2ND TERM

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TOPIC: BIOLOGY OF HEREDITARY (GENETICS)
SUB-TOPIC: TRANSMISSION AND EXPRESSION OF CHARACTERS IN ORGANISMS
BEHAVIOURAL OBJECTIVES: At the end of the lesson, the students should be able to:
a. Define genetics
b. Define heredity and variation
c. Mention transmittable characters in human
d. Mention transmittable characters in plants.

CONTENT:
Genetics is the branch of biology that deals with the study of heredity and variation. Heredity or inheritance refers to the transmission and expression of characters or traits in organisms from parent to off springs as well as among the off springs. The scientist that studies genetics is known as geneticist.
Those characters that parents pass to the off spring are known as transmittable characteristics. In human beings, they include- body stature, shape, height, baldness, colour of skin, hair, eyes, etc. Intelligence, blood group, sickle cell anemia, etc.

EVALUATION:
1. Define variation
2. Mention five transmittable characters in human beings and plants.

ASSIGNMENT:
Explain any five terms used in genetics.



PERIOD: 3
SUB-TOPIC: MONNOHYBRID CROSSING
BEHAVIOURAL OBJECTIVES: At the end of the lesson, students should be able to:
a. Explain terms used in genetics
b. State reasons for Mendel’s choice of pea plant.
c. State Mendel’s first law of inheritance.
CONTENT:

Genes are hereditary units or basic units of inheritance. They are responsible for the transmission of characters from parents to off springs. They are located on the loci of the chromosome. Some terms used in genetics are:
v. Characters or traits: They are inheritable attributes or features possessed by an organism e.g. skin colour, height etc.
vi. Allele morph: Pairs of genes that controls contrasting characters.
vii. Mutation: A change in the genetic makeup of an organism resulting in new characteristics.
viii. Mendel chose pea plant because:
- They have very short life span
- They are usually self pollinated
- They have several unique characteristics.
Mendel’s first law states that when two pure breed individuals showing a pair of contrasting characters are crossed then the characters will segregate out in definite proportions in the second filial generation.

EVALUATION:
i. Define the following terms
a. Allele morphs
b. Mutation
ii. State Mendel’s first law
ASSIGNMENT:
A farmer crossed two seen seeds with white and brown seed coats. If all the fi were white, find the following:
a. Fi
b. F2
c. Phenotype and genotype ratio
d. Cross fi with a homozygous white and show the crossing as well as the genotype ratio.




PERIOD: 4
SUB-TOPIC: DIHYBRID CROSSING
BEHAVIOURAL OBJECTIVES: At the end of the lesson, students should be able to:
a. State Mendel’s second law of inheritance
b. Draw and fill punnete table
c. Define test cross and back cross
CONTENT:
Mendel’s second law states that when two pure breed individuals showing two or more pairs of contrasting characters are crossed, then the characters segregate out in ardently in the second filial generation. Test cross is the crossing of an organism with the homozygous recessive organism. Back cross is the crossing of an organism with the homozygous recessive organism from the parental generation.

EVALUATION:
1. State Mendel’s second law
2. Define test cross
ASSSIGNMENT:
Draw and label a chromosome and DNA structures.

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