Answer:
Adaptation.
Explanation:
Adaptation occurs when the acid tolerance of several plant species has increased significantly in the polluted area. The main reason for this tolerance is the change in the genetic makeup or mutation occurs in the cell due to the exposure of DNA to the chemicals of the environment that cause pollution. The plant adopt the environment by producing certain chemicals that cancel the effects of pollutants and as a result, the plant survive.
With shorter necks, giraffe ancestors could not reach food-containing branches on tall trees. This resulted in the directional selection of giraffes with longer necks.
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Why is choosing a direction necessary? </h3>
It nearly appears obvious that the giraffe's long neck developed as a result of a lack of food in the lower branches of trees. The giraffe has a significant advantage because it is taller than any other mammal and can feed where few others can.
When compared to modern giraffes, the giraffe's ancient predecessors had a shorter neck. The plants that were lying at a higher level were inaccessible to them. Giraffe phenotypes have changed in various ways, and now have long necks to reach vegetation that is higher up. The extreme form is chosen above other features in directional selection. It was decided to choose the long-necked giraffe over the short-necked.
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The phenotype is - 75 % red and 25 %brown.
The genotype is hRhR - 25%
hBkhR - 50%
hBrhBk - 25%.
<h3><u>Explanation:</u></h3>
The cross given here is a simple dominant - recessive relationship between the three types of alleles of hair colour. The genes of this characteristics are present in autosomes, so will be segregated equally among all the sexes of the offsprings.
Now the genotype of auburn and red with black mother is given. So during gametogenesis, the gametes from the parents will be
Father - hBr and hR
Mother - hBk and hR
So, the probable combinations are hBrhBk, hBrhR and hBkhR.
The frequency of the combinations are 25%, 25% and 50% respectively.
The phenotypic ratio will be red : brown as 3:1.
2 is the answer hope this helps