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ASEXUAL & SEXUAL
REPRODUCTION
ASSESS YOUR LEARNING

Due Monday, November 3, 2014
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#s 1-8
REPRODUCTION PRODUCES NEW
INDIVIDUALS OF A SPECIES.

The way a species reproduces determines how
much variation the new individuals will have.
REPRODUCTION…

Can produce new individuals that are identical to
or very different from one another.
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Which produces greater variation in individual
organisms… Asexual or Sexual Reproduction?
ASEXUAL REPRODUCTION
 Involves
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only one parent.
All offspring that result from asexual
reproduction are identical to that parent.
In other words, the adult makes an exact copy of
itself.
There are several different forms of asexual
reproduction.
1. BINARY FISSION
BINARY FISSION


Only 1 cell organisms, and some protists, such as
amoebas and some algae, reproduce by binary
fission.
During binary fission, a cell splits exactly in
two, producing two identical individuals.

Binary = two
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Fission = splitting or dividing (cleavage)
REMEMBER…


The Protista Kingdom consists of unicellular
lifeforms (lifeforms with only one cell) who have a
nucleus.
The primary difference between protists and
monera (bacteria) is that protists are more
complex, having a nucleus.
2. BUDDING
ORGANISMS…


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Such as hydra and yeast reproduce
asexually by budding.
During budding, the parent produces a small
“bud”, or a smaller version of itself.
In most animals (like the hydra) and unicellular
fungus (yeast), the bud detaches and becomes a
new individual identical to its parent.
In some (such as coral) the offspring remains
attached to the parent, forming a large structure
composed of many identical individuals.
SPORE PRODUCTION
SPORES

Similar to seeds, but are produced by the division
of cells of the parent, not by the union of two
cells.
ONE INDIVIDUAL


Will produce many spores, and each spore can
develop into a new individual identical to the
parent.
Most fungi, green algae, some molds, and nonflowering plants, such as ferns, reproduce by
producing spores.
4. VEGETATIVE REPRODUCTION
THERE ARE DIFFERENT FORMS OF
VEGETATIVE REPRODUCTION

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Vegetative reproduction is the reproduction of a
plant that does not involve the formation of a
seed.
Most plants can reproduce this way.
IF YOU TAKE A “CUTTING” FROM A
PLANT…

And place it in water, the cutting will grow roots
and eventually develop into a whole new plant.

Many plants, such as strawberries or spider
plants, grow runners that produce new plants.
TUBERS…

Such as potatoes on a potato plant, and bulbs,
from which tulips develop, are also forms of
vegetative reproduction.
THE ROOTS OF AN ASPEN TREE…

Form a shoot called a “sucker”; if the sucker
becomes separated from the original tree, it will
grow into a new aspen tree.
IN ALL OF THESE FORMS OF VEGETATIVE
REPRODUCTION…

The individual new plants that are produced will
be genetically identical to their parent plant and
to one another.
DIAGRAM IT!!!
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
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Make a labeled diagram illustrating the kinds of
asexual to show how an organism reproduces by
that form.
Compare your diagrams.
Describe any similarities and differences between
them.
Hand in your work
PARTHENOGENESIS:


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“Virgin Birth” in Greek.
Describes the process that transforms
unfertilized eggs into mature organisms.
In bees, unfertilized eggs become the male
drones, and fertilized eggs become female
workers and queens.
Has been observed in snakes and plants (figs)
SEXUAL REPRODUCTION
SEXUAL REPRODUCTION…


Usually involves 2 individuals.
Most animals and flowering plants reproduce
sexually.
OFFSPRING…
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Will have a mix of characteristics of both
individuals.
DOES SEXUAL REPRODUCTION ALWAYS
INVOLVE A MALE AND A FEMALE?
SEXUAL REPRODUCTION IN PLANTS &
ANIMALS…

Relies on the union of specialized cells known as
gametes.
MALE GAMETES:
 Sperm
cells.
FEMALE GAMETES:

Egg cells (ova)
THE UNION OF THE SPERM AND EGG
 Happens
during mating and is called
fertilization.
THE CELL CREATED BY THE JOINING OF…
2
gametes (egg & sperm) is known as
a zygote.
THE ZYGOTE
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Is the first cell of a new individual. The zygote
then divides into two cells. The same divisions
are repeated during a process called cleavage.
CONTINUED CELL DIVISION:

Results in a new multicellular life form known as
an embryo.
DEPENDING ON THE SPECIES
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Development of the embryo may occur inside the
female parent, or outside, inside the egg.
SEXUAL REPRODUCTION IN PLANTS

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Most plants produce both male (sperm) and
female (egg) gametes.
Some produce only female and only male.
Pollen: contains the male gametes; found in the
stamen (male part of plant).
Ovules: contain the female gametes; found in the
pistil (female part of the plant).
POLLINATION OCCURS WHEN POLLEN IS
TRANSFERRED FROM THE ANTHER TO THE
STIGMA.
CROSS-POLLINATION…
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Occurs when the pollen of one plant is carried to
the stigma of another by wind, water, or animals.
CROSS-FERTILIZATION

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Occurs when a grain of this pollen produces a
long tube that eventually grows down the style
into the ovary that contains the ovules.
In most plants, the embryo is produced inside a
seed.
THE SEED…
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
Protects the embryo and stores food the the
embryo for when it starts to grow into a new
individual.
Unlike animals, the new embryo may not begin
to grow for some time (remain dormant) until it
has suitable growing conditions.
ASEXUAL REPRODUCTION
Advantages
Produces lots of
individuals very
quickly-less energy
 E.G. Bacteria- every
20 minutes; 12 hrs, 10
million copies of itself
 Great advantage in
environments that
don’t change muchwarm/moist

Disadvantages
If conditions
change/become
unfavourable, the
entire population may
be wiped out.
 E.G. Every single one
of the 10 million could
be wiped out by an
anti-biotic.

SEXUAL
REPRODUCTION
Advantages

Provides lots of
variation which helps
a species survive
environmental
change.
Disadvantages
Takes a lot of energy
and time.
 Can only produce a
limited number of
offspring.

ORGANISM THAT REPRODUCE SEXUALLY &
ASEXUALLY
Most plants can.
 Seeds (sexually) or Cuttings/Bulbs/Runners
(asexually)


When plants reproduce by asexually, the
offspring is genetically identical to the parent.
SOME ANIMALS CAN REPRODUCE
SEXUALLY & ASEXUALLY:
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Aphids (small insects); throughout the growing
season, females produce live female young
without fertilization (asexual reproduction).
SOME ANIMALS CAN REPRODUCE
SEXUALLY & ASEXUALLY:

In the fall, when the temperature drops, the
female produces males & females who then
reproduce sexually, and lay eggs that will hatch
in the spring.
SOME ANIMALS CAN REPRODUCE
SEXUALLY & ASEXUALLY:

Sponges can also reproduce sexually and
asexually.
SOME ANIMALS CAN REPRODUCE
SEXUALLY & ASEXUALLY:
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Jellyfish alternate between sexual and asexual
reproduction.
HERMAPHRODITES
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Can produce both male and female gametes
(common garden worms & slugs).
Prefer to mate with other individuals, but in
times of environmental stress, can fertilize
themselves.
In humans, hermaphroditism is an extremely
rare sex anomaly. A true hermaphrodite is an
individual who has both ovarian and testicular
tissue (both reproductive organs).