Biodiversity 11: From Spores To Seeds

Front 1

Common name of Salvina Molesta?

Back 1

Kariba weed

molesta, it molests water ways

kariba is a damm is gummed up

Front 2

Structure of Kariba weed?

Back 2

floating rhizome

leaves protude out of water, waxy hairs of the leaves help keep it afloat and leaves water-repellant

can double weight in 2 1/2 days (tropics)

Front 3

A method of controlling kariba weed biologically?

Back 3

Using a species of weevil that only eats kariba

Front 4

Which water fern can cause concern in UK?

Back 4

Azolla

Growth used to be killed in winter, but is now surviving

Front 5

Azolla can be a problem in UK, however it is beneficial in other parts of the world?

and why?

Back 5

importance to rice paddies as 'green,' fertiliser

has a cyanobacterium in its leaves, (Anabeana azollae)

Can contribute to rice's need of nitrogen as the heat will kill the azolla, leaving the nitrogen to be used by the rice

Front 6

What has it been suggested that Azolla contributed to?

Back 6

single-handedly changing climate to ice-age

Front 7

What factor is primarily the reason for water ferns success?

Back 7

Asexual reproduction, their rhizomes with horizontal growth and branching

However they are heterosporous like Seleginella ( different spores)

Front 8

Advantage of Sporophytes opposed to free-living spores (heterospores)?

Back 8

free-living spores are are vulnerable compared with sporophytes

Front 9

In heterosporous plants what are the spores produced and the structures that produce them?

Back 9

Megasporangia produce megaspores, large spores with metabolic reserves for growing embryo

Microsporangia produce microspores, small spores, which generate only numerous motile sperm

They have no free-living gametophyte

Front 10

In a heterosporous system, where does fertilisation occur?

Back 10

system relies on motile sperm

fertilisation occurs within megaspore wall (internal fertilisation)

The male microspore releases sperm into the megasporangia, fertilising female megaspores

Front 11

How do we think seed plants arose?

Back 11

from a heterosporous system,

instead of dispersing megaspores, they were retained on parent plant

new generation provided for and protected in megasporangia

The produced gametophyte (much reduced, not free-living etc) is completely dependent on parent

Front 12

In a seed bearing plant what is the old megasporangia now called?

How would the megaspore b fertilised?

Back 12

Ovule

Often reduced to produce only 1 megaspore

fertilised by sperm generated by pollen grain

Front 13

How does production of seeds represent another method for plant to disperse genes?

Back 13

seeds produced and megaspores and microspores still being produced

Front 14

What were the first successful organisms with seeds?

Back 14

gymnosperms

4 phyla of extant plants recognised

Front 15

sExamples of Ginkgophyta?

Back 15

Gingko Biloba: Features:

now living fossil,

enviromental tolerance, even pollution, why its planted in lots of cities

tolerates extremes of temp and dessication

deciduous plant, losing leaves to survive low light and low temp

Front 16

ginka reproduction method?

Back 16

pollens generated, which travels to ovules of female plants

the microspores release the sperm in the ovule (has largest sperm)

fertilisation produces very smelly seeds, why female plants are illegal to plant somewhere

smelly seeds may have attracted now extinct animal

Front 17

Apperance of Cycads?

Back 17

trunks look like tree ferns, limited woody vasualr tissue

mainly supported by large wood leaf bases and the vascular traces that lead to them

leaves are evergreen and metabollicaly expensive

Front 18

When do Cycads produce cones?

Back 18

very occassionally cones are products, again metabollically expensive

when they do produce cones, no leaves are made

Front 19

Cycads and Ginkgo are dioecious, what is this?

consequences of this?

Back 19

seperate male and female plants

male gametes have to be transported to female, many animal mediated transfer