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2 years ago

10. A fish is characterized by the presence of

Biology

2 answers:

egoroff_w [7]2 years ago

3 0

Answer:

Explanation:

Fishes are aquatic vertebrates having scales, pharyngeal gill slits and paired fins. ... Most fish are ectothermic ("cold-blooded"), allowing their body temperatures to vary as ambient temperatures change. fishes have scales that covers the skin of fishes. Thus, the correct answer is option D.

joja [24]2 years ago

3 0

Answer:

D) All of the above

Explanation:

Fishes are aquatic vertebrates having scales, pharyngeal gill slits and paired fins. They lack limbs with digits. Most fish are ectothermic ("cold-blooded"), allowing their body temperatures to vary as ambient temperatures change. fishes have scales that covers the skin of fishes.

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2 years ago

n mice, dwarfism is caused by an X-linked recessive allele, and pink coat is caused by an autosomal dominant allele (coats are n

nexus9112 [7]

Answer:

The probability of getting a dwarf and pink female is 1/2

Explanation:

In mice, dwarfism is caused by an X-linked recessive allele, and pink coat is caused by an autosomal dominant allele where coats are normally brownish.

A dwarf female from a pure line will have Xd Xd where d represent the recessive trait and the female is also brownish (pp).

A pink male from a pure line will be XPY where P represent the dominant allele but not a dwarf (D).

Xd Xd Xp Xp

XD XDXd XDXd XP XPXp XPXp F1 generation

Y XdY XdY Y XpY XpY

P XDXd x XdY XPXp x XpY

XD Xd XP Xp

Xd XDXd XdXd Xp XPXp XpXp F2 generation

Y XDY XdY Y XPY XpY

The probability of getting a dwarf and pink female is 1/2

5 0

2 years ago

Cystic fibrosis (CF) is one of most common recessive disorders among Caucasians it affects 1 in 1,700 newborns. What is the expe

Phantasy [73]

Answer: The expected frequency of carriers is P(Aa)=0.046.

The proportion of childs with CF is P(aa)=0.024.

25% of having a child with CF (aa).

Explanation:

Hardy-Weinberg's principle states that in a large enough population, in which mating occurs randomly and which is not subject to mutation, selection or migration, gene and genotype frequencies remain constant from one generation to the next one, once a state of equilibrium has been reached which in autosomal loci is reached after one generation. So, a population is said to be in balance when the alleles in polymorphic systems maintain their frequency in the population over generations.

Given the gene allele frequencies in the gene pool of a population, it is possible to calculate the expected frequencies of the progeny's genotypes and phenotypes. If P = percentage of the allele A (dominant) and q = percentage of the allele a (recessive), the checkerboard method can be used to produce all possible random combinations of these gametes.

Note that p + q = 1, that is, the percentages of gametes A and a must equal 100% to include all gametes in the gene pool.

The genotypic frequencies added together should also equal 1 or 100%, and all the equations can be summarized as follows:

$p+q=1\\(p+q)^{2} = p^{2} +2pq+q^{2} = 1\\P(AA)=p^{2} \\P(aa)=q^{2} \\P(Aa)=2pq1$

So, there are 1700 individuals and only one is affected. Since it is a recessive disorder, the genotype of that individual must be aa. So the genotypic frequency of aa is 1/1700=0.000588.

Then, $P(aa)=q^{2}=0.000588$ . And with that we can calculate the value of q,

$P(a)=q=\sqrt{0.000588}=0.024$

And since we know that p+q=1, we can find out the value of p.

$p+0.024=1\\1-0.024=p\\p=0.976$

Next, we find out the genotypic frequency of the genotype AA:

$P(A)=p=0.976\\P(AA)=p^{2} = 0.976^{2}=0.95$

Now, we can find out the genotypic frequency of the genotype Aa:

$P(Aa)=2pq=2 x 0.976 x 0.024 = 0.046$

Notice than:

$p^{2} + 2pq + q^{2} = 1\\x^{2} 0.976^{2} + 2 x 0.976 x 0.024 + 0.024^{2} = 1$

Then, the expected frequency of carriers is P(Aa)=0.046

The proportion of childs with CF is P(aa)=0.024

If two parents are carriers, then their genotypes are Aa.

Gametes produced by them can only have one allele of the gene. So they can either produce A gametes, or a gametes.

In the punnett square, we can see that there genotypic ratio is 2:1:1 and the phenotypic ratio is 3:1. So, there is a probability of 25% of having an unaffected child, with both normal alleles (AA); 50% of having a carrier child (Aa) and 25% (0.25) of having a child with CF (aa).

5 0

3 years ago