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BIOL1010/1011 > Plants: Lecture 2 > Flashcards

Plants: Lecture 2 Flashcards

1
Q

What is alternation of generations?

A

Alternation of generations refers to instances where there is a multicellular haploid and diploid component/stage/phase in the life cycle.

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2
Q

What types of plants have alternation of generations?

A

Alternation of generations occurs in all land plants.

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3
Q

How did alternation of generations arise in plant groups?

A

It arose independently in evolutionary history many times, also occurring in other groups.

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4
Q

What is the name of the haploid generation?

A

The haploid generation is called the Gametophyte.

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5
Q

What does the gametophyte make?

A

The gametophyte directly makes gametes.

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6
Q

What is the diploid structure?

A

The diploid structure is called the sporophyte.

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7
Q

What does the sporophyte make?

A

The sporophyte makes spores by meiosis.

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8
Q

In land plants, what does meiosis make?

A

In land plants, meiosis results in the making of spores.

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9
Q

What process do spores undergo to create the gametophyte?

A

Spores undergo mitosis to create the multicellular gametophyte.

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10
Q

What is a spore?

A

A spore is a single cell that can divide to produce a multicellular organism that often has a protective coat (called sporopollenin).

  • Can develop into another entity without cells needing to unite.
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11
Q

What is a gamete?

A

A single cell that can and must unite with another gamete to create a diploid zygote.

  • Cannot develop without unification
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12
Q

Example of a green alga without alternation of generations?

A

Chlamydomonas (Chlorophyta) spend most of their lives as single-celled, haploid organisms. They live in ponds or moist soils and have two flagella.

  • Cannot undergo alternation of generations because they do not have a true multicellular haploid and also have no multicellular diploid.
  • Instead they have + and - individuals that do not undergo alternation of generations.
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13
Q

How did alternation of generations originate?

A

Alternation of generations originated when a zygote delays meiosis and instead continues to grow and divide.

  • The result of this is a multicellular diploid.
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14
Q

What does the origination of alternation of generations mean?

A

The multicellular haploid (archegonium & gametophyte) contains the zygote, which undergoes delayed meiosis and instead undergoes mitotic divisions, producing the multicellular sporophyte (multicellular diploid). This also results in the embryophyte condition of a multicellular haploid housing a multicellular diploid.

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15
Q

How many divisions of land plants are there?

A

There are 10 divisions of land plants or embryophytes.

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16
Q

What are the 4 main divisions of land plants?

A

The 4 main divisions are Mosses, Ferns, Conifers, and Angiosperms.

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17
Q

How many species of mosses are there?

A

The division of Bryophyta (mosses) contains around 15,000 species.

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18
Q

Basic facts about division Bryophyta?

A
  • They are low growing (cm tall)
  • They are confined to damp areas
  • They have no true leaves
  • They are gametophyte dominant
  • They are homosporous
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19
Q

Why are mosses confined to damp areas?

A

They are confined to damp areas for two reasons:

  • They have swimming sperm, meaning water must be present for the sperm to reach the egg. This is why they are low growing.
  • They have no true vascular tissue and only contain a rudimentary vascular system. It is not well developed enough to be large and cannot support the whole plant by sending nutrients.
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20
Q

Why don’t they have true leaves?

A

True leaves need to have a vascular system, which mosses lack.

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21
Q

What does it mean to be sporophyte or gametophyte dominant?

A

The state that is more dominant is the more long-lived state. This means that it is what we see when we look at the plant.

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22
Q

Where do moss sporophytes arise from?

A

Moss sporophytes arise from the gametophytes. They are dependent on the gametophyte and live for a short period of time.

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23
Q

Moss life cycle?

A
  • Spore germinates, and grows into the gametophyte.
  • Male gametophyte contains sperm that undergo mitosis and divide.
  • A raindrop (water in general) moves the sperm from the antheridium to meet the female egg.
  • The female gametophyte develops in the archegonia
  • Egg and sperm meet when raindrop lands on female structure. Fertilization occurs.
  • The zygote (sporophyte) sits in the archegonium as it develops (embryophyte condition)
  • The sporophyte is dependent on the gametophyte which photosynthesizes and gives nutrients to the sporophyte.
  • Sporangium (top of plant) is a vessel that creates and contains spores, and is responsible for undergoing meiosis to make more spores.
  • Repeat
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24
Q

Where do moss sporophytes grow out of?

A

Moss sporophytes grow out of the top of gametophytes.

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25
Q

How is sperm made in the antheridia?

A

Sperm is made by mitosis in the antheridia (male gametophyte)

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26
Q

Where is the egg contained?

A

The egg is contained in the archegonium (female gametophyte)

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27
Q

What is the sporangium?

A

The sporangium is where cells undergo meiosis (each cell creating 4 new cells)

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28
Q

What was the next big step in evolution?

A

The next big step in evolution was vascular tissue.

29
Q

What is the importance of vascular tissue?

A

Vascular tissues provides support and supply through its structures: Xylem and Phloem.

  • Allows plants to grow taller due to increased rigidity and hormones, sugar, water and more.
30
Q

What was the first plant to be recorded as having vascular tissues?

A

Cooksonia was the first plant group to be recorded as having a vascular system in the fossil record. Roughly 410 mya

31
Q

What plants are in division pterophyta?

A

Ferns, Horsetails, and other “Winged Plants” are part of division pterophyta.

32
Q

How many species are in division pterophyta?

A

There are roughly 20,000 species, with most of them being tropical.

33
Q

When did division pterophyta appear?

A

They appeared roughly 400 mya.

34
Q

Features of division pterophyta plants?

A
  • They have vascular tissue: called xylem and phloem which are in charge of support and supply
  • Swimming sperm
  • Sporophyte dominant
  • Can be homosporous or heterosporous
35
Q

Fern/Pterophyta life cycle?

A
  • spore is dispersed
  • spore germinates and grows
  • one side of structure produces sperm (antheridium) and the other produces eggs (archegonium).
  • sperm is released into the archegonium and fertilizes the egg, forming a zygote/sporophyte
  • gametophyte disintegrates
  • sporophyte matures and their sporangium undergo meiosis.
  • repeats
36
Q

How do “vacuum” sporangium work?

A

They throw their spores when the outside layer bursts open. It is under tension until it busts open and throws the spores a few centimetres.

37
Q

What is the other method of dispersing spores?

A

The cinnamon fern contains 2 kinds of leaves: photosynthesizing leaves and sporangia leaves.

  • The release of spores is more like a clam shell opening as it quickly opens, flings the spores, and closes once again.
38
Q

What is homospory?

A

Homospory is when a plant has one size of spore coming from meiosis.

39
Q

What is heterospory?

A

Heterospory is when meiosis results in 2 sizes of spores.

40
Q

Process of homosporous spore production?

A
  • Sporangium
  • Single type of spore
  • Typically a bisexual gametophyte (both female and male structure together)
  • Creates egg and sperm
41
Q

Heterosporous spore production?

A

Female side:
- Megasporangium
- Megaspore
- Female gametophyte
- Egg (large)

Male side:
- Microsporangium
- Microspore
- Male gametophyte
- Sperm (small)

42
Q

What plants tend to be homosporous?

A

Mosses and most ferns

43
Q

What plants tend to be heterosporous?

A

Some ferns and all seed plants

44
Q

What change led to land plant evolution?

A

The development of pollen and seeds (If you have seeds you have pollen) led to land plants being what we know them as.

45
Q

What are the 5 divisions of seed plants?

A
  • Cycadophyta
  • Ginkgophyta
  • Gnetophyta
  • Coniferophyta
  • Anthophyta
46
Q

What do seed plants have?

A

Seed plants have both seeds and pollen

47
Q

What is a seed made up of?

A

A seed is made up of an embryo, nutrients, and a seed coat.

48
Q

What does a seed develop from?

A

A seed develops from an ovule (an immature seed).

49
Q

What is an ovule?

A
  • A novel structure appearing in seed plants
  • The site of female meiosis
  • Contains the female gametophyte, female sex organs, egg and embryo
  • Where fertilization occurs
  • Where embryo arises and matures
50
Q

What is meant by the ovule being the site of female reproduction?

A

This means that it needs a female gametophyte and an egg. To do this it needs to make a spore which is made from a sporangium.

51
Q

What happens to cells inside the megasporangium?

A

These cells undergo mitosis, forming the embryo

52
Q

What is the micropyle?

A

The micropyle is the opening where pollen enters the seed

53
Q

What is the integumentary?

A

It is the structure that eventually becomes the seed coat.

54
Q

What does the megasporangium create?

A

It creates a cell that will undergo meiosis, where 3 of 4 cells will die and leave one viable.

55
Q

What becomes the megagametophyte?

A

A single functional megaspore becomes the megagametophyte.

56
Q

What does a mature ovule become?

A

A mature ovule becomes the seed.

  • Integument = seed coat
  • Female gametophyte = food
  • Megaspore = embryo
57
Q

What is a seed composed of?

A

It is composed of an embryo, nutrition ad a seed coat

  • Develops from the ovule
58
Q

Where does pollen come from?

A

Pollen makes/contains sperm, and also the mature multicellular male gametophyte

  • it is only a few cells in size
59
Q

How many species are there of division Coniferophyta?

A

There are roughly 50,000 species of conifers

60
Q

Facts about conifers?

A
  • Their reproductive organs are in cones
  • Sporophyte dominant
  • Heterosporous
  • Microgametophyte = pollen
  • Megagametophyte is within ovule, making the egg and nourishing embryo.
61
Q

Main difference of the conifer life cycle?

A

The conifers wait roughly a year between sperm/pollen arrival and fertilization.

62
Q

What is the “nutrition” in conifers?

A

In conifers, the nutrition for the embryo is the megagametophyte.

63
Q

What is the megagametophyte?

A

Structure that makes the egg in the archegonium and nourishes the embryo

64
Q

What is the microgametophyte?

A

The pollen grain that makes sperm.

65
Q

Why do male cones make and release so much pollen?

A

They release and make a lot of pollen because it travels by wind and you need a lot of pollen for this method to ensure that the maximum amount of fertilization occurs.

66
Q

Summary of conifers?

A
  • Seeds and pollen
  • Separate male and female cones
  • Naked seeds called gymnosperms
  • Seed embryo is nourished by megagametophyte
  • Slow reproduction
67
Q

Why might there only be 550 species of conifers?

A

Many think this may be due to the slow reproduction time for the trees

68
Q

Jack pine reproduction example?

A

Summer 1:
- Initiate male and female cones

Summer 2:
- Male meiosis (pollen)
- Pollination
- Female meiosis after pollination

Summer 3:
- Fertilization (summer)
- Mature seeds (late summer/fall)

69
Q

When do conifer seeds germinate?

A

They will only germinate/release when a fire comes.

BIOL1010/1011 (22 decks)

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