Living Environment Reproduction and Development

A. Two Types of Reproduction AsexualSexual One parent No gametes Involves mitosis only Offspring are identical to parent Involves two parents Gametes Involves meiosis to make gametes Offspring are genetically different from parents

B. Types of Asexual Reproduction 1. binary fission – one cell divides into two cells, similar to mitosis Ex: bacteria, paramecia, ameba

2. Budding – offspring develops as an outgrowth of parent’s body Ex: yeast

3. Spores – reproductive cells that can mature into the adult organism Ex: molds, ferns, mushrooms

4. Regeneration – new organism can grow from a part of the parent Ex: planaria, starfish

5. Vegetative propagation – part of a plant is used to grow a new plant Ex : runners on strawberries, bulbs, cuttings

CFU How are binary fission and budding alike? How are they different?

C. Sexual Reproduction Genes carried on gametes formed by meiosis Male and female gametes join – fertilization Zygote – fertilized egg

D. Internal vs. External Fertilization ExternalInternal Gametes join outside of body Most live in water Little parental care of young Ex: fish, frogs Gametes join inside of body Can reproduce on land Usually some care of young Ex: mammals, birds

E. Early Development Zygote undergoes repeated cell divisions (mitosis) – cleavage. Stem cells in the early embryo begin to differentiate or take on different “roles” forming various tissues and organs.

CFU Fill in the correct process. Body cell ________________ Gamete ________________ Zygote _____________ and ________________ Multicellular Organism

8 cell embryo – 3 week embryo