First Term Lesson Note for Week Two
Class : JSS 3
Subject : Basic Science
Topic : Family Traits
Duration : 40 Minutes
Period : Single Period
Reference Book :
- Basic Science for Junior Secondary school, Book 3.
- Lagos State Unified schemes of work for Junior Secondary school.
- Online Resources
Instructional Material : Chart showing examples of family Traits.
Learning Objectives : By the end of the lesson learners will be able to
i. Define Family Traits
ii. List example of family Traits
iii. Differentiate between dominant and recessive traits.
Content :
FAMILY TRAITS
Family Traits can be defined as transmittable characteristics which are passed from parent to offspring or children or progeny from one generation to another through reproduction.
Examples of Family Traits
1. Colours of skin ( dark or fair complexion)
2. Colour of eyes (dark brown, blue eyeballs)
3. Colour of hair (black, brown, Grey)
4. Height (Tallness or Shortness)
5. Intelligence
6. Shape of nose
7. Blood groups ( A, B, AB or O)
8. Albinism
9. Ability to roll tongue.
Examples of trait in plants are : colour of flower, shape of fruits, tallness or height, size of leaf, taste of fruit, leaf texture, etc.
Genetics is the scientific study of heredity and variation in living things. These heredity and variation occurs during reproduction in living things through transfer of materials from parents to their offspring.
The scientist who study genetics are called Geneticist.
Heredity is a branch of genetics which deals with the study of how children or offsprings take after their parents. It can be defined as the study of how characteristics are passed on from one generation to the next.
Variation can be described as the differences between parents and offspring, and among the offspring that exist.
Gene : This is a unit inside a cell which controls a particular quality of a living thing that has been passed on from it’s parent.
Genotype : This is the sum total of the genes that an offspring inherits from it’s parents is known as the genotype or genetic make-up. The actual Physical expression of characters in the organisms is Phenotype.
Chromosomes : These are structures located within the nucleus of a living cell. Chromosomes contain the gene. They occur in pairs. Human beings have 23 pairs = 46.
Meaning of Dominant and Recessive Traits.
Dominant Trait or gene is a feature that appears in each generation. This is a trait that completely dominates or dictates the appearance of the offspring. Dominant trait is that character that over shadows another in the offspring.
Recessive traits or genes are features or characteristics which appear in one generation and disappear in another. The recessive traits are usually suppressed by the dominant traits.
Heredity and Environmental factors
Aside genes, environmental factors also determine how an inherited trait develop in an individual. The environmental factors that affect
inherited traits are :
i. Diseases
ii. Food that we eat (balanced and unbalanced diet)
iii. Weather conditions
iv. Health facilities availability or non-availability
v. Insects and other animals.
Importance of Family Traits.
1. It can be used to know how a particular trait in a family is either inherited or transmitted from one generation to the other.
2. It can be used to detect diseases that run in a family.
Application Areas of Genetics.
- To determine the paternity of a child whose fatherhood is being disputed.
- Crime detection: The use of fingerprints and blood group can help in detecting criminals by Law enforcement agencies.
- Choosing of the sex of a baby that a couple may want is now possible through genetics.
- Blood transfusion : It is useful in determining compatible blood groups before blood transfusion to prevent agglutination and death of the recipient.
- In Agriculture, genetics helps to increase yield, and improve quality of product.
Presentation Steps :
Step 1 : Revision of the previous lesson with the learners.
Step 2 : Introduces the new topic to the learners by explaining family Traits and gives examples.
Step 3 : Explain some terms used in genetics and differentiate between dominant and recessive.
Step 4 : Mentions some importance of family Traits and Identify the application area of genetics
Evaluation :
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Conclusion :