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Home Q & A Board Biology-Related Homework Help Genetics and Developmental Biology
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Anonymous sara5656
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2 months ago
1) Which of the following statements does NOT describe an environmental influence on the expression of a gene?

a. Colder incubation temperatures of gecko eggs yield more females and warmer temperatures yield more males.

b. Siamese cats have darkened paws, nose, and tip of tail due to a gene that allows their skin and fur to darken in the parts of their bodies that need to retain more heat, their extremities.

c. More than a single gene is involved in the expression of human height, weight, and skin colour.

d. Exposure to sunlight increases melanin production in human skin.




2) Melanin is a skin pigmentation that absorbs and dissipates broadband UV rays. Since UV radiation causes DNA damage, melanin pigments protect the skin and reduce the risk of cancer. When skin is exposed to sunlight, melanin production is increased, causing the skin to tan. This demonstrates that

a. the environment causes mutations that increase the chance of survival

b. the environment causes mutations that have no effect on the chance of survival

c. the expression of some genes is influenced by the environment

d. the environment causes mutations that have a large effect on the chance of survival







3) In corn plants, a dominant allele (K) allows kernel colour and a recessive allele (k) inhibits kernel colour when homozygous. On a different chromosome, the dominant gene P causes purple kernel colour and the homozygous recessive genotype causes red kernel colour.

A true breeding white corn plant was crossed with a purple corn plant, yielding 50% red corn plants and 50% purple corn plants.

What are the genotypes of the parental corn plants?

a. KKPP    X       kkPp


b. KkPP    X          kkPP


c. KKPp     X      kkpp

d. kkPp     X         KkPp




4) There are two genes that determine the coat colour expression in dogs: eumelanin and merle. These genes are located on two separate chromosomes.

For the eumelanin gene, black coat colour (E) is dominant over red coat colour (e).

The merle gene controls the degree to which these coat colours are expressed through incomplete dominance.

The following table describes the merle gene expression.

         Genotype                                       Phenotype
               MM                                                    White 

               Mm                                   Half colour (Grey or light red)

               mm                                       Full colour (Black or Red)


A grey dog that is heterozygous for the eumelanin gene mates with a light red dog.

What is the probability they would have a grey puppy?

a. 0.38

b. 0.25

c. 0.13

d. 0.50






5) What is the probability they would have a grey or light red puppy?

a. 0.13

b. 0.50

c. 0.25

d. 0.38






6) Two dogs heterozygous for both traits were crossed. What phenotypic ratio is expected in their offspring?


    Phenotype:                                   ANSWER:

        White                                           ANSWER

         Grey                                           ANSWER

        Black                                           ANSWER

         Light Red                                     ANSWER

          Red                                             ANSWER






7) Feather colour in parakeets is controlled by two genes. Blue colour (B) is dominant over absence of colour (b). Yellow colour (Y) is dominant over absence of colour (y). When a B allele and a Y allele are present, a green parakeet is produced.

The probability of obtaining a female or male parakeet is the same as for humans.

What is the probability of obtaining a male green parakeet when a green parakeet heterozygous for both genes is crossed with a white parakeet?


a. 0.50

b. 0.25

c. 0.13

d. 0.75





8) SEE IMAGE ATTACHED



9) The coat colour of dogs is an example of an epistatic interaction. The common alleles are black (B) and brown (b). There is a separate gene on a separate chromosome that influences coat colour; it prevents colour formation and causes a white coat.

L = prevents color formation and causes a white coat
l = allows colour formation to occur.

If the P1 generation is a white dog (LlBb) crossed with a black dog (llBb), then which of the following represents the correct phenotypes of the F1 offspring?


a.   Phenotypes
White             Black             Brown
1 /2             3 / 8            1 / 8


b.      Phenotypes
White               Black              Brown
1 /2                      1 / 8              3 / 8


c.      Phenotypes
White                      Black                  Brown
3 / 8                    1 /2                  1 / 8


d.     Phenotypes
White                Black                    Brown
1 / 8              1 /2                     3 / 8






10) SEE IMAGE ATTACHED



11) If the P1 generation is a rose comb (RRpp) crossed with a pea comb (rrPP), which of the following represents the correct genotype and phenotype of the F1 offspring?


a. Genotype                  Phenotype
         RrPp                    pea comb


b. Genotype                   Phenotype
         RrPp                  walnut comb


c. Genotype             Phenotype
        RRPP                  walnut comb

d. Genotype                       Phenotype
         RRPP                       Single comb








12) Which of the following represents the correct phenotypes of the F2 offspring?

a. Phenotype
Single          Walnut          Pea             Rose
1 / 16          9 / 16       3 / 16             3 / 16



b. Phenotype
Single                 Walnut           Pea           Rose
3 / 16                   1 / 16      9 / 16           3 / 16



c. Phenotype
Single                     Walnut               Pea           Rose
3 / 16                     9 / 16                1 / 16             3 / 16


d. Phenotype
Single                     Walnut                Pea               Rose
9 / 16                      3 / 16                  3 /16       1 / 16






13) The Labrador Retriever’s coat colours are black, yellow, and chocolate.

Yellow is produced by the presence of a recessive epistatic gene, which has the effect of masking the black and chocolate colour genes. Black (B) is dominant to chocolate (b).

Therefore, the possible genotypes and corresponding phenotypes are:

Phenotype                    Possible Genotypes

Black                                        G__B__

Brown                                        G__bb

Yellow                                           gg__

Predict the percentage of offspring that would be black in colour for each of the following crosses. Record your answer as a whole number.

Cross:                GgBb   X  GgBB                       GGBb  X   GGBb

Percentage
of
Offspring:               Answer %                                 Answer  %








14) Below is a simplified chart for polygenic trait of eye colour. The amount of melanin in the iris is what determines the colour of the eye. People with brown eyes have more melanin in their iris than people with blue eyes. The amount of melanin is controlled by how many dominant alleles a person has for eye colour as follows:


Number of                   Genotypes                 Phenotypes
Dominant
 Alleles

     4                                   AABB                  Very dark brown eyes


     3                               AaBB or AABb                 Brown eyes


     2                    AaBb, aaBB etc.                Light brown or hazel
                                                                                          eyes


     1                       Aabb or aaBb                         Dark blue eyes


0                                  aabb                                 Light blue eyes





Which of the following parental crosses explains how two brown-eyed parents can produce a blue-eyed child?

a. AaBB      X     AaBb


b. AaBB      X        AABb


c. Aabb        X         AABB


d. AABB       X          AaBb
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3 Replies
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wrote...
#1
Staff Member
2 months ago
Q1
C

Q2
A

Q3
D

Explanation:

So, the cross between true breeding white corn plant and purple corn plant will have the genotypes kkpp(white) and KKPp(purple).

The cross,

P1      kkpp (white corn)         ×             KKPp (purple corn)

             ↓                                                 ↓

G1       kp                                             KP, Kp

                                                ↓

F1        

 

kp

kp

KP

KkPp

Purple corn plant

KkPp

Purple corn plant

Kp

Kkpp

Red corn plant

Kkpp

Red corn plant

So the offsprings produced is 50% red corn and 50% purple plants.

Q4
D

Q7
A

Heterozygous green parakeet has BbYy genotype - possible allele combinations passed down: BY, bY, By, by

White parakeet has bbyy genotype - possible allele combinations passed down: by

When put in a punnet square, total genotypes are: BbYy, bbYy, Bbyy, bbyy

Their phenotype colour, in the above order are: green, yellow, blue, white.

So probability of yellow or blue is 2/4 or 50%. (Parent genotypes were listed above)

Q13

In both cases the chances of having a Lab Retriever with a black coat is 75%.

To solve this question I have created a Punett square for the combination of GgBb x GgBB. Because there are two genes for each genotype there are 4 possible combinations that could result in the breeding of the individuals GgBb and GgBB. As you can see for the individual GgBb the possible combinations that could be passed on to their offspring are; GB, Gb, gB and gb. You know right away that any combination of genes with GB will result in offspring with a black coat because G means that there is no possibility of yellow offspring and B is the dominent gene for black.  see ATTCHEMENT


Q14
A
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Answer verified by a subject expert
Anonymousbio_man
wrote...
#2
2 months ago
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1) Which of the following statements does NOT describe an environmental influence on the expression of a gene?

a. Colder incubation temperatures of gecko eggs yield more females and warmer temperatures yield more males.

b. Siamese cats have darkened paws, nose, and tip of tail due to a gene that allows their skin and fur to darken in the parts of their bodies that need to retain more heat, their extremities.

c. More than a single gene is involved in the expression of human height, weight, and skin colour.

d. Exposure to sunlight increases melanin production in human skin.

2) Melanin is a skin pigmentation that absorbs and dissipates broadband UV rays. Since UV radiation causes DNA damage, melanin pigments protect the skin and reduce the risk of cancer. When skin is exposed to sunlight, melanin production is increased, causing the skin to tan. This demonstrates that

a. the environment causes mutations that increase the chance of survival

b. the environment causes mutations that have no effect on the chance of survival

c. the expression of some genes is influenced by the environment

d. the environment causes mutations that have a large effect on the chance of survival

3) In corn plants, a dominant allele (K) allows kernel colour and a recessive allele (k) inhibits kernel colour when homozygous. On a different chromosome, the dominant gene P causes purple kernel colour and the homozygous recessive genotype causes red kernel colour.

A true breeding white corn plant was crossed with a purple corn plant, yielding 50% red corn plants and 50% purple corn plants.

What are the genotypes of the parental corn plants?

a. KKPP    X       kkPp


b. KkPP    X          kkPP


c. KKPp     X      kkpp

d. kkPp     X         KkPp

4) There are two genes that determine the coat colour expression in dogs: eumelanin and merle. These genes are located on two separate chromosomes.

For the eumelanin gene, black coat colour (E) is dominant over red coat colour (e).

The merle gene controls the degree to which these coat colours are expressed through incomplete dominance.

The following table describes the merle gene expression.

         Genotype                                       Phenotype
               MM                                                    White

               Mm                                   Half colour (Grey or light red)

               mm                                       Full colour (Black or Red)


A grey dog that is heterozygous for the eumelanin gene mates with a light red dog.

What is the probability they would have a grey puppy?

a. 0.38

b. 0.25

c. 0.13

d. 0.50

5) What is the probability they would have a grey or light red puppy?

a. 0.13

b. 0.50

c. 0.25

d. 0.38

As Given in the problem- EE (results Black Coat), Ee (will give Grey/Light red; due to incomplete dominance) and ee (will result either full Black or Red).

Now, as asked if we cross between a dog heterozygous for eumelanin (Ee) and a dog having light red phenotype (because of Ee, clear from the given table also) , the probability of having a grey or light red puppy will be 50% or 0.50, as shown in the image below.

6) Two dogs heterozygous for both traits were crossed. What phenotypic ratio is expected in their offspring?


    Phenotype:                                   ANSWER:

        White                                           ANSWER

         Grey                                           ANSWER

        Black                                           ANSWER

         Light Red                                     ANSWER

          Red                                             ANSWER

white-4,
grey-6,
black-3,
light red-2,
red-1

7) Feather colour in parakeets is controlled by two genes. Blue colour (B) is dominant over absence of colour (b). Yellow colour (Y) is dominant over absence of colour (y). When a B allele and a Y allele are present, a green parakeet is produced.

The probability of obtaining a female or male parakeet is the same as for humans.

What is the probability of obtaining a male green parakeet when a green parakeet heterozygous for both genes is crossed with a white parakeet?


a. 0.50

b. 0.25

c. 0.13

d. 0.75

9) The coat colour of dogs is an example of an epistatic interaction. The common alleles are black (B) and brown (b). There is a separate gene on a separate chromosome that influences coat colour; it prevents colour formation and causes a white coat.

L = prevents color formation and causes a white coat
l = allows colour formation to occur.

If the P1 generation is a white dog (LlBb) crossed with a black dog (llBb), then which of the following represents the correct phenotypes of the F1 offspring?

a.   Phenotypes
White             Black             Brown
1 /2             3 / 8            1 / 8


b.      Phenotypes
White               Black              Brown
1 /2                      1 / 8              3 / 8


c.      Phenotypes
White                      Black                  Brown
3 / 8                    1 /2                  1 / 8


d.     Phenotypes
White                Black                    Brown
1 / 8              1 /2                     3 / 8
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Anonymous Author
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#3
2 months ago
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