Chapter 9 Lesson 2 "How Organisms Reproduce"

Materials:

• One piece of blank scratch paper per student.
• Worksheet, "Observing Mitosis"
• Worksheet, "Reproduction"
• compound light microscope and Prepared slides of an onion tip. Look around these are very common and you may have them. We did in Koyukuk. If you don't have no fear. Your students will be able to use these pictures of onion root tips under a compound scope. These were taken by one of my old college professors let me know what you think.

Objective:

• Students will recognize the advantages and disadvantages of sexual reproduction.
• Students will recognize the advantages and disadvantages of sexual reproduction.
• Students will compare mitosis and meiosis.
• Students will trace the steps in the fertilization of an egg.

Teacher Input: Introduce the student question, "How do animals give off the same DNA to their offspring?" Ask students what must happen for the fetus on page 208 to grow and develop. After a brief discussion mention that pregnant women should not get x-rayed. Do they have any reason why? Why type of cells are affected by an x-ray? What could happen if a pregnant women is exposed to x-rays? Show the picture of Mitosis and explain that type of cell division. Next show the picture of Meiosis or Meiosis, and explain that type of cell division.

Guided Practice: Have the students write down the terms asexual reproduction on the top of a blank sheet of paper. Then draw two overlapping circles underneath the words. Ask if they remember what type of diagram it is and what it is used for. Introduce the two types of reproduction using these pictures: asexual1, asexual2. Sexual Reproduction in the Human Life Cycle. Now give them these facts and have them list them in the right place on the Venn diagram.

• Exact copies of DNA passed to the offspring.
• bacteria and yeasts
• has two parents
• plant reproduction
• cell reproduction as you grow
• mitosis
• animal reproduction.
• meiosis
• takes longer to produce offspring
• Organism can reproduce alone.
• produces diverse offspring.
• offspring lack diversity
• two cells join to form one

Ask the students to define fertilization. Explain that there are two types, internal and external. Use a comparison of two fish spices to explain the difference. Use these pictures to help:

Internal fertilization.

External fertilization

Help students with definitions encountered in this section: mitosis, chromosome, gamete, meiosis, external fertilization and internal fertilization.

Independent Practice: Students will now complete the Reproduction workbook activity.

End of day 1.

Day 2,

Students will begin by using these pictures or their microscopes to answer the questions about the onion root tip lab. During the lab activity a slide show of the onion root tips will be presented over the video conference equipment. Following the lab students should take the quiz on lesson 2.

Check for Understanding: Students will take the quiz on lesson 2 "How organisms reproduce"

Conclusion: Cells divide forming new cells. In cells with a nucleus this division happens first. followed by division of the entire cell into two new cells, each with its own nucleus. Mitosis and meiosis refer to the division of a cell's nucleus during cell division. Meiosis occurs during the formation of sex cells that will later combine with other sex cells to form a complete organism. Mitosis occurs for growth and development as well as asexual reproduction. Both have the cells DNA duplicated but in Meiosis the cell division happens twice which leaves cells with half the original DNA.

Duration:

30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).

Alaska Content Standards Addressed in this lesson:

• SCI A-9 Students will understand the transfers and transformations of matter and energy that link living things and their physical environment, fro molecules to ecosystems. (Flow of Matter and Energy)
• SCI A-10 Students will understand that living things are made up mostly of cells and that all life processes occur in Cells (Cells)
• SCI A-11 Students will understand that similar features are passed on by genes through reproduction (Heredity).
• SCI A-12 Students will distinguish the patterns of similarity and differences in the living world in order to understand the diversity of life and understand the theories that describe the importance of diversity for species and ecosystems.
• SCI A-13 Students will understand the theory of natural selection as an explanation for evidence of changes in life forms over time (Evolution and Natural Selection).
• SCI A-14 Students will understand
  • the interdependence between living things and their environments:,
  • that the living environments consists of individuals, populations, and communities: and
  • that a small change in a portion of an environment may affect the entire environment (Interdependence);

• SCI A-15 Students will use science to understand and describe the local environment (Local Knowledge); and:
• SCI B- 1 Students will use the processes of science; these processes include observing, classifying, measuring, interpreting data, inferring, communicating, controlling variables, developing models and theories, hypothesizing, predicting, and experimenting;
• SCI B- 2. Students will design and conduct scientific investigations using appropriate instruments
• SCI B- 3. Students will understand that scientific inquiry often involves different ways of thinking, curiosity, and the exploration of multiple paths.
• SCI B - 4. understand that personal integrity, skepticism, openness to new ideas, creativity, collaborative effort, and logical reasoning are all aspects of scientific inquiry.
• SCI B - 5. employ ethical standards, including unbiased data collection and factual reporting of results; and
• SCI B - 6. employ strict adherence to safety procedures in conducting scientific investigations.
• SCI C - 1. know how the words "fact," "observation," "concept," "principle," "law," and "theory" are generally used in the scientific community;
• SCI C -2. understand that scientific knowledge is validated by repeated specific experiments that conclude in similar results;
• SCI C- 3. understand that society, culture, history, and environment affect the development of scientific knowledge;
• SCI C- 6. understand that scientific discovery is often a combination of an accidental happening and observation by a knowledgeable person with an open mind;
• SCI C- 7. understand that major scientific breakthroughs may link large amounts of knowledge, build upon the contributions of many scientists, and cross different lines of study; and
• SCI C- 8. understand that acceptance of a new idea depends upon sup- porting evidence and that new ideas that conflict with beliefs or common sense are often resisted.
• SCI D- 1. apply scientific knowledge and skills to understand issues and everyday events;
• SCI D-2. understand that scientific innovations may affect our economy, safety, environment, health, and society and that these effects may be long or short term, positive or negative, and expected or unexpected;
• SCI D- 4. evaluate the scientific and social merits of solutions to everyday problems;
• SCI D- 5. participate in reasoned discussions of public policy related to scientific innovations and proposed technological solutions to problems; and
• SCI D- 6. act upon reasoned decisions and evaluate the effectiveness of the action.