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There are two base colors of rats, black and agouti. Agouti is the 'wild-type' rat, and it is designated with an A and is dominant. Black is the recessive form of agouti, and is designated with an a. So if you have a black rat, he is doubly recessive (aa). When you say 'white rat', I'm assuming you mean your rat is a pink-eyed-white or an albino. Rats can get this way in two different ways, either they are homozygous for albinism (cc) or they have so many other recessives that it washes out their color entirely. I am willing to bet it is an albino, as they are very common in pet stores.
The problem with albinos is that when a rat is homozygous for albinism (cc), it makes them albino no matter what their other genes are. This rat could have all kinds of recessives hidden or it could have none. Since you bred your two rats and got both black and 'white' babies, I would say that your black rat carries the albino gene 'c' and your albino rat does not carry any recessives that your black rat has, except for black of course (a). So your albino rat is technically a black rat with two copies of the albino gene. I know it seems kind of confusing =)
For more information about rat care including genetics please visit my website at http://careguide.evergreenrattery.com or feel free to email me at info@evergreenrattery.com . Good luck with your rats!
What else can I help you with?
If a homozygous dominant is crossed with a homozygous recessive for a given trait the offspring will be?
The phenotype will show the dominant trait. All dominant traits mask recessive ones; If the genotype is heterozygous (One dominant and one recessive) the organism's phenotype will be dominant.
If R is dominant to r the offspring of the cross of RR with rr will be homozygous?
R R r Rr Rr r Rr Rr That is the Punnet Square. The genotype will be 100% Rr in the cross. The phenotype will be whatever phenotype is constituted by your dominant allele.
Diagram a cross between a known homozygous recessive organism and an unknown. half of the offspring demonstrate the dominant trait and half the recessive?
In this cross, the homozygous recessive organism has a genotype of "aa," where "a" represents the recessive allele. The unknown organism, which we can denote as "A?" (where "A" represents the dominant allele), must be heterozygous ("Aa") to produce offspring with both dominant and recessive traits. When crossed (aa x Aa), the resulting offspring would be 50% "Aa" (exhibiting the dominant trait) and 50% "aa" (exhibiting the recessive trait). Thus, the genotype and phenotype ratios confirm the unknown organism is heterozygous.
What is the list of genotypic ratio for all possible offspring's for DDxdd?
To determine the genotypic ratio for the cross DD (homozygous dominant) and dd (homozygous recessive), we can set up a Punnett square. All offspring will inherit one dominant allele (D) from the DD parent and one recessive allele (d) from the dd parent, resulting in 100% Dd (heterozygous) offspring. Therefore, the genotypic ratio for the offspring is 100% Dd, or simply 1:0:0 for DD:Dd:dd.
What information would tell you if a cross showed complete dominance?
If a cross between two organisms shows complete dominance, all individuals in the first generation (F1) will display the dominant trait. This indicates that the dominant allele is fully expressed, masking the recessive allele. To confirm complete dominance, further crosses involving the F1 generation can be conducted to observe the phenotypic ratio of the offspring.
If a homozygous dominant is crossed with a homozygous recessive for a given trait the offspring will be?
The phenotype will show the dominant trait. All dominant traits mask recessive ones; If the genotype is heterozygous (One dominant and one recessive) the organism's phenotype will be dominant.
What fraction of the progeny of the cross BbTt x BBtt will have black fur and long tails?
50% of the progeny will have black fur and long tails. This is because all of the offspring will inherit at least one dominant B allele for black fur, and 50% will inherit a dominant T allele for long tails.
A female quinea pig homozygous dominant for black fur color is mated with a male homozygous for white fur In a litter of eight offspring there would probably be?
To answer this, first determine the genotypes of the parents. The female is homozygous dominant, which means it carries two copies of the black allele (which we will designate B), so its genotype we can represent as BB. The male is homozygous for the recessive trait (white, designated as b), so its genotype can be represented as bb. So the cross looks like this: BB X bb Next, we must determine the types of gametes each parent can produce. In this case it's easy, because both are homozygous. The female can only produce B gametes, while the male can only produce b gametes. Since the offspring carry one allele from each parent, all of the offspring can have only one genotype: Bb. Since black (B) is the dominant allele, and every offspring carries the dominant allele, all eight of the offspring from this cross will be black.
Mendel crossed a true green podded plant with a true yellow podded plant. All the offspring from this cross had green pods. Green is the?
Green is the dominant trait in this cross. Mendel's results demonstrate that when a dominant allele (for green pods) is present, it masks the effect of the recessive allele (for yellow pods), resulting in all offspring exhibiting the dominant phenotype. Thus, the true yellow podded plant contributes a recessive allele that does not express in the presence of the dominant green allele.
In a BB x bb cross?
In a BB x bb cross, all offspring will have the genotype Bb. The offspring will exhibit the dominant trait of the B allele.
What is the result of a cross between an individual who is homozygous dominant and another who is homozygous recessive for a trait?
All the offspring will be heterozygous with a phenotype showing the dominant trait. Let the alleles be H (dominant) and h (recessive). All the gametes from the first individual will be H, and from the other, h. Thus all the offspring must be Hh.
If R is dominant to r the offspring of the cross of RR with rr will be homozygous?
R R r Rr Rr r Rr Rr That is the Punnet Square. The genotype will be 100% Rr in the cross. The phenotype will be whatever phenotype is constituted by your dominant allele.
What best describes the F1 offspring of mendels two factor cross?
The F1 offspring of Mendel's two-factor cross will all display the dominant phenotype for both traits due to the dominance of the alleles. They will be heterozygous for both traits, carrying one dominant and one recessive allele for each trait.
The cross between the homozygous tall parent and the honozygous short parent produces only tall offspring what is the term used to describe the allele for shortness?
The term used to describe the allele for shortness is recessive. In this case, the allele for shortness is masked or overridden by the dominant allele for tallness.
Which type of cross would produce 100 percent heterozygous offspring?
A cross between two homozygous parents will form a 100 percent chance of a heterozygous offspring. One homozygous parent must have the dominant allele, and the other must have the recessive allele. So, if the circumstances are correct, these characteristics will make for a 100 percent chance of a heterozygous offspring.
Diagram a cross between a known homozygous recessive organism and an unknown. half of the offspring demonstrate the dominant trait and half the recessive?
In this cross, the homozygous recessive organism has a genotype of "aa," where "a" represents the recessive allele. The unknown organism, which we can denote as "A?" (where "A" represents the dominant allele), must be heterozygous ("Aa") to produce offspring with both dominant and recessive traits. When crossed (aa x Aa), the resulting offspring would be 50% "Aa" (exhibiting the dominant trait) and 50% "aa" (exhibiting the recessive trait). Thus, the genotype and phenotype ratios confirm the unknown organism is heterozygous.
A cross of a black chicken with a white chicken produces all blue offspring this type of inheritance is known as?
This cross of a black chicken with a white chicken producing an all black and white speckled offspring is an inheritance known as co-dominant inheritance.
