chapter 1 Flashcards
(113 cards)
1
Q
From what did land plants evolve from? and what do they share?What is it supported by?
A
Land plants evolved from green algae. Both shared a common ancestor over 1 BYA.
This is supported by DNA sequence data: a fresh water green algae, gave rise to the land plants.
2
Q
What are land plants and green algae collectively known as?
What is the exception?
A
green plants
the exception is brown and red algae
3
Q
The green plants are photoautotrophic(autotrophs), what does this mean?
A
they obtain their energy from photosynthesis.
Note: Not all photoautotrophs are plants (ex. Some bacteria and protists are photosynthetic.)
4
Q
What features do plants and algae share?
A
*Both are photosynthetic and have the same photosynthetic pigments (chlorophyll a+b).
*Both store their excess carbohydrates as starch.
5
Q
Where do most algae live, and where did they evolve to live?
A
In the sea. They evolved to live in freshwater environments.
6
Q
The green algae are divided into 2 groups; What are they? What functions do they have?
A
a)The chlorophytes, which never made it to land(aquatic/mainly in sea)
b)The charophytes, (group of fresh water algae) which are a sister clade to all the land plants.
7
Q
What are the charophytes and the land plants referred to?
A
Streptophytes
8
Q
Unlike their ancestors, what do charophytes(land plants) have?
A
-Multicellular haploid and diploid stages in their life cycles.
-a diploid embryo: innovation of the land plants.
9
Q
To live on lands, plants developed adaptations to overcome what problems?
A
1-Water loss
2-harmful effects of the sun
3-poor dissemination(spread) of gametes for reproduction.
10
Q
How did fungi help plants to colonize the land?
A
They helped to make nutrients available to plants.
11
Q
What adaptation did plants develop to prevent water loss and protect from desiccation(drying out)?
A
Development of a waxy and impermeable cover called cuticle on the outer plant surfaces.
12
Q
Does the cuticle allow gas exchange? Why or why not?
A
No, the cuticle is impermeable.
13
Q
What adaptation did plants develop to allow gas exchange?
A
Development of tiny openings called stomata.
14
Q
What adaptation did plants develop to move water and nutrients?
A
Development of a conducting system; vascular tissues.
15
Q
What effect does the development of a conducting system; vascular tissues have on the plants’ size?
A
Plants increase in size, they grow tall.
16
Q
Xylem
A
conducts water
17
Q
Phloem
A
conducts sugars and dissolved nutrients
18
Q
What are plants with vascular tissues called? What can they do wrt size?
A
tracheophytes ; they can grow tall
19
Q
Which plants lack vascular tissues and are always small/restricted in size?
A
Primitive plants; bryophtes and mosses
20
Q
Which vascular tissue conducts water?
A
the xylem
21
Q
Which vascular tissue conducts sugar and dissolved nutrients?
A
the phloem
22
Q
Tracheophytes
A
plants with vascular tissues; they can grow tall
23
Q
Primitive plants(Bryophytes/mosses)
A
plants that lack vascular tissues and are always small/restricted in size
24
Q
What adaptation did plants develop to mask deleterious recessive mutations caused by exposure to high UV radiation land?
A
They shift to a dominant diploid generation (stage) in the life cycle.
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What happens as a result of plants shifting to a dominant diploid generation in their life cycle?
Larger number of alleles persist in the gene pool, creating greater genetic diversity.
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What adaptation did plants develop to protect the embryo from desiccation?
Development of reproductive strategies suitable to life on land.
27
What are the multicellular sex organs of plants called?
Gametangia
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What is the female gametangium that produces a single egg called?
archegonium
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What is the male gametangium that produces many sperm called?
antheridium
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After fertilization, what happens to the zygote?
the zygote develops into a multicellular embryo within the archegonium.
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Gametangia
multicellular sex organs of plants
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Archegonium
the female gametangium that produces a single egg
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Antheridium
the male gametangium that produces many sperm?
34
Are plants unicellular or multicellular?
Multicellular
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What are the 2 main phases in plants' life cycle?
They have a multicellular haploid and a multicellular diploid phase in their life cycle.
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What does haplodiplontic life cycle mean?
with multicellular (N) haploid and (2N) diploid stages.
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What is the haploid generation called?
Gametophyte
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What is the diploid generation called?
Sporophyte
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What happens during the gametophyte generation?
It starts with (N) haploid spores. Each spore germinates into a gametophyte. At maturity, the gametophyte produces gametangia: Each archegonium produces an egg (N) and each antheridium produces many sperm (N)
In plants, gametes are produced as a result of mitosis.
Egg and sperm unite via fertilization producing a zygote (2N) which is the start of the sporophyte generation.
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What happens during the sporophyte generation?
It starts with the diploid zygote. The zygote grows into a multicellular embryo and then into a sporophyte plant. The sporophyte produces at maturity sporangia= cases bearing spore-mother cells or sporocytes (2N). Within sporangia, sporocytes undergo meiosis.
Each sporocyte produces 4 haploid spores.
In plants, spores are produces as a result of meiosis
41
What type of life cycle do animals and humans have?
They have a diplontic life cycle: only the diploid stage is multicellular( the haploid gametes are unicellular)
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In animals, the (N) haploid gametes are produced as a result of what?
Meiosis
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After the gametes fuse, what happens?
they produce a (2N) zygote which grows by mitosis to form a multicellular embryo
44
In animals, what is the only haploid (N) stage/organ?
gamete
45
What are the seedless non-tracheophytes that reproduce via spores?
Bryophytes(Mosses and liverworts)
46
What are the seedless Tracheophytes (vascular) that reproduce via spores?
Ferns and their allies
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What are the Tracheophytes (vascular) that reproduce via naked/exposed seeds?
Gymnosperms(conifers)
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What are the Tracheophytes (vascular) that reproduce via seeds that are within fruits?
Angiosperms(flowering plants)
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What are the 10 characteristics of bryophytes?
1-closest living descendants of the first land plants.
2-nontracheophytes(or non-vascular plants).
3-lack vascular tissues which makes them smaller in size.
4-lack tracheids.
5-They have other simple conducting cells in their gametophytes.
6-They have close associations with fungi, mycorrhizal associations, which enhances water uptake.
7-reproduce via spores.
8-dominant gametophyte generation.
9 -gametophyte photosynthetic and free living
10- sporophyte small, non-photosynthetic, and attached on the gametophyte.
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Tracheids
transport/water conducting cells
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Bryophytes include 3 phylums:
1-The mosses (Phylum Bryophyta)
2-The liverworts (Phylum Hepaticophyta)
3-The hornworts (Phylum Anthocerophyta)
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Where are the bryophytes found? And why?
They are found in moist places because they need water to reproduce sexually
53
What are the 5 characteristics of mosses(Bryophyta)?
1-Each plant is a gametophyte(N) haploid and has tiny root structures called rhizoids.
2-Rhizoids anchor the plant; consists of several cells that absorb water.
3-It has a stem like structure that bears leaf-like blades.
4-The gametophyte is green and photosynthetic.
5-It is the dominant generation; it is conspicuous and persistent.
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Moss life cycle(Steps)
1-At maturity, gametangia(Archegonia(1egg) and Antherida(many flagellated sperm))are born at the top of the gametophyte.
Water is needed for fertilization to occur.
2-The flagellated sperm swim through a water film and unite with the egg to form a (2N) zygote.
3-zygote develops into sporophyte(2N)(brown and non-photosynthetic) which grows on gametophyte because it's nutritionally dependent on it.
4-The sporangium contains spore-mother cells or sporocytes(2N) which undergo meiosis.
Each sporocyte results in 4 haploid spores.
5-At maturity, the sporangium dries and pops off, releasing spores.
6-If a spore lands on a suitable (wet) soil, it can directly germinate into a gametophyte; or it can germinate and grows into a thread of cells called protonema, which branches to form rhizoids and buds.
Each bud develops into a gametophyte plant.
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protonema
cells which branch to form rhizoids and buds.
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Where can mosses live?
Mosses can live in harsh environments and can withstand periods of drought.
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Where are mosses most abundant in? And where are they most found?
They are abundant in the Artic and Antarctic; but most are found in the tropics.
58
What are most moss species sensitive to?
Many species are sensitive to pollution and don’t grow in and near cities.
59
What Moss species can absorb a lot of water and can be used commercially as soil conditioner (to add to potting soils) or as fuel when dry?
peat moss (Sphagnum sp.)
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peat moss (Sphagnumsp.)
can absorb a lot of water and can be used commercially as soil conditioner (to add to potting soils) or as fuel when dry.
61
What are the 3 main characteristics of liverworts(hepaticophyta)?
1-lobed and flattened gametophytes.
2-form umbrella-shaped gametangia.
3-undergo asexual reproduction via gemma cups
62
Gemma cups
small discs of haploid gametophyte tissues; dispersed by rain…and germinate directly into new gametophytes.
63
What are the earliest land plants?
Hornworts
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Main Characteristics of hornworts(Anthocerotophyta)
The sporophyte is embedded in the gametophyte tissue (thallus); from which it derives some of its nutrients.
The sporophytes look like green horns rising from the gametophyte.
Meiosis occur within the horns and spores are released.
the cells have a single large chloroplast (similar to those found in algae).
65
How are the sporophytes of hornworts similar to the vascular plant sporophytes?
1- they are green and photosynthetic.
2-they have stomata to regulate gas exchange.
66
Who are the closest relatives to the tracheophytes? How is this group viewed?
Hornworts; This group is viewed as the transition from the dominant gametophyte to dominant sporophyte generation of the tracheophytes.
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4 characteristics of tracheophytes
-vascular plants
-first appeared 410 MYA
-sporophyte is the dominant generations
-now extinct
68
To which phylum do the first tracheophytes belong to?
Phylum Rhyniophyta.
69
Example of tracheophytes
cooksonia; no roots, no leaves, only branching stems.
70
What are the 4 main features of vascular plants?
1-Dominant sporophyte generation
2-Presence of cuticle and stomata(successful colonizers of the land)
3-Development of vascular tissues ;xylem and phloem.(phloem for sugar and hormone conduction)
4-plants can increase in size/grow tall.
71
where do vascular tissues develop?
They develop in SPOROPHYTE, not GAMETOPHYTE.
72
How many extant phyla and clades are Tracheophytes (vascular plants) included in?
Vascular plants include seven extant phyla grouped in three clades.
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clade: seedless
1. Lycophytes (club mosses)
2. Pterophytes (ferns, whisk ferns, and horsetails)
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clade: seeds
3.seed plants: gymnosperms and angiosperms
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What is the trend in vascular plants?
-Gametophyte has been reduced in size relative to the sporophyte during the evolution of tracheophytes.
-Similar reduction in multicellular gametangia has occurred as well.
-Development of heterospory.
76
Define homosporous
homosporous = they produce one type of spore.
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Define heterosporous
heterosporous = they produce two types of (N) spores: microspores and megaspores.
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Which plants are homosporous?
Mosses and ferns
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Which plants are heterosporous?
Some clubmosses and all seed plants
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Mosses and ferns are homosporous or heterosporous?
homosporous
81
Some club mosses and all seed plants are homosporous or heterosporous?
heterosporous
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Microspore
germinates into a male gametophyte that produces only antheridia (giving sperms).
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Megaspore
germinates into a female gametophyte that produces only archegonia (giving one egg/archegonium).
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Characteristics of lycophyta (club mosses) 6
1-sperm motile
2-homo/heterosporous
3-external water necessary for fertilization.
4-They resemble mosses, but they are vascular and have a dominant sporophyte generation.
5-vascular stems, lycophylls(small leaves with 1 vein), and rhizoids.
6-worldwide distribution, abundant in tropics.
85
Characteristics of pterophyta (ferns) 4
1-Primarily homosporous
2-Sperm motile.
3-External water necessary for fertilization.
4-Sporophytes and gametophytes are photosynthetic
5-Conspicuous and dominant sporophyte;-a small gametophyte: non-vascular, free-living, and green.
86
Characteristics of pterophyta (Horsetails) 8
1-Homosporous.
2-Sperm motile.
3-External water necessary for fertilization.
4-Only 1 genus: Equisetum species.
5-Sporophyte consists of 2 types of stems: sterile, green and photosynthetic, or reproductive, brown, non-photosynthetic that bear sporangia at their tips.
6-The stems of horsetails have silica in their epidermal cells, giving them the common name scouring rush
7-Stems ribbed, hollow, jointed, either photosynthetic or non-photosynthetic.
8-Leaves scalelike, in whorls; non-photosynthetic at maturity
87
Characteristics of pterophyta (Whisk ferns) 6
1-Homosporous.
2-Sperm motile.
3-External water necessary for fertilization.
4-No differentiation between root and shoot. No leaves. No roots. Branching stems.
5-found in tropics
6-At maturity, yellow sporangia are born at the tips of the stems.
88
Which seedless vascular plant is either homosporous or heterosporous?
club mosses; phylum lycophyta
89
Which seedless vascular plant has both sporophytes and gametophytes photosynthetic?
ferns; phylum pterophyta
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Which seedless vascular plant has scale-like leaves in whorls that are non-photosynthetic at maturity?
Horsetails; phylum pterophyta
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Which seedless vascular plant has no leaves?
Whisk ferns; phylum pterophyta
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When did stems evolve?
Stems evolved early, prior to roots.
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What do fossils of early vascular plants (like Cooksonia) reveal?
They reveal stems, but no roots or leaves
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How did the lack of roots in cooksonia limit their size?
1-Roots anchor plants to the ground, preventing them from falling over, knowing that tall plants need strong roots.
2-An extensive root system is needed to ensure a large plant’s need for water is met, as a large plant has a large surface area for water loss.
95
What are the roots' function?Where are they only found?
1-found only in the tracheophytes.
2-provide support and transport.
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Why do lycophytes lack roots?
they diverged from other tracheophytes before roots appeared.
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What are leaves' function? And how many types are there?
They increase the surface area for photosynthesis. There are 2 types: Lycophylls and Euphylls.
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Lycophylls
Lycophyll= a leaf with one single vascular strand
-small, simple, leaves with unbranched veins (1 vein/leaf).
-only found in Lycophytes (clubmosses)
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Euphylls
-Euphyll= a leaf with many vascular strands or with many branched veins.
-referred to as true leaves.
-found in ferns, and the seed plants.
-arose from branching stems
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What are seeds' functions?
1-Seeds are highly resistant structures that protect embryos from environmental stresses
2-They contain food supply for the young emerging plant.
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Seeds are another innovation of what?
the advanced tracheophytes: Gymnosperm and Angiosperm.
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which vascular plants do not have seeds?
Lycophytes (clubmosses) and pterophytes (ferns)
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What is the function of fruits in the flowering plants; angiosperms?
They add a layer of protection to seeds and attract animals that assist in seed dispersal, expanding the potential range of the species.
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pterophytes general characteristics
3
1-They are seedless, vascular plants, with a dominant sporophyte generation.
2-They are (mainly) homosporous.
3-Their sperm are flagellated, and they need water for fertilization to occur.
105
Why do stems of horsetails have the name scouring rush?
The stems of horsetails have silica in their epidermal cells, giving them the common name scouring rush.
106
In the fern life cycle, what does the sporophyte consist of?
-rhizome= horizontal, underground stem
-roots
-leaves called fronds
107
In the fern life cycle, how are the fronds formed?
When a young leaf emerges from the soil, it is tightly coiled; it is called fiddlehead; as it grows, it expands into a frond.
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fiddlehead
young leaf that emerges from the soil
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frond
compound leaf (made of many leaflets).
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Fern life-cycle
At maturity, the sporophyte produces sporangia, usually found in clusters called sori, on the back of fronds.
Within the sporangia, (2N) spore mother cells undergo meiosis and produce (N) spores.
The spores are expulsed from the sporangia by a snapping action.
Spores germinate into a haploid gametophyte.
The gametophyte is heart-shaped, non-vascular, very small and green.
It is one cell thick (except at its center).
It has rhizoids for anchorage.
It grows flat on the soil.
It produces antheridia and archegonia on its underside.
Water is needed for fertilization to occur.
Water droplet carries the flagellated sperm to the base of the archegonium, where the egg is fertilized.
The (2N) zygote develops into a new sporophyte, that grows and kills the gametophyte.
111
In the fern life-cycle, why is water needed for fertilization to occur?
Water droplet carries the flagellated sperm to the base of the archegonium, where the egg is fertilized.
112
What does it mean when we say that leaves are microphylls?
microphylls(have only one strand of vascular tissue).
Most likely evolved as simple side extensions of the stem
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sporophylls
Microphylls bearing sporangia are sporophylls.
Grouped into club-shaped :strobili
