1. Why Sex?: http://www.youtube.com/watch?v=gRpEt61XM4M&safe=active
Sexual Reproduction
Why Sex?:

2. Monoploid gametes (n) are produced by meiosis or “_____________” with half the chromosomal material as the parent cell
________________________________ takes place resulting in greater genetic variation

3. ________________ (egg/sperm) come from 2 separate parents.
Gametes fuse together during _________________ creating a _________ (diploid 2n)

4. Advantages of Sexual Reproduction:
Offspring genetically _________from parents
This variation means that even if changes in environment occur some offspring may survive (__________________)

5. Sexual Reproduction in Simple Organisms
Conjugation:
often found between ____
___________________ like bacteria
Bridge of cytoplasm between cells allows exchange of genetic material
Can occur even though the species normally reproduces asexually through binary fission

6. Sexual Reproduction in Animals
Usually involves two different sexes
Gametes develop in specialized organs (_____________)
Ovaries produce eggs (n) (ova)
Usually larger, round and ______________
Often contain stored food in the form of yolk
Testes produce sperm (n)
Usually motile
Has a head (containing DNA), middle (containing Mitochondria) and tail (flagellum)
Head has _____________________, helps penetrate egg

7. Gametogenesis (meiotic division)
Oogenesis: one primary sex cell develops into _________________and several __________

8. Gametogenesis (meiotic division)
Spermatogenesis: one primary sex cell develops into _________________

9. Hermaphrodites Have _________________________
Usually found in animals that _____________ and it may be hard to locate mates
Two animals meet and fertilize each other
Ex: earthworm

10. Fertilization
Monoploid sperm (n) & Monoploid egg (n) come together to make ____________ zygote (2n)
All _______________________ in zygote come from egg
Membrane forms around egg after fertilization preventing other sperm from entering

11. External Fertilization
_______________ outside body of female.
Requires ______________ for sperm to swim to egg
Often occurs with aquatic animals
___________ numbers of eggs and sperm are released to increase chance of fertilization
Timing of release controlled by hormones and sexual signaling
Ex: _______________& _______

12. Internal Fertilization
Fusion of gametes occurs within moist __________ environment of female’s reproductive tract
Occurs in ________________________________
terrestrial vertebrates
Allowed for a way for animals to evolve to live on land!
Requires specialized sex organ to carry sperm from males body to females (____________)
Seminal fluid (semen) provides _______________ for sperm to swim

13. Internal Fertilization
After fertilization the embryo is either:
enclosed in a ____________ and is ejected to develop outside of females body (oviparous)
ex: chicken egg
remains and develops in a special __________ of females body
ex: human uterus

14. Advantages of Internal Fertilization:
Gametes not _____________ in environment where they could be destroyed
Chances of fertilization _____________
Don’t need __________________________
they require a huge amount of energy to make!
Still have ________________ of sperm released to guarantee fertilization takes place

15. Parthenogenisis
Development of an _______________ into an adult animal without fusion with sperm
Ex: many insects including bees, wasps, ants, also some lizards
In bees an unfertilized egg will become a male drone and fertilized eggs become female workers or queens

16. Early Embryonic Development
Cleavage:
series of ____________ cell divisions of zygote
# of cells increases but growth _____________
Morula:
___________________
Blastula:

18. Three cell layers form:
Gastrulation:
Cells of blastula _____________________ forming gastrula
Opening is called the blastopore
This later becomes the opening to digestive system
Three cell layers form:
______________, _________________ & ______________

20. Growth & Differentiation of Cells
Three cell layers of gastrula differentiate into different tissues of body (___________________)
Ectoderm (outer layer)
_______________________________________
Mesoderm (middle layer)
Endoderm (inner layer)

21. Differentiation Differentiation occurs because:
different sections of DNA called genes _____________________ in different cells, controlling what type of cell it will become
_____________________________ between adjoining cells can also influence cell type and development

22. Development & Growth of Embryo
Development is the process by which the embryo becomes the organism.
An embryo needs:
protection from elements
a way to get __________________
regulate temperature
get rid of it’s __________________

23. External Development In Water:
nourishment comes from ______________, gets oxygen from water, wastes diffuse into water
Requires little or no ____________________
Some animals guard eggs or fan water currents to provide more oxygen

24. On Land Need large egg with yolk (nourishment) protected by a shell
A self sustained watery environment
____________________ allows oxygen in and carbon dioxide out
Ex: Reptiles, Birds and Monotremes (Ex: platypus)

25. Structure of a Typical Egg
Hard porous shell containing special membranes
Chorion:
outermost membrane lining inside of shell
_____________________ with external environment
Allantois:
exchange of ______________ take place
Metabolic wastes (like uric acid )collect here
Site for ____________________________
Amniotic Sac:
fluid filled sac surrounding embryo
________________________ from shock
Yolk Sac:
Source of ____________ for embryo
Has blood vessels to carry food to embryo

27. Internal Development Mammals: Internal fertilization
Embryo develops in ________ or ______________
When born offspring receives nourishment from mother from __________________
Only _______________ are produced at a time

28. Placental Mammals:
Embryo becomes implanted in the _________________
_____________ that serves as a organ for exchange of _________,
_______ and ________________ between embryo’s blood and mothers blood
Provides embryo with site for:
__________, ____________ and
__________________
Embryo becomes attached to a placenta by an __________________
No direct mixing of blood

29. Non Placental Mammals Pouched: Egg Laying:
Marsupials (like Kangaroo)
Egg Laying:
_____________ (Echidna), _____________________
Embryos are born _______________________. Must complete development in a pouch.
No _____________________ of young in uterus
Crawls into pouch, attaches ________________ to complete development
Baby Echidna:
Kangaroo Giving Birth

30. Try These Questions What is the function of the placenta?
Why do fish produce more eggs than birds?
What advantage is it to have an egg shell on dry land?
How do the eggs that develop in water obtain nourishment and oxygen?
What happens during gastrulation?