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Evolution of classification system Flashcards

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1
Q

Early classification systems only used…

A

Observable features to place organisms into groups

e.g whether they lay eggs, can fly

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2
Q

What is the problem of using the observable features to categorise organisms into groups?

A

Scientists don’t always agree on the RELATIVE IMPORTANCE of different features and groups based SOLELY on PHYSICAL FEATURES may not show how RELATED organisms are.

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3
Q

Give an example of an aquatic organism that ‘looks’ similar but scientifically arent.

A

Sharks and whales, look quite similar and they both live in the SEA. But they’re NOT actually CLOSELY RELATED. Whales and MAMMALS and sharks are CARTILAGINOUS FISH- two completely different classes.

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4
Q

Classification systems are NOW based on…

A

Observable features along with OTHER EVIDENCE.

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5
Q

The MORE SIMILAR organisms are, the MORE RELATED they are. We now use a wide range of evidence to see HOW SIMILAR, and therefore how related, organisms are.

For example, Molecular evidence, explain?

A

Molecular evidence - the similarities in PROTEINS and DNA.
MORE CLOSELY RELATED organisms will have MORE SIMILAR molecules.

> You can COMPARE things like how DNA is stored and the SEQUENCE of DNA bases.
E.G the BASE SEQUENCE for human and chimpanzee DNA is about 94% the SAME.

> You can also compare the SEQUENCE of AMINO ACIDS in proteins from different organisms.
E.G. CYTOCHROME C is a short protein found in many species. The more SIMILAR the AMINO ACID SEQUENCE of cytochrome C in two different species, the MORE CLOSELY RELATED the species are likely to be.

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6
Q

The MORE SIMILAR organisms are, the MORE RELATED they are. We now use a wide range of evidence to see HOW SIMILAR, and therefore how related, organisms are.

For example, Embrylogical evidence, explain?

A

Embryological evidence -The similarities in the EARLY STAGES of an organism’s DEVELOPMENT.

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7
Q

The MORE SIMILAR organisms are, the MORE RELATED they are. We now use a wide range of evidence to see HOW SIMILAR, and therefore how related, organisms are.

For example, Anatomical evidence, explain?

A

Anatomical evidence - the similarities in STRUCTURE and FUNCTION of different body parts.

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8
Q

The MORE SIMILAR organisms are, the MORE RELATED they are. We now use a wide range of evidence to see HOW SIMILAR, and therefore how related, organisms are.

For example, Behavioral evidence, explain?

A

Behavioral evidence -The similarities in BEHAVIOUR and SOCIAL ORGANISATION of organisms.

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9
Q

How can new technologies aid in classification?

A

New technologies (e.g, new DNA techniques, better microscopes) can result in NEW DISCOVERIES being made and the RELATIONSHIPS between organisms being CLARIFIED.

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10
Q

How is communication of new findings valuable for classification.

A

Scientists can share their new discoveries in MEETINGS and SCIENTIFIC JOURNALS.

How organisms are CLASSIFIED is CONTINUALLY REVISED to take account of any NEW FINDINGS that scientists DISCOVER.

Skunks were classified in the family MUSTELIDAE until MOLECULAR EVIDENCE revealed their DNA SEQUENCE ws significantly different to other members of that family. So thy were reclassified into the family MEPHITIDAE.

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11
Q

The five kingdom classification system has now been replaced with the …

A

three domain system.

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12
Q

In the older SYSTEMS the LARGEST GROUPS were the …

A 
FIVE KINGDOMS - all organisms were placed into ONE of these groups:
>Protocista
>Fungi
>Animilia
>Plantae
>Prokaryotae
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13
Q

In 1990, the…

A

three domain system was proposed. The new system has three domains - LARGE SUPERKINGDOMS that are ABOVE the kingdoms in the TAXONOMIC HIERARCHY.

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14
Q

In the three domain system, organisms that were in the kingdom ….

A

Prokaryotae (which contains unicellular organisms WITHOUT A NUCLEUS) are seperated into two domains - Archaea and Bacteria.

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15
Q

Organisms with cells that CONTAIN A NUCLEUS are placed in the DOMAIN …

A

EUKARYA

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16
Q

The lower hierarchy stays the SAME:

A

Kingdom, Phylum, class, order, family, species

17
Q

Molecular evidence led to the proposal of the …

A

Three domain system.

18
Q

The three domain system was proposed because of …

A

new evidence, mainly molecular.

E.g. the Prokaryotae were reclassified into two domains because new evidence showed large differences between archea and bacteria.

19
Q

Evidence to suggest prokaryote had to be split into two domains because of:

> molecular evidence, explain why?

A

Molecular evidence - The enzyme RNA POLYMERASE (needed to make RNA) is DIFFERENT in Bacteria and Archea.

Archea, but not bacteria, have similar HISTONES (proteins that bind to DNA) to EUKARYA.

20
Q

Evidence to suggest prokaryote had to be split into two domains because of:

> Cell membrane evidence, explain why?

A

Cell membrane evidence - The BONDS of the LIPDS in the CELL MEMBRANE of bacteria and Archea are DIFFERENT. The development and composition of FLAGELLAE are also different.

21
Q

What do scientist ‘agree’ that happened to Archea and Bacteria?

A

Most scientist now AGREE that Archea and Bacteria EVOLVED SEPERATLY and that Archea are MORE CLOSELY RELATED to Eukarya than Bacteria.
The three domain system reflects how DIFFERENT the Archea and Bacteria are.

22
Q

The development of the three domain systemm is an example of how …

A

Scientific knowledge is always changing and improving.

23
Q

A gibbon is a type of ape. Describe one way in which scientist could use molecular evidence to determine how closely gibbons are related to humans.

A

Scientist could compare the amino acid sequences of a protein found in both humans and gibons (e.g. cytochrome c). The more similar the amino acids sequence of the protein, the more closely related they are likely to be.

24
Q

The three domain system of classification places Cyanobacteria in the domain bacteria. Describe three differences between organisms in the Bacteria and Archea domains.

A

> RNA polymerase is different in Archea and Bacteria.
Archea, but not Bacteria, have histones similar to Eukarya
The bonds of the lipids in the cell membrane of Archea and Bacteria are different.
Extra: The development and composition of flagelae in Archea and Bacteria are different.

Biology (18 decks)

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