Species and taxonomy

Question 1

What is classification?

Answer 1

The organisation of living organisms into groups.

Question 2

What is a species?

Answer 2

They are capable of breeding to produce living, fertile offspring. So when a species reproduce sexually, any of the genes of the individual can be combined with any other.

Question 3

What is the binomial system and what features does it have?

Answer 3

The system where organisms are identified by 2 names.

• It is a universal system based on Latin or Greek names.
• The first name is the generic name - denotes the genus to which the organism belongs to. (surname)
• The second name is called the specific name - denotes the species to which the organism belongs to. (first name)

Question 4

What are the rules of writing the binomial name?

Answer 4

The first letter of the generic name is in capital.
The specific name which is not known can be written as sp. e.g. Felix sp.
Underline when you write them.

Question 5

How can members of the same species distinguish from each other?

Answer 5

Members of the same species have similar/same genes so they resemble each other physically or biochemically which can help them distinguish each other in different species.

Question 6

How does behaviour help species to distinguish from each other?

Answer 6

Their behaviour is very similar in the way in which they act. The ability to display behaviour is genetically determined. It has evolved and it influences the chances of survival.

Question 7

How does courtship behaviour (an animal try to attract a mate) help to enable the success of matings?

Answer 7

• Recognising members of the same species - ensure that matings only takes place between members of the same species because only the same species can produce fertile offsprings.
• Identify a mate that is capable of breeding - both partners need to be sexually mature, fertile and receptive to mating.
• Form a pair bond - will lead to successful mating and raising of offspring.
• Synchronise mating - so it takes place when there’s the maximum probability of sperm and egg meeting.
• Become able to breed - by bringing a member of the opposite sex into the physiological state that allows breeding to occur.

Question 8

Why do men use courtship behaviour?

Answer 8

Because female is only receptive of breeding for a period of time when they produce egg so men use courtship behaviour to determine if the female is at the receptive stage.
If she responds in an appropriate behavioural response, courtship continues and likely for an offspring. If not, the men turn his attention elsewhere.

Question 9

What is taxonomy?

Answer 9

The theory and practice of biological classification is called taxonomy.

Question 10

What are the 2 forms of biological classification?

Answer 10

1) Artificial classification - Divides organisms according to differences that are useful at the time e.g. size, number of legs. They are described as analogous characteristics where they have the same function but do not evolve from the same origin. e.g. butterflies and birds both use their wings to fly but they are originated in different ways.
2) Phylogenetic classification - It’s partly based on homologous characteristics.
a) is based upon the evolutionary relationship between organisms and their ancestors.
b) classifies species into groups using shared features passed from their ancestors.
c) arranges the groups into hierarchy, in which the groups are contained within larger groups with no overlap.

Question 11

What is a taxon?

Answer 11

Each group within a phylogenetic biological classification.

Question 12

What is the taxonomic rank?

Answer 12

Domain - highest taxonomic rank and three are recognised as bacteria, archaea (a group of prokaryotes) and eukarya.

Question 13

What are the features of bacteria?

Answer 13

A group of single-celled prokaryotes:

• Doesn’t have membrane-bounded organelles e.g. nuclei or mitochondria.
• Unicellular
• Small ribosomes - 70s
• Cell walls are made of murein
• Single loop of naked DNA made up of nucleic acids but not histones.

Question 14

What are the features of archaea?

Answer 14

A group of single-celled prokaryotes which originally classified as bacteria because they look so similar.
They differ from bacteria by:
- Their genes and protein synthesis are more similar to eukaryotes.
- Membranes contain fatty acid chains attached to glycerol by ether linkage.
- No murein in their cell walls.
- They have a more complex form of RNA polymerase.

Question 15

What are the features of eukarya?

Answer 15

A group of organisms made up of 1 or more eukaryotic cells:

• Have membrane-bounded organelles e.g. mitochondria and chloroplast.
• Membranes contain fatty acid chains attached to glycerol by ether linkage
• Not all have cells with a cell wall, but when they do, it’s not made up of murein.
• Ribosomes are larger - 80s.

Question 16

What are the 4 kingdoms that eukarya domain divides into?

Answer 16

• Protoctista
• Fungi
• Plantae
• Animalia

Question 17

What is the classification rank?

Answer 17

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species 

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Question 18

What is phylogeny?

Answer 18

The evolutionary relationship between organisms is known as phylogeny.

Question 19

How is phylogeny represented?

Answer 19

The phylogenetic relationships of different species are represented by a tree-like diagram. The oldest species is at the base and the most recent ones at the ends of the branches.