Answer:
Yes, dogs do have a internal organization
Explanation:
(division of labour)
Answer: The correct answer is -
D) giraffes having increasingly longer necks over time.
Natural selection is an evolutionary mechanism that was proposed by Darwin.
According to this mechanism, organisms that are better capable of adapting to their changing environmental conditions, survive and increase their number through reproduction whereas other are eliminated from the population.
Example - Long neck of Giraffe, which is much elongated, lofty stature, that was beautifully adapted for browsing on the higher tree branches. This was an adaptation with slow and gradual change in the gene frequency as the lower vegetation was eaten by other animals. Due to this, giraffes had to search for other source (that was higher tree branches).
This is considered as a peculiar example of natural selection.
Answer:
e. Epistatic interaction of the two genes
Explanation:
The 9:7 ratio is typical of the Duplicate Recessive Epistasis.
The expected phenotypic ratiio of the offsrping of a dihybrid cross is:
9 A_B_
3 A_bb
3 aaB_
1 aabb
In the Duplicate Recessive Epistasis, the A_bb, aaB_ and aabb individuals all have the same phenotype, making for the ratio 9:7. What those three genotypes have in common is that in all of them at least one of the two genes is homozygous recessive (either <em>aa</em> or <em>bb</em>).
This usually happens one the products of genes A and B are enzymes of the same metabolic pathway.
Whenever both A and B are present, the pathway can produce the final product and a certain phenotype. However, if any of the dominant alleles is missing, the enzyme is not produced and therefore the final product of pathway is not produced, giving the other phenotype.
