1. 2nd type of cell division Creates sex cells
Meiosis
2nd type of cell division Creates sex cells
The reason why ________ differ
Genetic information of ________ is mixed
No two sperm or ova are alike Ab AB ab aB

2. Asexual Reproduction
Genetic ______ produced by _______
Works okay in ______ environments
____ population growth: all individuals bear young
Binary fission
Parent splits into 2 daughter cells
Common among single-celled organisms
Paramecium

3. 2) Multiple fission
_______ divides many times
Cytoplasm divides many times
Some cytoplasm for each _______
Amoeba:

4. A small clone “buds” from the adult’s ____
3) Budding
A small clone “buds” from the adult’s ____
Drops off and becomes independent
Or stays connected and starts a ______
Hydra
Sponge colony

5. 4) Fragmentation
If an adult gets broken into pieces, _________
can become a new individual
flatworm
Seastar

6. Evolution of sexual reproduction
Might have began as a way to ______ damaged DNA
Asexual species lack _________ chromosome pairs
With chromosome prs from 2 individuals (parents),
damaged one can be repaired _______ good one
Began in early ____________ organisms, ~1.2 b.y.a.
Had ______ to produce haploid sex cells (gametes)

7. Life cycle of sexually-reproducing species
Starts with adults:
Adults are made up of _______ cells = body cells
Each cell has the full number of chromosomes
2n (paired set) = _______ number
46 in humans

8. Adults produce sex cells, or _______, by meiosis Occurs in _______
Halves the normal number of chromosomes
Haploid sperm fertilizes _________ ovum
Results in one _________ zygote
Zygote develops into embryo, fetus, & baby
Grows by mitosis
Baby
Adults
Embryo
mitosis
fertilization
Zygote
(fertilized
egg)
Sperm
meiosis
Ovum

9. The human life cycle has diploid and haploid stages
“n” = types of chromosomes
“1n = haploid condition
“2n” = diploid condition
_________
Baby
Adults
mitosis
_______
Zygote
sperm
meiosis
fertilization
ovum

10. How does meiosis differ from mitosis?
Most stages are the same
But meiosis separates chromosomes __________
1st time during meiosis __
2nd time during meiosis __

11. X X x x Prophase of Meiosis 1 Homologous chromosomes unite
Referred to as _______
Tetrads X X x x
Sketch 1

12. Homologous chromosomes swap parts Known as ______________
Point of
Crossing over
Nuclear
envelope
Results in _________ chromosomes
Have a mix of parental information
Sketch 2

13. X X x x Metaphase of Meiosis 1: ______ line up on metaphase plate
Not individual chromosomes as in mitosis X x X x
Metaphase
plate
Sketch 3

14. Crossed-over segments
Anaphase of Meiosis 1
Homologous chromosomes get separated
Not sister chromatids as in mitosis X x X x
Crossed-over segments
also get separated
Sketch 4

15. X X x x Telophase of Meiosis 1 Results in __ daughter cells Sketch 5
Recall:
Parent (diploid) cell had 4 chromosomes
These have 2, one of each type X x
Sketch 5

16. Next comes Meiosis 2:
The second separation of chromosomes
Similar to mitosis:
_____________ get separated
Not tetrads as in Meiosis 1
Somewhat different than mitosis in that:
Starts with 2 _______ cells (result if meiosis 1)
Ends with ___ haploid gametes

17. Sketch 6
Prophase of
Meiosis 2
Metaphase of
Meiosis 2 X X x x X x
Same

18. different haploid ___ cells
Sketch 7
Telophase of
Meiosis 2
Anaphase of
Meiosis 2   
Results in 4
different haploid ___ cells     
Recombined
chromosome  
Same  

19. Review: metaphase in mitosis versus meiosis 1X x
mitosis
Meiosis 1 x X
_______
_____________

20. X Meiosis provides genetic variation among ______
1. Parts of parental chromosomes get exchanged
= ______________
2. Parental chromosomes position randomly across metaphase plate (orientation of tetrad)
= _________________ X
Vs.

21. x x x x x x x x x x x x x x x x x x x x
3. Orientation of homologous pairs along metaphase plate is independent = ___________________
Haploid cell no. 1 x x x x x x x x x x x x x x x
(n=5 organism) x x x x x
Haploid cell no. 2

22. Parthenogenesis (Greek: virgin creation)
Some sexually-reproducing species can reproduce asexually (without genetic ______)
Parthenogenesis (Greek: virgin creation)
Embryos develop from unfertilized (haploid) _____
In early cell division, chromosome # gets _______
Some whiptail lizard populations are all _______
Also found in certain scorpions,
aphids, bees, amphibians, & fish
____ are ecologically “expensive”
because they can’t bear young
Hermaphroditic/monoecious: individuals have
genitalia of ____ sexes
Common in flowering plants, invertebrate animals
Dioecious: individuals have ______ sexes