Traits- Inheritance and types
Inheritance and Heredity
Traits- Inheritance and Types
This concept mainly deals with the principles of inheritance and variation.
After reading the concept, students will be able to:
- Give examples of inherited traits and acquired traits.
- Understand the difference between inherited and acquired trait.
- Identify the following inherited traits-
- Freckles on skin.
- Right and left-handedness in humans.
- Tongue rolling in humans.
- Understand what is sickle cell anaemia and what is haemophilia disease.
- Know about muscular dystrophy in humans.
Each concept is explained to class 5 students using descriptions, illustrations, and concept maps. After you go through a concept, assess your learning by solving the two printable worksheets given at the end of the page.
Download the worksheets and check your answers with the worksheet solutions for the concept of the Principles of Inheritance and Variation provided in PDF format.
Traits :
Every individual has specific characteristics acquired from their parents or previous generations. The same is transferred to the next generations as well. These characteristics are called traits.
Inheritance :
The passage of these traits from one generation to another is called inheritance.
Variations :
Every individual is unique when the genetic makeup is considered. Traits are modified slightly with the passing generations which leads to variations. These variations may arise due to the following reasons
- Change in habitat
- Change in weather and environment
- Exposure to certain chemicals
- Variations are natural and are necessary for the continuity of life on earth. Variations allow the individuals to change as per the external changes which helps them to survive in all possible conditions.
Genes
- Genes determine what traits are passed down from the parents to their offspring.
- Genes constitute of genetic material, which is located in the nucleus of every cell of our body.
- A child inherits equal quantities of genetic material from each of its parents
Inherited Traits:
- The traits that are passed from parents to offspring are called inherited traits.
- These traits are classified as dominant and recessive.
- Dominant traits are expressed in every condition in an individual.
- Recessive traits are expressed only when they have a pair of genes to support them.
- Inherited traits are transferred from one generation to another.
Ear lobes
- The soft fleshy part present in the lower region of the outer ear is called the ear lobe.
- Ear lobes are either free or attached.
- Free earlobes is a dominant trait whereas attached earlobe is a recessive trait.
Hair and skin colour
- The colour of skin and hair too depends on the genes we inherit from our parents.
- The colour of our hair and skin depends on melanin.
Freckles
- The presence of freckles is a dominant trait, whereas the absence of freckles is a recessive trait
Handedness
- Right handedness is a dominant trait whereas left-handedness is a recessive trait.
Nose width
- The broad nose is a dominant trait whereas the narrow nose is recessive.
Rolling the tongue
- The ability to toll the tongue is a dominant trait whereas the opposite is recessive.
Length of the toe
- A longer second toe than the first toe is a dominant trait, whereas the first toe being longer than the second is a recessive trait.
Acquired Traits
- Traits that are acquired after our birth while we grow up till our death are called acquired traits.
- Acquired traits do not pass from one generation to another.
- The traits can be acquired due to any of the following reasons:
Examples of acquired traits are as follows:
Scars
- Scars may develop due to an injury, accident or vaccination.
Building of muscles
- There is a considerable increase in the mass of muscles after our birth. As our body grows further, the muscles in our skeletal system develop.
- Exercise is also a vital factor that leads to muscle development.
Vaccination
- The process of injecting the causal organism of a disease into a living body, in dead or mildly active form, is called vaccination.
- Vaccination leads to the development of antibodies in our body, which increases our body's immunity toward that particular causal organism.
- The vaccination process has eradicated several deadly viral diseases like smallpox, leprosy, tetanus, mumps and AIDS.
Role of External Factors in Acquired Traits
Habits and interests
- People develop habits based on their interest and their requirements.
- People learn knitting in cold areas where the sweater is worn throughout the year, whereas those living in hot regions do not have such an inclination toward knitting.
- Children develop hobbies based on their interests. Some enjoy singing while others enjoy playing basketball.
Habitat
- People living in hilly areas do not tend to gain height as they carry heavy loads during their everyday chores.
- People living in the mountains have more red blood cells in their blood than those who live in the plains because the level of oxygen decreases as we go up.
- People living in Kerala speak Malayalam to converse, whereas those in Delhi prefer Hindi.
- People in south India consume rice as a major component of their diet, whereas those in north India consume wheat-based products.
Food and Health
- People develop resistance to diseases depending on the kind of food they eat and the physical activity.
- Not eating healthy food makes us prone to diseases.
Age
- An increase in age leads to several changes in the body, leading to the development of certain characteristics.
For example
- Greying of hair, appearance of wrinkles, weakening of bones, development of breathing problems, weak eyesight etc.
Inheritance of Diseases
Sickle celled Anaemia
- This disease affects the shape of the RBCs, which are responsible for carrying oxygen to different parts of the body.
- They become crescent-shaped, which leads to a lowering of oxygen in the body to a considerable level.
Haemophilia
- This disease affects the clotting of blood.
- It was initially named the Christmas disease after the person in whom it was diagnosed for the first time.
Muscular dystrophy
- This disease causes progressive loss of muscle mass, affecting muscular functions like locomotion.
Huntington’s Disease
- This disease leads to the gradual breakdown of neurons which affects the brain leading to certain imbalances in the body.
New Words
Nucleus- The nerve cells which are the structuraland functional unit of nervous system
RBC- : Also known as red blood cell. It is one of the cells found in blood which is responsible for transferring the oxygen to various cells of body.\
Did You Know?
- Humans have 90% of the genetic material that matches mice and 98% that matches chimpanzees.
- Genes are made of DNA, and it stands for Deoxyribonucleic Acid.
- We get half of the DNA from the mother and half from the father.
- The phenomenon of gradual changes observed in a population over time that leads to the development of new species is called evolution.
