Oparin and Haldane's theory and Miller's experiment are the proof that long complex molecules that carry information such as DNA, might have formed on early earth.
Explanation:
Oparin and Haldane Hypothesis states that life on Early earth could have evolved by chemical evolution.
Oparin and Haldane said that the reducing atmosphere of the early earth caused simple inorganic molecules to react by using sunlight and formed molecules like amino acids and nucleotides.
These monomers combined to form polymers, they would have attained self-replicating tendency eventually these would have assembled into structures and these macromolecules had also made membrane-bound organelle.
Although this hypothesis is not fully accepted but part of it which talks about formation of molecules is accepted.
Millers and Urey in their experiment created an artificial reducing environment like that of early earth. They used a heated pool of water, atmospheric gases like H2O,CH4,N2, NH4 and sparks of electricity. After running the experiment for some days they found that amino acids, sugars, lipids and other organic molecules had formed.
Their hypothesis is not fully accepted but part of is evident that organic building block is formed from inorganic constituent on the earth.
When it comes to population evolution and genetics, we cannot fail to cite the Hardy-Weinberg principle which emphasizes that if evolutionary factors such as natural selection, mutation, migration and genetic oscillation do not act on a particular population, the frequencies genotypic proportions will remain constant.
The five requirements for a population to be in Hardy-Weinberg equilibrium are:
- Large-scale breeding population: For a population to be in Hardy-Weinberg equilibrium, it is important that this population is large, as small populations favor genetic drift (unanticipated fluctuations in allele frequencies from one generation to another).
- Random mating: In order for the Hardy-Weinberg equilibrium to occur, it is necessary that the mating occur at random, with no preference for certain groups within the population. In this case, we say that the population is in panmixia, that is, they all mate at random.
- No mutations: Mutations alter the total alleles present in a population (gene pool). Therefore, in a Hardy-Weinberg equilibrium population, no mutations should occur.
- No gene flow: When there is gene flow due to migration or immigration of individuals, some genes may be included or excluded from the population. Thus, in an equilibrium situation, no gene flow occurs.
- Lack of natural selection: For a population to be in Hardy-Weinberg equilibrium, natural selection must not be acting on it. If natural selection acts, some genotypes will be selected, modifying the allelic frequencies of the population.
Answer:
The correct answer will be option-D.
Explanation:
Calcium plays an important role in muscle contraction as they are released from the sarcoplasmic reticulum after they receive electric impulse.
Calcium triggers the muscle contraction cycle as these calcium ions bind to the troponin-tropomyosin complex. This binding exposes the myosin-binding site on the actin on which high energy myosin binds and cross-bridge is formed.
This cross-bridge formation causes the contraction of the sarcomere and therefore muscle contracts.
Thus, option-D is the correct answer.
The answer is chloroplasts
