Heredity and Evolution
Difference between Acquired and Inherited Traits
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
The individuals of a family (parents and offspring) have more similarity in comparison to others. This is because certain characteristics are passed from the parents to the offsprings without any variation..
Heredity is defined as the transmission of characteristics from one generation to another. These characteristics may be physical, mental, or physiological.
Commonly observed heritable features are curly hair, a particular type of ear lobe, hair on ears etc.
Transmission of traits from the parents to progeny - Mendel’s Work
Gregor Johann Mendel (1822 – 1884) was the first to carryout the study on the transmission of characteristics from the parents to the offsprings. He proposed that heredity is controlled by factors, which are now believed to be segments of chromosomes or genes.
Mendel performed experiments on a garden pea (Pisum sativum) with different visible contrasting characters. He selected seven contrasting pairs of characters or traits in a garden pea. These include round/wrinkled seeds, tall/short plants, green/yellow pod colour, purple/white flower colour, axial/terminal flower, green/yellow seed colour, and inflated/pinched ripe pods.
Mendel performed experiments in three stages:
Selection of parents: Mendel selected true breeding pea plants with contrasting characteristics for his experiment. True breeding plant is the one that produces an offspring with the same characteristics on self-pollination. For example, a tall plant is sai...
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