(a) Darwin's theory of Natural Selection is widely accepted but some limitations have been identified by modern biologists. Mention the limitations identified. (b) Name and state the most accepted theory of evolution in modern times. (c) Mention any two ways the limitations identified in Darwin's theory of evolution are explained in modern biology.

Correct Answer:

(a) Darwin’s theory could not explain how the variations arise.
(b) Synthetic theory of evolution: Origin of species is based on the interaction of genetic variation and natural selection.
(c) Mutation, recombinants formed during meiosis/hybridization/crossing over/sexual reproduction.

Step-by-Step Explanation:

(a) Limitations of Darwin's Theory of Natural Selection:
While Charles Darwin's theory of natural selection successfully explained how species adapt to their environments and evolve over time, it had a major limitation during his time. Darwin realized that variations among individuals are the raw material for evolution, but he could not explain the cellular or molecular mechanisms behind how these variations actually arise and how they are inherited from one generation to the next. This was because the field of genetics had not yet been established.

(b) Most Accepted Modern Theory of Evolution:
The most widely accepted explanation of evolution today is the Synthetic Theory of Evolution (often referred to as Modern Synthesis). This theory state-of-the-artly merges Darwinian natural selection with Mendelian genetics. It states that the origin of new species is based on the interaction of genetic variation (such as changes in allele frequencies within a gene pool) and natural selection, which determines which of these variations are successfully passed on to future generations.

(c) Explanation of Variations in Modern Biology:
Modern biology fills the gaps in Darwin's theory by identifying the exact sources of genetic variation. Two primary ways these variations are explained include:
1. Mutation: Random changes in the DNA sequence that introduce entirely new alleles into a population.
2. Recombination (Crossing Over/Meiosis/Sexual Reproduction/Hybridization): The shuffling and recombination of existing genes during sexual reproduction (specifically during crossing over in meiosis) and hybridization, which creates unique combinations of traits in offspring.