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20. Human influences on ecosystems
A section of Biology, 0610
Listing 10 of 393 questions
shows the Galapagos iguana, Amblyrhynchus cristatus. State two features that are used to classify animals, such as the Galapagos iguana, as reptiles. State two features that are present in plant cells that are not present in the cells of reptiles. Galapagos iguanas feed on seaweed which contains starch and other carbohydrates. State the name of the enzyme that digests starch. State the names of two parts of the alimentary canal where starch is digested. There are many threats to wildlife in the Galapagos. Describe ways in which endangered species can be conserved. One aim of conservation is to maintain resources in natural ecosystems. State three resources that natural ecosystems provide for humans.
0610_w18_qp_42
THEORY
2018
Paper 4, Variant 2
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shows the changes in the percentage of the total global fish stocks that are overfished and those that are sustainable. percentage of the total global fish stocks 1975 1980 1985 1990 1995 2000 year Key overfished sustainable 2005 2010 2015 2020 Use the information in to: State the percentage of fish stocks that were sustainable in 2020. % State which five-year period had the greatest increase in sustainable fish populations. Overfishing is one reason why populations of fish decline. Explain the risks to a species if its population size decreases. Describe and explain how fish stocks can be managed sustainably and how overfishing can be prevented through conservation.
0610_w23_qp_41
THEORY
2023
Paper 4, Variant 1
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Scientists recorded the percentage of endangered species in each of the five groups of vertebrates, in 2000 and 2011. shows the results. percentage of endangered species in each vertebrate group amphibians mammals birds vertebrate group reptiles fish key: State the vertebrate group that had the largest increase in the percentage of endangered species between 2000 and 2011. State the vertebrate group that had a decrease in the percentage of endangered species. State the percentage of fish species that were endangered in 2011. % State one feature of birds which distinguishes them from the other groups of vertebrates. One reason species become endangered is pollution from discarded waste such as plastic. Describe two ways of preventing plastic waste entering the environment. Reducing pollution can help to conserve species. Outline other ways that can be used to conserve endangered animal species. Differences between the features of the five groups of vertebrates have arisen over very long periods of time. These differences are the result of natural selection. The box on the left contains the term ‘Natural selection’. The boxes on the right contain some sentence endings. Draw three lines to link the term ‘Natural selection’ with three sentence endings to make three correct sentences. involves humans choosing the best animals. involves only the best adapted organisms surviving and breeding. involves passing on alleles to offspring. Natural selection occurs because all offspring are identical to their parents. occurs as there are not enough resources for every individual. only occurs in animals.
0610_m22_qp_32
THEORY
2022
Paper 3, Variant 2
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Use The Ruddy duck, Oxyura jamaicensis, is a native of America. A flock of 20 birds was introduced into Britain from America before 1950. The original flock settled quickly in their new habitat and started breeding. Numbers now exceed 6000. The White-headed duck, Oxyura leucocephala, (a native of Spain) is a closely related species to the Ruddy duck. Female White-headed ducks are more attracted to male Ruddy ducks than to males of their own species. Cross-breeding between the two species produces a new variety of fertile duck. The White-headed duck is now threatened with extinction. Some conservationists are considering a plan to kill the British population of Ruddy ducks to prevent the White-headed duck becoming extinct. shows a male Ruddy duck. State two features, visible in , that distinguish birds, such as the Ruddy duck, from other vertebrate groups. With reference to an example from the passage, describe what is meant by the term binomial system. State two reasons, based on information in the passage, why the Ruddy duck and White-headed duck are considered to be closely related. Examiner's Use Explain why Ruddy ducks would not become extinct, even if British conservationists carried out their plan. Suggest one factor, other than the breeding habits of the Ruddy duck, that could result in the extinction of a bird such as the White-headed duck. The Ruddy duck feeds on seeds and insect larvae. The ducks are eaten by foxes and humans. Explain why these feeding relationships can be displayed in a food web, but not in a food chain.
0610_s05_qp_3
THEORY
2005
Paper 3, Variant 0
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Climate change is one reason why a plant species could become endangered. State other reasons why a plant species could become endangered. Describe how human actions are causing climate change. Seed banks are used to conserve endangered plant species. shows some of the steps involved in managing a seed bank. seeds are collected from many populations of each species seeds are checked using X-rays seeds are stored at low temperatures in the seed bank a small sample of seeds is germinated Explain why seeds from one species are collected from many populations to store in a seed bank. Seeds are X-rayed before they are stored to check that they contain an embryo. State one possible consequence of using ionising radiation on seeds. Seeds stored at low temperatures have very low respiration rates. Explain why. One purpose of seed banks is to reintroduce plant species into their natural environment. A survey was done to find out why some reintroduction programmes are not successful. shows the results of the survey. percentage of species that were not successfully reintroduced reason unknown wrong habitat changing habitat seeds did not germinate reasons why reintroductions failed seedlings too young too few individuals wrong season Some of the seeds in the reintroduction programmes did not germinate. State the conditions that are necessary for seeds to germinate. Some reintroduction programmes failed because the seedlings were too young. Young seedlings only have a few small roots. Explain why it would be important to reintroduce plants with many large roots. The low number of individuals also caused some reintroduction programmes to fail. State the name of the phase in a population growth curve where the number of individuals is very low.
0610_s21_qp_42
THEORY
2021
Paper 4, Variant 2
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For Examiner's Use Table 1.1 shows some features of the five groups of vertebrates. Complete Table 1.1 to compare the five groups of vertebrates using a tick () to indicate if the group shows the feature, or a cross () if not. The first row has been completed for you. Table 1.1 group of vertebrates scaly skin external ear feathers mammary glands birds     bony fish amphibians reptiles mammals shows a southern cassowary, Casuarius casuarius, which is a large bird that cannot fly. It lives in rainforests in northern Australia and southern New Guinea. The cassowary feeds on fruits and helps to disperse seeds for many tree species, such as the cassowary plum. Suggest why the cassowary can digest the fruit but not the seeds of rainforest trees. For Examiner's Use Describe one method of seed dispersal that does not require animals. State two environmental conditions that seeds require so that they can germinate. 1. 2. Cassowaries are an endangered species. Many are killed on the roads and development threatens their rainforest habitat. Cassowaries, as with many other rainforest species, cannot survive in small nature reserves. Suggest why species, such as cassowaries, cannot survive in small nature reserves.
0610_w13_qp_31
THEORY
2013
Paper 3, Variant 1
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Questions Discovered
393