Bsci 207 Exam 2

Front 1

For sex organism does not need

Back 1

sex organs or multicellularity

Front 2

Requirements for sex

Back 2

diploid phase of life, meiosis, union of haploid meiotic products

Front 3

origination of eukaryotic sex

Back 3

in unicellular organisms

Front 4

syngamy

Back 4

fusion of two cells, or their nuclei, in reproduction

Front 5

fertilization

Back 5

union of egg and sperm to create a fertilized egg called a zygote

Front 6

Haplontic Life Cycle

Back 6

only diploid for one meiotic cell cycle

Front 7

Mature organism in haplontic life cycle

Back 7

haploid (n)

Front 8

Only diploid in haplontic life cycle

Back 8

zygote (2n)

Front 9

Haplontic organisms

Back 9

most protists, fungi and some green algae

Front 10

Features of haplontic sex

Back 10

cells spend most of their life as haploids, sex optional, zygote immediately undergoes meisos, no stable diploid phase at all

Front 11

Alternation of generations life cycle

Back 11

organism passes through haploid and diploid stages that are both multicellular

Front 12

Alternation of generations organisms

Back 12

most plants and some fungi

Front 13

Diploid stages in alternation of generation life cycle

Back 13

zygote and sporophyte

Front 14

Haploid stages in alternation of generations life cycle

Back 14

spore, gametophyte, and gametes (male and female)

Front 15

gametophyte

Back 15

gamete producing and usually haploid phase, producing the zygote from which the sporophyte arises. Dominate form in bryophytes

Front 16

Feature of alternation of generations life cycle

Back 16

allows for extended periods of either ploidy

Front 17

Diplontic life cycle

Back 17

only haploid stage is gametes

Front 18

Diploid phases in diplontic life cycle

Back 18

zygote and mature organism

Front 19

Diplontic organisms

Back 19

found in animals, brown algae and some fungi

Front 20

weird sex in paramecium

Back 20

contains micronucleus and macronucleus, haploids exchange micronuclei and macronucleus disintegrates

Front 21

micronucleus

Back 21

contains complete genome in one or two copies

Front 22

macronucleus

Back 22

many copies of active genes only

Front 23

Anisogamy

Back 23

in multicellular organisms, large and small gamete

Front 24

Isogamy

Back 24

protists gametes are the entire organism, same size but different mating type

Front 25

Cost of males

Back 25

disadvantage of anisogamous sex- eggs provide nearly all material for zygote, reproduction is female limited

Front 26

cost of meiosis

Back 26

disadvantage of anisogamous sex- meiosis and outcrossing costly even without dedicated male sex. Sexual females only half as related to offspring as asexual females

Front 27

Dandelion sex

Back 27

dandelions became asexual, essentially all angiosperms outcross, sex was feature of first angiosperms

Front 28

Bdelloid Rotifers

Back 28

no males- reproduce by parthogenesis

Front 29

Benefits of sex

Back 29

1. increasing genetic diversity allows for adaptation to ever changing environments (red queen- parasites or hosts)

2. sex allows for faster adaptation- beneficial alleles can be combined more quickly

3. eliminates harmful mutations

Front 30

Outcrossing and males

Back 30

increase in frequency after stress

Front 31

Sex after stress

Back 31

under stressful conditions progeny of crosses do better than those that come from self fertility

Front 32

Gonochrism

Back 32

2 sexes- male and female, development must be regulated to prevent intersexual forms (often by sex chromosomes)

Front 33

hermaphroditism

Back 33

1 sex- makes sperm and eggs, common in animals

Front 34

monoecy

Back 34

1 sex- hermaphrodite with separate male and female flowers

Front 35

selfing

Back 35

1 sex- hermaphrodite (not mating)

Front 36

gynodiecy

Back 36

2 sexes- hermaphrodite and female

Front 37

androdioecy

Back 37

2 sexes- hermaphrodite (selfing) and male

Front 38

parthogenesis

Back 38

1 sex- female (no males)

Front 39

outcrossing between hermaphrodites

Back 39

the norm in angiosperms

Front 40

evolution of mixed strategies in plants

Back 40

ancestor of angiosperms was hermaphroditic, male and female sexes evolve by loss of floral organs for opposite sex, androdiecy exists but very rare

Front 41

Why evolve selfing?

Back 41

selfing is handy when mates are scarce

Front 42

Animal life cycles can mix outcrossing and

Back 42

asexuality- ie daphnia. As weather cools or food limited sexual morphs are made which produce resistant resting eggs viable long term

Front 43

Complete commitment to asexuality

Back 43

ie cnedimepherous uniparens lizards- formed by corss between two species with different chromosome numbers, can't do meiosis. Parthogenesis may be spontaneous solution to keep lineage alive

Front 44

Asexual reproduction without embryos

Back 44

budding, cloning, fragmentation (ie root cloning)

Front 45

Chytrid (water) fungi

Back 45

haplodiplontic and include only fungi in which alternation of generation occurs.

Front 46

Features of chytrid sex cycles

Back 46

make motile spores and gametes (only fungi which do), gametes moderately anisogamous, female gametes release a pheremone that attracts male gametes. Zygote forms small diploid myecelium before meiosis and sporulation.

Front 47

Non-chytrid (terrestrial) fungal life cycles

Back 47

haplontic and isogamous

Front 48

Non-chytrid features of sex cycles

Back 48

haploid spores form by mitosis or meiosis, gametes remain attached to mycelium, many cell cycles pass between gamete membrane fusion (plasmogamy) and nuclear fusion (karyogamy). Karyogamy essential before meiosis

Front 49

Plasmogamy

Back 49

stage in sexual reproduction of fungi in which cytoplasm of two parents cells (usually from mycelia) fuses together without fusion of the nuclei, effectively bringing two haploid nuclei closer together in same cell

Front 50

Karyogamy

Back 50

final step in the process of fusing two haploid eukaryotic cells, and refers specifically to the fusion of the two nuclei. Before karyogamy, each haploid cell has one complete copy of organisms genome.

Front 51

heterokaryon

Back 51

multinucleate cell that contains genetically different nuclei.

Front 52

Basidiomycota life cycle features

Back 52

in soil heterokaryotic mycelia form and produce mushroom, in gills haploid nuclei fuse, go meiotic and make spores, spores launched as buds from basidium

Front 53

Ascomycota life cycle features

Back 53

have reproductive structures with many spore producing asci. heterokaryosis mycelia form and make spore producing organ. haploid nuclei fuse, go meiotic and make eight spores. spores burst from ascus

Front 54

Migration onto land of fungi

Back 54

altered reproduction from haplodiplontic/anisogamous to haplontic and isogamous. Negligible embryonic development and gametes cant swim. Seperation of plasmogamy and karyogamy occured and evolution of special fruiting bodies for spore dispersal on land.

Front 55

embryos need stuff

Back 55

hypothesis for anisogamy- most multicellular organisms build offspring via an embryo, the zygote must be big enough to support development of functional multicellular organism before it can feed, total mass must come from two gametes that fuse

Front 56

motility essential for fertilization?

Back 56

hypothesis for anisogamy- multicellular organisms are typicall much bigger and much further apart than protists, gametes will have to find each other over tens to hundreds of meters, random impacts will almost never occur