Biology: Biological Classification

Flashcards based on the Biological Classification lecture notes.

Who was the earliest to attempt a more scientific basis for classification?

Aristotle

What simple morphological characters did Aristotle use to classify plants?

Trees, shrubs, and herbs

How did Aristotle divide animals?

Those with red blood and those without

What two kingdoms were included in Linnaeus' Two Kingdom system of classification?

Plantae and Animalia

What distinctions did the Two Kingdom system fail to make?

Eukaryotes and prokaryotes, unicellular and multicellular organisms, and photosynthetic and non-photosynthetic organisms

Why was the two kingdom classification found inadequate?

A large number of organisms did not fall into either category.

Besides gross morphology, what other characteristics became important for classification?

Cell structure, nature of wall, mode of nutrition, habitat, methods of reproduction, evolutionary relationships, etc.

Who proposed the Five Kingdom Classification?

R.H. Whittaker (1969)

What are the names of the five kingdoms defined by Whittaker?

Monera, Protista, Fungi, Plantae, and Animalia

What main criteria for classification were used by Whittaker?

Cell structure, body organisation, mode of nutrition, reproduction, and phylogenetic relationships

What does the three-domain system propose?

Divides the Kingdom Monera into two domains, leaving the remaining eukaryotic kingdoms in the third domain, leading to a six kingdom classification

What character unified bacteria, blue green algae, fungi, mosses, ferns, gymnosperms and the angiosperms under ‘Plants’ in earlier classification systems?

All the organisms included had a cell wall in their cells

What prokaryotic and eukaryotic groups were placed together in earlier classification systems?

Prokaryotic bacteria and blue green algae (cyanobacteria) with other groups which were eukaryotic

What unicellular and multicellular organisms were placed together under algae?

Chlamydomonas and Spirogyra

What distinction did the earlier classification system not differentiate?

The heterotrophic group – fungi, and the autotrophic green plants

What is the primary component of fungi cell walls?

Chitin

What is the primary component of green plant cell walls?

Cellulose

What kingdoms were prokaryotic organisms grouped under?

Kingdom Monera

What kingdom were unicellular eukaryotic organisms placed in?

Kingdom Protista

Name examples of organisms brought together into Kingdom Protista, despite being in different kingdoms in earlier classifications?

Chlamydomonas, Chlorella, Paramoecium and Amoeba

What three types of similarities does an evolved classification system reflect?

Morphological, physiological and reproductive

What does phylogenetic mean?

Based on evolutionary relationships

What kingdoms are studied in the chapter?

Kingdoms Monera, Protista and Fungi

What two kingdoms will be dealt with separately in chapters 3 and 4?

Kingdoms Plantae and Animalia

What kingdom are bacteria members off?

Kingdom Monera

What are the four categories bacteria are grouped under based on their shape?

Coccus, Bacillus, Vibrio, and Spirillum

List three extreme habitats where bacteria can survive.

Hot springs, deserts, snow and deep oceans

What are the two types of autotrophic bacteria?

Photosynthetic autotrophic and chemosynthetic autotrophic

What special characteristic do Archaebacteria have?

They live in some of the most harsh habitats

Name three harsh habitats where archaebacteria live.

Extreme salty areas (halophiles), hot springs (thermoacidophiles) and marshy areas (methanogens)

What is responsible for the survival of archaebacteria in extreme conditions?

A different cell wall structure

Where are methanogens present?

In the gut of several ruminant animals such as cows and buffaloes

What are eubacteria also known as?

True bacteria

What is chlorophyll in cyanobacteria similar to?

Green plants

What type of autotrophs are cyanobacteria?

Photosynthetic autotrophs

What surrounds cyanobacteria when they form colonies?

Gelatinous sheath

What are heterocysts?

Specialised cells that fix atmospheric nitrogen

What inorganic substances do chemosynthetic autotrophic bacteria oxidise?

Nitrates, nitrites and ammonia

What role do chemosynthetic autotrophic bacteria play in recycling nutrients?

Recycling nutrients like nitrogen, phosphorous, iron and sulphur

What are the majority of heterotrophic bacteria?

Important decomposers

Name three ways heterotrophic bacteria benefit human affairs.

Making curd from milk, production of antibiotics, fixing nitrogen in legume roots, etc.

Name four diseases caused by bacteria.

Cholera, typhoid, tetanus, citrus canker

How do bacteria mainly reproduce?

Fission

How do bacteria reproduce under unfavourable conditions?

Produce spores

What is unique about Mycoplasma?

They completely lack a cell wall

What kingdom are all single-celled eukaryotes placed under?

Protista

Name five types of organisms included under Protista.

Chrysophytes, Dinoflagellates, Euglenoids, Slime moulds and Protozoans

Where are members of Protista primarily found?

Aquatic environments

What does protistan cell body contain?

A well defined nucleus and other membrane-bound organelles

How do protists reproduce?

Asexually and sexually by a process involving cell fusion and zygote formation

What does the group Chrysophytes include?

Diatoms and golden algae (desmids)

What are diatoms and golden algae (desmids) also called?

Plankton

What are diatom cell walls embedded with?

Silica

What is 'diatomaceous earth'?

Large amount of cell wall deposits left behind by diatoms

How is diatomaceous earth used?

In polishing, filtration of oils and syrups

What are diatoms considered in the oceans?

Chief ‘producers’

What organisms are mostly marine and photosynthetic?

Dinoflagellates

What is on the outer surface of dinoflagellates' cell wall?

Stiff cellulose plates

What causes red tides?

Rapid multiplication of red dinoflagellates (Example: Gonyaulax)

Where are the majority of euglenoids found?

Fresh water organisms found in stagnant water

What do euglenoids have instead of a cell wall?

A protein rich layer called pellicle

What happens to euglenoids when deprived of sunlight?

They behave like heterotrophs by predating on other smaller organisms

What kind of protists are slime molds?

Saprophytic

What is plasmodium?

An aggregation formed by slime molds under suitable conditions

What do slime molds form during unfavorable conditions?

Fruiting bodies bearing spores at their tips

What are protozoans believed to be?

Primitive relatives of animals

Name the four major groups of protozoans.

Amoeboid protozoans, Flagellated protozoans, Ciliated protozoans, Sporozoans

How do amoeboid protozoans move and capture their prey?

By putting out pseudopodia (false feet) as in Amoeba

What do marine forms of amoeboid protozoans have on their surface?

Silica shells

What diseases do parasitic flagellated protozoans cause?

Sleeping sickness

What helps ciliated protozoans move actively?

Thousands of cilia

What is the most notorious sporozoan?

Plasmodium (malarial parasite)

What diseases does Plasmodium cause?

Malaria

What type of organisms constitute a unique kingdom of heterotrophic organisms?

Fungi

Name two examples of fungi.

Mushroom, toadstools, yeast

Name a disease caused by fungi.

Wheat rust

Name an antibiotic sourced from fungi.

Penicillium

What places do fungi prefer to grow in?

Warm and humid places

What are the long, slender thread-like structures that fungi consist of called?

Hyphae

What is the network of hyphae known as?

Mycelium

What are coenocytic hyphae?

Continuous tubes filled with multinucleated cytoplasm

What are the cell walls of fungi composed of?

Chitin and polysaccharides

How do saprophytes obtain nutrition?

Absorb soluble organic matter from dead substrates

What are organisms called that depend on living plants and animals for nutrition?

Parasites

What are symbionts?

Organisms that live in association with algae as lichens and with roots of higher plants as mycorrhiza

Name three vegetative means of reproduction in fungi.

Fragmentation, fission and budding

Name three types of asexual spores.

Conidia, sporangiospores or zoospores

Name three types of sexual spores.

Oospores, ascospores and basidiospores

What are the three steps of the sexual cycle in fungi?

Plasmogamy, karyogamy, and meiosis

What is dikaryophase of fungus?

An intervening dikaryotic stage (n + n, i.e., two nuclei per cell)

What forms the basis for the division of the kingdom into various classes?

The morphology of the mycelium, mode of spore formation and fruiting bodies

Where are members of phycomycetes found?

In aquatic habitats and on decaying wood in moist and damp places or as obligate parasites on plants

What are the two types of asexual reproduction in phycomycetes?

Zoospores (motile) or by aplanospores (non-motile)

Name three common examples of phycomycetes.

Mucor, Rhizopus and Albugo

What are ascomycetes commonly known as?

Sac-fungi

Name three examples of ascomycetes.

Penicillium, Saccharomyces, Aspergillus, Claviceps and Neurospora

What are asexual spores of ascomycetes called?

Conidia

What are sexual spores of ascomycetes called?

Ascospores

What are asci arranged in?

Fruiting bodies called ascocarps

What are common forms of basidiomycetes?

Mushrooms, bracket fungi or puffballs