Ch. 2 Lesson 1: Reproduction 5th Grade
NOTES
What are sexual and asexual reproduction?
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Species survival depends on its ability to produce new members.
Every organism comes from a parent organism through the process of
reproduction.
Reproduction: the transfer of genetic material from parent to offspring.
Genetic material controls how the new individual will look and function.
Two main types of reproduction:
o Sexual reproduction
o Asexual reproduction
Sexual reproduction: production of a new organism from two parents
A sperm cell from a male and an egg cell from a female join into a single unit
during fertilization.
Genetic material from both parents is contained inside the fertilized egg cell.
The fertilized egg will develop into a new individual.
A trait is any characteristic of a living thing (Ex. Height and color of a flower)
Asexual reproduction: the production of a new organism from a single parent.
Offspring has the same genetic information as the parent and are identical to the
original parent.
Male and female sex cells do not combine during asexual reproduction.
All members of the bacteria kingdoms and most unicellular protists reproduce
asexually.
Most fungi and many plants can reproduce asexually during a part of their lives
and sexually during another.
Jellyfish, corals, worms, and some echinoderms can form new offspring asexually
Some kinds of frogs, lizards, frogs, and insects can reproduce asexually.
How do organisms reproduce asexually?
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There are many methods of asexual reproduction.
This eliminates the need for an organism to find a mate.
Splitting:
o Reproduce by splitting into two cells
o Organism makes a copy of its own genetic material
o Some bacteria can divide into 2 new organisms every 10-20 minutes
Budding:
o Cnidarians, sponges, and come fungi reproduce this way.
o A small part of the parent’s body grows into a tiny and complete version
of the parent
o Sometimes the bud breaks off and continues to grow
o With coral, the bud stays attached to the parent
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Other forms of asexual reproduction in animals:
o With some species of fish, insects, frogs, and lizards, the females produce
eggs but fertilization by male sex cells doesn’t take place.
o Eggs develop into a new animal without fertilization – queen bees lay eggs
and some are fertilized and some not, the fertilized eggs become
females/worker bees and the unfertilized eggs become males/drone bees.
Vegetative Propagation:
o Plants undergo a form of asexual reproduction.
o Vegetative propagation: is asexual reproduction in plants that produces
new plants from leaves, roots, or stems.
o Runners are plant stems that lie on or under the ground and sprout up as
new plants – many plants reproduce by producing these. Ex.: strawberry
plants, most grasses, aspen trees, and ferns
How do sexual and asexual reproduction compare?
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Asexual reproduction is more convenient and the organism doesn’t have to
depend on another organism and can live in isolation.
Asexual organisms are usually well suited to their environment and their offspring
are also.
Sexual reproduction promotes a variety in species.
Sexual reproduction gives rise to offspring that may be better suited to
environmental changes than either parent – offspring are not identical to either
parent.
In sexual reproduction the offspring may be bigger, smaller, or faster than others
– fast mice are less likely to be caught than slow mice and may survive more
frequently than slower mice, so over time the fast mice will reproduce and pass
this trait onto their offspring.