Transcript Alteration of Generations, bryophyte, fern - MAH-SBHS

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The recovery of the black robin from near
extinction is an internationally renowned
conservation success story
In 1980 there were only 5 black robins in NZ,
with just a single breeding pair left. Today
the population is over 250. This has caused
changes in the black robin gene pool.
a) Define the term gene pool
b) Discuss how this near-extinction affected
the gene pool of the black robin and why
it is still classified as endangered
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Explain how enzymes function as
catalysts
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Enzyme activity may be affected by
Temperature
pH
Co-factor/co-enzymes
Inhibitors
Discuss how enzyme activity is affected by
these factors
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Describe the structure of the cell
membrane. You may use labelled
diagrams in your answer
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Discuss the importance of the cell
membrane in maintaining a constant
internal environment for the cell
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Name two organelles that plants have
that animals do not and their function
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Define founder effect
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How three taxonomic groups of plants
reproduce
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Compare and contrast the three types
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Describe how the plants are adapted for
their environment in relation to
reproduction
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Vegetative reproduction (asexual)
› Low metabolic cost to the plant
› Allows efficient exploitation of the resources in
the environment
› Does not promote genetic diversity
› Environmental change and pathogens present
risks
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Sexual reproduction:
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Promotes genetic diversity in a population
Involves the alternation of generations
High metabolic cost to the plant
Allows species survival in changing environment
…is the biological process by which new
individual organisms are produced. Genes
are passed on to the next generation,
which ensures continuation of the species
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Variation in plants exists from sexual
reproduction
› INVOLVES AN ALTERNATION OF GENERATIONS
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Involves a haploid stage (n) called
gametophyte (gamete producing plant)
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Involves a diploid stage (2n) called a
sporophyte (spore-producing plant)
Sexual reproduction occurs in all types of
plants
 Involves the “alternation of generations”
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Definitions:
› Sporophyte = diploid or 2n stage, produces
spores by meiosis
› Gametophyte = haploid or n stage, produces
gametes by mitosis
› Spore = haploid structure that develops directly
into an organism (the gametophyte)
› Gamete = haploid structure that fuses through
fertilisation to produce a diploid zygote (the
sporophyte)
fuses
through
fertilisation
to produce
a diploid
zygote
that develop
directly into an
organism (the
gametophyte)
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To do: Stick in the handout and fill in the
words
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Explain in your own words what is
happening
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A minute, typically one-celled,
reproductive unit capable of giving rise
to a new individual without sexual fusion,
characteristic of lower plants, fungi, and
protozoans
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(in a plant exhibiting alternation of
generations) A haploid reproductive cell
that gives rise to a gametophyte
1. Bryophytes
 Mosses, liverworts and hornworts.
liverwort
moss
hornwort
moss
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Lack water gathering roots and specialised vascular
tissues for transport
Usually less than 15cm in height but may sprawl over
a considerable area
Absorb moisture and minerals through above ground
structures via diffusion and therefore grow in moist
environments
They do not have roots as such however they are
anchored to the substrate they grow in by rhizoids
They have small leaf like structures however they lack
the specialised tissues of the true leaf and are only
one to a few cells thick.
The body of the plant is designed for storage and
support
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The gametophyte phase dominates
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Gametes are produced by mitosis in structures called
the antheridium (male) and archegonium (female)
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Bi-flagellate sperm are released by the antheridium that
swim to the archegonium in the process of fertilisation
[No water = No reproduction]
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The zygote develops into a sporophyte phase that is
often totally dependent on the gametophyte for
nutrition
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The sporophyte consists of a foot, stalk and single
sporangium that produces and spreads spores by
meiosis
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What is the name of the structure that
produces sperm on the male gametophyte
of mosses?
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Describe two ways in which bryophytes are
dependent on liquid water
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If you looked at the chromosome numbers
of what looked like a complete small moss
plant, which part would be diploid and
which part haploid?
Structure
Function
Bi-flagellate sperm
Allows sperm to swim from
antheridium to archegonium to
achieve fertilisation
Sporangia of sporophyte
raised into the air
Archegonia produce
chemical signals for sperm
Sporangia explosively
discharge spores
Sporophyte grows on the
gametophyte
Structure
Function
Bi-flagellate sperm
Allows sperm to swim from
antheridium to archegonium to
achieve fertilisation
Sporangia of sporophyte
raised into the air
Ensures efficient dispersal of spores
Archegonia produce
Allows sperm to home in on the
chemical signals for sperm correct location for fertilisation
Sporangia explosively
discharge spores
Ensures efficient dispersal of spores
Sporophyte grows on the
gametophyte
Sporophyte does not need to be
independent or photosynthesise
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In groups of 3
› Use the play dough to ‘model’ the
bryophyte life cycle
› You will need to be able to explain it to
another group
 Include the structures etc..
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What is a bryophyte?
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Define gametophyte and sporophyte?
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What is the cytoplasm?
Ferns are vascular plants that can grow
much larger than bryophytes
 Presence of vascular system allows
internal transport of water and food
 Leaves (fronds) are made up of leaflets
(pinnae), efficiently capturing light, ferns
are often found in lower levels of a forest
 Leaves are composed of a variety of
different cell types
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Spores give rise to bisexual gametophytes.
The spores develop into a flat membranous type
structure with rhizoids. The antheridia and
archegonia grow on the underside.
The gametophyte contains both the male and
female parts (The male part = the antheridia and
the female part = archegonia). (ie male and
female parts on the same gametophyte)
The antheridia and archegonia mature at different
times ensuring cross fertilisation.
Flagellated sperm are produced by the antheridia
and therefore requiring water for fertilisation
Fertilisation occurs in the archegonia and
development of the sporophyte also occurs here.
Initially the sporophyte receives nutrients form the
gametophyte however, it soon becomes
photosynthetically independent.
Once the sporophyte is independent, the
gametophyte disintegrates
Diagram also pg. 298 (Bayley)
 Once finished you will need to collect a
rearrange sentences sheet from Mrs H
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Then draw a table that outlines
similarities and differences between the
reproduction of moss and ferns
Similar
Different
Require moist environment
Water for fertilisation has to be
present
Ferns more complex
Grow larger - Have vascular tissues
Rhizoids present
Bryophytes: Sporophyte is
dependent on gametophyte for
nutrients
Gametophyte is dominant stage
Alternation of generations
Spores are produced
Ferns: Sporophyte not dependent
on gametophyte
Sporophyte is the dominant stage
Separate male and female
gametophytes
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Dioecious refers to a plant population
having separate male and female
plants.
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Monoecious, an individual that has both
male and female reproductive units on
the same plant;
What are they?
 Flower Structure
 Male and Female Gametes
 Reproductive cycle
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Angiosperms (flowering plants) are the
most abundant and successful plant
group
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300,000 different species counted so far
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Vascular plants with a wide range of
sizes, adaptations and habitats
 Angiosperms
are the final
improvement on plant reproduction;
 They grow their seeds inside an ovary;
 The ovary is embedded inside a
flower;
 After fertilisation the flower falls away
and the ovary swells to become a
fruit.
Angiosperm sporophytes produce unique
reproductive structures called flowers
 Flowers consist of four types of highly
modified leaves
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Sepals
Petals
Stamen
Pistil (or carpel)
Their site of attachment to the stem is the
receptacle
Reproduction and Development
Reproduction and Development
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Copy diagram on the board and
reasons for the changes
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Sepals and petals are nonreproductive
organs
› Sepals – protect the other three, the floral
bud
› Petals – attract pollinators and act as
“landing pads”
Reproduction and Development
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Anthers and carpels are male and
female reproductive organs, respectively
› Anther – consists of filament (long, thin) and
anther (pollen)
› Carpel – consists of stigma (sticky opening),
style (long tube connecting stigma to ovary),
ovary (houses ovules; becomes fruit), and
ovules (develops female gametes; become
seeds)
› COPY DIAGRAMS ON BOARD
Reproduction and Development
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Complete flowers – have all four floral
organs
› Ex: Trillium
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Incomplete flowers – missing one or more
of the four floral organs
Reproduction and Development
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Bisexual flower (perfect flower) is
equipped with both stamens and
carpals
› All complete and many incomplete flowers
are bisexual
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A unisexual flower is missing either
stamens (carpellate flower) or carpels
(staminate flower)
Reproduction and Development
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Monoecious plants: staminate and
carpellate flowers at separate locations
on the same individual plant
› Ex: corn ears derived from clusters of
carpellate flowers; tassels consist of
staminate flowers
Reproduction and Development
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Dioecious plants: staminate and
carpellate flowers on separate plants
› Ex: Date palms and Sagittaria (below) have
carpellate individuals that produce dates
and staminate individuals that produce
pollen
Reproduction and Development
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http://www.youtube.com/watch?v=bUj
VHUf4d1I
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http://users.rcn.com/jkimball.ma.ultranet
/BiologyPages/A/Angiosperm.html
Sporophyte generation dominates
 Reproduction is independent of water
 Reproduction requires pollen transfer to
the stigma, usually by wind or animal
pollinators
 Reproduction involves a “double
fertilisation”
 Reproduction is made more effective by
using seeds to distribute embryonic
plants
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Gametophyte generation reduced to
small number of cells that are
dependent on the sporophyte
Insects
 Birds
 Snails
 Wasps
 Bats
 Wind
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Self vs cross pollination
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Seed dispersal occurs by:
› Wind (e.g. dandelion, sycamore)
› Water
› Animals (e.g. succulent fruit, hooked fruit)
› Explosive methods (e.g. legumes)
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Complete the exercises on page 258,
Biozone
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Pollination is the transfer of pollen from the
anther to the stigma, usually by wind or animals
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Use pages 292-294 to answer these questions:
› What are the major differences between wind and
animal pollinated flowers?
› How do flowering plants ensure they do not self
fertilise?
› What is the difference between pollination and
fertilisation?
› Describe the events between pollination and
fertilisation, what has to happen? What is the
“double fertilisation?”
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The new sporophyte in angiosperms is packaged into a
seed for dispersal
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Use pages 294-297 to answer these questions:
› What is a fruit? What part of the flower develops into the fruit
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and the seed?
What is the difference between a monocotyledon seed and
a dicotyledon seed?
Draw a labelled diagram of a typical seed, along with the
labels and their functions
What are the main mechanisms for dispersing seeds?
What are the factors required for seed germination?
What advantage do angiosperms have over mosses and
ferns by producing fruit and seeds?
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Germination requires the following factors:
› Oxygen
› Water
› Correct temperature
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Germination involves re-starting the
metabolism of the seed
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Photosynthesis only occurs when chlorophyll is
produced in new leaves in the emerging shoot
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Prepare a table comparing mosses, ferns and
angiosperms for the following features:
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Dominant generation
Which generation is dependent on the other
Requirements for water in reproduction
Environments that the plant can live in
Methods to avoid self-fertilisation
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Prepare simple diagrams, with labels, showing the
reproductive cycles of the three plant groups
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Begin linking structures and functions to the plant and its
lifestyle that can be used in an essay question