Sci 9 Lesson 6 April 12 - Sexual Reproduction

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  • 1. Homework from last class:
    • Complete the Meiosis cut and paste worksheet activity
    • Complete 6-1B activity on p. 197
    Trisomy 18 karyotye
  • 2. Chapter 6 pp. 204-220 Ch. 6.2 Sexual Reproduction
  • 3. Sexual Reproduction
    • What is sexual reproduction ?
    • Sexual reproduction brings non-identical gametes together to form a new organism .
    • Occurs in 3 stages :
    • Mating - the process by which gametes are
    • bought together at same place and same
    • time
    • Fertilization - process by which egg and
    • sperm join to form a new organism
    • Development - the process by which an
    • organism develops as an embryo
    pp. 204 - 206
  • 4. Methods of Fertilization
    • External or Internal Fertilization
    • In order for external or internal fertilization to produce a successfully developing embryo, certain conditions must be met :
    • The embryo must have enough nutrients.
    • The temperature must not be too cold
    • or too hot.
    • There must be enough moisture so that
    • the embryo does not dry out.
    • The embryo must be protected from
    • predators and items in the environment
    • that can potentially harm it.
    p. 207 A dog embryo
  • 5. External Fertilization
    • external fertilization: sperm and egg join outside parents’ bodies
    • Advantages
    • Very little energy required to mate
    • Large numbers of offspring produced
    • Offspring can be spread widely in the environment - less competition between each other and parents
    • Disadvantages
    • Many gametes will not survive
    • Many eggs will not be fertilized
    • Offspring are often not protected by parents, so many of them die
    pp. 208 - 209 External fertilization in frogs
  • 6. Internal Fertilization
    • internal fertilization: sperm and egg join inside parents, embryo is nourished inside mother
    • Advantages
    • Embryo protected from predators
    • Offspring more likely to survive, as many species will protect their them while they mature
    • Disadvantages
    • Much more energy required to find mate
    • Fewer zygotes produced, resulting in less offspring
    • More energy required to raise and care for offspring
    p. 210 - 211 Internal fertilization in sea turtles
  • 7. Pollination
    • Pollination: transfer of male gametes ( pollen ) from male reproductive parts of a plant to the female reproductive parts of a plant ( ovules )
    • A form of internal fertilization in plants.
    • Pollen can be carried by wind or other organisms .
    pp. 212 - 214 Stamen: male reproductive organ Pistil: female reproductive organ
  • 8. Video – “Life’s Greatest Miracle”
  • 9.
    • Embryonic development: the early development of an organism
    • (the first 2 months after fertilization in humans)
    • Stages
    • End of the first week - ball of cells called morula
    • End of second week - hollow ball
    • called a blastula
      • Cells at this stage are stem cells , and have the ability to develop into any kind of cell
    • In the next stage the embryo is known as a gastrula and develops
    • 3 layers:
    • ectoderm (skin, nerves) mesoderm (muscles, bones) endoderm (lungs, liver, digestive system lining)
    Embryonic Development pp. 216 - 217
  • 10. Fetal Development
    • Differentiation: the process where cell layers form the organs and tissues of a baby; divided into 3 trimesters.
    • First Trimester (0-12 weeks)
    • Organ systems begin to develop and form. Bone cells form.
    • Second Trimester (12-24 weeks)
    • Rapid growth from 12-16 weeks.
    • Third Trimester (24+ weeks)
    • Continued growth, especially of brain. Fat begins to deposit at 32 weeks to keep fetus warm at birth.
    pp. 218 - 219
  • 11. Sexual Reproduction: Advantages and Disadvantages p. 220
  • 12. Homework for next class:
    • Complete Sexual Reproduction crossword puzzle
    • Complete Check Your Understanding Qs on p. 223:
    • #s 1, 2, 6, 13, 14, 15, 16
    • Read over class notes and check class blog
    • http://www.msoonscience.blogspot.com
  • 13. Works Cited
    • Images taken from the following sources:
    • http://www.genetics.com.au/factsheet/fs30.asp
    • http://idle.slashdot.org/story/09/02/12/1647241/Zoo-Offers-Erotic-Tour-For-Valentines-Day
    • http://www.emailvariety.com/tag/dolphin/
    • http://www.turtles.org/i3404006.jpg
    • http://www.teachersdomain.org/asset/oer08_img_flowerimage/
    • http://mydcdoctor.com/custom_content/c_137923_first_trimester.html
    • http://ethics.davidson.edu/index.php/2010/02/the-moral-status-of-human-embryos/