WEEK 4: REPRODUCTION

TOPIC: Reproduction

MAIN AIM: To help the learners understand the reproductive system 

SUBSIDIARY AIM: By the end of the lesson, learners should be able to;

1. Define reproduction
2. List and explain the types of reproduction 
3. Explain the terms associated with reproduction in vertebrate

PERSONAL AIM: To keep strictly to time allotted to  each stage of the lesson

PREVIOUS KNOWLEDGE: The learners know about reproduction from their previous lesson 

TEACHING AIDS: Research work from the internet, pictures 

PROCEDURE: The teacher present the lesson with the following steps 

STEP ONE: Definition of Reproduction

 Reproduction is the process by which living organisms give rise to /produce young ones (offspring) of the same kind or species. Reproduction can be by asexual or sexual means. Asexual reproduction involves only one parent while sexual reproduction involves two parents; male and female parents. There must be union of sex cells (fertilization) for sexual reproduction to occur.

Reproductive systems in vertebrates are made up of organs that enable vertebrates to produce offspring that are similar to themselves. All vertebrates reproduce by sexual means. The reproductive systems of vertebrates consist of gonads (for the production of sex cells or gametes) and reproductive ducts and glands (for secretion of essential substances).

For reproduction to occur there must be fusion of male and female gametes, a process known as fertilization.  

STEP 2: Types of fertilization

1. Internal fertilization
2. External fertilization

Internal fertilization: This is the type of fertilization that occurs inside the body of the female parent. The male animal introduces spermatozoa into the body of the male during mating or copulation. A sperm cell then fertilizes the egg to form a zygote. This type of fertilization occurs in most reptiles, birds and mammals.

External fertilization: This is the type of fertilization in which the eggs are laid into the external environment (usually inside water bodies). The eggs and sperms are released at the same time. The sperms fertilize the eggs outside the females body. After mating, the male and female animals go their separate ways.This kind of fertilization is seen in some fishes and amphibians.

STEP 3: TERMS ASSOCIATED WITH REPRODUCTION IN VERTEBRATES

OVIPARITY: This is a reproductive process in which the female organism lays eggs into the external environment. The eggs may be fertilized internally or externally. Vertebrates involved include fishes, amphibians, birds, reptiles, 

VIVIPARITY:  In this reproductive process, the young ones develop inside the body of the female and obtain nourishment from the mother. When the young one(s) develop fully, they are given birth to alive. In this method of reproduction, fertilization is internal. 

OVIVIPARITY/OVOVIPARITY: In this reproductive process, the eggs are retained inside the body of the female but the embryo derives its nutrients from the yolk in the egg and not directly from the mother. The eggs hatch after full development and the young ones are released out of the body of the female parent. Examples can be seen in reptiles like snakes and some fishes like basking shark.

EVALUATION: 

1. Define reproduction
2. List and explain the types of reproduction 
3. Explain the terms associated with reproduction in vertebrate

CONCLUSION: The teacher concludes the lesson by summarizing the topic from the beginning and give assignment to the learner.

ASSIGNMENT: 

1. Define reproduction
2. List and explain the types of reproduction