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B3 Life on Earth

B3 Life on Earth. Lesson 10: We need Diversity. Objectives. MUST understand what biodiversity is and why it is important SHOULD explain the increasing extinction rate of species COULD describe how and why species are classified. Key Words. You need to be able to define the following:

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B3 Life on Earth

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  1. B3 Life on Earth Lesson 10: We need Diversity

  2. Objectives • MUST understand what biodiversity is and why it is important • SHOULD explain the increasing extinction rate of species • COULD describe how and why species are classified

  3. Key Words • You need to be able to define the following: • Biodiversity • Genetic diversity • Mass extinction event

  4. Textbook Answers 1) A measure of the variety of organisms that exist − the number of different species and the number of organisms in each species. 2) We do not know what species may be useful to humans; we also have a responsibility to preserve the natural world for future generations.

  5. Textbook Answers 3) The graph shows that from 1800 to the present day, both human population and the number of species extinctions have increased; the rate of the growth of human populations and the rate of increase of species extinctions has increased from about 1950 to the present day. 4) Humans are destroying habitats and over-exploiting natural populations for food, for example in the case of the overfishing of cod; climate change also threatens species that have very specific habitat requirements; the likely increase in the number of extreme weather events such as floods, hurricanes and droughts will change habitats more rapidly than most species can adapt.

  6. Textbook Answers 5) Shows exactly how closely related the organisms are; the more similar the DNA, the more closely related. 6) Loss of potentially useful species and loss of whole ecosystems if particular important species are lost. Benefits to society from the loss of biodiversity include: roads mean faster transport of people and goods; new buildings maybe homes or shops or other services for the growing human population. The issue could be addressed by better planning laws (e.g. maintaining the most important places for biodiversity as natural habitats and not allowing any developments that threatened these spaces).

  7. Worksheet Answers Activity 2 (Standard demand) • Table: 1800, 500; 1820, 500; 1840, 500; 1860, 600; 1880, 800; 1900, 1000; 1920, 1500; 1940, 3000; 1960, 5000; 1980, 8000; 2000, 20 000 1) 500−1000. Q2 1000−20 000 3) It has risen much more rapidly in recent years than previously. 4) It is likely that the increasing rate of human population increase has had an effect. 5) Somewhere between 50 000 and 70 000; rates have more than doubled in last 20 years and can be expected to more than double again.

  8. Worksheet Answers Activity 3 (High demand) • Exemplar sentences: A worldwide classification system allows scientists to accurately identify species and make sure they are all referring to the same organisms. Species are classified according to their characteristics. DNAanalysis can be used to classify an organism if it is difficult to decide how it should be classified. A worldwide classification system helps scientists to monitor species populations.

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