Variations and Inheritance

Do you know how to identify different organisms? To separate different organisms on the basis of differences? In this lesson we will go through:

1. How to separate different organisms?

2. What is Variation and Inheritance?

3. What is Selective Breeding?

4. What is Natural Selection?

5. Natural Selection in real life.

Keys:

Keys are a set of questions regarding a specific organism, that we want to identify out of a group of organisms. The questions are based on the answers, yes or no. We continue to answer questions regarding the organism until we arrive at the name of the organism. For example,

What is Variation and Inheritance?

A specie is a group of organisms that share the same features and can interbreed to produce a fertile offspring. But what causes variations in specie? Variation are caused by genes and the environment. Organisms belonging to a similar specie may have different genes and sometimes the organisms from a specie live in different environments. In order to adapt to the environment, changes may occur in the organisms belonging to the same specie. Such as many human beings have different eye colors because of different genes, sometimes people have a fair or dark complexation due to their different surroundings.

Now, what is Inheritance? Inheritance is the passing of features from parents to offspring. The features and characteristics of an organism are determined by its genes. Genes are made up of DNA and carry the information that needs to be transferred from parents to offspring. These genes carry a set of instructions for building a new organism. All organism have genes. Half of genes come from male parent and half from female parent. These genes are found inside the nucleus of every cell. They are found on long threads called chromosomes. Each gene is a set of instruction for the cell. The gene tells the cell how to make a particular substance. For example, one gene contains the information for making brown hair. As we grow, our cells divide to make more and more cells. Each time a cell divides, a complete set of chromosome and genes is passed on to the new cell. But how does the first cell came into being? The first cell was zygote, it was formed when the female gamete from the mother's egg fuses with male gamete in the father's sperm cell. The egg cell contained genes from the mother and the sperm cell contained genes from the father, hence exactly half of the chromosomes and genes come from each of the parent. Every cell in a human body has 46 chromosomes, 23 from male parent and 23 from female parent. So the genes are a mixture of those from our mother and father.

What is Selective Breeding?

In selective breeding people choose organisms from a population of organisms that shows variations. They choose the organisms with characteristics that they themselves want, they let those individuals breed and hence the individuals pass on their genes and characteristics to their offspring, forming an organism with the required characteristics and features.

What is Natural Breeding?

In natural breeding, there are variations among the individuals belonging to population of organisms. Individuals that have characteristics that provide the best adaptations to their habitat are more likely to survive. Only the individuals with best adaptations survive to breed. These individuals pass on their unique features and characteristics to their offspring.

Natural Selection in real life:

It often happens that we are recommended anti-biotics to cure diseases caused by bacteria. Have you ever noticed that when anti-biotics are taken for a long time, the bacteria becomes resistant towards the anti-biotics. This is because the bacteria develop features and characteristics to adapt to it's environment, which is the presence of anti-biotics. When the bacteria becomes resistant, anti-biotics are unable to cure the disease.

*all pictures are taken from google*