Heredity is the process by which the characteristics of an organism are passed on to its offspring. It serves as the basis for the commonality among the generations of a species. The rules of heredity govern which traits are more likely to be inherited compared to others.

• Reproduction: Heredity is the consequence of the reproductive processes of organisms. Species like human beings and various animals that reproduce sexually tend to have offsprings with distinct features and characteristics.
• Genes: Gene is the basic functional and physical unit of hereditary characters. They determine the appearance, structure, and other major characteristics of organisms.

Gregor Mendel, the father of genetics, conducted research experiments on garden peas to study the concept of inheritance and heredity. Based on his observation of inheritance patterns, he deduced the following laws:

• Law of Segregation: It states that inherited traits are passed in pairs. In the case of human beings, each pair carries one gene from the mother and another gene from the father. In other words, both parents contribute equally to the genetic makeup of the child.
• Law of Dominance: If both the dominant and recessive traits are present in an organism, the former being more expressive can be seen while the latter is not visible.
• Law of Independent Assortment: During the process of inheritance, genes of separate traits stay independent and uninfluenced by each other.

These principles together form the laws of inheritance/ heredity.

As you must have noticed, some of your habits, preferences, and talents are quite different from your parents. These traits that a person develops due to environmental factors are called acquired traits. However, your physical characteristics (height, complexion, eye colour, etc.) show similarities with those of your parents. The features that are passed on from one generation to another are called the inherited traits.

Unlike inherited traits, the acquired traits are not controlled by the genes, and thus, are not transmitted to the next generations.

Charles Darwin, known as the father of evolution, was the first person to throw light on the concept of evolution. In his book ‘On the Origin of Species’, he described that the organisms display changes in their physical and behavioural characteristics over time so as to acclimatize to the changing environment. Such modifications are a result of the natural process by which some organisms go extinct, while the others thrive. Theory of evolution is also summed up by the phrase ‘survival of the fittest’.

Speciation is a process by which new and distinct species of organisms are formed on account of the evolutionary factors like reproductive isolation, genetic drift, natural selection, etc. The existence of several subspecies of any particular parent species owes to the phenomenon of natural or artificial speciation.

Evolutionary relationships between different species are identified by tracing their alike characteristics in a backward direction. Simply stated, these species share some features due to a common ancestor.

Homologous organs are ones which possess a similar structure but perform different functions in different species. For example, the wings of birds and forelimbs of mammals are homologous. Contrarily, the analogous organs have a similar function yet a different structure—for example, the wings of birds and that of butterflies.

Fossils

Fossils serve as important evolutionary evidence. These are basically the preserved remains of an animal or plant that has perished million years ago. Fossils are examined to study the structure of ancient species and find evolutionary relationships.

The human species is known to originate from the family of primates. Human beings have exhibited great diversity since the time of their existence. While the complete history of human evolution cannot be accurately traced, it is accepted that the earliest humans were found in Africa. Thereafter, they moved to different parts of the world.

The theories of heredity and evolution have played a significant role in the development of key biological concepts. Genetics, the study of heredity, holds a major contribution in the field of medical science, in terms of disease prevention, treatment, and therapies. With the further research on hereditary and evolutionary factors, the system of healthcare is expected to witness greater advancements in the near future.

1. What is heredity and evolution Class 10?

Heredity and evolution chapter of class 10th dwells upon the rules of inheritance in human beings, the genetic variation, sex determination, and the basic concepts of evolution.

2. What is the basic concept of evolution?

The basic concept of evolution is that the biological populations change over time due to a number of factors like selection, genetic drift, mutation, and gene flow. For example, if there is a huge increase in the environmental temperature, only the organisms that can withstand heat will survive.

3. What is the importance of heredity in evolution?

The phenomenon of heredity decides which traits have been transferred from the parents to the offspring. While the dominant traits are passed along for a long time, the weak traits undergo modifications so as to bring the evolution of the species. Thus, it is important to study the hereditary factors to identify the evolutionary processes.

4. How are hereditary changes responsible for evolution?

Hereditary changes occur to enable the adaptation of organisms to the environment. The variations in inherited traits are collectively caused by natural selection, which in turn leads to evolution.

5. What is the difference between heredity and evolution?

Heredity is the transference of traits from parents to offspring. On the other hand, evolution refers to the gradual changes and improvements in the characteristics of organisms over subsequent generations.