CBSE Questions for Class 12 Medical Biology Evolution Quiz 16 - MCQExams.com

The "Cambrian Explosion" alludes to the sudden appearance in the fossil record of complex creatures with mineralized skeletal remains. It might speak to the most critical transformative occasion in the historical backdrop of life on Earth. The start of the blast is commonly set around 542 million years prior, amid the Cambrian Period toward the beginning of the Palaeozoic Era.

So, the correct option is 'Cambrian'.

• Tasmanian wolf is a marsupial while the wolf is a placental warm-blooded creature and this shows convergent evolution.
• Convergent evolution refers to the formation of similar traits by unrelated groups of organisms. 
  
• As they are distantly related and occupying similar natural surroundings frequently grow autonomously similar morphological highlights that make them appear to be similar.

• The earth contains different layers of sediments, of which the bottom layer is the oldest layer and the upper layer is the most recent layer. Based on the age of rocks, a time scale was prepared and it is called the geological time scale, it depicts the different stages of the evolution of life on the earth over the past millions of years.
• It consists of three Eons, that consists of Eras which are divided into Periods that may be further subdivided into Epochs. These Eras, Periods, Epochs depict the time of origin and the dominance of the certain group of animals during certain Eras or Periods. It provides the most direct evidence for the concept of evolution.
  
• In order from oldest to youngest, the three Eons are as follows

• Cro-magnon man was originated 50,000-10,000 years ago'
  
• They lived in caves
• The first fossil was discovered in 1868.
• Large forehead.
• well developed speech
• Semi-circular and large jaw.
• Cranial capacity- 1650 c.c.

• Peking man is homo erectus pekinensis and Sinanthropus erectus
• Lived in built home
• hunts and wears 
• cranial capacity 850-1300 c.c.
• Complete erect posture

• Five factors that alter the Hardy-Weinberg equilibrium are Gene flow, Genetic drift, Mutation, Genetic recombination an Natural selection.
  
• These factors disrupt the genetic equilibrium by changing the allelic frequencies within the population.

• The Hardy-Weinberg principle states that allele frequencies in a population are stable and are constant from generation to generation. 
  
• Various factors like mutations, recombination during sexual reproduction, Genetic Drift, Gene Migration and Natural Selection can alter allele frequency leading to evolution.
  

• According to the Hardy-Weinberg principle the gene pool (total genes and their alleles in a population) remains constant. This is called genetic equilibrium. Sum total of all the allelic frequencies is 1. 
  
• So, the sum of Allelic frequencies,

• Adaptive radiation of marsupials in Australia, convergent evolution of placental mammals in Australia, the evolution of finches in Galapagos islands are examples of evolution due to environmental changes and do not involve human intervention.
  
• The appearance of antibiotic-resistant microbes and dark winged moth in England during the post-industrialization period is due to repeated and prolonged use of antibiotics and industrial pollution respectively involving human intervention, hence called anthropogenic evolution.

A. All living organisms were created same day [NO DIFFERENCE IN THEIR APPEARANCE]. 
B. They were created in the present form [NO EVOLUTION]. 
C. Their bodies and organs are fully developed to meet the requirement to run the life [NO ADAPTATION]

So the correct answer is "changeable flora and fauna".

frequency = no. of individuals with allele distribution/total no. of individuals 

              t$$^2$$ = 40/200 = 1/5

                    t = 0.4472 = 0.45

as we know , T + t = 1

                        T = 1-0.45

                        T = 0.55

So, correct answer to the question is 'T=0.55, t=0.45'. 

1. Allopatric speciation, also known as geographic speciation, is speciation that occurs when biological populations of the same species become isolated due to geographical changes such as mountain building or social changes such as emigration.
   
2. The cladistic species concept defines species as the group of organisms between two speciation events, or between one speciation event and one extinction event, or (for living species) that are descended from a speciation event.
   
3. Instantaneous speciation refers to the “Sudden/Abrupt development of new species”, which is reproductively and ecologically isolated from the parental species.