Lesson Notes By Weeks and Term v4 - SHS 3

Lesson Video

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Performance objectives

• Identify and describe the main components of animal and plant cells.
• Explain the functions of various cell organelles.
• Compare and contrast the structures of animal and plant cells.
• Apply knowledge of cell structure to real-life Ghanaian contexts.

Lesson summary

This lesson explores the fascinating concept of human variation – why we are all unique, from our fingerprints to how our bodies fight disease. We see this diversity every day in Ghana, in the rich tapestry of our different ethnic groups, family resemblances, and individual talents. This variation is not just about physical appearance; it is a fundamental principle of biology rooted in our genes. Understanding it is crucial for advancements in medicine, justice, and even our social harmony. We will investigate how scientists and doctors use their knowledge of these differences to save lives, solve crimes, and improve human health and well-being.

Lesson notes

Teacher's Note: Begin the lesson with a quick "Think-Pair-Share" activity. Ask learners to look at their partners and identify three ways they are different from each other (e.g., height, skin tone, shape of nose, hair texture) and one way they are similar. This creates an engaging entry point. A. What is Variation?

Variation refers to the differences that exist among individuals of the same species. In humans, this is why no two people (except identical twins) are exactly alike. These differences are caused by two main factors: Genetic Factors: Differences in the genes we inherit from our parents. This is called heritable variation. Environmental Factors: The effect of our surroundings and lifestyle (e.g., diet affecting weight, sunlight affecting skin tan).

Our focus today is on genetic variation, which is the raw material for evolution and the basis for many applications in science. B. Types of Genetic Variation

There are two main types of variation we can observe: Discontinuous Variation: Definition: This is a type of variation that shows a limited number of distinct, clear-cut categories or phenotypes, with no in-between forms. Cause: It is usually controlled by one or a few genes. Environmental factors have little to no effect. Examples in Ghana: Blood Groups: You are either group A, B, AB, or O. There is nothing in between. Ability to Roll Tongue: You can either roll your tongue into a 'U' shape, or you cannot. Albinism: A person either has albinism or they do not. PTC Tasting: (Phenylthiocarbamide) Some people can taste this chemical as bitter, while others cannot taste it at all. Continuous Variation: Definition: This type of variation shows a complete range of measurements from one extreme to the other, with many intermediate forms. Cause: It is usually controlled by many genes (polygenic inheritance) and is often influenced by environmental factors. Examples in Ghana: Height: People are not just "tall" or "short." There is a wide range of heights in our class and country. Skin Colour: There is a beautiful spectrum of skin tones in Ghana, from very dark to lighter shades, not just two or three distinct colours. Weight: An individual's weight can fall anywhere along a wide continuum. Intelligence: Measured by IQ, it shows a normal distribution (a bell-shaped curve) in the population. C. Advantages and Disadvantages of Variation

Evaluation guide

• Describe the application of principles of variation among humans to improve life.
• Think Pair Share: through think pair sharing, the learner research and share with another learner the
• advantages and disadvantages associated with genetic variation among humans. A general class
• discussion follows, think pair share allows many learners to share their thoughts, as it also fosters social