Classification

Question 1

Define the following terms:
- Classification
- Taxonomy
- Species

Answer 1

• Classification; placing living things into groups according to their shared similarities. (1)
• Taxonomy; the study of differences between species. (1)
• Species; a group of organisms with similar morphological, physiological, biochemical and behavioural features (1) which can interbreed to produce fertile offspring. (1)

Question 2

What is a mnemonic for the hierarchical/linnaean classification system. (1)

Answer 2

E.g. King Phillip Came Over For Good Soup (1)

Question 3

A later development added a further level of classification. What is this?

Answer 3

Domain (1)

Question 4

Describe how binomial nomenclature works (including how it is written). (3)

This system is universal. Explain the advantage of this. (1)

Answer 4

• The first word is the genus; works as the generic name. (1)
• The second word is the species; works as the specific name. (1)
• Genus must be capitalised, both words must be italics/underlined. (1)
• Biologists across the world can discuss organisms and be certain they are discussing the same ones. (1)

Question 5

Name the five kingdoms. (5)

Answer 5

• Prokaryotae
• Animalia
• Fungi
• Plantae
• Protoctista

Question 6

Explain what developments lead to the domain system. (3)

Answer 6

• By studying genetics, we have a better understanding of evolutionary links. (1)
• We can compare DNA and proteins in organisms. (1)
• We are able to group organisms based on things such as the nucleotide sequence of their rRNA, how they react to antibiotics and phospholipid membrane structure. (1)

Question 7

Describe the relationship between phylogeny and classification. (1)

Answer 7

• Phylogeny is used to correct/confirm classification groups. (1)

Question 8

Briefly describe Darwin’s observations/conclusions that lead to the theory of evolution by natural selection. (3)

Answer 8

• Population tends to remain around the same numbers.
• Organisms within a species vary.
• Some variations are inherited by offspring.
• There is competition for survival.
• Individuals with superior adaptations are more likely to survive and reproduce.
• Due to these individuals being more likely to reproduce, it is likely that the helpful adaptations will pass on to offspring.
• This is natural selection.
• Over generations, evolution occurs through natural selection.

Question 9

Who is Alfred Wallace? (2)

Answer 9

Wallace had come to similar conclusions around the same time. (1) Wallace and Darwin did a joint presentation on the theory of evolution together. (1)

Question 10

How does the fossil record show how old a fossil is, ecological links between organisms and how closely related organisms are? (3)

Answer 10

• We can tell how old a fossil is from how deep the layer of sediment it was found in was. (1)
• The sequence of how organisms are found may suggest ecological links, e.g plant fossils appearing before animal fossils depicting that animals require plants to survive. (1)
• We can tell how closely related the organisms that caused the formations of the fossils are by comparing structural characteristics. (1)

Question 11

Describe two ways that palaeontology can be evidence for evolution. (4)

Answer 11

• Simple organisms (e.g simple algae, bacteria) are found in the oldest rocks while more complex organisms (e.g vertebrae) are found in more recent rocks. (1) This is evidence for the idea that simple organisms have gradually evolved. (1)
• Similarities between fossils can be studied to show how closely related organisms may show signs of common ancestry. (1) This is evidence for organisms having evolved from common ancestors. (1)

Question 12

How can molecular evidence/comparative biochemistry demonstrate evolution by natural selection? (5)

Answer 12

• Some molecules change over time, some important molecules are conserved (e.g rRNA). (1)
• Slight changes in these molecules can help us understand evolutionary links. (1)
• Neutral changes in the biochemistry of an organism are normal and often are not affected by natural selection (they provide neither advantage nor disadvantage). (1)
• Two organisms can be compared by comparing a particular molecule, by looking at the order of DNA bases or amino acid sequences of proteins. (1)
• By the number of differences, scientists can figure out the two organisms’ last shared ancestor. (1)

Question 13

What is the difference between interspecific variation and intraspecific variation? (1)

Answer 13

Interspecific variation is the similarities and differences between organisms of different species, while intraspecific variation is between organisms of the same species. (1)

Question 14

What is the difference between discontinuous variation and continuous variation? (1)

Answer 14

Continuous variation is quantitative and discontinuous variation is qualitative. (1)

Question 15

Explain the following genetic causes of variation (4):
- Alleles
- Mutations
- Meiosis
- Chance

Answer 15

• Alleles; there may be intraspecific variation in a species population due to different individuals inheriting different alleles. (1)
• Mutations; changes in DNA will result in changes in genes. This therefore changes the proteins coded for, This affects physical and metabolic characteristics. (1)
• Meiosis; the gametes produced by meiosis genetically vary due to ‘crossing over’ occurring between chromatids and independent assortment during metaphase. (1)
• Chance; the form of genetic variation is down to random fertilisation - it is up to chance which of the female and male gametes combine. (1)

Question 16

Why are plants more affected by environmental causes of variation than animals (e.g plants in a place that does not receive much sunlight)? (3)

Answer 16

Animals can move and therefore move, for example, to a place with abundant food sources and shelter. (1) However, a plant in a shady area is unable to move and will therefore be affected more (1), and it will likely grow to be not as large as plants in places with more sunlight. (1)

Question 17

What are the three types of adaptations organisms have to their environment. (1)

Answer 17

• Physiological
• Behavioural
• Anatomical

Question 18

Provide two examples for each (6):
- Physiological adaptations
- Behavioural adaptations
- Anatomical adaptations

Answer 18

Physiological:
- Poison; e.g plants produce poison in their leaves to deter predators. (1)
- Antibiotics; e.g some bacteria produce antibiotics to kill off surrounding species. (1)
- Water holding; e.g desert plants can hold a lot of water in their tissues. (1)

Behavioural:
- Survival; e.g opposums play dead around rabbits. (1)
- Courtship; e.g scorpions dance to attract mates. (1)
- Seasonal; bears hibernate during winter, when food sources deplete. (1)

Anatomical;
- Body covering; e.g feathers, hair, spines, scales etc. Feathers help birds fly. (1)
- Camouflage; makes it harder for predators to spot them. (1)
- Teeth; the shape and type will cater to the animal’s diet. (1)
- Mimicry; copying another animal’s sounds or appearance to deter predators by seeming more dangerous. (1)

Question 19

Fill in the blanks about the effects of natural selection on a population (3):

___ variation and reproductive success results in an increased ___ of the population possessing the ___ characteristics.

Answer 19

• Genetic (1)
• Proportion (1)
• Advantageous (1)