Each step is a trophic level, which represents the feeding position or level where an organ ism exists in a particular food chain or food web. The word trophic refers to feeding (or eating).
In each step of a food chain, only 10% of the energy moves from one trophic level to the next. If the grass represents 100% of the energy available, then the rabbit would only have 10% available, and the fox would then only have 1% available. In other words, it would take 100 pounds of grass to support ten pounds of rabbit and then one pound of fox. An herbivore is an animal that eats plants. Plants are producers in food chains, and any organism that eats plants is a consumer. Animals that eat other animals are also consumers. All animals are some kind of consumer because they cannot make their own food. First-order consumers such as herbivores are at the second level of a food chain (plants are at the first level), but they are the first level of consumer. Second-order consumers are other animals that eat herbivores. Third trophic-level organisms are another way of saying second-order consumers (they are at the third trophic level after herbivores and plants).
Food webs are complex groupings of interacting food chains. Organisms may play different roles in different food chains. Food webs with a number of diverse organisms are considered more stable than single food chains. Primary consumers are the first level of consumers, but also the second trophic level. The first trophic level contains the producers (plants).
Organisms interact with each other, and the most common interaction is within the structure of a food chain in which one organism is the food and energy source for another organism. All food chains start with plants as producers because they can photosynthesize and capture sunlight energy. Animals are consumers and eat either plants or each other. Several food chains can be interwoven to create a food web in which many organisms interact with each other.
1. The steps in a food chain or food web are called …….. and represent the …….. of an organism.
a) biomic levels; energy level c) trophic levels; feeding level
b) trophic levels; energy level d) energy levels; feeding level
2. In this food chain, grass → rabbit → fox how much of the energy captured in the grass’s tissue is available to the fox?
a) 100% b) 50% c) 10% d) 1%
3. Another term for herbivores is …….. .
a) plants c) first-order consumers
b) second-order consumers d) third trophic-level organisms
4. Several interacting food chains form a …….. .
a) food pyramid c) food column
b) food web d) food triangle
5. Herbivores are at the second trophic level and can also be called …….. .
a) primary producers c) secondary consumers
b) primary consumers d) secondary producers
6.17. Match the two parts of the sentences.
1. The largest extinction event occurred 250 million years ago,
2. The more we know about wild land biodiversity,
3. Contamination of the air, land and water results largely
4. Some species will need to be helped along artificially
5. Urban development can degrade a habitat
6. Forests not only harbour untold numbers of different species
7. The plant uses the sunlight energy to make food molecules,
8. Energy becomes a part of the animal communities
a) from the use of machines such automobile.b) because plants and soil are replaced with asphalt and concrete.c) when 95 percent of marine species died.d) which are stirred within the tissues of the plant.e) through those who eat plants.f) the more we can use it without damaging.g) by creating seed banks.h) but also play a critical role in regulating climate.
6.18. Match the titles with the notions.
1. Community 7. Food chain
2. Consumers 8. Genetic engineering
3. Decomposers 9. Habitat
4. Ecosystem 10. Natural selection
5. Evolution 11. Photosynthesis
6. Extinction 12. Producers
a) All green plants, which make food from simple materials by photosynthesis. They are the basis of all food chains.
b) A specific area, small or large, that is inhabited by a particular community of plants and animals.
c) A virtually self-contained system, consisting of a community of plants and animals in a given habitat, together with their environment.
d) The dying out of a species of living thing, and hence its complete disappearance from the earth.
e) The plants and animals within a certain habitat.
f) The means by which plants use the sun’s energy to build their food (carbohydrates) from water and carbon dioxide.
g) The theory of evolutionary processes first expounded by Charles Darwin. It suggests that those individual organisms within a species which have the best adaptations to their environment are the most likely to survive long enough to breed, hence these adaptations become established in later generations, and the species as a whole gradually “improves”.
h) Organisms that feed on other organisms.
i) Organisms that live by breaking down dead bodies, releasing the minerals they contain.
j) Altering genes to create organisms that are useful to man. Genes carry information about an organism’s basic characteristics.
k) The long-term process of change in organisms, often occurring over millions of years.
l) A chain of organisms, linked together because each is food for the next in line. Energy passes from one level (trophic level) to the next. All the food chains in an ecosystem are connected together in a complex food web.
6.19. Project work.
We are interfering with biodiversity on a great many levels, from the molecular (genetic modification) all the way through habitats and possibly global climate change as well. However, the many predictions made about species and habitats losses need to be carefully examined in each case and not just taken at face value. Many are based on computer simulations and emotions can get in the way of clear practical thinking. So, your project work may touch upon the following items:
1. Human activity could lead to extinction of a species by over-hunting, e.g. elephants, rhinos, whales, destruction of habitats, e.g. logging, farming, building, introduction of alien species, e.g. cats, rats, cane toads, pesticide use, e.g. honey bees, predatory insects.
2. We can attempt to protect species from extinction by making it illegal to kill the threatened animals or uproot or destroy the protected plants. Habitats of the species can be conserved. Breeding the endangered species in captivity and releasing them later can save a species from extinction.
3. Modern agriculture destroys the natural vegetation (e.g. woodland, hedgerows) on a site, which means a natural habitat is lost. A cultivated area has little biodiversity. The use of pesticides can destroy harmless or beneficial organisms as well as agricultural pests.
4. Biofuelcan be obtained from sugar (sugar-cane), maize, sunflower oil, palm oil.
5. Biodiversity conservation is an international problem requiring international solutions and the role of international organisations is a vital one.
UNIT 7 WATER
7.1. Study the information and answer the following questions after it.
Water is a very important part of our environment. But how important is it? How many ways of using water do you know? Here are some of them.
Drinking People need to drink clean water every day. Over 1.5 billion people do not have clean drinking water.
WashingTaking a regular shower or bath is part of our lives. We also use water to wash the dishes, our clothes, and the house. The problem is, this fresh water then becomes waste water.
Cooking Do you want to cook some pasta or rice? You need water! Preparing salad? You wash it in water. Boiling potatoes? Water again!
The WHO (World Health Organization) says that a person needs 19 litres of water a day. One in three Asians do not have safe drinking water, and one in two has no sanitation. Over 1.5 billion people do not have clean drinking water.
Animals Like humans, animals need to drink water to survive.
Irrigation Plants need water, too. So farmers use it to help their crops to grow. With water, dry land can produce crops. When there is no rain, irrigation is necessary for agriculture.
Fish Fish live in fresh water, in lakes and rivers. Many fish live in salt water, in the ocean. These fish are wild, but in many countries there are now also fish farms.
Machinery Machines use water.
Transport We transport things by water. Ships travel on the seas, rivers and canals.
Energy Countries where it rains a lot, or with high mountains, use water to produce electricity.
The WHO says that the largest water users are: Agriculture 70%, Industry 20% and Domestic Use 10%.
► 1. How many ways do we use water?
2. How many ways do you use water?
3. What is WHO?
4. What is the difference / similarity between drinkingwater, clean water, fresh water and waste water? Use a dictionary to help you.
5. What is irrigation? Where and why is it used?
7.2. Can we live without water? Of course not. Read the text below to support this idea and answer the questions after it.
The human body is about 65 per cent water. If you stopped drinking water (or drinks and food containing water) you would die within three or four days. But the water you drink must be clean.
Each day an average person uses the following amounts of water:
Toilet flushing 35 litres Bathing 30 litres
Cooking and drinking 30 litres Using a shower 12-20 litres
The average daily total per person is 140 litres. The average family uses 480 litres of water a day.
Water can carry diseases. According to a recent report published by the United Nations, every day throughout the world about 25,000 people die from diseases related to dirty water.
It takes 31,600 litres of water to make one car and 4,124 litres to make one tonne of steel. It takes 53 litres of water to make one pair of leather shoes and 9 litres of water to make every paper that you read.
● How much of the human body is water?
● How much water does an average person use for bathing?
● How many people die per day from disease related to dirty water?
● How many litres of water does it take to make one pair of leather shoes?
● How long can a person live without water?
7.3. Here are some words and phrases relating to water. Match them with their definitions.
1. running water
a) an amount of wetness caused by the presence of water
2. water shortage
b) how much water there is in something
c) water that is flowing
4. water content
d) a continuous movement of water
e) an animal or plant lives or grows in water
f) animals that are able to live both in water and on land
g) things that does not let water pass through
9. aquatic species
i) when there is not much water available
j) a very large amount of water that moves quickly and strongly
k) very large amount of water covering land and causing serious damage
2. A system of canals carries water to …….. the soil in hot countries.
3. The water …….. of the River Thames gas risen in the past few days.
4. A …….. is a special wall across a stream to stop the water from flowing.
5. Parts of coastal dam collapsed, causing serious …….. in the town.
6. Be careful! The lake is quite …….. here.
7. This river is not navigable because it’s too …….. for boats.
8. After five days of heavy rain the Telle River was a …….. .
9. Condensed milk is produced by removing about 50% of the water …….. of whole milk.
10. …….. is a long period of time when there is no rain and crops die.
7.5. Match the two parts of the sentences.
1. Helicopters search for people
a) water birds.
2. It is dangerous to swim in the sea here
b) the village was flooded.
3. A water lily is a beautiful plant
c) before installing the new heating system.
4. My eyes watered
d) because the current is so strong.
5. A gull, sawn, pelican, flamingo are
e) that sell books.
6. They turned off the water supply
f) who climbed trees to escape from flood waters.
7. After two days of continuous rain,
g) when I cut the onions.
8. Waterstone’s shops are large stores in Great Britain
h) that grows in water and has flat floating on the surface.
7.6. We all need water. The problem is, there’s often too much – or too little. And there are other problems, too. Let’s look at some of them.
Too much: When it rains a lot, the level of the rivers rises. The water runs over the banks. People often drown. Their cars and houses are ruined. Animals drown, too. Many big cities in Asia, Latin America and Europe often have floods.
Too little: Sometimes it doesn’t rain for a long time. Plants die. Animals die, too. People have no food. Many countries in Africa have big problems with droughts. Every year, these droughts get worse and worse.
Industry often pollutes water with chemicals. Some farmers also use too many chemicals. These enter the rivers and lakes. They kill the plants and fish.
Increased use of water
People can live 40-50 days without food, but only 4 days without water. People today vary in how much water they consume per day; in some places each person averages 5 litres, in other places 210 litres. People are using far more water today than they did 75 years ago.
The amount of fresh water
75% of fresh water resources are frozen in the ice at the North and South Poles. Most of the rest is in or under the soil and less than 1% is actually available for human use in streams, rivers, lakes, swamps and springs.
Every country wants water for its people. So they build dams to collect it, and to produce hydroelectricity. Sometimes they divert rivers to provide more water. Different communities inside a country need water for different purposes. For example, in Spain, there are plans to build a big dam on the River Ebro to provide irrigation for farmers. But the fishermen at the mouth of the river do not want this. It will destroy the fish and affect their lives.
The world is getting warmer, so water levels are rising. Climates are changing. Some countries are becoming hotter and drier. This affects agriculture. People want to control global warming, but they cannot agree about the best solutions.
7.7. Are these statements true (T) or false (F)?
1. The human body is about 65% water.
2. Fresh water lakes contain salt.
3. People can live 40 days without water.
4. Resources of river, lake and underground fresh waters are distributed unevenly on the continents.
5. The total area of lakes in Russia is larger than in Great Britain.
6. Rivers and lakes not only supply water resources, but are also used as transport systems and fisheries.
7. Dumping sewage into seas is not dangerous.
8. Today water recycling in industrial enterprises is a reality.
7.8. Read the information carefully and pay attention to the verbs in bold.
When water is heatedto 100°Celsius, it boils and becomes steam. When steam touches a cold surface, it condenses and becomes water again. When water is cooledbelow 0°Celsius, it freezes and becomes ice. If the temperature increases, the ice melts.
► To check your good memory represent the text above without looking at it.
7.9. Study the information and do the exercises after it.