4.3 ocr alevel biology

What is the biggest taxonomic group?

Kingdom

What are the seven groups?

Kingdom, Phylum, Class, Order, Family, Genus, Species

Why do scientists classify organisms?

To identify species, to predict characteristics, and to find evolutionary links

What is the most recent level of hierarchy added to the taxonomic groups?

Domain

What are the three domains?

Archaea, Bacteria, Eukarya

What are the species of humans?

Homo sapiens

What is the definition of a species?

A group able to reproduce to produce fertile offspring

What is an example of an animal that is infertile and therefore not a species?

A mule bred by a donkey and horse

Why are some animals infertile?

Their cells contain an odd number of chromosomes so meiosis cannot take place

What language is binomial nomenclature?

Latin

How does binomial nomenclature work?

All species are given a name of two parts: the first is the genus (generic name) and the second is the species (specific name)

When naming an organism scientifically, how should it be written?

Italics or underlined

Is the first letter of the genus name upper or lower case?

Upper case

What genus does "Ambystoma mexicanum" belong to?

Ambystoma

What species does "Capra aegagrus" belong to?

Aegagrus

Which kingdom contains single-celled organisms without membrane-bound organelles?

Prokaryotae

What are the five kingdoms?

Prokaryotae, Protoctista, Fungi, Plantae, Animalia

Which kingdom contains single-celled organisms with membrane-bound organelles?

Protoctista

What do protoctista sometimes contain?

Chloroplasts

How are nutrients absorbed in prokaryotae?

Through cell walls or produced internally by photosynthesis

How are nutrients acquired in protoctista?

By photosynthesis (autotrophic feeders), ingestion (heterotrophic feeders), or both; some are parasitic

Which kingdom contains both unicellular and multicellular organisms?

Fungi

Which kingdom contains autotrophic, multicellular organisms?

Plantae

What is an example of fungi?

Mushrooms, moulds, yeast

What is the cell wall of fungi composed of?

Chitin

Do fungi have chloroplasts or chlorophyll?

No

What is the body of fungi made of?

Threads called hyphae

How are nutrients acquired in fungi?

By absorption from decaying material (saprophytic feeders) or parasitically

How do fungi store food?

Glycogen

Which kingdom contains the most organisms?

Animalia

Which kingdom is the second largest?

Plantae

What type of feeders are Plantae?

Autotrophic (make their own food)

How do Plantae store food?

As starch

What is the cell wall of plants made of?

Cellulose

Do animals have cell walls?

No

How do Animalia move?

Using cilia, flagella, or contractile proteins

How are nutrients acquired in Animalia?

By ingestion (heterotrophic feeders)

Which kingdom contains multicellular heterotrophic organisms?

Animalia

Which kingdom is unicellular and has no nucleus or other membrane-bound organelles?

Prokaryotae

How many kingdoms are in the Eukarya domain?

4

Which kingdom is split between the Bacteria and Archaea domains?

Prokaryotae

What are the three domains?

Archaea, Bacteria, Eukarya

How do organisms in the three domains differ?

They have unique rRNA and different ribosomes

What ribosomes do Eukarya have?

80S

What RNA polymerase do Eukarya have?

Contains 12 proteins

What ribosomes do Archaea have?

70S

What RNA polymerase do Archaea have?

Contains 8–10 proteins

What ribosomes do Bacteria have?

70S

What RNA polymerase do Bacteria have?

Contains 5 proteins

Which kingdom does an amoeba belong to?

Protoctista

How is the Prokaryotae kingdom divided?

Into Archaebacteria and Eubacteria

What are the six kingdoms in the six-kingdom system?

Archaebacteria, Eubacteria, Protoctista, Fungi, Plantae, Animalia

Why are Eubacteria and Archaebacteria separate kingdoms?

Eubacteria contain peptidoglycan in their cell walls; Archaebacteria do not

What are the three main classification systems?

Three-domain, six-kingdom, five-kingdom

Which bacterial domain contains most species?

Eubacteria

Where can Archaebacteria live?

Extreme environments

Where can Eubacteria live?

All environments

What is phylogeny?

The study of evolutionary relationships among organisms

How is phylogeny represented?

Phylogenetic tree

In a phylogenetic tree, where are earliest species found?

At the base

In a phylogenetic tree, where are the most recent species found?

At the tips

Where has evidence for phylogenetic trees come from?

Fossils

What do the nodes of a tree represent?

Common ancestors of descendants

What are two descendants split from the same node called?

Sister groups

If branches are close, what does it mean?

They have a closer evolutionary relationship

What is one advantage of phylogeny?

Produces a continuous tree rather than discrete ranks

What is a limitation of classification that phylogeny solves?

Linnaean groups imply equivalence between ranks

What was Darwin’s theory of evolution?

Natural selection

What are three types of evidence for evolution?

Paleontology, comparative anatomy, comparative biochemistry

How are fossils formed?

When remains are preserved in rocks

What is paleontology?

Study of fossils

What is the fossil record?

Record of organism evolution through time

Why is the fossil record incomplete?

Some organisms decompose, conditions not always right, fossils destroyed or undiscovered

What is comparative anatomy?

Study of similarities/differences in species anatomy

What is a homologous structure?

Structure with same underlying design but different appearance/function

Give an example of a homologous structure.

Pentadactyl limb in vertebrates

What does a homologous structure provide evidence for?

Divergent evolution

What is divergent evolution?

Species evolve different adaptations from a common ancestor

How does divergent evolution occur?

Species diversify to adapt to habitats via migration or loss of habitat

What is comparative biochemistry?

Study of similarities/differences in molecules controlling life

Which two molecules are often studied in biochemistry?

Cytochrome c, ribosomal RNA

How can scientists estimate when species shared a common ancestor?

Compare molecular differences against mutation rates

What does the hypothesis of neutral evolution state?

Most variability occurs outside functional regions, so function unaffected

What is variation?

Differences in characteristics between organisms

What is variation between species?

Interspecific

What is variation within a species?

Intraspecific

What are two causes of variation?

Genetic material (genetic variation) and environment

How is genetic variation caused?

Alleles, mutations, meiosis, sexual reproduction, chance

Is variation greater in asexual or sexual reproduction?

Sexual

What does asexual reproduction produce?

Clones; variation only by mutation

Give an example of environmental variation.

Scars

Most variation is caused by…?

Both genetic and environmental factors (e.g. height, skin colour)

What is discontinuous variation?

Characteristic with discrete categories

How is discontinuous variation represented?

Bar chart or pie chart

What is continuous variation?

Characteristic that can take any value in a range

What is a continuum?

Graduation in values across extremes

How is continuous variation represented?

Frequency table or histogram

What shape curve does continuous variation form?

Normal distribution curve

What are characteristics of a normal distribution curve?

Mean=median=mode, bell-shaped, 50% below/above mean, extremes rare

Give an example of discontinuous variation.

Blood groups