CBSE Questions for Class 12 Medical Biology Evolution Quiz 1 - MCQExams.com

• The correct match of hominids and their brain sizes are:
• Homo habilis - $$650-800$$ cc
• Homo neanderthalensis - $$1400$$ cc
• Homo erectus - $$900$$ cc
• Homo sapiens - $$1350$$ cc.

• The Hardy-Weinberg principle provides the mathematical framework for genetic equilibrium. Genetic equilibrium describes the condition of an allele or genotype in a gene pool (such as a population) where the frequency does not change from generation to generation. 
• Genetic equilibrium describes a theoretical state that is the basis for determining whether and in what ways populations may deviate from it.
• The Hardy-Weinberg equilibrium can be disturbed by a number of forces, including mutations, natural selection, non-random mating, genetic drift, and gene flow (immigration, emigration, or migration).

• Origin and evolution were about 30-35 million years ago. 
• Originated from Egypt
• The oldest and the most primitive is Parapithecus.

• Precambrian is one of the four eras in earth's geological history. 
• Precambrian actually meant period before the Cambrian period of the Palaeozoic era. 
• Precambrian is divided into three periods- Azoic (no life), Archaeozoic (invisible life) and Proterozoic (age of early life). 
• It is believed that life appeared in Archeozoic period of Precambrian era.

Correct Option: D

Explanation:

• Any factor, which can disturb the frequency of alleles in a population is likely to affect the Hardy-Weinberg equilibrium. 
• The alleles in a population can be altered by mutation, migration, genetic drift, recombination, and natural selection.

Solution:

• Correct answer is option A.
• Explanation for correct option:
• An eon is the largest timespan in the geological timeline. An eon is subdivided into eras.
• The Azoic Era was the oldest and long-lasting stage in the development of earth. There was no evidence of life in this era.
• The Azoic era is the era when origin of the continental shelf occurred. 
• The continental shelf (Pangaea) was formed by the silica rich granite rocks of less density.

According to Darwin, Marsupials were considered inferior with respect to placentals. These species thrived where there was no competition or in other words in the absence of natural selection. Marsupials existence in Australia and New Zealand gives us clue about the geological period and we get evidence that these continents were joined long ago. As per continental drift theory around 30 to 40 million years ago, South America and Australia were joined in the Southern hemisphere and it is believed that marsupials could have migrated between these islands which proves both the continental drift and the related geological period.