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4 years ago

Dimples (D) and brown hair (A) are dominant traits. Answer the following questions based on the dihybrid cross shown:

1 answer:

5 0

1. DDAA, DdAa
2. DDaa, Dada
3. ddAA, ddAa
4. ddaa
5. The phenotypic ratio is 9:3:3:1 where 9 combinations will produce offspring with both dominant phenotypes (dimples and brown hair), 3 will produce offspring with one dominant phenotype and one receive phenotype (dimples, blonde hair), 3 will produce offspring with one receive phenotype and one dominant phenotype (no dimples, brown hair), and one will produce offspring with both recessive phenotypes (no dimples, blonde hair)

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Lisa is in the eighth grade. Normally she is active in clubs, plays sports, and gets good grades, but lately she hasn’t been fee

Monica [59]

Whats the question here?? are you asking which disease she has????

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3 years ago

Suppose that a gene for coat color in mice has two alleles, B and b, where B is completely dominant and encodes a black coat col

pogonyaev

Answer:

Genotype= Bb

Phenotype= Black coat

Explanation:

A single gene coding for coat color in mice is involved here. An allele is a contrasting or variant form of a gene. Most genes possess two alleles.

According to Mendel's findings in his law of dominance, an allele is capable of masking the expression of another gene. The allele masking or being expressed is called a DOMINANT allele while the allele being masked is called a RECESSIVE allele.

The alleles of a particular gene can either be in a homozygous or heterozygous state. The alleles are homozygous when they are the same in that gene while it is heterozygous when they contain two different alleles i.e. a combination of the dominant and recessive allele.

In this case of a gene coding for coat color in mice, The allele coding for Black coat (B) is dominant over that coding for brown coat (b). This means that in an heterozygous state, allele B will mask the expression of allele b.

The genotype of an organism is the actual genetic make-up of that organism while its phenotype is just its phyaically expressed trait.

Since a heterozygous organism has a combination of two different alleles, hence, the mouse in an heterozygous state for coat color will have a Bb genotype.

Also, since the allele for black coat coloration (B) is dominant over the brown coat coloration (b), thus, in a heterozygous state, the black colour allele will mask the expression of the brown color allele, and express itself (exercise its dominance).

Therefore, a Bb genotypic mouse will produce a black coat phenotype.

N.B: A recessive trait can only be expressed when the organism is homozygous recessive for a particular gene i.e. have the same recessive genes but a dominant phenotype can have a homozygous or heterozygous genotype.

8 0

4 years ago

What is the function of the contractile vacuole?

Natalka [10]

Contractile vacuoles<span> protect a cell from absorbing too much water and potentially exploding by excreting excess water. Wastes, such as ammonia, are soluble in water; they are excreted from the cell along with excess water by the </span>contractile vacuoles<span>.</span>

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4 years ago

Read 2 more answers

The layer of clay that marks the boundary between the Mesozoic and Cenozoic is rich in what element?

Fed [463]

c. Iridium

Explanation:

The layer of clay that marks the boundary between the Mesozoic and Cenozoic is rich in iridium. Iridium is an element that is rare on the earth crust. It is found in other astronomical bodies.

The Cenozoic/Mesozoic boundary is an extinction time zone on earth in which nearly all organisms were wiped out.
During this period in time, scientists believed that a large bolide collided with the surface of the earth sending all lives to death.
Meteorites are rich in iridium and during the collision, they released a significant proportion in earth materials.
This is why iridium was observed by Walter Alvarez in significant proportion in Italy.

Learn more:

Meteorite brainly.com/question/6372454

#learnwithBrainly

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4 years ago

A biologist set up an experiment to study nine mice on day one of the study the mice were measured for a variety of characterist

Ratling [72]

Attached is the complete problem that I found on the internet.

First question.
The constants (variables that stay the same throughout the study for all groups) were the hours of light per day, the amount and frequency of food that was given, the surrounding settings such as the presence of a wheel for exercise and the cage size, T0 (time at which all the rats were measured for the experiment purposes), and days under the experiment.

Second question.
The independent variable (variable that we control in order to study the dependent variable) is the time.

Third question.
The dependent variable (variable that we pretend to analyse under the set conditions) can be either the rats' weight or length.

Fourth question.
During the experiment I need to collect data related to the conditions of the experiment, whether they are being constant or not. Data such as temperature, hours of light, food given, etc.

Fifth question.
There is a flaw on the formation of the groups. The groups should be balanced in all the demographic characteristics, such as length and weight, and also balanced in number of rats. The total number of rats is nine, so the most acceptable would be to have 3 rats per group of study and not 4 or 2, an in the last two groups. As for the demographic characteristics, it should be taken into consideration the initial length and weight of each rat before grouping them so that the groups in themselves were not a variable. As we can observe there is a great variation, mostly on the last group, made up only of two rats, one of average weight and length and the other with the lowest length and weight.

Sixth question.
At a medium temperature (70ºF) there seems to be a greater increase of weight, between 40 to 55 grams more. In the other groups there's an increase of weight as well but more discreet. The group exposed at a higher temperature (85ºF) had a weight gaining of 23 to 32 grams, and the group exposed to a lower temperature (50ºF) gained from 9 to 20 grams. Temperature might be related to the weight gaining but not in a directly proportional way.
Considering now the length, there seems to be no significant changes related to the temperatures of 70ºF and 85ºF. In these cases the rats increased in length in a like manner way. What was evident though, was that the rats on the group exposed to the lowest temperature (50ºF) had only grown from 0 to 0.2 cm even with some weight gaining that clearly was not accompanied by the length. Temperature might be related to the length of the rats: lower temperatures inhibit rats' growth.

8 0

3 years ago