Angiosperm reproduction

Question 1

Which reproductive features are unique to angiosperms?

Answer 1

Flowers, fruits, double fertilizations

Question 2

What are the main phases of the alternation of generations?

Answer 2

Gametophyte: haploid (n) from meiosis of microspores and megaspores up to fertilization.

Sporophyte: diploid (2n) from fertilization up to production of spores by sporocytes.

Question 3

what are microsporocytes and megasporocytes?

Answer 3

• Microsporocytes are microspores’ mother cells.

- Megasporoctyes are megaspore mother cells

Question 4

How do gametophytes and gametophores relate to gametes?

Answer 4

• Gametophytes produce gametes in gametophores.

Question 5

Where do microspores and megaspores begin?

Answer 5

• Microspores begin in pollen sacs in the anther where they are produced by microsporocytes
• Megaspores begin in the ovaries in the ovules where they are produced by megasporocytes.

Question 6

What are some of the key features of macrogametes?

Answer 6

Plant ovaries contain ovules, the inner layer of which is an embryo sac or macrogametophyte. Ovules are attached to the placenta by a funiculus and covered with layers of integument which layer become seed coat when the ovules from seeds in the fruit. There’s a gap in the funiculus called a microphyle which allows sperm to enter to fertilise egg.

Eggs/macrogametes are produced by the macrogametophyte, and

Question 7

Where are pollen grains?

Answer 7

Pollen grains stay in the anther until it dehisces.

Question 8

What are the 4 parts of a flower?

Answer 8

• The calyx, the corolla, the androecium, the gynoecium.

Question 9

Where is the flower on the plant?

Answer 9

The flower grows out of the apical or axillary bud on a pedicel (flower stalk).

Question 10

What is a peduncle?

Answer 10

The peduncle is the main axis from which the pedicel connects to stem.

Question 11

What are the three parts of a carpel?

Answer 11

the three parts of a carpel are the stigma, the style, and the ovary.

Question 12

What are locules?

Answer 12

Locules are chambers of the ovary that contain ovules.

Question 13

what is placentation?

Answer 13

Placentation is patterning of how seeds are attatched to the ovary

Question 14

What are the parts of the stamen?

Answer 14

A stamen consists of an anther at the top of a filament.

Question 15

How does germinates pollen get to ovary in a hermaphrodite flower?

Answer 15

Pollen in the anther moves down the style from stamens surrounding carpel to access the ovary containting 1+ ovules.

Question 16

Monoecious vs hermaphrodite plants?

Answer 16

Monoecious: separate male flowers and female flowers on the one plant

Hermaphrodite: every flower on a single plant has both male and female parts.

Question 17

Protoandry vs protogyny?

Answer 17

Protoandry: male gamete matures first
Protogyny: female gamete matures first

Question 18

Haploid vs diploid?

Answer 18

Haploid: single copy of each chromosome
Diploid: paired copies of each chromosome

Question 19

What are somatic cells?

Answer 19

Any cells but sex cells

Question 20

Meiosis vs mitosis?

Answer 20

Mitosis in somatic cells; 2 diploid daughter cells

Meiosis in sex cells: 4 haploid daughter cells (genetic material halved) (two rounds of division)

Question 21

Where does the haploid phase begin and end?

Answer 21

The haploid phase begins at haploid microspores/megaspores produced by diploid microsporocytes/megasporocytes

Question 22

How does the anther release pollen?

Answer 22

The anther produces pollen through dehiscence

Question 23

What happens when two haploid cells combine?

Answer 23

When two haploid (gamete) cells combine they form a diploid zygote.

Question 24

What is the function of the stigma?

Answer 24

The stigma is the receptacle for pollen.

Question 25

What is pollination?

Answer 25

Pollination is the transfer of pollen from an anther to a stigma.

Question 26

how do you get from the megasporangium phase to the egg cell with 7 cells + 8 nuclei?

Answer 26

Diploid megasporocyte in the megasporangium undergoes meiosis to produce four megaspores, only one of which survives.

This one surviving megaspore undergoes miTosis 3 times with no cell division.

This produces a large cell with 8 nuclei.

This undergoes to form 7-celled embryo sac.

This includes 3 antipodal cells, 2 synergids, 2 polar nuclei (diploid) and 1 egg.

Egg cell becomes embryo once fertilized.

Question 27

What is cytokinesis?

Answer 27

cytokinesis is division of the cytoplasm (mitosis: division of nuclear material)

Question 28

How do you get from the microsporangium phase to the sperm cell?

Answer 28

Pollen sacs contain diploid microsporocytes which divide by meiosis to produce 4 haploid microspores.

Each microspore then undergoes miTosis to produce 2 cells: a generative cell and a tube cell (which engulfs the generative cell).

This generative cell undergoes miTosis to produce 2 sperm cells/microgametes.

Question 29

What is a microsporangium?

Answer 29

Microsporangium is pollen sac, inner layer is tapetum, which breaks down to provide nutrients and wall material for pollen grain.

Question 30

What are the three cells of the microgametophyte?

Answer 30

The microgametophyte consists of three cells: 2 sperm cells and a tube nucleus.