Download sexual reproduction

July 29, 2015
Topic 3
Passing It On
In this topic you will...
1) Distinguish between sexual and asexual reproduction
2) Identify examples of asexual and sexual reproduction
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HOW ARE CHARACTERISTICS PASSED FROM ONE
GENERATION TO THE NEXT?
- characteristics are passed
from parents to offspring
- these traits are called
inherited or heritable traits
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ASEXUAL REPRODUCTION
- Only one parent supplies the information to the offspring.
- Characteristics of the parent are the same as the offspring
ADVANTAGES
- No need to find a mate
- Reproduction can occur rapidly
DISADVANTAGES
- If environment changes the organism cannot adapt
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TYPES OF ASEXUAL REPRODUCTION
Your Turn...
Read pages 26 to 30 in your textbook and complete the chart
on the next page. For each type of asexual reproduction
explain the process, the advantages and disadvantages and
examples of organisms that reproduce that way.
1. binary fission
2. asexual spores
3. vegetative growth in plants
eg meristem
4. budding
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Binary Fission
Process
- single celled organisms
- cell duplicates its contents
- cell divides
Advantages
- can happen quickly
- only one parent required
Disadvantages
- no variation can occur
Examples
- bacteria, amoeba
Binary Fission (1:03)
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Asexual spores
Process
- single celled structures called spores
Advantages
- can happen quickly
- only one parent required
Disadvantages
- no variation can occur
Examples
- fungi and algae
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Vegetative Growth
(asexual reproduction in plants)
Process
- meristem is an area of rapidly reproducing cells at tips or roots
and stems
- meristems cells can specialize to make roots stems and leaves of
the plant
Advantages
- plants can reproduce from clippings
- can happen quickly
- only one parent required
Disadvantages
- no variation can occur
Examples
- plants
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Budding
Process
-cells near the base produce a new group of cells called a bud
Advantages
- can happen quickly
- only one parent required
Disadvantages
- no variation can occur
Examples
- cacti, sponges and hydra
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Cloning Controversy
What is Cloning?
- cloning in biology is the process of producing populations of
genetically- identical individuals
3:18
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Who is Dolly the
Sheep?
-
on July 5, 1996 dolly the
first cloned sheep was born
-
first mammal cloned
-
she lived to the age of 6
-
died on Feb. 14, 2003 of
lung disease and severe
arthritis
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Can people be cloned?
- not yet many claims have been made but have not been verified
Ethical Issues to be Considered
4 Corners Discussion... (Your group will answer the questions
and share your thoughts.)
1. What are the advantages and disadvantages?
2. Should there be any controls on experiments?
3. Who should be allowed to perform human cloning and
under what conditions?
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SEXUAL REPRODUCTION
- two parents supply the genetic material
- offspring is a combinations of characteristics of both parents
36 sec
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BEST OF BOTH
WORLDS
- many organisms can
produce sexually and
asexually.
- some molds like
Rhizopus (bread mold)
produce spores
(asexual) but also
produce zygospores
that are a combination
of genetic material
from two sources
(sexual).
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BACTERIAL CONJUGATION
- Primitive form of sexual reproduction
- A connection forms between two cells and genetic material is
exchanged.
- A form of genetic recombination occurs but not
reproduction because there is no increase in number.
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Sexual Reproduction in Plant
- plants reproduce by producing seeds
- angiosperms are flowering
plants
- gymnosperms produce
seeds in cones
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Sexual Reproduction in Plants
2:40mins
page 33 Label diagrams
A. - style, stigma and ovary are female parts (PISTIL)
- anthers are the male part which produce pollen grains
B. - pollen grain lands on stigma and forms a tube to fertilize
the egg
C. - prior to fertilizations other cells form the cotyledon to
nourish the embryo
D. - in angiosperms fruit surrounds the developing seed
- fruit develops from the wall of the ovary
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Sexual Reproduction in Animals
- for sexual reproduction in animals to be successful specific
requirements must be met.
- both male and female gametes must arrive in the same place at
the same time.
- gametes are delicate and require a moist environment
Sperm
Egg
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- for organisms that live in a liquid environment fertilization
occurs outside the female.
- for organisms that live on land, fertilization occurs inside the
female
- internal fertilization protects the egg cells inside the body, where
conditions are warm and moist (mammals)
- zygotes require specific conditions to develop
- after the zygote develops and divides many times it
becomes an embryo and later becomes a fetus.
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Look at page 51, draw and label the stages of the
human life cycle in Figure 1.47 in your notes
And Fill in the chart in your notes using the
information in your drawing.
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Your Turn...
Topic 3 Review
We will complete Topic 3 Review as a
KAHOOT
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