Quiz#4: Seed Plants

Question 1

heterosporous

Answer 1

the system in which there are two types of spores..megaspore(female) and microspore(male) these then undergo mitosis to produce two types of gametophytes…mega and micro gametophyte…this is why there is a division of labor because then one concentrates on the egg and the other on the sperm once they undergoe mitosis to produce the gameetes……so now the plant will also have to develop two sporangia to hold the egg and another to hold the sperm..these will be the micro and mega sporangium…however even tho they had to make this,,,this system seemed to offer new advantages and this is shown in the idea that it evolved multiple times….so convergent evolution…so favored by nat selection because it allowed for specialzation

Question 2

microspore

Answer 2

the microspore is the male sore produced in the heterospory system within the plant reproductive cycle.

Question 3

seed

Answer 3

consists of a plant embryo, together with a food source, surrounded by a protective coat. This evolved after the seedless vascular plants.(club mosss, whisk ferns, horestails)..in most seed plants, the multicellular seed is the end product of the stage where the gametes fuse and form an embryonic sporophyte that enters a temporary dormant stage……the seed is the greatest evioltuionary suceess of the seed plant , which are the dominant life forms of mostterrestrial floras

Question 4

vascular plants-branched out

Answer 4

from the earliest rhyniophytes that were the earliest vascular plants, came the lycophytes and monilophytes who that contained new ftrs such as true roots, true leaves differentiatiom bw two spore types

Question 5

overtopping

Answer 5

synmorphy of euphyllophytes(true leaf plants) that was a growth pattern in wchih one branch differentiates and grows beyond the others, giving the ability to compete for photosynthesis and anabiling to shade other dichotomously growing plants…..this allowed the rise of new leaf types

Question 6

megaspospore

Answer 6

the spore produced in the heterospory system that goes on to develop in into the megagametophyte that will then produce the female gamete.

Question 7

megagametophyte

Answer 7

the gametophyte that will go on to develop into a female gamete..in a heteresopory system of alternation of generations

Question 8

mirrcorgametophyte

Answer 8

the gameteophyte that undergoes mitosis to make male gametes

Question 9

secondary growth

Answer 9

growth of a plant in the diameter of their stems and rootS allowing the plant or tree to grow thicker..so increase in girth

Question 10

gymnosperms

Answer 10

are one of the two clades within the seedplants that show secondary growth….also in these seed plants we start to see that the lefe cylce is different than in the nnvascular pplants..a difference being that the sporophyte is less dependent even more thatn in the ferns.(seedless vascular)…….the earliest gymnosperms had swiimming sperms that later evlved other means to bring egg and sperm to fuse(so independent from water allowing them to survive in drier environments.

Question 11

angiosperms

Answer 11

other clade of seed plants that evolved seeds and pollen…flowers…the synapomorphies characterizing them are double fertilization, production of endosperm, carpel enclosing seed and ovule, flowers, fruits, phloem reduced gametophytes…so sporophyte dominant…also they contain vessel elepents in their xylem and companion cells in the phloem as well as secondary groth

Question 12

pollen grain

Answer 12

this is male gametophyte that forms from the microspore that undergoes miitosis to form this tyo of male gametophyte…these are released from the microsporangium that holds the spore that will undergoe meiosis and become microspore that are sispersed by the wind or an animal pollinator….the walls of this pollen grain contan sporopollenin which is th most chemically resistant biological compound that protects the pollen form dehydration and chemical damage(contributes to survival)

Question 13

integument

Answer 13

the sporophyte structres surrounding the female megasporangium protecting it… the megasproangium and the integument will make up the ovule.

Question 14

seed coat

Answer 14

the sead coat develops from the itnegument that protects th egametosporeangium…this sead coat protects the embryo form excessive drying and against potential predators

Question 15

endosperm

Answer 15

the tissue that supplies nutrition for the embryo since in angiosperms the megasporangium tissue is reduced and does not give much nutrition to the emrbyo, as it does in the gymnosperm.

Question 16

wood

Answer 16

extensively proliferated xylem that allows for high growth in plants and therefore more photosynthesis and ability to ocmpete…while the younger of the wood transorts water , the older becomes clogged and not functional for transport but even then they still provide structural support.

Question 17

carpel

Answer 17

modified leaf in the angiosperms that encloses the seeds and the ovules…it also interacts with the incoming poollen to prevent self pollination, thus increasing genetic diversity and favoring crosspollination.

Question 18

Pollen tube

Answer 18

Slender tube elongated by the microgametophyte or pollen grain that elongates this tube and digests its way down to the female gametophyte and releases the sperm and fertikization ocurrs

Question 18

double fertilization

Answer 18

considered the single most reliable distinguishable feature in angiosperms..it occurs when two male gametes contained in a single microgametophyte participate in fertilization events within the megagametophyte of an angiosperm. One of the sperm fuses with egg and the other combines with two other haplod nuclei within the female gametophyte to form a 3n so triploid nucleus which will divide to form endosperm tissue

Question 19

Define homospory and distinguish from heterospory

Answer 19

So homospory is when the sporophyte produces only one type of spore that undergoes mitosis to produce one multicellular gametophyte which will undergo mitosis and are contained in the antheridium and archegonium before becoming egg and sperm..both haploid still….on the contrast….the heterospry priduces two types of spores micro and mega spores each contained in separate sporangia the micro and megasporangia.(.before undergoing meiosis)they then become teo types of ganetophytes..micro and mega gametophyte.. That each are soecialized to becme egg and sperm

Question 20

Define the key innovations in seed plants

Answer 20

Pollen, seeds, wood are major innovations1)when dispersal ocurrs water wasnt exactly neded anymore with later seed plants so pollen grains were protected by chemically resistent compund that protected ahainst dehydration and chrmical danage 2)So seed plants have the well packaged seed that protects the embryo and has ability to renain dormant until the conditions are fit for the sporophyte to produce…in contrast to seedless plants that directly develop into a sporophyte and either survive or die dependingvon there environment..this distinction allowed seed plants to protect their embryo from drying and against predators besides structural protection when beingdispersed…so enormous evolutionary success…2) seed plants were enabled to produce wood which can be seen as an extensive xylem allowing taller growth to capture light

Question 21

What is secondary growth?

Answer 21

Type of growth in the diameter of stems…it led some plants to develop extensively thickened woody stems that resulted in the proliferation of xylem

Question 22

What is the importance of pollen in plants?

Answer 22

The emergence of pollen allowed them to obtain independence from h20 that used to be required for reproduction. The evolution of the pollen grain allowed for the better protection of the plants gametes. Now the pollen grain would transfer the sperm into the female gametophyte to then fuse and form a zygote.

Question 23

Do Swimming sperm still exist in seed plants

Answer 23

swimming sperm was lost before the angiosperm lineage. The seed plants that had swimming sperm still were the earliest groups of gymnosperms(cycads and ginkos) while later gymnosperms evolved better ways to undergo fertilization

Question 24

what is the role of the pollen tube?

Answer 24

the pollen tube is used by the pollen grain to digest the sperms down to the female gametophyte.

Question 25

what benefits to secondary growth and seed provide to the seed plants

Answer 25

seed plants are able to grow larger and thicker with more complex growth allowing them to compete with other plants that may be shading it, and also the seed evolution allowed the gametes and zygotes to be much more protected allowing it to be more successful

Question 26

gymnosperms

Answer 26

seed plants w/o flowers with an ambiguous monophyly..it has only tracheids.the clade includes cycads, ginkos, gnetophytes, and conifers….and contains un protected ovaries

Question 27

monocot

Answer 27

one of the two largest angiosperm clade…that havea single embryonic cotyledon…lost the BVC

Question 28

eudicots

Answer 28

the other large angiosperm clade that contains two embryonic cotyledon