Paper 2: Topic 6 Inheritance, variation & evolution - Classification of living organisms

Question 1

Define the term ‘classification’

Answer 1

The process of placing living organisms into groups

Question 2

Name the two scientists who developed classification systems

Answer 2

1. Carl Linneaus
2. Carl Woese

Question 3

How did Linnaeus categorise living organisms

Answer 3

Traditionally living things have been classified into groups depending on their structure and characteristics

Question 4

Place these groups into the correct order staring with the largest group Class Order Kingdom Species Phylum Genus Family

Answer 4

Kingdom → Phylum → Class → Order → Family → Genus → Species

Hint: try remembering the saying “Keep Penis Clean Or Forget Good Sex” – no offence meant here!

Question 5

Give 2 reasons why some organisms have been reclassified in recent years

Answer 5

1. Evidence of internal structures has become more developed due to improvements in microscopes
2. Understanding of biochemical processes has progressed

• This has caused new models of classification to be proposed.

Question 6

Explain how Carl Woese’s classification differs from Carl Linnaeus’s system

Answer 6

• Woese developed a 3 domain system
• This includes 3 groups which are each larger than Kingdom

Question 7

Name the 3 domains used in Woese’s classification system

Answer 7

1. Archaea
2. Bacteria
3. Eukaryota

Question 8

Describe the type of organisms that are placed in the archaea domain

Answer 8

• Simple prokaryotic bacteria
• Generally found in extreme habitats e.g. hot springs, salt lakes

Question 9

Describe the type of organisms that are placed in the bacteria domain

Answer 9

• True bacteria
• They look similar to archaea but carry out different biochemical reactions
• E.g. E. coli, Staphylococcus

Question 10

Describe the type of organisms that are placed in the eukaryota domain

Answer 10

• Broad range of organisms
• Includes animals, plants, fungi and protists

Question 11

What is the term used to describe the naming system used in classification

Answer 11

Binomial name

Question 12

What term terms make up the binomial name of any organism

Answer 12

• Genus followed by species
• E.g. Humans are correctly named as Homo sapiens
• Homo = Genus
• sapiens = species

Question 13

How should a Scientist write the Latin Binomial name?

Answer 13

The genus must always have a capital letter

The species always begins with a lower case letter

Both genus and species should be typed in italics or underlined if hand written

Question 14

State 4 advantages of using a Latin binomial name when talking about an organism

Answer 14

1. The binomial name is used worldwide
2. It overcomes difficulties with different Scientists using different languages
3. It avoids some organisms being called different names in different countries
4. It therefore makes sharing of information and data between Scientists easier as they know they are all referring to the same organism

Question 15

Describe how evolutionary relationships can be shown

Answer 15

By the use of evolutionary trees

Question 16

Answer 16

Question 17

Where on an evolutionary tree is the most common ancestor found?

Answer 17

At the base of the evolutionary tree

Question 18

Where on an evolutionary tree is the most recent species found?

Answer 18

At the tip of the longest branch = Bonobos

Question 19

How are organisms that are closely related to each other shown on an evolutionary tree?

Answer 19

They are shown coming off one branch of the tree The closer the branching the more closely related they are

Question 20

Which arrow shows speciation?

Answer 20

The arrow at the branching point