Heredity and Evolution
Difference between Acquired and Inherited Traits
In a family, do siblings show more resemblance with each other or with their cousins?
We observe that we look more like our own brothers and sisters than our cousins i.e. siblings resemble more than cousins.
Why is it so?
Let us consider an example. Ram and Anuj are siblings, while Rajat is their cousin. Now, Ram and Anuj are more closely related, as they share a recent common ancestor i.e. their parents. However, Ram and Rajat are also related, but less closely than Ram and Anuj. Ram and Rajat share a common ancestor i.e. their grandparents.
With subsequent generations, variations make organisms more different than their ancestors.
Therefore, we can classify organisms according to their resemblance, which is similar to creating an evolutionary tree.
Classification refers to identification, naming, and grouping of organisms into a formal system based on similarities in internal and external structure, or evolutionary history. It determines the methods for organizing the diversity of life on Earth.
An acquired trait is experienced by an individual during his life time. It involves changes in non-reproductive tissues (or somatic cells), which cannot be passed on to the germ cells or progeny.
Inherited trait is a distinguishing quality or characteristic, which one acquires from the ancestors. These involve changes in the DNA. Hence, they are transmitted to the progeny.
Consider the following example to understand inherited traits.
Early understandings of inheritance and evolution
During his voyage, Charles Darwin observed many forms of life. He put forth his theory that evolution occurred as a result of natural selection. Also, variations occur in a population and beneficial variations are selected by nature.
However, he could not explain the reason for the occurrence of variations in the environment. This is because laws of inheritance, inherited and acquired traits, etc. were not known during that time.
Though Mendel performed various experiments and put forth the laws of inheritance, the two scientists never met. As a result, a complete understanding on mechanism of variations could not be established.
Some interesting facts:
Do you know that Goliath beetle of Africa is the heaviest insect in the world? It weights around 99.22 g.
Some beetles are even smaller than protozoa.
Video(s) by teachers
Have you ever thought how a baby boy or a baby girl is born? What directs the zygote to form a baby boy or a baby girl? What determines the sex of a child? Let us explore.
The answer to these questions lie in thread-like structures called chromosomes. These chromosomes are present in the nucleus of all cells. Thus, they are also present in the zygote. They carry the instruction for determining the sex of the baby.
But how many chromosomes do humans have and do all of them deter…
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