Chapter 18 Science, Technology and Ourselves

Chapter 18 Science, Technology and Ourselves

CHAPTER 18 – SCIENCE, TECHNOLOGY AND OURSELVES

CONCEPT MAP

Note: In order to benefit fully from the modules in this final chapter, students need to be familiar with the topics covered in earlier modules including, in particular, most of those in Chapters 12 to 16. Many of the topics, especially those covered from Module 18.5 onwards, might provide a basis for interesting class debates. If you use debates, make sure that students distinguish clearly between scientifically established facts and personal opinions. Insist that students back up their statements with appropriate evidence.

18.1 SPACESHIP EARTH

Aims:

  • To make students aware (i) that we depend on the resources of planet Earth, (ii) that in recent times we have been using these resources faster and faster, and (iii) that these resources are limited.
  • To provide a broad conceptual framework (advance organiser) for the topics to be studied in the remainder of this chapter.

Activities:

  • Discuss with students the photo of the Earth in space, emphasising the relative smallness and isolation of our planet. Make them aware of our dependence on Earth’s natural resources and how dramatically our demands on these have been increasing, especially in recent years.
  • Encourage students to do their own research into these issues and report back to the class.Clarify what we mean by human values, and draw their attention to the importance of values in making decisions about the competing demands of technological progress and the ecological health of the planet.
  • Review the contents of this chapter as summarised in the last paragraph in the module. With some classes it might be appropriate to use the concept map above, or your own simplified version of it, as an advance organiser.

18.2 THE EARLY HISTORY OF LIFE ON EARTH

Aims:

  • To provide students with basic information about the early history of life on Earth from the formation of the planet to the rise of mammals.
  • To help students understand the basic ideas involved in adaptation and evolution by natural selection (through natural variation, ‘survival of the fittest’, and inheritance).

Activities:

  • Discuss key events in the early history of life on Earth using the information provided in the text of this module. If possible, make use of additional relevant pictures from books, magazines and/or the internet.
  • Stress the principles of adaptation and evolution by natural selection using the text in the box and referring to the examples previously given in Modules 15.4 (re plants), 15.4 (re animals) and 16.14 (re drug resistance in bacteria). Emphasise that populations of the same species, living in different habitats, gradually diverge as they adapt to their different living conditions. In time they become different species; this may takehundredsto millions of generations, depending on the species and the circumstances.
  • Use the questions at the end of the module for homework or small-group work in class. Discuss students’ answers and be encouraging, but take the opportunity to correct any misunderstandings.

Answers:

  • Q1. (i) The kingdoms in order of evolution are: Monera, Protista (including algae), Plants, Animals and Fungi at about the same time. (ii) The classes of vertebrates in order of evolution are: Fish, Amphibians, Reptiles, Mammals, Birds.
  • Q2. Blue-green ‘algae’ are not true algae; they are a kind of bacteria that can carry out photosynthesis. They were an important step in the evolution of true algae (and subsequently plants). They also changed the atmosphere from one rich in carbon dioxide to one rich in oxygen; this changed the whole course of evolution in favour of larger, multi-cellular organisms which could use oxygen as a rich source of energy.
  • Q3. (i) The mudskipper in the picture is adapted for coming out of the water by the following obvious features: eyes on top of its head to look around before and after it comes out of the water; strong front fins that can be used as legs. (Although it is not obvious from the picture, it can also gulp air through its mouth in addition to breathing through its gills like a normal fish). (ii) Fish evolved into amphibians. (iii) To evolve into an amphibian, the mudskipper would need to develop proper lungs for breathing (loosing its gills) and back legs to move properly on land.

18.3 THE RISE AND SPREAD OF HUMANS

Aims:

  • To inform students about the biologiststaxonomic classification of humans.
  • To make students awareof the basic story the evolution and spread of humans over the past 5 million years, and help them to identify and understand some key stages in that process.
  • To make students aware of the nature of genes as the chemical units responsible for inheritance.

Activities:

  • Review the biologists taxonomy (as studied in Module 15.3) and the classification of humans as Homo sapiens.
  • Discuss with students what they think they know about genes. Correct any misconceptions if necessary and help them to understand the simple description of genes provided in the module.
  • Go through the basic story of the evolution of humans, emphasising the most significant steps and the time scale as outlined in the text of the module. Emphasise the factors that have led to the extraordinary evolutionary success of humans. (Much remains to be discovered about human evolution and there are conflicting theories and interpretations. However the basic account given in the module is fairly uncontroversial).
  • Use the questions at the end of the module for homework or small-group work in class. Discuss students’ answers and be encouraging, but take the opportunity to correct any misunderstandings.

Answers:

  • Q1. (i) Primates are an order of mammals that includes all monkeys and similar animals. (ii) Taxonomy is thebranch of biology concerned with the classification and naming of organisms; the resulting classification is also called a taxonomy. (iii) Genes arechemical units (part of DNA molecules) that pass on certain characteristics from parents to their offspring. (iv) Fossils arethe remains organisms from the distant past preserved in rocks. (v) Predators are organisms (animals) that hunt and kill prey.
  • Q2. (i) Homo habilis, Homo erectus, Homo neanderthalensis, Homo sapiens. (ii)All of these except Homo sapiens are extinct because Homo sapiens displaced them (by killing them, and/or competing with them successfully for food so the others starved, and/or interbreeding with and gradually replacing them).
  • Q3. Students answers will vary, but a good answer should emphasise the factors given in the text box at the bottom of the module (and any similar factors leading to evolutionary success).

18.4 THE BIOSPHERE AND ECOLOGY

Aims:

  • To introduce students to the concept of the biosphere and to review the main ecological principles covered in Modules 15.7 to 15.11.
  • To remind students that interfering with natural food-webs often leads to unintended consequences.

Activities:

  • Introduce the notion of the biosphere and establish in students’ minds that the principles of ecology apply to the biosphere as a whole and to every part of it.
  • Review the principles of ecology as outlined in the text of the module. (If students are not familiar with these, you should study Modules 5.7 to 5.11 with them before continuing).
  • As regards the unintended consequences of interfering with food webs, examples are given in the text of the module involving the removal of insects (considered to be pests) and the adding a plant (because it was considered to be decorative!). Make sure that students understand these basic examples and add more of your own, focussing on locally relevant cases.
  • Use the questions at the end of the module for homework or small-group work in class. Discuss students’ answers and be encouraging, but take the opportunity to correct any misunderstandings.

Answers:

  • Q1. (i) The biosphere is the outer layer of the Earth which supports life, including the continents, the oceans, the lower parts of the atmosphere and every living organism. (ii) Ecosystems are communities of organisms living together in a particular place, together with their environment. (iii) Producers are organisms(plants, algae and blue-green algae)that make complex organic molecules from simple inorganic molecules by photosynthesis; the organisms at the start of any food chain.(iv) Consumers are organisms (animals) that obtain the complex organic molecules they need by eating consumers or each other. (v) Decomposers are organisms (bacteria and fungi) that live by breaking down the complex organic molecules of producers and consumers into simple inorganic molecules. (vi) Food webs are complex networks linking together a number of food chains.
  • Q2. Students answers will vary, but a good answer should emphasise the unexpected consequences of either removing new organismsfrom, or adding new organisms to, a food web.
  • Q3.The energy that the owl uses for flying comes from the sun by the following route: energy from the sun is absorbed by the grass by photosynthesis (efficiency 1%); energy from the grass is transferred to the mouse when it eats the grass (efficiency 10%); energy from the mouse is transferred to the owl when it eats the mouse (efficiency 10%).

18.5 CARRYING CAPACITY

Aims:

  • To introduce students to the ecological notion of carrying capacity and help them to understand how this limits the population of a particular species.
  • To help students apply the notion of carrying capacity to the Earth and its human population, identifying some of the factors tending to limit that population.

Activities:

  • Introduce the notion of carrying capacity as applied to farming. Refer to relevant local, regional and national examples wherever possible.
  • Expand the idea to apply to ecosystems in general, again referring to local examples likely to be familiar to students.
  • Discuss how the population of a new consumer species might vary when breeding pairs are introduced into a new ecosystem. Use the graphs given in the module and discuss how the ideas illustrated by these might apply in familiar local ecosystems.
  • Finally discuss how all these notions apply to the biosphere and its human population. Identify factors that are likely to impact the Earth’s carrying capacity, focussing on local and topical examples as well as the more general ones given in the text.
  • Use the questions at the end of the module for homework or small-group work in class. Discuss students’ answers and be encouraging, but take the opportunity to correct any misunderstandings.

Answers:

  • Q1. The carrying capacity of … (i) a farmer’s field is the number of animals that can graze there permanently. … (ii) an ecosystem for a particular species is the maximum population of the species that the system can sustain indefinitely. … (iii) the Earth for Homo sapiens is the maximum human population that the planet can sustain indefinitely.
  • Q2. Factors that effect Earth’s carrying capacity for its human population include: (i) Limited area of the Earth’s surface that is suitable for human habitation – only about 12% is habitable. (ii) Availability of food – space and fertile soil are needed, and also transport to get the food to the consumer. (iii) Availability of water –some of this has to be pure enough for drinking and it has to be delivered to the consumer. (iv) Availability of shelter – humans need homes for protection from the climate, privacy etc and materials are needed to construct these. (v) Availability of energy to provide and transport food, water and materials. (vi) The standard of living that is regarded as acceptable – carrying capacity will be higher if we accept a low standard of living (for ourselves and others), but lower if we want a high standard of living.
  • Q3. If the Earth’s human population follows graph 1, the world will probably be a bit more crowded but otherwise will remain more or less as it is at present. If it follows graph 2, the Earth’s carrying capacity will be exceeded resulting in famine, mass movements of people as they look for food and water, war and the breakdown of law and order as others try to protect their food and water, and ultimately a drastic fall in population as billions starve to death or die in conflict.

18.6 POLLUTION

Aims:

  • To introduce students to the idea of pollution.
  • To make them familiar with a range of examples (including both local and universal examples) of the pollution of air, land and water, identifying some of the main causes and effects of pollution.

Activities:

  • Introduce the idea of pollution and encourage students to talk about local examples, and notorious international ones, that they know about. Include the idea of pollution by energy especially sound (as described in Module 7.17) and heat (referred to later in this module under water pollution).
  • Use the text of the module to help them identify some of the main sources of pollution of air, land and water. Help them to make lists of sources, contaminants and their bad effects, focussing on local as well as universal examples. If appropriate, ask a local environmentalist to talk to the class about pollution.
  • Use the questions at the end of the module for homework or small-group work in class. For question 2, distribute different notorious examples to different students and read the best answers to the class. Discuss students’ answers to both questions and be encouraging, but take the opportunity to correct any misunderstandings.

Answers:

  • Q1. (i) Polluted air is likely to be contaminated by carbon monoxide (causes poisoning), carbon dioxide (causes global warming), oxides of sulphur and nitrogen (cause acid rain that kills vegetation and slowly destroys buildings; also damages the respiratory system), fine particles of dangerous substances including radio-active substances (cause damage to the respiratory system and different kinds of poisoning – some of them long term). (ii) Polluted water is likely to be contaminated by the waste bi-products of industry and mining, by industrial chemicals that leak or spill from containers or pipes, and by agricultural chemicals including pesticides and fertilisers that wash off the land into rivers and lakes (these are all likely to be poisonous to the environment and humans). Water may also be polluted by human litter especially plastic litter which looks unsightly, harbours insect pests and eventually kills off fish and other aquatic life by reducing light and oxygen. Finally water may also be polluted by human sewage including urine and faeces; these can spread dangerous diseases such as cholera.
  • Q2. The necessary information can be found on the internet, or in magazines or books.

18.7 THE GREENHOUSE EFFECT AND GLOBAL WARMING

Aims:

  • To make students aware that the temperature of the Earth depends on the equilibrium between energy gained from the sun and energy lost by radiation into space.
  • To provide students with basic information about the greenhouse effect and help them understand how it works.
  • To make students aware of global warming and its association with rising levels of carbon dioxide from industrial activities and deforestation.

Activities:

  • Use the text in the first paragraph of the module to get across to students the idea that the Earth’s temperature depends on the equilibrium between incoming and outgoing energy.
  • If students are familiar with greenhouses (or you can take them to a greenhouse), establish that it lets heat in but does not let all of it out again. If possible, make a small model greenhouse using transparent plastic sheeting an a simple wooden framework.Place it in outside in the sun. After some time use a thermometer to compare the temperature inside and outside the model.
  • Use the text of the second paragraph of the module to establish the nature of the greenhouse effectin the atmosphere and identify the three main greenhouse gases. (Note that the greenhouse effect is not controversial; it has been an established part of physics, chemistry and meteorological science for well over 100 years). If you want to go beyond the text in the module, you could discuss the important role of water vapour and mention that clouds (which consist of water droplets) also have a significant effect, however the level of water in the atmosphere varies and is beyond our control. The level of CO2, however, is now very much influenced by human activity. You could help students to understand, for example, that even a relatively small rise in temperature due to higher CO2 levels will tend to cause more water to evaporate from the oceans thus magnifyingthe greenhouse effect. You could also discuss the role of methane as a gas that often escapes into atmosphere during the mining of fossil fuels. It is also a bi-product of decaying vegetation and of digestion in domestic cattle and similar mammals.
  • Use the text in the third paragraph of the module to get across the idea of global warming and consequent climate change. If necessary, make them aware that these ideas are well established and accepted by all leading international and national institutions of science, including institutions specialising in physics, chemistry, meteorology and climate studies. The much publicised misinformation peddled by ‘climate change deniers’ is promoted by mainly those with vested interests in the continuing use of fossil fuels; it belongs in the same category as the misinformation promoted by religions organisations that used to deny that the Earth is spherical, and that it orbits the sun!
  • Use the questions at the end of the module for homework or small-group work in class. Discuss students’ answers and be encouraging, but take the opportunity to correct any misunderstandings.

Answers:

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