Lecture 21: Alternation of generation

Question 1

Sporophyte

Answer 1

plant that produces spores

Question 2

What is the ploidy of the sporophyte phaseof the plants life cycle?

Answer 2

Diploid (2n)

Question 3

What is meiosis?

Answer 3

Cell division where 1 diploid cell (2n) divides to form 4 haploid cells (n)

Question 4

What is a spore?

Answer 4

The product of meiosis…. haploid cells resulting from meiotic cell division

Question 5

What does the spore mark?

Answer 5

The initiation of the gametophyte generation

Question 6

What is a gametophyte?

Answer 6

A plant that produces gametes (like egg and sperm)

Question 7

What is the ploidy of the gametophyte phase of a plant’s life cycle??

Answer 7

haploid (n)

Question 8

What is a gamete?

Answer 8

Egg and sperm….produced from the mitotic cell divisions of the gametophyte

Question 9

What happen to the 2 gametes at fertilization?

Answer 9

egg and sperm fuse to produce a zygote

Question 10

What is a zygote?

Answer 10

The product of egg and sperm fusion

Question 11

What ploidy is a zygote?

Answer 11

A diploid because it results from the fusion of 2 haploid gametes

Question 12

What marks the initiation of the sporophyte generation?

Answer 12

the zygote

Question 13

Alternation of generations (between sporophyte and gametophyte stages) can vary among plants for (3 things)

Answer 13

• physical appearance of each stage (size, form, vigor)
• time spent in each stage (is it persistent? emphemeral ?)
• mechanics of gamete production and fusion (are there many or few cell divisions? How do the gametes find each other?)

Question 14

What ploidy is moss in the gameteophyte stage?

Answer 14

haploid (n)

Question 15

What is a bryophyte? Give an example.

Answer 15

A non-flowering plant (moss and fern)

Question 16

What is the haploid gametophyte in moss?

Answer 16

The green bit!

Question 17

What does the sporophyte form on moss?

Answer 17

a sporangium (capsule) in which cell divide meiotically and form spores

Question 18

What is the relationship between the sporophyte and the gametophyte in moss?

Answer 18

Sporophyte grows on, is supported by and gain nutrition from gametophyte

Question 19

What does the sporophyte generation look like in a fern?

Answer 19

What we regularly think of as a fern

Question 20

What are sori?

Answer 20

Sporangia in fern (formed on the underside of fronds)

Question 21

Characteristics of sori

Answer 21

conspicuous, hardy, long-lived

Question 22

What is a prothallus?

Answer 22

heart-shaped structure where antheridia and archegonia form on surface

Question 23

What do gametes form inside through mitotic divisions?

Answer 23

Antheridia

Question 24

Characteristics of prothallus

Answer 24

inconspicuous, fragile, short lived

Question 25

What happens during pollen formation in flowering plants?

Answer 25

Haploid spore divides by mitosis so within each pollen grain there are 2 cells

Question 26

What are the 2 cells in a pollen grain?

Answer 26

1 tube cell and 1 generative cell

Question 27

What does pollen consist of?

Answer 27

4 haploid cells formed with a spore with a protective coat (exine coat)

Question 28

Why do flowering plants need 2 sperm cells?

Answer 28

So 1 can fertilize the egg to form a zygote while 1 gets with 2 female nuclei to produce endosperm

Question 29

What happens to a male gametophyte in angiosperms? (flowering plants)

Answer 29

It is reduced to just 3 cells held within a pollen grain (1 tube cell and 2 sperm) are dispersed via wind and pollinators

Question 30

What happens to the microspore mother cells in an anter?

Answer 30

They divide by meiosis to form 4 haploid cells

Question 31

What happens to the megaspore mother cell?

Answer 31

Divides by meiosis in megasporangium (located in ovule)

Question 32

How many of the cells survive after the megaspore mother cell divides by meiosis?

Answer 32

1/4

Question 33

How many mitotic divisions does the megaspore mother cell undergo? How many cells does it yield?

Answer 33

3.....8 cells arrange in an embryo sac to prepare for fertilization (**female gameteophyte is reduced to 8 cells at this point)

Question 34

What forms the embryo of the seed?

Answer 34

A fusion of the egg and sperm makes the zygote

Question 35

Dispersal agent of moss

Answer 35

water

Question 36

dispersal agent of fern

Answer 36

water

Question 37

Dispersal agent of angiosperm

Answer 37

wind and pollinators

Question 38

What is the male gameteophyte type in moss?

Answer 38

Flagellated

Question 39

What is the male gameteophyte type in ferns?

Answer 39

flagellated

Question 40

What is the male gameteophyte type in angiosperm

Answer 40

non-flagella

Question 41

Dominant generation in moss

Answer 41

gameteophyte

Question 42

Dominant generation in ferns

Answer 42

sporophyte

Question 43

Dominant generation in angiosperms

Answer 43

sporophyte