The Differences Between Asexual and Sexual Reproduction
Organisms need to make more organisms like themselves and they do this through
reproduction. Reproduction is the production of offspring or new individuals through a sexual or
asexual process. Reproduction is the creation of new individuals from previously existing organisms.
Most organisms reproduce sexually which includes the fertilization of an egg and sperm, BUT some
organisms reproduce asexually without fertilization of an egg and sperm.
Asexual reproduction is the simplest form of reproduction, occurring in many simple plants,
animals, bacteria, protists, fungi, and micro-organisms. In asexual reproduction there is only one
parent. The result of asexual reproduction is an offspring that is identical to the parent. It can be
considered a clone of the parent because it has the exact same genetic information (DNA) as the
parent.
One example of asexual reproduction is binary fission in bacteria. In binary fission one cell
divides to form two identical cells. A cell first copies its genetic material (DNA) and then divides into
two separate cells. Each new cell has its own complete copy of the parent’s genetic information
(DNA). Another example of an organism that reproduces asexually is the hydra. The hydra uses a form
of asexual reproduction called budding. In budding part of the parent develops into a new organism.
The new organism then pinches off from the parent and lives independently. The new organism is
genetically identical (same DNA) to its parent. The flatworm Planaria can also reproduce asexually by
fragmentation. In this form the body of the parent breaks into two distinct pieces, and each piece will
become a new offspring.
An advantage of asexual reproduction is that an organism can reproduce by itself and it can
happen quickly. Asexual reproduction can lead to a rapid population growth in the species (lots of
them). A disadvantage to asexual reproduction is that only clones are reproduced and there is no
genetic variation (differences in the species). An organism would not be able to adapt and evolve to a
changing environment. That means they would die if the environment changes.
The majority of animals such as humans reproduce by sexual reproduction. In sexual
reproduction, two parents combine their genetic material (DNA) to produce offspring that are
genetically DIFFERENT from both parents. Genetic material from the parents is transferred in a special
cell called a sperm (from the male) and an egg (from the female). When the egg and the sperm join
together it is called fertilization. During fertilization, the egg and sperm combine their single sets of
chromosomes to form a zygote containing two sets of chromosomes for a species (half from each
parent). When a cell has 2 set of chromosomes, it is called diploid.
With sexual reproduction the offspring receives half of its genetic material from its father and
half from its mother. However, the mitochondrion that the offspring got from its mother (in the egg)
has DNA as well.
An advantage of sexual reproduction is genetic variation (differences within the species). With
genetic variation an organism has a higher chance of adapting and surviving. The disadvantage of
sexual reproduction is that two organisms are involved therefore it takes longer for offspring to be
made.
Questions
1. What is reproduction? ___________________________________________________
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2. What are the two forms of reproduction? ____________________________________
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3. How many parents are there in asexual reproduction? _________________________
4. What kinds of organisms reproduce asexually? ________________________________
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5. In asexual reproduction, the offspring’s genetic material will be _____________ to the
parent’s genetic material. They are _________________ of each other.
6. What is an advantage of asexual reproduction? _________________________________
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7. What is a disadvantage of asexual reproduction? ________________________________
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8. How many parents are there in sexual reproduction? ____________________________
9. What kinds of organisms reproduce sexually? ___________________________________
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10.When the egg and sperm join, this is called ______________________________________.
11.In sexual reproduction, the offspring’s genetic material is __________________________
from the parent’s genetic material.
12.What is an advantage of sexual reproduction? ____________________________________
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13.What is a disadvantage of sexual reproduction? ___________________________________
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14.Which organelle has DNA in it and is only inherited from the mother?
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15. Flowering plants produce eggs in the flower. The pollen in the flower is the male sex cell.
Would pollination be asexual or sexual reproduction? ______________________________
Why? _____________________________________________________________________
16. Write whether these organisms reproduce sexually or asexually.