Lesson Notes By Weeks and Term - Senior Secondary 3

Biology of heredity 2

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TERM – 1ST TERM

WEEK SIX

Class: Senior Secondary School 3

Age: 17 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Biology

Topic: Biology Of Heredity 2

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

  1. Explains
  2. Identify basic ecological concepts
  3. Identify components of the ecosystem

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,

demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S

ACTIVITY

STEP 1

INTRODUCTION

The teacher discusses  Mandels experiments with red and white flowered peas.

Students pay

attention

STEP 2

EXPLANATION

Teacher show students a chart depicting products of cross fertilization and self fertilization.

Students pay

attention and spot their differences.

STEP 3

DEMONSTRATIO

N

Teacher discusses the applications of the principles of heredity

Students pay

attention and

participate

STEP 4

NOTE TAKING

The teacher writes a summarized

note on the board

 

The students

copy the note in

their books

 

NOTE

BIOLOGY OF HEREDITY 2

Mendel's work in Genetic

Gregor Mendel a monk in Austria (1822 -1884) is referred to as father of Genetics because of his work which formed the foundation for scientific study of heredity and variation. Gregor Mendel carried out several experiment on how hereditary characters were being transmitted from generation to generation. He worked with garden pea called possum sativum. Pea because

- Peas are usually self-pollinating.

- They have a very short life span than animals and some other plants.

Procedure

  1. Selection of Traits: Mendel chose traits that showed clear variations, such as seed color, flower color, and plant height.
  2. Pure Breeding: He selected pea plants that were true-breeding for specific traits, meaning they consistently produced offspring with the same trait.
  3. Cross-Pollination: To control the mating process, Mendel manually transferred pollen from the male reproductive organ (anther) of one pea plant to the female reproductive organ (stigma) of another. This process is called cross-pollination.
  4. Observation: Mendel carefully observed and recorded the traits of the parent plants (f1 generation) and their offspring (f2 generation) through several generations.

           

  1. Formulation of Laws: Based on his observations, Mendel formulated the Laws of Inheritance, including the Law of Segregation and the Law of Independent Assortment.

Mendelian traits:

Mendel discovered trait or characters that be transmitted from parents to offspring. He studied various inherited characteristics in pea plant. The traits or character are: height/length, colour of seeds, and surface of seed coat. Other examples of traits that can be transmitted from parents to offspring include: the blood group, the Rhesus factor, skin colour eye colour shape and body weight.

Mendelian Laws of inheritance

Mendel's Laws of heredity explains the principals of Mendelian inheritance. Mendelproduced offspring of pea plant by self-polling on and cross –pollination and as a result of his experiments, he came out with his certain deductions termed Mendel's law. The two laws are

  1. First law (Law of segregation) states that genes are responsible for the development of individual and that they are independently transmitted from one generation to another without undergoing any alteration.
  2. Second Law (Law of independence assortment of genes) states that each character behaves as a separate unit and pair of alleles for a given character distributes itself in the gemetes during formation does not affect the way other allelic pair for other character distribute themselves.

Application of the principles of heredity

  1. In agriculture, the principles of heredity are applied through selective breeding to improve seeds and enhance disease resistance in crops. By selecting plants with desirable traits such as high yield, pest resistance, or tolerance to specific environmental conditions, breeders can create new varieties that inherit these advantageous characteristics. This process, known as genetic improvement, plays a crucial role in developing crop varieties that contribute to sustainable and resilient agriculture.
  2. In medicine, the principles of heredity are vital in understanding and managing conditions like sickle cell disease. Sickle cell disease is a genetic disorder where an individual inherits abnormal hemoglobin genes. By recognizing the hereditary nature of this condition, healthcare professionals can provide targeted interventions, genetic counseling, and potentially gene therapies.
  3. The principles of heredity play a role in determining blood group compatibility. Blood groups are inherited traits, with the ABO and Rh systems being the most significant. Understanding heredity helps in predicting potential blood group combinations between parents and their offspring. This information is crucial in blood transfusions and organ transplants, ensuring compatibility to prevent adverse reactions. Genetic knowledge about blood groups guides medical professionals in selecting suitable donors and recipients, improving the success and safety of these medical procedures.

Gross Fertilization and Self fertilization

- Gross Fertilization: Gross fertilization refers to the fusion of gametes (sperm and egg) from two different individuals, typically in the context of sexual reproduction. This term is often used in contrast to self-fertilization.

- Self-Fertilization: Self-fertilization occurs when a single individual is capable of producing both male and female gametes and can fertilize its own eggs. This is a form of fertilization that takes place within the same organism.

Outbreeding and inbreeding

- Outbreeding: Outbreeding involves the mating of individuals that are less closely related. It is a breeding strategy that promotes genetic diversity within a population. Outbreeding can occur naturally in a population or be encouraged through selective breeding practices.

- Inbreeding:  Inbreeding involves the mating of individuals that are closely related, such as siblings or close relatives. This can lead to an increase in homozygosity, meaning that certain genetic traits may become more prevalent. Inbreeding can have both positive and negative effects, as it may amplify both desirable and undesirable traits.

- Crossbreeding involves mating individuals from different breeds or populations. It's often done to combine desirable traits from each parent, promoting genetic diversity and potentially enhancing certain characteristics in the offspring.

EVALUATION: 1. State the two mendelian laws of genetics.

  1. Identify and explain the applications of the principles of heredity
  2. Differentiate between self fertilization and cross fertilization

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively