Asexual versus Sexual Reproduction – Test review
Science 9
Asexual Reproduction occurs when there is only one parent that gives rise to an
offspring which has the identical genetic makeup of the parent. It occurs in most single
celled organisms such as bacteria and some multicellular organisms such as fungi and
some plants.
Sexual reproduction involves the combining of genetic information from two parents to
produce a new organism that is a combination of both parents. It occurs in most complex
organisms.
1. Complete the following table comparing asexual and sexual reproduction.
Asexual reproduction
Sexual reproduction
Number of parents
Genetic information of
offspring compared to
parents
Complexity of organism
that uses this method
Example of an organism
that uses this method
2. Complete the summary table below by describing the five asexual methods of
reproduction and providing an example of an organism that utilizes each method. You
may want to draw a diagram along with your description.
Description
Example
Sexual Reproduction
During Sexual Reproduction two specialized cells called sex cells or gametes (egg and
sperm) are involved. Each gamete has only half the amount of DNA in a normal cell and
are produced by a specialized type of division called meiosis. The reason why the
gametes only contain half the DNA is so that when the new cell or zygote forms it will
contain the correct amount of DNA. Zygotes are not identical to the parents. This
means that Sexual Reproduction produces variation in offspring. This variation is
important in a changing environment where an organism may have to be slightly
different to survive.
Animal Sexual Reproduction
As in plants, animals must have a single sperm join its nuclear material with the nuclear
material of an egg to form a zygote. Different species have different methods to achieve
this result. Their fertilization patterns dictate how this is achieved. Sperm and egg must
remain moist so that the egg is penetrable and the sperm can swim to it. An external
fertilization pattern occurs when the gametes (sex cells) meet outside the bodies of both
parents. To keep the sperm and egg moist it must occur in an aquatic environment.
Internal fertilization occurs inside the female body in terrestrial or land animals. The
sperm is transferred using a specialized structure from the male into the female body.
The sperm must swim to the egg inside the female body where fertilization will take
place. Some land animals such as birds and reptiles will then form a hard outer covering
or shell around the zygote after which development will continue outside of the female
body. Animals such as kangaroos and koala bears have specialized pouches where the
young embryo will continue to develop and still others such as cows, dogs and humans
have the young embryo complete development inside the female womb.
1. What is the main advantage of sexual reproduction?
2. What is a zygote? How is it different from daughter cells produced by asexual
reproduction?
3. Classify the following as either sexual or asexual reproduction. Explain your choice.
a) A small piece of a cactus breaks off the plant, falls to the ground, and begins to grow.
b) Pollen from a male poplar tree fertilizes sex cells on a female poplar tree.
c) Two earthworms each produce sperm and eggs and fertilize each other.
d) A flatworm is cut in half and grows intro two flatworms.
3. Complete the concept map using the following terms:
gametes, fragmentation, budding, hermaphrodites, binary fission,
spore formation, and
regeneration.