adaption of seed plant

8/2/2019 Adaption of Seed Plant

1/23

1. Describe the adaptations of seed plantsthat have contributed to their success on

land.1. Reduction of the gametophyte

2. Origin of the seed zygote with food

supply and protective coat3. Evolution of pollen plants no longer tied

to water for fertilization


2/23

2. List the four divisions of gymnosperms.

1. Cycadophyta cycads

2. Ginkgophyta ginkgoes3. Gnetophyta gnetophytes

4. Coniferophyta conifers


3/23

3. Describe the structures of ovulate andpollen cones of a pine and distinguish

between the two. Pollen cones have microsporangia; undergo meiosis

to produce haploid microspores which develop intopollen

Ovulate cones have megasporangia; undergomeiosis to produce large megaspores that developinto the female gametophyte

most trees bear both pollen & ovulate cones(heterosporous) which develop on differentbranches


4/23

4. Describe the life history of a pine and indicatewhich structures are part of the gametophyte

generation and which are part of the sporophytegeneration.

It takes 3 years to complete the pine life cycle1. Pollen grain burrows into ovule2. Cell undergoes meiosis to make 4 haploid megaspores;

one survives and grows into the multicellulargametophyte

3. 2 or 3 archegonia, each with an egg, develop inside4. More than a year after pollination, eggs are ready to

be fertilized pollen tube grows through

5. One zygote develops into pine embryo (sporophyte)6. The pine seed then blows away and germinates

elsewhere


5/23


6/23

5. Point out the major life cycle differences

in ferns and pines. Pines are much more complex

Pine reproduction takes about 3 years

Pines dont need water for fertilization


7/23

6. Distinguish between pollination and

fertilization. Pollination pollen into stigma of carpel

- is a prerequisite to fertilization

Fertilization the union of haploidgametes to form a diploid zygote


8/23

7. Describe a pine seed and indicate whichstructures are old sporophyte, gametophyte,

and new sporophyte.Pine seed:

1. Embryo 2n new sporophyte2. Food source n gametophyte

3. Surrounding seed coat 2n old

sporophyte


9/23

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 leafs stomata are found in pits,

reducing water loss

Little surface area for evaporation


10/23

9. List and give examples of the two classes

of Anthophyta.1. Monocotyledons (monocots)

- parallel leaf veins

- grasses2. Dicotyledons (dicots)

- netted leaf veins

- lettuce, maples


11/23

10. Compare the life cycles of mosses, ferns, conifers,and flowering plants in terms of: dominant life cycle stage

(gametophyte/sporophyte), whether they arehomosporous or heterosporous, mechanism of gamete

transfer

Mosses gametophyte, heterosporous,sperm swim to egg

Ferns sporophyte, homosporous, wateris necessary

Conifers sporophyte, heterosporous,pollen fertilizes ovary

Flowering plants sporophyte,heterosporous, pollen fertilizes ovary


12/23

11. Describe some refinements in vasculartissue that occurred during angiosperm

evolution. Conifers have tracheids which conduct

water (the early type of xylem cell)

Angiosperms also have xylem, but usevessel elements, which is a more efficientcell than the tracheids


13/23


14/23

12. Explain how evolution of the flowerenhanced the reproductive efficiency of

angiosperms. The ovary dropped below the petals and

sepals where the ovules are better

protected


15/23


16/23

13. Identify the following floral structures anddescribe a function for each: sepals, anther, petals,

stigma, stamens, style, carpels, ovary, filament

Sepals sterile leaves, enclose budPetals sterile, aid in attracting pollinatorsStamen produces pollenCarpel evolved from seed-bearing leaf rolled into tubeStigma part of carpel that is sticky and receives the

pollenOvary protects ovules which develop into seedsFilament

stalk of stamenAnther terminal sac of stamen where pollen is

producedStyle leads to ovary


17/23

14. Describe four commonly recognizedevolutionary trends in floral structure found

in various angiosperm lineages.1. The number of floral parts have become

reduced

2. Floral parts have become fused together3. Symmetry has changed from radial to

bilateral

4. The ovary has dropped below the petalsand sepals where the ovules are betterprotected


18/23

15. Define fruit and explain how fruits aremodified in ways that help disperse seeds.

Fruit a ripened ovary that protects dormantseeds and aids in their dispersal; some fruits (likeapples) 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 thedigestive tract of the animal and end up elsewhere


19/23

16. Diagram the generalized life cycle of anangiosperm, identify which structures are haploid,and explain how it differs from the life cycle of a

pine.1. Pollen lands on a sticky stigma2. Pollen grain germinates on stigma by growing a

pollen tube down the style of the carpel

3. Reaches ovary and pollen tube grows through itsmicropyle and discharges 2 sperm into embryosac

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 sacscentral cell to form a triploid endosperm

5. After double fertilization, the ovule maturesinto a seed, and is ready for dispersal


20/23


21/23

17. Explain how an angiosperm seed differsfrom that of a pine.

Pine seeds have old and new sporophyteand gametophyte incorporated into the

seed itself Angiosperm seeds have fruits that help

disperse the seeds and the fruit is usuallythe endosperm (3n)


22/23

18. Explain why paleobotantists have difficultypiecing together the origin of angiosperms and

describe some current theories on how flowering

plants may have evolved.

Angios have a relatively sudden appearance inthe fossil record there are no clear links toancestors

Theories:

1. Angios originated where fossilization wasunlikely

2. Angios evolved and radiated relatively abruptly(punctuated equilibrium)

- perhaps angios evolved from seed ferns, anextinct group of unspecialized gymnosperms


23/23

19. Explain how animals may have influencedthe evolution of terrestrial plants, and vice

versa. It is a consequence of interdependence

Coevolution reciprocal evolutionaryresponses among two or more interactingspecies; an adaptive change in one speciesis in response to evolutionary change in theother species

adaption of seed plant

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