Transcript Pine seed - Cloudfront.net

Ferns that are pretty 
Chapter 30 Reading Quiz
1.
2.
3.
4.
5.
An embryo packaged with a food supply
and a protective coat is a …
What is the transfer of pollen to ovules
called?
What is the only living species of
Ginkgophyta?
How many species of Coniferophyta are
there?
What are the two main classes of
Anthophyta?
1. Describe the adaptations of seed plants
that have contributed to their success on
land.
1. Reduction of the gametophyte
2. Origin of the seed  zygote with food
supply and protective coat
3. Evolution of pollen – plants no longer tied
to water for fertilization 
2. List the four divisions of gymnosperms.
1.
2.
3.
4.
Cycadophyta  cycads
Ginkgophyta  ginkgoes
Gnetophyta  gnetophytes
Coniferophyta  conifers 
3. Describe the structures of ovulate and
pollen cones of a pine and distinguish
between the two.
• Pollen cones have microsporangia; undergo meiosis
to produce haploid microspores which develop into
pollen
• Ovulate cones have megasporangia; undergo
meiosis to produce large megaspores that develop
into the female gametophyte
 most trees bear both pollen & ovulate cones
(heterosporous) which develop on different
branches 
4. Describe the life history of a pine and indicate
which structures are part of the gametophyte
generation and which are part of the sporophyte
generation.
•
1.
2.
3.
4.
5.
6.
It takes 3 years to complete the pine life cycle
Pollen grain burrows into ovule
Cell undergoes meiosis to make 4 haploid megaspores;
one survives and grows into the multicellular
gametophyte
2 or 3 archegonia, each with an egg, develop inside
More than a year after pollination, eggs are ready to
be fertilized – pollen tube grows through
One zygote develops into pine embryo (sporophyte)
The pine “seed” then blows away and germinates
elsewhere 
5. Point out the major life cycle differences
in ferns and pines.
• Pines are much more complex
• Pine reproduction takes about 3 years
• Pines don’t need water for fertilization 
6. Distinguish between pollination and
fertilization.
• Pollination  pollen into stigma of carpel
- is a prerequisite to fertilization
• Fertilization  the union
of haploid gametes to form
a diploid zygote 
7. Describe a pine seed and indicate which
structures are old sporophyte, gametophyte,
and new sporophyte.
Pine seed:
1. Embryo  2n  new sporophyte
2. Food source  n  gametophyte
3. Surrounding seed coat  2n  old
sporophyte 
8. Describe how the needle-shaped leaves of
pines and firs are adapted to dry conditions.
• There is a thick cuticle that covers each
leaf
• The leaf’s stomata are found in pits,
reducing water loss
• Little surface area for evaporation 
9. List and give examples of the two classes
of Anthophyta.
1.
Monocotyledons (monocots)
- parallel leaf veins
- grasses
2. Dicotyledons (dicots)
- netted leaf veins
- lettuce, maples 
10. Compare the life cycles of mosses, ferns, conifers,
and flowering plants in terms of: dominant life cycle stage
(gametophyte/sporophyte), whether they are
homosporous or heterosporous, mechanism of gamete
transfer
• Mosses  gametophyte, heterosporous,
sperm swim to egg
• Ferns  sporophyte, homosporous, water
is necessary
• Conifers  sporophyte, heterosporous,
pollen fertilizes ovary
• Flowering plants  sporophyte,
heterosporous, pollen fertilizes ovary 
11. Describe some refinements in vascular
tissue that occurred during angiosperm
evolution.
• Conifers have tracheids which conduct
water (the early type of xylem cell)
• Angiosperms also have xylem, but use
vessel elements, which is a more efficient
cell than the tracheids 
12. Explain how evolution of the flower
enhanced the reproductive efficiency of
angiosperms.
• The ovary dropped below the petals and
sepals where the ovules are better
protected 
13. Identify the following floral structures and
describe a function for each: sepals, anther, petals,
stigma, stamens, style, carpels, ovary, filament
Sepals  sterile leaves, enclose bud
Petals  sterile, aid in attracting pollinators
Stamen  produces pollen
Carpel  evolved from seed-bearing leaf rolled into tube
Stigma  part of carpel that is sticky and receives the
pollen
Ovary  protects ovules which develop into seeds
Filament  stalk of stamen
Anther  terminal sac of stamen where pollen is
produced
Style  leads to ovary 
14. Describe four commonly recognized
evolutionary trends in floral structure found
in various angiosperm lineages.
1.
The number of floral parts have become
reduced
2. Floral parts have become fused together
3. Symmetry has changed from radial to
bilateral
4. The ovary has dropped below the petals
and sepals where the ovules are better
protected 
15. Define fruit and explain how fruits are
modified in ways that help disperse seeds.
• Fruit  a ripened ovary that protects dormant
seeds and aids in their dispersal; some fruits (like
apples) incorporate other floral parts along with
the ovary
• Dispersal techniques 
- wind dispersal (dandelions)
- burr-like fruit that cling to animal fur
- edible fruit whose seeds go through the
digestive tract of the animal and end up elsewhere

16. Diagram the generalized life cycle of an
angiosperm, identify which structures are haploid,
and explain how it differs from the life cycle of a
pine.
1. Pollen lands on a sticky stigma
2. Pollen grain germinates on stigma by growing a
pollen tube down the style of the carpel
3. Reaches ovary and pollen tube grows through its
micropyle and discharges 2 sperm into embryo
sac
4. Double fertilization occurs when one sperm
unites with the egg to form the diploid zygote;
the other fuses with 2 nuclei in the embryo sac’s
central cell to form a triploid endosperm
5. After double fertilization, the ovule matures
into a seed, and is ready for dispersal 
17. Explain how an angiosperm seed differs
from that of a pine.
• Pine seeds  have old and new sporophyte
and gametophyte incorporated into the
seed itself
• Angiosperm seeds  have fruits that help
disperse the seeds and the fruit is usually
the endosperm (3n) 
18. Explain why paleobotantists have difficulty
piecing together the origin of angiosperms and
describe some current theories on how flowering
plants may have evolved.
•
Angios have a relatively sudden appearance in
the fossil record – there are no clear links to
ancestors
Theories:
1. Angios originated where fossilization was
unlikely
2. Angios evolved and radiated relatively abruptly
(punctuated equilibrium)
- perhaps angios evolved from seed ferns, an
extinct group of unspecialized gymnosperms 
19. Explain how animals may have influenced
the evolution of terrestrial plants, and vice
versa.
• It is a consequence of interdependence
Coevolution  reciprocal evolutionary
responses among two or more interacting
species; an adaptive change in one species
is in response to evolutionary change in the
other species 