Natural Selection & Genetic ModificationEdexcel GCSE Biology: Topic test

20 questions, 54 marks

Edexcel GCSE Biology

Natural Selection & Genetic Modification topic test

Total 54 marks

Name

Class

Date

1
Warfarin is a poison used to control rat populations. When warfarin was first used widely in the 1950s, it killed most rats effectively. Today, in many areas, most rats carry a genetic mutation that makes them resistant to warfarin, and the poison is far less effective at controlling rat populations.
(a)
What does the change from warfarin killing most rats effectively to most rats now carrying resistance provide evidence for?
[1 mark]
ADarwin's theory of evolution by natural selection
BThe theory that acquired characteristics can be inherited
CThe idea that rats can choose to develop resistance when threatened
DThe idea that warfarin becomes chemically weaker over time
(b)
What happened to warfarin-resistant rats in areas where the poison was used, that explains why resistance became common?
[1 mark]
AThey were unaffected by warfarin but produced fewer offspring than non-resistant rats
BThey survived exposure to warfarin and reproduced, passing the resistance allele on to their offspring
CThey developed resistance during their own lifetime and passed this learned trait to their offspring
DThey migrated away from areas where warfarin was used
(c)
Explain the process by which warfarin resistance became common in rat populations over time.
[2 marks]
Total for question 1: 4 marks
2
For much of the 20th century, scientists classified all living organisms into five kingdoms, including a single kingdom for all bacteria-like organisms. In the 1970s, Carl Woese compared the genetic sequences of many different single-celled organisms and found that some organisms that had been classified together as 'bacteria' were, genetically, as different from each other as animals are from plants.
(a)
What kind of evidence led Carl Woese to propose reclassifying organisms into three domains rather than five kingdoms?
[1 mark]
AComparisons of body size and shape
BComparisons of fossil records
CComparisons of genetic (DNA/RNA) sequences
DComparisons of the number of legs each organism has
(b)
What are the names of the three domains proposed in this classification system?
[1 mark]
AAnimalia, Plantae and Fungi
BProkaryotae, Protista and Fungi
CVertebrates, Invertebrates and Microbes
DBacteria, Archaea and Eukarya
(c)
Explain why genetic analysis, rather than physical/visible features alone, was needed to reveal that some organisms previously grouped together as 'bacteria' were genetically very different from one another.
[2 marks]
Total for question 2: 4 marks
3
A plant breeder wants to develop a variety of wheat that is more resistant to a fungal disease that regularly destroys part of the crop. Each year, over several generations, she identifies the wheat plants in her fields that show the least damage from the fungus and breeds only these plants together to produce the next generation's seed.
(a)
Explain the process of selective breeding used by the plant breeder to develop a more disease-resistant wheat variety.
[3 marks]
(b)
Explain one disadvantage of developing a wheat variety by this selective breeding process, in terms of genetic variation within the crop.
[4 marks]
Total for question 3: 7 marks
4
A student compares two processes: wild rats becoming resistant to warfarin poison over many generations without any deliberate human breeding programme, and a plant breeder deliberately selecting and breeding only disease-resistant wheat plants together over several generations.
(a)
Explain how natural selection in the wild rat population led to increased warfarin resistance over generations, referring to variation, survival, reproduction and how the frequency of the resistance allele changed.
[6 marks]
(b)
Explain how selective breeding of the wheat is similar to and different from natural selection in the rat population, focusing on the role of the plant breeder as the source of selection pressure.
[6 marks]
Total for question 4: 12 marks
5
Charles Darwin observed that different islands in the Galapagos archipelago were home to finches with differently shaped beaks. Islands with mainly hard, tough seeds had finches with large, strong beaks, while islands with mainly small, soft seeds or insects had finches with smaller, more slender beaks.
(a)
Which scientist independently developed a very similar theory of evolution by natural selection at around the same time as Darwin, leading them to jointly present their ideas?
[1 mark]
AAlfred Wallace
BCarl Woese
CGregor Mendel
DRobert Koch
(b)
What is the best explanation, using natural selection, for the different beak shapes seen on different Galapagos islands?
[1 mark]
AFinches choose to grow the beak shape best suited to their island's food during their lifetime
BNatural selection favoured whichever pre-existing beak-shape variation was best suited to the food available on each island, so that variation became more common there
CAll finches on every island have identical beak shapes, and the difference is only in feather colour
DBeak shape is entirely determined by the environment and has no genetic basis
(c)
Explain, using natural selection, why finches with large, strong beaks became common on islands with mainly hard, tough seeds.
[2 marks]
Total for question 5: 4 marks
6
Scientists want to produce human insulin using genetically modified bacteria. They cut out the human gene that codes for insulin using an enzyme, and use a different enzyme to insert this gene into a circular piece of bacterial DNA, which is then introduced into bacterial cells so that the bacteria can produce human insulin.
(a)
What is the name of the enzyme used to cut out the human insulin gene and cut open the bacterial DNA?
[1 mark]
ALigase
BAmylase
CRestriction enzyme
DPolymerase
(b)
What is the name of the circular piece of bacterial DNA used to carry the human insulin gene into the bacterial cell?
[1 mark]
AChromosome
BNucleus
CRibosome
DPlasmid
(c)
Explain the role of the ligase enzyme and 'sticky ends' in joining the human insulin gene into the bacterial plasmid.
[2 marks]
Total for question 6: 4 marks
7
Golden rice is a genetically modified variety of rice that has been given genes from other species that allow it to produce beta-carotene (which the body converts to vitamin A) in its grains. Ordinary rice does not produce beta-carotene in its grains. Golden rice has been developed to help reduce vitamin A deficiency in regions where rice is a dietary staple and vitamin A deficiency is common.
(a)
Explain one advantage of golden rice compared with ordinary rice for people in regions with vitamin A deficiency.
[3 marks]
(b)
Evaluate one disadvantage or concern that might be raised about introducing a genetically modified crop such as golden rice.
[4 marks]
Total for question 7: 7 marks
8
Unlike selective breeding, which relies on choosing and breeding organisms that already show a naturally occurring desirable variation, genetic engineering allows scientists to take a specific gene from a completely different species and insert it directly into another organism's genome, such as inserting a herbicide-tolerance gene from a soil bacterium into a soybean crop, allowing farmers to spray a weedkiller that kills weeds without harming the crop.
(a)
Explain why, in a natural population without genetic engineering, a completely new characteristic controlled by a gene from a completely unrelated species (such as bacterial herbicide tolerance) could never normally arise in a crop plant through natural selection alone.
[6 marks]
(b)
Explain how genetic engineering allows this crop plant to gain the herbicide-tolerance characteristic far more quickly than would be possible through selective breeding, and evaluate one advantage and one disadvantage of using genetic engineering rather than selective breeding to achieve this.
[6 marks]
Total for question 8: 12 marks

End of questions