G.C.E. Advanced Level Biology - Evolution and Diversity of Organisms

Comprehensive flashcards covering evolution, historical theories, taxonomy, domains, protists, plant diversity, fungal biology, and invertebrate/vertebrate zoology from the G.C.E. Advanced Level Biology Resource Book.

When were Earth and the other planets of the solar system formed?

About $4.6\text{ billion}$ years ago.

What was the composition of Earth's first atmosphere before life originated?

It was thick with water vapour along with compounds released by volcanic eruptions: nitrogen and its oxides, carbon dioxide, methane, ammonia, hydrogen, and a little oxygen, forming a reducing atmosphere.

How old are the oldest micro-organism fossils providing direct evidence for life on early Earth?

About $3.5\text{ billion}$ years old.

What are the four main stages in the biochemical evolution of the first cells?

1. Abiotic synthesis of small organic molecules from inorganic molecules; 2. Polymerization into macromolecules; 3. Packaging into membranes to produce protocells; 4. Origin of self-replicating nucleic acids making inheritance possible.

Who proposed the 'primitive soup' concept, and what characterized early protocells?

Haldane suggested the primitive soup; RNA accumulated into lipid-bound vesicles to form protocells capable of enzyme-catalyzed activities, growth, replication, and evolution.

When did the first photosynthetic organisms originate, and how did they alter the Earth's environment?

Before $2.7\text{ billion}$ years ago; their photosynthetic oxygen production oxidized $Fe^{2+}$ ions, precipitated dissolved iron, saturated water bodies with $O_2$, and increased atmospheric oxygen.

According to the fossil record, when did the first eukaryotic organisms and the oldest known protists appear?

First eukaryotic organisms appeared about $1.8\text{ billion}$ years ago; the oldest known protists (similar to small red algae) appeared $1.2\text{ billion}$ years ago.

When did sponges evolve and when did the ancestors of arthropods and chordates originate?

Sponges evolved $700\text{ million}$ years ago, and ancestors of arthropods and chordates originated $670\text{ million}$ years ago.

When did the colonization of land by fungi, plants, and animals begin?

After about $500\text{ million}$ years ago.

When did the earliest tetrapods evolve and from what group did they originate?

They formed about $365\text{ million}$ years ago from lobed-finned fish.

When did the divergence of the human lineage from other primates occur, and when did the human species originate?

Lineage divergence began $6\text{ to }7\text{ million}$ years ago; the origin of the human species took place $195{,}000\text{ years}$ ago.

What are the four geological eons of Earth's history in chronological order?

Hadean, Archaean, Proterozoic, and Phanerozoic.

What are the three eras that comprise the Phanerozoic eon?

Palaeozoic, Mesozoic, and Cenozoic.

What two principles formed the basis of Lamarck's evolutionary hypothesis published in $1809$?

1. Use and disuse; 2. Inheritance of acquired characteristics.

What are the four stages of the process of natural selection?

Overproduction, variation, competition and survival of the fittest, and natural selection of favourable traits.

What is Neo-Darwinism?

The integration of Charles Darwin's theory of natural selection, Mendelian genetics as the basis for biological inheritance, and population genetics.

How do artificial classification and natural classification differ?

Artificial classification groups organisms by a few pre-selected unifying characters for convenience (ignoring evolutionary relationships); natural classification reflects true evolutionary relationships based on phylogeny.

What contributions did Carolus Linnaeus, Ernst Haeckel, and Robert H. Whittaker make to taxonomy?

Linnaeus ($1753$) introduced binomial nomenclature and hierarchical classification into two kingdoms; Haeckel ($1866$) introduced Kingdom Protista and taxon Phylum; Whittaker ($1969$) introduced the five-kingdom system.

Who introduced the three-domain system of classification in $1977$, and how are the domains related?

Carl Woese; the first major split occurred when Bacteria diverged, leaving Archaea and Eukarya more closely related to each other than to Bacteria.

How do Bacteria, Archaea, and Eukarya differ in cell wall composition?

Bacteria contain peptidoglycan; Archaea contain proteins and polysaccharides (lacking peptidoglycan); Eukarya contain cellulose, hemicellulose, pectin, or chitin.

How do the three domains compare regarding histones associated with DNA and initiator amino acids for protein synthesis?

Bacteria lack histones and use formyl-methionine; Archaea have histones in some species and use methionine; Eukarya have histones present and use methionine.

What are the photosynthetic pigments and stored food of the green alga Ulva?

Photosynthetic pigments are chlorophylls a and b; stored food is starch.

What photosynthetic pigments and stored food are characteristic of Gelidium?

Photosynthetic pigments are chlorophylls a, d, and phycobiliproteins; stored food is Floridean starch.

What cell wall materials, pigments, and food storage products characterize Sargassum?

Cell wall contains cellulose and alginic acid; pigments are chlorophylls a, c, and xanthophyll; stored food is laminarin.

What are the distinguishing structural features and storage products of Diatoms?

They possess a two-part overlapping glass-like cell wall composed of silica and pectin; stored foods are oil and chrysolaminarin.

What is the dominant generation in Phylum Bryophyta, and what are its features?

The haploid gametophyte is dominant, photosynthetic, and independent; the sporophyte remains attached to and nutritionally dependent on the female gametophyte.

How do club mosses and spike mosses differ in spore production?

All club mosses (e.g., Lycopodium) are homosporous; all spike mosses (e.g., Selaginella) are heterosporous.

What are the key evolutionary adaptations of seed plants?

Production of seeds, highly reduced microscopic gametophytes, heterospory, production of ovules and eggs, and pollen grains protected by sporopollenin.

What unique anatomical characteristic distinguishes Phylum Gnetophyta from other gymnosperms?

They are the only gymnosperms that have vessels in their xylem.

How do monocotyledons and dicotyledons differ in root systems, leaf venation, and flower parts?

Monocots have fibrous roots, parallel leaf venation, and trimerous flowers; dicots have taproot systems, reticulate leaf venation, and tetramerous or pentamerous flowers.

What are the structural features of fungal hyphae in septate versus coenocytic fungi?

Septate hyphae are divided by cross walls with pores allowing organelle movement; coenocytic fungi lack septa and form continuous multinucleated filaments.

What types of sexual spores and fruiting bodies are produced by Ascomycota and Basidiomycota?

Ascomycota produce endogenous ascospores (typically $8$ per ascus) inside ascocarps; Basidiomycota produce exogenous basidiospores on basidia within basidiocarps.

What are cnidocytes and nematocysts in Phylum Cnidaria?

Cnidocytes are unique defense and prey-capturing cells that contain capsule-like organelle projections called cnidae; nematocysts are specialized cnidae with stinging threads.

What excretory structures are present in flatworms (Phylum Platyhelminthes)?

Protonephridia consisting of a network of tubules with ciliated structures called flame bulbs to maintain osmotic balance.

What body wall and muscular features are characteristic of Phylum Nematoda?

The body is covered by a tough cuticle that undergoes ecdysis, and the body wall is composed only of longitudinal muscles involved in locomotion.

What evolutionary milestone first appeared in Phylum Annelida?

They are the first animals to possess a true coelom and the first animals to show cephalization.

What are the three main body parts of molluscs and the function of the radula?

The body is divided into a muscular foot, visceral mass, and mantle; the radula is a minutely toothed chitinous ribbon in the mouth used for feeding.

What are the excretory organs and respiratory structures of Phylum Arthropoda?

Excretion occurs via Malpighian tubules (excreting uric acid); respiration occurs via gills (aquatic), tracheal systems (terrestrial), or book lungs (arachnids).

What are the four hallmark morphological features of Phylum Chordata?

A longitudinal flexible notochord, a dorsal hollow single nerve cord, pharyngeal slits or clefts, and a muscular post-anal tail.

How do Chondrichthyes and Osteichthyes differ in skeleton, gill cover, and caudal fin shape?

Chondrichthyes have a cartilaginous skeleton, gills without an operculum, and a heterocercal caudal fin; Osteichthyes have a bony skeleton, an operculum covering the gills, and a homocercal caudal fin.