A problem for farmers

Give one example of a potential threat to health by the use of GM crops.

Down's Syndrome is an example of a condition caused by the change to a DNA. a) What is the correct term to describe a random change in DNA?

What is an example of an agent that can increase the chance of a change in DNA occurring?

The diagrams below show the light and dark varieties of a moth which can be found in woodland areas. These moths rest on the bark of trees during the day and can be eaten by birds. Normally the bark of the trees in the woodland is light coloured. However, in industrial areas, pollutants cause the tree bark to darken. Woodland area Industrial area a) The peppered moths show variation. Explain why variation is important for the survival of a population.

Describe the next stage, once the population has become separated by an isolation barrier.

Read the following passage and answer the questions based on it. Genetic modification (GM) of crops began with the discovery that the soil bacterium Agrobacterium could be used to transfer useful genes from unrelated species into plants. The Bt gene is one of the most commonly inserted. It produces a pesticide toxin that is harmless to humans but is capable of killing insect pests. Many new crop types have been produced. Most of these are modified to be pest, disease or weedkiller resistant, and include wheat, maize, oilseed rape, potatoes, peanuts, tomatoes, peas, sweet peppers, lettuce and onions. Supporters argue that drought resistant or salt resistant varieties can flourish in poor conditions. Insect-repelling crops protect the environment by minimising pesticide use. Golden rice with extra vitamin A or protein-enhanced potatoes can improve nutrition. Critics fear that GM foods could have unforeseen effects. Toxic proteins might be produced or antibiotic-resistance genes may be transferred to human gut bacteria. Modified crops could become weedkiller resistant "superweeds". Modified crops could also accidentally breed with wild plants or other crops. This could be serious if, for example, the crops which had been modified to produce medicines bred with food crops. Investigations have shown that accidental gene transfer does occur. One study showed that modified pollen from GM plants was carried by the wind for tens of kilometres. Another study proved that genes have spread from the USA to Mexico. a) What role does the bacterium Agrobacterium play in the genetic modification of crops?

Crops can be genetically modified to make them resistant to pests, diseases and weedkillers. Give another example of genetic modification that has been applied to potatoes.

Explain why a plant, which is modified to be weedkiller resistant could be: i) Useful to farmers

1. A gardener treated the soil in the area where he planted vegetables with a fertiliser to increase crop yield. The fertiliser leached into a nearby river adding unwanted nitrates which had a negative impact on the ecosystem. a) Name the process which involves leaching of fertilisers.

Describe why underwater plants die because of this process.

Explain why this process results in the death of fish.

following diagram shows the stages in the formation of a new species. a) What name can be given to this process?

population can become separated into 2 sub-populations through various barriers. State a type of barrier.

The table below compares the rate of extinction of mammal species over two different time periods. The ratio of extinction rates between 1200 - 1700 compared to is 1800 - 2000 A. 55:750 B.750:55 C.11:150 D. 150:11

The diagram below represents four populations of animals P, Q, R and 5 and areas of interbreeding. Interbreeding takes place in the shaded areas. How many species may evolve over time? A.1 B.2 C.3 D.4

Which term refers to the process by which organisms that are better adapted to their environment survive and breed? A. Natural Selection B. Speciation C. Mutation D. Genetic engineering

What is the correct order for the events of speciation? A. Isolation, mutation, selection B. Mutation, isolation, selection C. Mutation, selection, isolation D. Selection, mutation, isolation

The graph below shows information about the growth of the human population. If the population continues to increase at the same rate as between 1975 and 2000, predict the population size in 2025. A. 1300 B. 1400 C. 1200 D. 2000

The build-up of pesticides in a food chain reaching lethal levels is known as A. Biological control B. Bioaccumulation C. Algal bloom D. Genetic modification

Which of the following is a source of new alleles in a population? A. Mutation B. Isolation C. Natural selection D. Environmental conditions

Which of the following statements describes the sequence of events when fertiliser leaches into a loch? A. Algal bloom develops - algae die — oxygen concentration increases B. Algal bloom develops — algae die — oxygen concentration decreases C. Oxygen concentration increases - algal bloom develops — algae die D. Algae die → oxygen concentration decreases - algal bloom develops

The following graph shows the changes in wheat yield over a fifty-year period. The percentage increase in wheat yield from 1950 to 2000 is A. 5 B. 40 C. 250 D. 350

Which substances are synthesised by plants using nitrate taken up from soil? A. Sugar B. Ammonia C. Pesticides D. Amino acids

Each variety of moth has an inherited characteristic that makes an organism well suited to survival in its environment. What is this called?

Lichen is an example of a species that can indicate the levels of pollution. What name is given to this type of species?

A factory has been built near a woodland area. What impact will this have on the number of dark peppered moths?

The process of natural selection happens when certain individuals gain an advantage over other individuals. This can also be called survival of the fittest Using your understanding to describe the process of natural selection.