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7
Science
Cells and Heredity
U2L3 – Sexual and Asexual
Reproduction
Types of Reproduction:


Asexual Reproduction
* new organisms from one parent
* DNA of offspring is identical to DNA of
parent.
Sexual Reproduction
* sex cells from two parents combine
* DNA of offspring is different from either
parent.
Examples of Asexual
Reproduction

Vegetative Reproduction
* grow off of parent plant
or sprout to form new plant
*runner – above ground stem
(strawberry)
*tubers – underground stem
(potato)
*plantlets – tiny plants that grow
along edges of plant leaves

Binary Fission
*Division of parent organism into 2 parts
* ex. Bacteria, Paramecium (Protist)
*Type of reproduction of prokaryotes

Budding
* small, exact copy of adult grows from
body of parent
* ex. Hydra, yeast

Regeneration
* whole new organism grows from each piece
of parent
* ex. Sponge, sea stars, planaria (flatworm)
* regrowing damaged or lost body parts

Spore
* specialized cell that can survive harsh
conditions
* light; carried by wind
* ex: fungus, fern
Sexual Reproduction
Two sex cells (egg and sperm) come together –
process called fertilization.
 Sperm – formed in male reproductive organs
 Egg – formed in female reproductive organs
-- much larger & contains food material
New cell formed by
fertilization is called
a zygote
Read and do pg. 116
Advantages of asexual
reproduction

Organism can reproduce quickly

Offspring are identical to parent, to any favorable traits
are passed on

Parent does not need to find a partner

All offspring can make more offspring (not just females)

Advantages of sexual
reproduction
Increases genetic variation

Offspring have different traits than their parents

Especially important if the environment changes
 Read page 119
Write this question in your notebook:
“Why do MOST organisms use sexual
reproduction and not asexual
reproduction?”