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Session 3. Animal Life Cycles
Learning Goals
During this session, you will have an opportunity to
build understandings to help you:
- Describe the life stages in
the life cycle of an animal
- Comprehend the role of DNA in ensuring
the continuity of life from generation to generation
Video Overview
There are life processes that are so much a part of our experience
that it’s easy to take them for granted. Reproduction is one
of these processes. It seems quite simple: life cycles result in
offspring that resemble their parents. The life cycle patterns
of different
life forms vary, but the outcome is always the same – the continuity
of life is ensured from generation to generation. The next two
sessions explore two different life cycle patterns: animals and
plants. In
Session 3 we’ll focus on the Animal kingdom as one example of
life cycles that involve sexual reproduction. We’ll also explore
the underlying role of DNA in the process of reproduction.
View this video==> 
Video Outline
What was it before? Dr. Rodger Bybee, representing Science
T.R.A.C.S. of the Biological Sciences Curriculum Study (BSCS),
brings us into
the world of elementary school children as they answer this question
during their investigation of life cycles. Research on children’s
ideas is played out in the Science Studio where second and third
graders discuss “what comes before an egg?” An exploration
of the role of DNA in reproduction follows, starting with body
cell reproduction. This is contrasted with sex
cell production, which
results
in the
reliable transfer of hereditary information from parents to offspring
in sexual reproduction.
An interview with Dr. Sigal Klipstein answers
the question: “What
comes AFTER an egg?” as she describes the process of embryo
development in animals. She also contrasts the technology of cloning with
sexual reproduction and describes some pros and cons of this process.
Mary Bitterlich’s third graders
in Lakewood, Colorado offer us a firsthand view of the study of animal
life cycles. We visit
them as
they finish a Science T.R.A.C.S unit where the darkling beetle – an
insect – is their animal example.
An overview of different life
cycle patterns within the Animal kingdom follows, including fish,
amphibians, birds, reptiles and
mammals. Finally, Bottle Biology returns,
with Dr. Paul Williams introducing us to the “Brassica &
Butterfly System,” one
strand of this Web-based activity that brings together the life
cycles of a plant and an animal.
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