BIO 201 Exam 3

Protist

The informal name of the group of mostly unicellular eukaryotes

1. Protists constitute a polyphyletic group

Four Supergroups of Eukrayotes

1. Excavata

2. Archaeplastida

3. SAR Clade

4. Unikonta

Excavata

1. Characterized by their cytoskeletons

2. Some members have an excavated groove

3. protists with modified mitochondria and protists with unique flagella

4. Includes the diplomonads, parabasalids, and euglenozoans

Diplomonads and Parabasalids

1. Lack plastids

2. Have modified mitochondria

3. Most live in anaerobic environments

Diplomonads

1. Reduced mitochondria called mitosomes

2. Derive energy from anaerobic biochemical pathways

3. Often parasites

4. Have 2 equal sized nuclei and multiple flagella

Parabasalids

1. Reduced mitochondria called hydrogenosomes that generate energy anaerobically

2. Break down cellular in the termite gut

SAR Clade

The diverse monophyletic supergroup named for the first three letters of its three major clades:

1. Stramenophiles

2. Alveolates

3. Rhizarians

Stramenophiles

1. Includes some of the most important photosynthetic organisms on Earth

2. Most are identified by a ‘hariy’ flagellum paired with a ‘smooth’ flagellum

3. Include diatoms, golden algae, and brown algae

Diatoms

A unicellular algae with a unique two-part glass like wall of silicon dioxide

1. A major component phytoplankton and highly diverse

Golden Algae

Named for their color, which results from their yellow and brown carotenoids

1. Cells are usually biflagellated, with both flagella near one end

2. All golden algae are photosynthetic and some are mixotrophs

Brown Algae

The largest and most complex algae

1. All are multlicellular and most are marine

2. Include many species most commonly called seaweed

Alternation of Generations

The alteration of multicellular haploid and diploid forms that the most complex life cycles include

Heteromorphic Generations

Are structurally different

Isomorphic Generations

Look similar

Gametophyte

A haploid multicellular organism that develops from a haploid spore that has one set of chromosomes

Spore

A minute, typically one celled, reproductive unit capable of giving rise to a new individual without sexual fusion, a characteristic of flowers, fungi, and protozoans

Alveolates

Have a membrane enclosed sacs (alveoli) just under the plasma membrane

1. Dinoflagellates > 1,555 species

2. apicomplexans - unicellular and spore forming, obligate indoparasites

3. Ciliates - hair like organelles called cilia

Dinoflagellates

1. 2 flagella and each cell is reinforced by cellulose plates

2. They are abundant components of both marine and freshwater phytoplankton

3. Diverse groups of aquatic phototrophs, mixotrophs, and heterotrophs

4. Toxic ‘red tides’ are caused by dinoflagellate blooms

Apicomplexans

Parasites of animals and can cause serious human diseases

1. They spread through their host as infectious cells called sporozoites

2. One end, the apex, contains a complex of organelles specialized for penetrating host cells and tissues

Ciliates

Large varied group of protists named for the use of cilia to move or feed

Conjugation

How genetic variation results, in which 2 individuals exchange haploid micronuclei

1. sexual process but separate from reproduction, which usually occurs in binary fission

Closest relatives of land plants

Green and red algae

1. photosynthetic descendants of this ancient protist evolved into red algae and green algae

2. Land plants are descended from the green algae

Archaeplastida

The supergroup that includes red algae, green algae, and land plants

Red Algae

Their reddish color is due to an accessory pigment called phycoerythrin which masks the green of chlorophyll

1. color varies in shallow/deep waters

2. usually multicellular; most abundant large algae in the tropics

Green Algae

Named for their grass-green chloroplasts

1. plants are descended from green algae

2. green algae are a paraphyletic group

3. two main groups are charophytes and the chlorophytes

4. charophytes are most closely related to land plants

5. Most chlorophytes have complex life cycles with both sexual and asexual stages

Unikonta

The supergroup that includes animals, fungi, and some protists

1. 2 clades: amoebozoans and opisthokonts

Many protists are

Important producers that obtain energy from the sun

1. In aquatic environments photosynthetic protists and prokaryotes are the main producers but are limited by nutrients

For much of Earth’s history

Terrestrial Earth was lifeless yaonC

Cyanobacteria and protists existed on land

1.2 billion years ago

Small plants, animals, and fungi

Emerged on land 500 years ago

Land plants have similar characteristics with charophytes

1. Rings of cellulose synthesizing proteins

2. Structure of flagellated sperm

3. Formation of a phragmoplast

4. DNA

Sporopollenin

A layer of durable polymer in charophytes that prevents exposed zygotes from dying out

5 key traits of plants that are absent in charophytes

1. Alternation of generations

2. multicellular, dependent embryos

3. walled spores produced in sporangia

4. Multlicellular gametangia

5. Apical meristems

Alteration of generations

The reproductive cycle in which plants alternate between two multicellular stages

1. The gametophyte is haploid and produces haploid gametes through mitosis

2. Fusion of gametes gives rise diploid sporophytes, which produce haploid spores through meiosis

3. The diploid embryo is retained within the tissue of the female gametophyte

Embryophyte

A term that land plants are called due to their dependency of the embryo on the parent

Cuticle

A waxy covering of the epidermis S

Stomata

Specialized cells that allow for gas exchange between outside air and plant

Origin and Diversification of Plants

1. Fossil evidence indicates that plants were on land at least 470 MYA

2. Fossilized spores and tissues have been extracted from 450 MYA rocks

3. Fossils of sporangium are at least 425 MYA

Vascular tissue

The absence or presence of it in land plants is a good way to informally group plants

1. Most plants have it, called vascular plants

2. Those without are called bryophytes

Lycophytes

Club mosses and their relatives

1. A clade of seedless vascular plants

Monilophytes

Ferns and their relatives

1. A clade of seedless vascular plants

Bryophytes are represented by three phyla of herbaceous plants

1. Liverworts

2. Mosses

3. Hornworts

Living vascular plants are categorized by

1. Life cycles with dominant sporophytes

2. vascular tissues called xylem and phloem

3. Well developed roots and leaves

Xylem

conducts most of the water and minerals and include tube shaped cells called tracheids

Ligin

support the water conducting cells and provide structural support

Phloem

has cells arranged into tubes that distribute sugars, amino acids, and other organic products

Roots

organs that anchor vascular plants and enable them to absorb water and nutrients from the soil

Leaves

organs that increase the surface area of vascular plants thereby capturing more solar energy that is used for photosynthesis

2 Categories of leaves

1. Microphylls - leaves with a single vein; evolution of sporangia

2. Megaphylls - leaves with highly branched vascular system; evolution from accumulation of branches on a stem

Sporophylls

modified leaves with sporangia

Sori

clusters of sporangia on the undersides of sporophylls

Stroboli

cone like structures formed from groups of sporophylls

Seed plants originated

350 million years ago

Adaptation

involves expressing suites of evolutionary innovations that arise blindly through mutation but prove useful in new environments provided they are expressed at the right time

Seeds

Consist of an embryo and nutrients surrounded by a protective coat

1. Changed the course of plant evolution, enabling their bearers to become dominant producers in most terrestrial ecosystems

2. can disperse over long distances by wind or other means

3. develops from a whole ovules

Seed germination

The process in which a plant emerges from a seed and begins to grow

Conditions for seed germination

1. Suitable temperature - for enzymes to work effectively

2. Oxygen - for aerobic respiration to provide energy for growing embryo Water - for chemical reactions to occur

3. Water - for chemical reactions to occur

Propelled Seed flight

Flight occurs for most plants at one stage of their life

1. Pollen

2. Seeds

3. Both

Passive seed flight

1. Wind

2. Winged animals

Traits common to all seed plants

1. reduced gametophytes

2. heterospory - the production of spores 2 different sizes/sexes

3. ovules - structure the develops into a seed when fertilized

4. pollen - male gametophyte

Angiosperms

Seed plants with reproductive structures called flowers and fruits

Pollen grains

are what microspores develop into and contain the male gametophytes

Pollination

The transfer of pollen to the part of the seed plant that has ovules

1. Pollination eliminates the need for water and be dispersed great distances

Gymnosperms

means ‘naked seed’

1. seeds are exposed on sporophylls that come from cones

Conifers

most common gymnosperms are cone bearing plants

4 Phyla of gymnosperms

1. Cycadophyta

2. Gingkophyta

3. Gnetophyta

4. Coniferophyta

Flower’s different modified leaves

1. Sepals

2. Petals

3. Stamens

4. Carpals

Sepals

Enclose the flower

Petals

Brightly colored and attractive pollinators

Stamen

produce pollen

1. consists of a stalk called the filament

2. A sac called the anther where the pollen is produced

Carpel

produces ovules

1. ovary is at the base and a style leading up to a stigma where the pollen is received

Complete flowers

have all four organs; bisexual

Fruit

Formed when the ovary wall thickens and matures

1. fruit seeds protect and aid in their dispersal

2. mature fruits can be either fleshy or dry

Micropyle

the pore that the ovule enters D

double fertilization

occurs when the when pollen tube discharges two sperm into the female gametophyte

endosperm

The food storing part of the female gametophyte after one sperm fertilizes the egg and the other combines with two nuclei in the central cell of the female gametophyte

cotyledon

the root and seed leaves inside a new seed

Plant defenses

1. chemical defenses

2. mechanical defenses

3. mimicry and camouflage

4. indirect defenses

5. leaf shedding and color

Beneficial effects of fungi

1. decomposition - nutrient and carbon recycling

2. biosynthetic factories - can be used to produce drugs, antibiotics, alcohol, acids, food

3. model organisms for biochemical and genetic studies

Harmful effects of fungi

1. Destruction of food, lumber, paper, and cloth

2. Animal and human diseases, including allergies

3. Toxins produced by poisonous mushrooms within food

Fungi

1. are heterotrophs that absorb nutrients from outside their bodies

2. use enzymes to break down

3. can be parasites, decomposers, or mutualists

Basic Structure of fungi

1. mostly multicellular - most common is multicellular filaments and yeast

2. Multicellular fungi are made up of hyphae

3. hyphae may contain septa - divide hyphae into different cells but contain pores

4. cell walls composed of chitin

5. eukaryotic cells

6. some can maintain 2 nuclei per cell

Septa

divides the fungi’s hyphae by dividing cells with pores allowing cell to cell movement

1. septa is like the cell wall

Coenocytic fungi

lack septa and have a continuous cytoplasmic mass with hundreds or thousands of nuclei

haustoria

a unique type of specilized fungi that allows them to penetrate the tissues of their host

Mycorrhizae

a mutually beneficial relationship between fungi and plant roots

ectomycorrhizal fungi

form sheaths of hyphae over a root and also grows into the extra cellular spaces of root cortex

Arbuscular mycorrhizal fungi

extend the hyphae through cell walls of root cells and into tubes formed by invagination of root cell membrane

Fungi Sexual reproduction

1. fungal nuclei are usually haploid with the exception of transient diploid formed during sexual life cycles

2. sexual reproduction requires the fusion of hyphae from different mating types

pheromones

fungi use these sexual signaling molecules to communicate their mating style

Plasmogamy

union of cytoplasm from two parent mycelia

Heterokayon

the haploid nuclei do not fuse right away by coexist in the mycelium

Dikaryotic

the stage of the mycelium when the haploid nuclei pair off two to a cell

Karyogamy

nuclear fusion which can take hours, days, or even centuries

1. haploid nuclei fuse, produce diploid cells

2. diploid phase is short and undergoes meiosis

3. karyogamy and meiosis produce genetic variation

Plasmogamy

Fungi asexual reproduction

Molds produce haploid spores by mitosis and form visible mycelia

1. yeasts also reproduce asexually

Ancestor of fungi

an aquatic, single flagellated protist

Nucleariids

are most closely related to to unicellular fungi

1. Animals are most closely related to unicellular choanoflagellates

Multicellularity

evolved at least twice

Fungi were the earliest colonizers of land

formed mutual relationships with land plants