do Genes Work?
A. Genes normally work in pairs.
1. We have two copies of each gene. One copy comes from each biological parent.
2. The chances are that for some genes, the alleles we inherited from each parent are different.
Alleles
DNA
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Which of the following state why offspring have similar characteristics to their parents?
Question
A) They inherit genes from their parents.
B) They have exactly the same alleles as both their parents.
C) They are not affected by the environment.
D) All of these.
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VII. How do Genes Work?
A. One allele may be dominant over another. This means that the effects of some alleles may mask the effects of other alleles.
1. For example, the gene that controls the shape of your hairline has two alleles.
B. People who have a widow’s peak hairline (in the shape of a downward ‘V’) possess the dominant allele.
C. People who do not have a widow’s peak possess the recessive allele.
Dominant Recessive
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People who have a widow’s peak either have:
People who don’t have a widow’s peak have two copies of the recessive allele.
• two copies of the dominant allele, or
• one copy of the dominant allele, and one copy of the recessive allele
Dominant
Recessive
Dominant
Recessive
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"Alleles are different forms of the same gene. For example, different alleles can code for different eye color." Is this statement true or false?
Answer True or False.
Question
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Can You Roll Your Tongue?
Tongue rolling works in the same way as the widow’s peak.
People who can roll their tongues into a U-shape possess either one or two copies of the dominant allele.
People who cannot roll their tongues possess two copies of the recessive allele.
Recessive allele
Dominant allele
Dominant
Recessive
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"Alleles for a gene can be recessive or dominant." Is this statement true or false?
Answer True or False.
Question
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VIII. Environmental Variation
A. The environment can also affect the way living things look and behave. This is known as environmental variation.
B. For example, identical twins both inherit exactly the same genes which control their characteristics. However, one twin could eat more or take up weight training and become larger than the other.
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D. Only very few characteristics are unaffected by the environment:
1. natural hair color
2. eye color
4. blood groups
E. Nearly every other characteristic is affected by environmental factors. These include skin color, academic and athletic ability.
3. inherited diseases
C. Many of the differences between people are caused by a combination of genetic and environmental traits.
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"The differences between living things of the same species are due to a combination of genetic traits and environmental conditions." Is this statement true or false?
Answer True or False.
Question
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IX. Variation in PlantsA. Plants are more easily affected by environmental changes than animals.
B. There are four main environmental factors that affect how well plants grow:
C. A plant grown in sunlight will grow much faster and may double in size compared to a plant grown in the shade.
1. sunlight
2. soil
4. moisture
3. temperature
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Are animals more easily affected by changes in environmental conditions than plants?
Answer Yes or No.
Question
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In this presentation you will: explore how traits can be inherited explore dominant and recessive traits explore how traits in offspring can be
predicted and visually represented
ClassAct SRS enabled.
Heredity Traits 1
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In this presentation, you will explore how the characteristics of living things vary, and how characteristic heredity traits are passed on through generations.
You will also see how heredity traits can be predicted in offspring when the genetic make up of the parents are known.
Heredity Traits 1
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I. Genes and Inheritance
A. Living things inherit their alleles from their biological parents.
B. Genes normally work in pairs. Living things have one copy of each gene from each biological parent.
D. Due to the way that genes are inherited, the probability of offspring inheriting certain alleles, and therefore expressing certain traits, can be easily predicted if the parents’ alleles are known.
C. The chances are that for some genes, the alleles that an organism inherits will be different.
Alleles
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"Living things inherit their genes from their biological parents." Is this statement true or false?
Answer True or False.
Question
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Can living things have different alleles for the same gene?
Answer Yes or No.
Question
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II. Dominant and Recessive Alleles
Recessive alleles
f f
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Dominant allele
A. In a gene pair, one allele can be dominant over another. This means that the effects of some alleles mask the effects of other alleles.
1. For example, the gene that controls the shape of your little finger has two alleles.
C. People who have a little finger that bends toward the other fingers either possess two dominant alleles (FF) or one dominant allele and one recessive allele (Ff).
B. People who have a little finger that does not bend toward the other fingers possess two recessive alleles (ff). F f F F
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D. We can see that the effect of the dominant F allele masks the effect of the recessive f allele. It is due to this that the F allele is said to be dominant.
F. Can you tell if you possess a dominant or recessive allele for finger shape?
E. Dominant and recessive alleles are usually shown by using upper case and lower case letters.
1. Upper case letters are used to represent a dominant allele.
2. Lower cases letter are used to represent a recessive allele.
Recessive alleles
Dominant allele
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Alleles
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III. Homozygous and Heterozygous
A. Individuals that have two of the same alleles for a gene are said to be homozygous.
B. Individuals that have two different alleles for the same gene are said to be heterozygous.
f f F F F f
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If an allele is recessive...
Question
A) ... it can mask the effect of dominant alleles.
B) ...it can be masked by the effects of dominant alleles.
C) ...it is normally shown by using upper case letters.
D) ...its effects can be seen in a heterozygous organism.
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IV. Genotype and Phenotype
A. The alleles that an individual possesses within its DNA are known as its genotype.
B. The visible characteristics that result from the individual’s alleles is known as its phenotype.
C. The inheritance of simple genetic traits that involve two different alleles of the same gene is known as monohybrid inheritance.
D. We will explore monohybrid inheritance in more detail on the following screens.
FF = Genotype
Bent finger = Phenotype
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V. Monohybrid Inheritance
A. Monohybrid inheritance is the inheritance of a single characteristic that is controlled by two alleles of the same gene; one dominant allele and one recessive allele.
B. The way that alleles can be passed down from parents to offspring can be shown by using Punnett squares.
Parent A
Parent B
B b
B
b
BB Bb
Bb bb
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50 %
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VI. Punnett Squares
A. A Punnett square is used to demonstrate all the possible genotypes that can result from the random fusion of parent gametes.
B. The alleles within the gametes of one parent are written across the top of the square.
C. The alleles within the gametes of the other parent are written down the side of the square.
D. The products of the different possible fusion of gametes are written in the appropriate boxes to show the different offspring genotypes that are possible.
E. When the square is complete, the proportion of the different possible offspring genotypes (and hence the phenotypes) can be estimated.
Parent A
Parent B
F f
f
f
Ff ff
Ff ff
50 %
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Using the wing size of fruit flies, we will see how the genotypes of parent flies can be inherited by their offspring. Two alleles (A and a) control the phenotype for wing size in fruit flies.
Flies with an AA genotype have a normal wing size.
Flies with an Aa genotype also have a normal wing size.
Flies with an aa genotype have a very small wing size.
Allele A is dominant over allele a, because flies with an Aa genotype have normal wings. Allele a only has an effect when it is homozygous, and is therefore said to be recessive. Next >
Genotype Wing phenotype
AA
Aa
aa
Normal
Normal
Small
Alleles for Wing Size in Fruit Flies
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The way that alleles can be passed from parents to their offspring can be shown in a number of ways. One of these ways is the monohybrid cross.
Sticking with the wing size of fruit flies we will see how the genotypes of parent flies can be inherited by their offspring.
Cells divide in the fruit flies’ ovaries and testis to produce gametes (cells that only have one copy of each gene).
We will cross the genotypes of a male homozygous normal winged fly (AA) with a female homozygous small winged fly (aa).
AA aa
AA AA aa aa
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A A A A a a a a
Monohybrid Inheritance in Fruit Flies
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Allele B is dominant over allele b. If an organism is heterozygous for these alleles, will the dominant allele reflect in the phenotype?
Answer Yes or No.
Question
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The male fly is AA homozygous and will produce gametes that all have the A allele.
Every zygote formed from this pair of flies will have the genotype Aa, and so will have the normal wing phenotype because A is dominant.
The female fly is aa homozygous and will produce gametes that all have the a allele.
When this pair of flies mate, their gametes fuse to form zygotes. Every zygote has two copies of each gene, one from each parent.
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Normalwing
Smallwing
Parent phenotypes
Parent genotypes
Gamete genotypes
AA aa
A a
Male gametes
A
aFemale gametes
Offspring genotype and phenotype:
Aa
Normal wing
Monohybrid Inheritance in Fruit Flies
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This type of cross has four possible genotype outcomes, each of which are equally likely, but there is only a 25% chance that an offspring will have the small wing phenotype.
In this case, half of each parent’s gametes will have A alleles and half will have a alleles. There is equal chance of an A gamete joining to an A or an a gamete from the other fly.
Sticking with fruit fly wing sizes we can see how the genotypes of parent flies can be inherited by their offspring when both parents are heterozygous (Aa).
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(Allele A is dominant to allele a)
a AA aand and
AaAa
Parent phenotypes
Parent genotypes
Gamete genotypes
Normal wing Normal wing
Offspring genotypes and phenotypes: a
a
AFemale gametes
Male gametes
A
AA
Normal wing
Aa
Normal wing
Aa
Normal wing
aa
Small wing
Monohybrid Inheritance in Fruit Flies
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It is important to remember that not all alleles are either dominant or recessive. Some alleles are codominant, so if an organism is heterozygous, both alleles affect the phenotype of the organism. For example, hair type.
We can also see the probabilities of different genotypes and phenotypes of each offspring.
From the simple cross diagrams involving dominant and recessive alleles of a gene, we have seen that the different gene combinations can produce different characteristics in offspring.
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Female gametes
a
A
Male gametes
A
a
AANormal wing
AaNormal wing
AaNormal wing
aaSmall wing
A
aFemale gametes
Male gametes
AaNormal wing
Monohybrid Inheritance in Fruit Flies
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This image shows an incomplete Punnett square for a cross concerning the tongue rolling allele. Which of the following options shows the correct offspring genotype for the square labeled X?
Question
A) TT
B) Tt
C) tt
D) None of these
Parent A
Parent B
T t
T
t
TT Tt
Tt X
T = dominant t = recessive
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Which of the following do Punnett squares show?
Question
A) The probabilities of the different genotypes of offspring.
B) The different genotypes of offspring.
C) The probabilities of the different phenotypes of offspring.
D) All of the above.