Life Cycle - Organisms (5B)Pre Lab

OBJECTIVES: Comparing asexual and sexual reproduction. Explaining the importance of reproduction. VOCABULARY: asexual reproduction sexual MATERIALS: worksheet

Students use a worksheet to compareasexual and sexual reproduction.

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BACKGROUND: Reproduction is important for the survival of all living things. Without a mechanism for reproduction, life would come to an end. There are two types of reproduction to learn in elementary grades, asexual and sexual reproduction. Many teachers are afraid of discussing reproduction, but if presented as a factual lesson it is easy for the students to understand the principles without the standard giggles.

Asexual reproduction refers to simple cell division that produces an exact duplicate of an organism. There are many different types of asexual reproduction which can be discussed to show students the variability of modes of reproduction. Some single-celled organisms reproduce by simple cell division, this is called binary fission. In this manner, the mother cell simply splits in half producing two daughter cells. Some cells reproduce by unequal division of the cells, this is called budding. In this process the bud forms as a knob on the mother cell. The nucleus divides and identical parts go to the mother cell and the bud. The bud may grow until it is as large as the mother cell and can form buds of its own. In some cases buds remain attached to the mother cell. In others, they break away and live as separate organisms.

Sexual reproduction involves the joining of male and female sex cells. The sperm refers to the male sex cell and the egg refers to the female sex cell.

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PROCEDURE: As you discuss this with students, tell them that trees, fish, flowers, and many other organisms have sperm and eggs. Tell students to look at organisms on their way home, to see if they can predict which ones reproduce by sexual or asexual means. There are some reproductive strategies that are difficult to classify for students. Ferns, fungi, and some protozoa reproduce by spore production. Spores are formed by divisions of special mother cells and are released from the parent organism. A single spore develops into a new organism. The worksheet shows students the difference between asexual and sexual reproduction. The answers are as follows: 1. yes; 2. in half; 3. little one celled creatures; 4. zygote 5. female, male, a baby; 6. larger organisms with organs; 7. larger organisms cannot simply divide, it is more efficient for little organisms to reproduce in that manner.