Name the phenomenon that governs the following: - 5

i) Green beetles living in green bushes are not eaten by the crows.

ii) Number of blue beetles in green bushes increases, only because the red beetles living there were trampled by a herd of elephants.

iii) No ‘medium height plants’ are obtained in F1 generation, upon crossing pure tall and dwarf pea plants.

iv) Tails of mice were surgically removed for several generations; still, mice had tails in the following generations.

v) A migrant beetle reproduces with the local population; as result genes of migrant beetle enter the new population.

OR

a) What are fossils and how is the age of fossils determined?

b). During artificial selection, which features of wild cabbage were selected to give rise to i) Cabbage ii) Cauliflower

i. This because of the natural selection of the green beetle while other coloured beetles could not stay live. Thus the natural selection of beetles colour to be green increases the survivability of the beetle's species in green bushes.

ii. The increase in the beetles in green bushes increase because of the phenomenon of genetic drift, where to maintain a balance in population some variation become more prone to danger while other gain advantage of survival.

iii. The dominance of T (tall type genotype) over t (short genotype) results Tt genetic coded to be tall and not medium

iv. The reappearance of the tail in the mouse is an example of an acquired trait. The change of cutting mouse tails has not affected the chromosomes of the mouse. Hence there is reappears of the trait in other generation.

v. The above statement is an example of gene flow phenomenon.

This implies that the genetic character of the migrant betel has flown from the new beetle to the existing population too. Hence this is an example of gene flow phenomenon.

OR

a). Fossils are an impression of pre-historic organisms in the different strata of the earth’s crust.

Fossil are formed when dead organism are not completely decomposed. The organism are not completely decomposed. The organisms may get trapped in resins of the tree, lave of volcanoes or hot mud which when hardens, retains the animal’s parts thus, forming fossil.

The age of a fossil can be determined by the following ways.

(A) Relative Method: By estimating the age of the layer of earth crust where the fossils found. Fossil near the surface are recent, and those in the deeper layers are more ancient.

(B) Radio-carbon dating method: By detecting the ratios of different isotopes of carbon in the fossils.

Fossil help in determining the connecting links between their primitive ones. e.g archaeopteryx.

The radioactive carbon has a half-life of approximately 5000 years.

b).

Artificial selection as the name suggests is a technique of growing plants with certain desired or specific characteristics by carefully choosing the set of desired characteristics from the parent plant.

In case of wild cabbage a huge number of different varieties have been formed by using the process of artificial selection which include broccoli, kale etc.

i) Cabbage

For the growth of cabbage from the wild cabbage by the process by the process of artificial selection, the short distance between the leaves is selected.

ii) Cauliflower

For the growth of cauliflower from the wild cabbage by the process by the process of artificial selection, the sterile flower forming a large flower is selected from wild cabbage.