Activities

Activity 1: Observing Contrasting Traits

Aim: To identify and list the seven pairs of contrasting traits in pea plants as studied by Mendel.

Procedure:

1. Study Figure 4.1 in your textbook.
2. Create a table listing the seven characters and their two opposing traits (Dominant and Recessive).
3. Observe plants in your local garden and try to identify any variations in flower colour, seed shape, or plant height.

Observation Table:

Conclusion: Mendel’s choice of discrete, non-blending traits was crucial for his success in formulating the laws of inheritance.

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Activity 2: Pedigree Analysis Exercise

Aim: To understand the standard symbols used in human pedigree analysis and trace a specific trait.

Procedure:

1. Learn the standard symbols for pedigree analysis (e.g., Circle for female, Square for male, Filled symbol for affected individual).
2. Study Figure 4.14 (a) and (b) in the textbook.
3. Identify the inheritance pattern (Autosomal Dominant vs. Autosomal Recessive) in each case.
4. Try to construct a simple pedigree chart for a trait in your own family (e.g., presence of earlobes or ability to roll the tongue).

Conclusion: Pedigree analysis is a powerful tool in human genetics to predict the likelihood of inheriting specific traits or disorders.

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Activity 3: Researching Polygenic Inheritance

Aim: To investigate how traits like human skin colour and height show continuous variation.

Procedure:

1. Measure the heights of your classmates and record them.
2. Plot the data on a graph (Frequency vs. Height).
3. Observe if the graph resembles a 'Bell Curve' (Normal Distribution).
4. Research how many genes are thought to control skin colour in humans.

Observation: Unlike Mendel's pea plants, human height does not fall into two distinct categories (Tall/Dwarf) but shows a gradient of variations.

Conclusion: Polygenic traits are controlled by multiple genes, and their expression is often influenced by environmental factors.

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Activity 4: Chromosomal vs. Genic Behaviour

Aim: To compare the behaviour of chromosomes and genes during cell division.

Procedure:

1. Study Table 4.3 in your textbook.
2. Note the similarities in how both occur in pairs and segregate during gamete formation.
3. Discuss why Sutton and Boveri concluded that chromosomes are the carriers of genes.

Comparison Table:

Conclusion: The parallel behaviour of chromosomes and genes forms the basis of the Chromosomal Theory of Inheritance.