Botany Exam 3

According to the description of "true leaves", a feature seen in true leaves but not in microphylls is;

the presence of branched veins

In the evolutionary history of land plants, which of these is a landmark evolutionary feature appeared in Lycophytes?

they evolved the dominant diploid sporophyte generation

Which sequence represents the correct order in which land plants became more advanced in structure and function during their evolution?

Bryophytes, Lycophytes, Pteridophytes, Gymnosperms, Angiosperms

Among all land plants, which phylum carries the smallest and least advanced sporophyte generation?

Phylum Hepatophyta

True stems with vascular tissues can be seen among:

Phylum Lycopodiophyta

Phylum Pteridophyta

Phylum Equisetophyta

Which statement is true about a difference between fern allies and true ferns?

True leaves are present in true ferns but not in fern allies

Why are gymnosperm seeds said to be naked?

They are not enclosed within a fruit.

Which two phyla are considered as the most primitive among Gymnosperms, and why?

Cycadophyta and Ginkgophyta because they have swimming sperm

The microgametophyte of a Gymnosperm should produce;

sperm

Your friend brags to you about his fearless adventures in the Alaskan wilderness where he was once lost for several weeks and survived by eating fruits of giant conifers that were the only available food in that area. You laugh and tell him, "that can't be true". Why?

Because conifers do not produce fruits

Ginkgo biloba is the only species in the phylum Ginkgophyta. Why have scientists given this one species its own phylum?

It is the only remaining species of a previously larger group

Gnetophytes have some advanced characteristics in common with angiosperms. Why are they classified as gymnosperms?

Their seeds are naked

In seed plants, which of the following would be dispersed away from the parent plant?

microgametophytes and seeds

Why do Bryophytes, Lycophytes and Peridophytes prefer to grow in moist habitats closer to water?

Because they have swimming sperm that need a film of water

What is always true about heterosporous plants?

they produce small male microspores and large female megaspores

Where do you find integument? What does integument become at later stages?

Around the megasporangium in the ovule of all seed plants, later becomes the seed coat

In Gymnosperms as well as in Angiosperms, the female gametophyte is very small. How does it feed the developing embryo?

It draws nutrients from the parent sporophyte tissues.

What characteristics among these are typical to both gymnosperms and angiosperms? Choose all that apply. Penalty for wrong answers. (Hint: 4 correct answers)

They are vascular plants with true stems and leaves

Their female gametophyte is contained within the

sporophyte

Their pollen represent the male gametophyte

Their male gametophyte travels to the female gametophyte

What is a correct statement describing a relationship between ovules and seeds in "both gymnosperms and angiosperms"?

the unfertilized egg cell inside the ovule becomes the embryo inside the developing seed after fertilization

Dicots and monocots differ from each other in several ways. Select all answer choices that describe differences between them. Penalty for wrong answers. (Hint: 3 correct answers)

Venation pattern in the leaves of dicots and monocots differ

Dicots produce two cotyledons, monocots produce only one

The arrangement of vascular bundles in dicot and monocot stems differ

Which of the following statements most accurately explain what recent molecular evidence shows about monocots and dicots?

dicots were the first to emerge, and monocots separated later from a dicot ancestor

Here is something to think about. Read patiently! You treated a developing flower of a self-pollinating diploid angiosperm with a chemical that disrupts sister chromatid separation in the anaphase II of meiosis during both microspore and megaspore formation, producing spores that have double the number of chromosomes. If the plant pollinates itself, what would you expect as the ploidy of the integument, zygote and endosperm?

integument 2N, zygote 4N, endosperm 6N

The double fertilization is seen;

in all angiosperms and some gymnosperms

What is carried inside the seed of a gymnosperm?

embryo of the future sporophyte

During the event known as double fertilization, which of these is/are fertilized by a sperm nucleus to generate the 3N endosperm?

Two polar nuclei

What is the function of the pollen tube in an Angiosperm?

delivering two sperm into the ovule

The zygote of an angiosperm undergoes _______________ to produce the embryo, that develops into the __________________ .

mitosis, future sporophyte

The fruit is;

a mature ovary

Refer to the ABC model of floral organ development. Gene A is expressed in whorls 1 & 2, gene B is expressed in whorls 2 and 3, gene C is expressed in whorls 3 & 4 (whorl 4 is the innermost). A scientist used genetic engineering techniques to express gene B in all whorls. What would the pattern of floral organs in the resulting transgenic plant be?

petals, petals, stamens, stamens

How do you tell if a symbiotic relationship is a mutualism or commensalism?

mutualism benefits both, commensalism benefits one without harming the other.

What words should go in the blanks? In the life cycle of a land plant, diploid sporophyte produces spores using cell division by ____, and haploid gametophyte produces gametes using cell division by ____ .

meiosis, mitosis

Heterospory is a feature that is invariably found in;

all seed plants

Which of these are true about heterospory? Choose all that apply. Penalty for wrong choices. (Hint: 3 correct answers)

There are megaspores and microspores

Heterospory first appeared in Lycophytes

Heterospory paved the way for plants to evolve seeds

Which of these is NOT a part of a gametic life cycle?

Alternation of generations

What happened to the gametophyte stage during the course of evolution of land plants?

became smaller and more dependent on sporophyte

The ABC model explains;

how different whorls of flower parts are determined

Coevolution can be defined as;

An alliance between species that influence the evolution of each other.

Your friend says; A symbiotic relationship between two organisms is beneficial to both organisms involved. You say:

False, these relationships may benefit both or only one partner.

A farmer owns a successful organic apple orchard. For many years he has had excellent yield from his trees. This year his orchard yielded very poorly even though he had not changed his farming strategies, and weather was very consistent. Which of the following reasons might best explain the drop in fruit production?

only answers A and C could be possible explanations

When flowers are self pollinated, they get their own pollen onto the stigma of a flower, therefore, it can be considered as a form of asexual reproduction.

False, because pollen and eggs are not identical due to meiosis in sporangia

A plant lives in a remote valley, with only a few other flowering plant species nearby. It reproduces only sexually by being pollinated only by one specific butterfly species, which pollinates most of the plant species in the valley. Also living in the valley is a bird that eats only the fruit of the plant and preys on the butterfly. Extinction of which of these three species would cause the extinction of the other two?

the butterfly

Why have some plants coevolved with animals for pollination, rather than depending on physical forces like wind and water for pollination?

because coevolved animals are more reliable in carrying pollen between flowers

Your aunt who is highly allergic to bee stings, loves flowers but would like to keep bees away. What would be your best advice to her about the types of flowers she should have in her garden?

plant mostly bright red, long tubular flowers without landing platforms

What is the advantage to a tomato plant in having green unripe fruit and red ripe fruit?

this lowers the chance that immature seeds are dispersed by animals

Early plants

-small

-no roots, stems, flowers, or seeds

-evolved from green algae (chlorophyta)

Order of seedless plant evolution

-Chlorophyta (green algae)

-Bryophytes

-Lycophytes (fern allies)

-Pteridophytes (true ferns)

Bryopyhtes

-Phylums Hepatophyta and Bryophyta

-next step from algae, need close water

-moist environments

-flagellated sperm need water

-no vascular tissue

-no true organs (stems, leaves, roots)

Bryophyte Life Cycle

-dominant gametophyte (haploid)

-diploid sporophyte grows and depends on dominant gametophyte

Where is the sporophyte the smallest?

In Phylum Hepatophyta (Bryophytes)

Phylum Hepatophyta (liverworts)

-simple body form

-rhizoids to anchor

-gametophyte forms archegoniophores and antheridiophores to produce gametes

-sperm fertilizes egg to form diploid zygote in archegonia

-sporophyte grows from zygote, still in archegoniophore

-sporophyte, thru meiosis, produces haploid spores

-haploid spores germinate to form haploid gametes

Commensalism

Benefit one, harm to other

antheridiophore

-male, in bryophytes

-disc shaped

-produce flagellated sperm

Phylum Bryophyta (mosses)

-erect body form

-no vascular system (no stems/leaves/roots)

-rhizoids to anchor

-archegonia and antheridia form at gametophyte tips

-sperm spreads by wind and water and swims to fertilize egg

-diploid zygote forms

-produces diploid sporophyte at female plant tip

Rhizoids

anchors, but does NOT absorb anything

Gemmae cups in Bryophytes

-for asexual reproduction

-gametes produced by MITOSIS

Importance of Bryophytes

-common starter species for poor soils

-common foundation for food chains

-wide distribution

Leaves come from

modified stems and branches

Cycad corraloid roots in symbiosis with cyanobacteria

Plants will provide nutrients/protection to the cyanobacterium

(ANABAEN, NOSTOC) which will provide fixe nitrogen and toxins to the plant

Example: Azolla is symbiotic with Anabaena

Plant Diseases Caused By Bacteria

Internal Defenses to recognize pathogen

Ex: Hypersensitive response and SAR

Plants Interaction with Fungi

Good: Mycorrhizal fungi. Decomposers that recycle nutrients from dead plant matter back to soil

Bad: Pathogens that cause diseases

What is a Fungi?

-Some Unicellular

-Most are multicellular and filamentous

Mycelium

Filaments aka HYPHAE make the body of the fungus (mycelium)

Mushrooms Eaten Are

Reproductive Organs of the fungus

Mycorrizhal

90% of plants benefit from it. Increases surface area for absorption. Plant will provide carbs to the fungus.

Fungal Mycelia

Help absorb phosphorus and nitrogen from soil

Ectomycorrhizae

have hyphae that do not enter into root cells

Endomycorrhizae

produce structures that enter root cells

Mycorrhizae inside plant roots come in two forms

Ectomycorrhizae

Endomycorrhizae

Pathogenic fungi

plant diseases are caused by fungi

Ex; mildews, rots, rusts, smuts, anthracnose

Plants have also developed mechanisms to resist

infections (coevolution for defense)

Monotropa

Completely heterotrophic

angiosperm that draws

nutrients from soil fungi.

Plants can be parasitic in fungi

Mutualistic Coevolution Between Plants and Animals

- pollination

- seed dispersal

- protection

Plant-animal coevolution strategies are important

to humans too

An apple orchard needs pollinating agents

for better yield

A squash garden needs pollinators to carry

pollen from male to female flowers

Self pollinating flowers

- Must be perfect flowers

- Anthers and stigma mature

at the same time

- Anthers can touch stigma

or placed above stigma

- Usually less colorful

Cross pollinating flowers

Show mechanisms that prevent self pollination and promote cross pollination

Mechanisms to promote cross pollination

- Stamens below stigma

- Imperfect flowers

-

- Self-incompatibility if

perfect flowers

- Male and female plants

Ex: Squash

Where does meiosis occur in the plant life cycle?

-diploid sporophyte produces haploid spores by MEIOSIS

-haploid spores develop into gametophytes

-gametophytes produce gametes by MITOSIS

-haploid gametes (female+male) come together to form genetically unique sporophyte zygote

How does meiosis increase genetic variation in plants?

Meiosis is a reduction division

-shuffles alleles in homologous chromosomes

-separates homologous chromosomes

-endless new allele combinations

-results in unique new cells

-produces cells with half the number of chromosomes

Result of Meiosis in Plants?

4 genetically different haploid spores

Meiosis events

-Meiosis I (PMAT I) Homologs seperate

-Cytokinesis I

-Meiosis II (PMAT II) Sister Chromatids seperate

-Cytokinesis II

3 Stages of Development in Flowering Plants

-Vegetative Stage

-Reproductive Stage

-Senescence

Vegetative Stage

-first stage of flowering plant development

-increase size

-produce more roots, leaves, and branches

Reproductive Stage

-second stage of flowering plant development

-produce flowers, fruits, and seeds for sexual reproduction

Senescence

-third stage of flowering plant development

-individual organs or whole plant wither and die

:(

What is the sexual organ in Angiosperms?

the flower

Flower Reproductive Organs

Pistil

-female part

-ovary and bottom

-stigma at top

-style connects ovary to stigma

Stamen

-male part

-anther at top

-filament raises it to stigma

Perianth

petals and sepals

Receptacle

The base of a flower

What causes vegetative meristem to become floral meristems?

-Internal signals (hormomes/metabolites_

-Environmental cues (temp, day length, stress factors)

How is pollen formed?

-meiosis inside of MICROsporangia in anthers prodice microspores that become pollen

Pollen grains contain

-tube cell

-tube cell nucleus

-generative cell

How is pollen dispersed?

-by anther dehisence

-pollen grains land on stigma

-pollen tube grows inside the style to reach ovary

-after pollenation, g cell nucleus divides by MITOSIS to produce 2 sperm nuclei

-tube nucleus controls the pollen tube growth into an ovule

ABC Floral Development

-A only = sepals

-A and B = petals

-B and C = stamens

-C only = carpels

What happens in the ovule during sexual reproduction?

-meiosis inside ovule produces megaspore that develops into a female (mega) gametophyte

-pollen tube grows into ovule

-one sperm nucleus fertilizes the egg cell nucleus

Microgametophyte

-male

-2 cells inside pollen

-dispersed from sporophyte

Megagametophyte

-female

-few cells inside ovule

-contained and nourished within sporophyte

After fertilization in plants

-zygote is the fertilized egg

-embryo inside seed

-becomes future sporophyte

Zygotic Life Cycle

-in protists (algae)

-DOMINANT HAPLOID

-produce spores through MEIOSIS

-zygote is the only diploid stage

Gametic Life Cycle

-animals, some algae

-produce gametes directly through meiosis

-gamete only haploid stage

-DOMINANT DIPLOID