Syllabus Edition

First teaching 2023

First exams 2025

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Classification (CIE A Level Biology)

Exam Questions

2 hours15 questions
1a
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2 marks

Domestic dogs, Canis familiaris, and wolves belong to the family Canidae.

Complete Table 1 below to show the classification of the domestic dog.

Table 1

Kingdom Animalia
  Chordata
Class  
  Carnivora
Family Canidae
  Canis
   
1b
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2 marks

It is still debated as to whether dogs and wolves are entirely different species or subspecies. It has been suggested that some wolves have bred with domestic dogs to produce fertile offspring, which would make them the same species according to the biological species concept.

Name and briefly describe another species concept that biologists may use to help determine if two animals are different species.

1c
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2 marks

The classification seen in Table 1 is described as a hierarchical system.

Explain what is meant by this.

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2a
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2 marks

The Archaea represent one of the domains of life on Earth.

Identify the other two domains.

2b
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4 marks

Describe the features of Archaea that mean they are classified as a distinct domain in the three domains system of classification.

2c
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3 marks

Fig. 2 below shows a bacterial cell and an animal cell as seen in a student's Biology textbook.

18-1-fig-2-1Fig. 2

Animal cells store their genetic material in a nucleus, whereas bacterial cells do not.

Give three other contrasts between bacterial cells and animal cells.

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3a
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2 marks

Fig. 1 below shows an American black bear, Ursus americanus (left) and an Asiatic black bear, Ursus thibetanus (right).

vvBKOsKI_american-black-bear UyXIkHRN_himalayan-black-bear
Public domain, via pixnio CC BY-SA 4.0 , via Wikimedia Commons

Fig. 1

State what can be concluded about the taxonomic classification of the American black bear and the Asiatic black bear from the information provided.

3b
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2 marks

Use Fig. 1 to explain why the American black bear and the Asiatic black bear might be classified as separate species under the morphological species concept.

3c
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2 marks

Explain how the classification of the two bear species could be tested using the biological species concept.

3d
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2 marks

The two-part Latin naming system used to identify the bears in Fig. 1 is known as the binomial naming system, and was invented by the taxonomist Carl Linnaeus.

After the introduction of the binomial naming system species were given new binomial names. Some examples are given in Table 1

Table 1

Common name in English Pre-Linnaean name(s) / additional common name(s) Name under binomial naming system
Plantain Plantago foliis ovato-lanceolatus pubescentibus, spica cylindrica, scapo tereti Plantago media
Briar rose

Rosa sylvestris inodora seu canina

Rosa sylvestris alba cum rubore, folio glabr
Rosa canina
7-spot ladybird

Ladybird

Ladybug

La Poussinière

Mariquita
Coccinella septempunctata

Use information in Table 1 to suggest the advantages of the binomial system of naming species.

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4a
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3 marks

Fig. 1 below shows part of a eukaryotic organism.

HKvY77Xf_fungi-mycelium-sq

Fig. 1

(i)

Identify the kingdom to which the organism in Fig. 1 belongs.

[1]

(ii)

Identify the structures labelled A and B in Fig. 1.

[2]

4b
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2 marks

Give two characteristic features of the eukaryotic kingdom identified in (a) (i) that are not visible in Fig. 1.

4c
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2 marks

Identify two other examples of eukaryotic kingdoms.

4d
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2 marks

Identify the levels of taxonomic classification immediately above and below that of kingdom.

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5a
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3 marks

Fig. 1 below represents the structure of a particular type of virus.

virus-structure1

Fig. 1

Structures PQ, and R are present in all viruses.

Identify the structures labelled PQ, and R.

5b
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2 marks

Viruses are not classified under the taxonomic system.

Use Fig. 1 and your own knowledge to suggest why this is the case.

5c
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2 marks

Describe the method that is used to classify viruses.

5d
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2 marks

Viral infections cannot be treated with antibiotics.

Explain why this is the case.

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1a2 marks

Identify all the eukaryotic kingdoms that contain...

(i)

Autotrophic organisms

[1]

(ii)

Heterotrophic organisms

[1]

1b4 marks

Table 1 contains information about the eukaryotic kingdoms.

Use your knowledge of the characteristics of these kingdoms to complete Table 1 using either a ✓ or an X in each box. Some sections have been completed for you.

Table 1

Feature Protoctista Fungi Plantae Animalia
Cell wall Present in some species     X
Cell vacuole      
Cilia/flagella Present in some species   X  
Motility Present in some species   X  
Nervous coordination   X  

1c3 marks

Fruit flies are a group of organisms within the kingdom Animalia. A student collected three different types of fruit fly to study. The three species of fruit fly were Ceratitis capitata, Dacus dorsalis and Dacus oleae.

What do these names suggest about the evolutionary relationships between these fruit fly species? Explain your answer.

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2a1 mark

Viruses are not included in the three-domain classification system.

Explain why.

2b5 marks

Discuss whether viruses should or should not be classed as living organisms.

2c2 marks

State the two main features that are used to classify viruses.

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3a
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3 marks

Archaea and Eukarya are two domains of life that exhibit distinct characteristics and evolutionary relationships.

Contrast the cellular structures of Archaea and Eukarya.

3b
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2 marks

Scientists compared four species from the kingdom Achaea. They compared the base sequence of their DNA to determine the evolutionary relationships between the species.

Their results are shown in Table 1. 

Table 1

Species The percentage similarity between non-coding multiple repeat base sequences
A B C D
A        
B 51.2      
C 48.3 48.3    
D 42.9 42.9 40.7  

Use the information in Table 1 to explain which two species are the closest evolutionary relatives.

3c
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3 marks

Archaea were previously classified as bacteria due to similarities in their features. 

Describe three features of archaea that led to their classification as a separate domain. 

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4
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8 marks

Outline the characteristic features of organisms in the domain Bacteria.

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5a
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5 marks

Table 1 below contains the taxonomic classification of orca, minke whales, and bottlenose dolphins.

Table 1

Orca Common minke whale Common bottlenose dolphin
Animalia Animalia Animalia
Chordata Chordata Chordata
Mammalia Mammalia Mammalia
Artiodactyla Artiodactyla Artiodactyla
Delphinidae Balaenopteridae Delphinidae
Orcinus Balaenoptera Tursiops
orca acutorostrata truncatus

(i)

Identify the phylum to which all three species belong.

[1]

(ii)

Give the binomial Latin name for the common minke whale.

[1]

(iii)

Orca are also known as killer whales.

Suggest why many would consider the name 'killer whale' to be inappropriate for this species.

[2]

(iv)

Identify the taxonomic rank that is missing from Table 1.

[1]

5b
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2 marks

Orca show wide variation in appearance and behaviour, and have been divided by marine scientists into groups known as 'ecotypes'. Fig. 1 below shows the distribution of some of the known orca ecotypes.

orca-ecotype-distribution-map

Fig. 1

There is some debate among scientists over whether orca ecotypes should be classified as separate species.

Use Fig. 1 to suggest why it might be difficult to determine whether orca ecotypes are the same species or several separate species.

5c
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3 marks

To avoid the classification difficulties discussed in part (b), scientists often use DNA data.

Explain how the scientists could use DNA data to determine whether or not orca ecotypes are different species.

5d
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1 mark

There have been rare instances of hybridisation events between closely related species that result in fertile offspring, for example Fig. 2 below shows the offspring of a cross between a female bottlenose dolphin and a male false killer whale. The individual in the photograph is known to have bred with another bottlenose dolphin and to have given birth to healthy offspring.

whale-dolphin-fertile-hybrid

Mark Interrante, CC BY-SA 2.0, via Flickr

Fig. 2

Scientists do not believe that the hybrid shown in Fig. 2 is an example of a new species.

Suggest why the individual in Fig. 2 is not considered to be a new species.

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1a2 marks

Specimen A and specimen B are similar species of invertebrates that live in the same habitat.

Scientists wanted to determine whether specimen A and specimen B are different species of invertebrate, or different forms of the same species.

In order to do this, they caught large numbers of each specimen type and measured the body mass and length of each individual before calculating the means and standard deviations (SD). Their results are shown in Table 1 below.

Table 1

Body measurement Specimen A Specimen B
Mean body mass / g (± SD) 0.68 (± 0.02) 0.67 (± 0.01)
Mean body length / mm (± SD) 21.4 (± 0.9) 19.2 (± 0.7)

Explain how the standard deviation can help with the interpretation of this data.

1b4 marks

The scientists hypothesised that the two specimens were different forms of the same invertebrate species.

Discuss this hypothesis using the information provided in part (a).

1c1 mark

Fig. 1 below shows the classification of some animals with antlers and horns.

18-1-fig-5-1
Fig. 1

State the number of different orders that are present in Fig.1 above.

1d2 marks

The scientific names of three great apes are shown in Table 2 below.

Table 2

Common Name Scientific Name
Orangutan Pongo pygmaeus
Chimpanzee Pan troglodytes
Bonobo Pan paniscus

Fig. 2 represents the hierarchical classification of these apes in the form of a diagram. 

18-1-fig-5-2
Fig. 2

The orangutan also belongs to the Hominidae family.

Use information provided in Table 2 to add the orangutan to Fig. 2. The orangutan should be represented by the letter X.

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2a
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3 marks

A team of biologists discovered a new organism inside a previously unexplored cave. They conducted several investigations in order to classify it.

They observed the following:

  • The organism is multicellular and possesses a well-defined nucleus within its cells
  • It has a cell wall composed of chitin
  • It reproduces asexually by budding
  • It exhibits heterotrophic nutrition

Identify the kingdom to which this organism most likely belong. Justify your answer.

2b
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3 marks

Describe three other characteristics that would further support your classification of this organism within the identified kingdom.

[3]

2c
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4 marks

Discuss the limitations of using only a few characteristics to classify organisms. Include examples to illustrate your points.

2d
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3 marks

The organism found does not have either a gas exchange system or a vascular system.

Suggest how the organism can survive without these structures.

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3a
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1 mark

Part of the genome of many viruses is a gene for the enzyme reverse transcriptase. As its name suggests, this enzyme can synthesise DNA from an RNA template, which is the reverse reaction to transcription within most other organisms' cells. 

Suggest one advantage to the virus of producing the enzyme reverse transcriptase. 

3b
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4 marks

Explain why viruses are not classified within the traditional three-domain system of Archaea, Prokaryotes and Eukaryotes. 

3c
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3 marks

The number of fully assembled virus particles (virions) released from an individual host cell after an infection can vary from tens of virions to tens of thousands. For example, the HIV virus can burst out around 5 000 virions from a single infected host T-cell.

(i)

Calculate the maximum theoretical number of T-cells that can be destroyed by a single host cell infection followed by one further cycle of infection.

(1)

(ii)

Suggest the implications to a human of your answer to part (i) in the light of the fact that a healthy adult human possesses around 50 million T-cells.

(2)

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4a
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5 marks

Fig. 1 shows Ailuropoda melanoleuca, the giant panda (left), and Ailurus fulgens, the red panda (right), both mammals native to China.

giant-panda red-panda
Public domain, via pxhere Mathias Appel, public domain, via Flickr

Fig. 1

Giant pandas and red pandas have the following characteristics:

  • They live in similar environments
  • They digest bamboo as a primary source of food
  • They have a pseudo-thumb (a sixth digit) used to grip and shred food

Table 1 shows the differences between a comparable sequence of mitochondrial DNA from the giant panda and the red panda.

Table 1

  DNA sequence
Giant panda ATT GGA GCA GAC TTA
Red panda ATT GGC ACT GAC CTA

A group of students concluded that the giant panda and the red panda are closely related species.

Use the information provided to discuss the students' conclusion.

4b
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4 marks

The DNA analysed in Table 1 was extracted from mitochondria and codes for mitochondrial proteins.

(i)

Identify two examples of mitochondrial proteins. Precise names of proteins are not required.

[2]

(ii)

Suggest why scientists researching evolutionary relationships may choose to analyse mitochondrial DNA rather than DNA that codes for other characteristics, e.g. fur colour.

[2]

4c
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5 marks

Table 2 contains the taxonomic classification of giant pandas, red pandas, and two other species considered to be relatives of the red panda.

Table 2

Giant panda Red panda Common raccoon Parailurus anglicus*
Eukaryota Eukaryota Eukaryota Eukaryota
Animalia Animalia Animalia Animalia
Chordata Chordata Chordata Chordata
Mammalia Mammalia Mammalia Mammalia
Carnivora Carnivora Carnivora Carnivora
Ursidae Ailuridae Procyonidae Ailuridae
Ailuropoda Ailurus Procyon Parailurus
melanoleuca fulgens iotor anglicus

*Now extinct

(i)

Identify the order to which all four species belong.

[1]

(ii)

Identify the closest relative of the red panda shown within Table 2. Justify your answer.

[2]

(iii)

Suggest how scientists may have gone about classifying the now extinct Parailurus anglicus.

[2]

4d
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4 marks

Current evidence shows that the closest living relative of the red panda shown in Table 2 is the common raccoon, though the common ancestor of the two species is thought to have lived between 30-40 million years ago, so the two groups of animals are now highly diverged from each other.

Explain how a common ancestor of red pandas and common raccoons may have diverged to give rise to new species.

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5a
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6 marks

The Fig. 1 below shows an image of Halobacterium salinarum, a member of the domain Archaea.

halobacterium-salinarum-archaea

CC BY-SA 4.0, via Wikimedia Commons

Fig. 1

(i)

The scale bar in Fig. 1 measures 3 cm, and line X measures 12.2 cm.

Use this information to calculate the actual length of the archaeon, marked X in in Fig. 1.

[2]

(ii)

Compare Halobacterium salinarum with a bacterial cell.

[4]

5b
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6 marks

Halobacterium salinarum have a protein in their cell surface membranes known as bacteriorhodopsin. The role of bacteriorhodopsin is shown in Fig. 2 below.

Bacteriorhodopsin is shown pumping protons across a cell membrane. The membrane also contains a molecule of ATP synthase.

Fig. 2

(i)

H. salinarum is a photoheterotroph, meaning that it can consume organic molecules, but it can also use light energy to produce ATP.

Suggest how bacteriorhodopsin allows H. salinarum to produce ATP.

[3]

(ii)

H. salinarum is found in environments with extremely high salt concentration.

Suggest how bacteriorhodopsin might work together with other membrane proteins, such as K+ and Cl- pumps, to aid survival in such extreme environments.

[3]

5c
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1 mark

One study found that H. salinarum can exist in extreme environments alongside structures known as viroids. Fig. 3 below shows an example of a viroid structure. Note that viroid RNA does not code for proteins.

A circular molecule of RNA is shown. It has several regions where the strand is folded into a helix.

Fig. 3

(i)

Viroids can infect plant cells.

Explain how the infectious action of a viroid might differ from that of a virus.

[2]

(ii)

Suggest two possible mechanisms for the classification of viroids.

[2]

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