The diagram below shows the evolution of the modern horse (Equus caballus).
Define the term 'evolution'.
[1 mark]
State the name of the mechanism which drives evolution.
[1 mark]
There are several sources that provide evidence for evolution, such as selective breeding.
List three other sources of evidence for evolution.
[3 marks]
State two visible differences between Eohippus and modern horses.
[2 marks]
Two populations of cluster pine trees (Pinus pinaster) grew on opposite sides of a large mountain range. After many generations, scientists attempted to cross breed individuals from the two populations with each other but could not succeed. The scientists concluded that speciation occurred between the two populations.
Define the term 'speciation'.
[1 mark]
State two reasons why speciation occurred between the two populations of pine trees.
[2 marks]
Islands will very often contain many species that are endemic to those regions.
Describe a possible reason for this occurrence.
[2 marks]
The blackworm (Lumbriculus variegatus) is a species of worm native to North America and Europe. Their habitat includes marshes, swamps and ponds and they are a popular food source for fish kept in aquariums. Blackworms have a very unique way of reproducing, the segments that make up its body are able to regenerate into a complete individual on its own. Sexual reproduction is very rare in these worms.
Image courtesy of Dvortygirl. Licensed under Creative Commons Attribution-Share Alike 3.0 Unported license. Reused and distributed under conditions found at: https://creativecommons.org/licenses/by-sa/3.0/deed.en
State the main source of variation in a blackworm population.
[1 mark]
List two other sources of variation in a population.
[2 marks]
The blackworm in the image above grew a second tail, presumably due to an injury sustained on the first one. Its ability to regenerate body parts can be considered a useful adaptation.
Define the term 'adaptation'.
[1 mark]
State the use of the regeneration abilities of the blackworm as an adaptation.
[1 mark]
It takes a very long time for blackworms to reach sexual maturity and they need to be of a large body size before they reach this stage of their development, which typically only occur in their natural habitat. Shorter blackworms will reproduce asexually by fragmentation which occurs at a much higher rate than sexual reproduction. In laboratory settings, the worms are often used in experiments and need to be replaced frequently.
State the effect it would have on the body size of a blackworm population taken from a natural habitat, if they were kept in laboratory settings for a period of time.
[1 mark]
The following diagram illustrates the development of antibiotic resistance in bacteria due to a mutation that occurred in a non-resistant population.
Label the bacteria that are present at A and B.
[2 marks]
State the selection pressure that is applied at C.
[1 mark]
The mutation for antibiotic resistance is passed on to other bacteria at point D.
List one of the processes by which this could be done.
[1 mark]
State one strategy that could be used to reduce the rate at which resistance evolves in bacteria.
[1 mark]
One mark is available for clarity of communication throughout this question.
Selective breeding has played an important role in the domestication of wild plant and animal species.
State three examples of selective breeding in agriculture, along with the improved characteristics of each.
[3 marks]
Outline the process of selective breeding.
[6 marks]
