I. Read and translate the text. Be ready to fulfil the tasks that follow.

ORIGIN OF LIFE

The evolution of life on Earth has involved the following sequence of events. The first living things to appear were the simplest creatures, one-celled organisms. From these came more complex, multicellular organisms. Becoming more complex meant more than just an increase in cell number. With more cells came cellular specialization, where certain cells within the multicellular organism carried out special tasks. Millions, even billions of years of organismal changes led to the living things we now call plants and animals.

Scientists generally concur that the time from the formation of our solar system until now has been on the order of some 4.5 billion years. Those who believe the world as we know it was created in six days are often called creationists. Their method of inquiry is based on the belief that the Bible is to be accepted as a completely accurate accounting of all about which it speaks. Scientists, on the other hand, utilize what they call the scientific method, which allows them to test hypotheses and theories, and to develop concepts and ideas. However, there are many good scientists who also happen to be creationists. Even though the two are often compared and contrasted, the fact is that creationism is not a science, and therefore it is not dealt with in most biology books.

An early hypothesis concerning the origin of living organisms from nonliving material is known as spontaneous generation. Aristotle believed insects and frogs were generated from moist soil. It wasn’t until 1668 that Francesco Redi, an Italian, challenged the concept of spontaneous generation when he tested the widespread belief that maggots were generated from rotting meat. He placed dead animals in a series of jars, some of which were covered with a fine muslin that kept flies out while allowing air in. Other jars containing dead animals were left open. Maggots appeared only on the meat in the jars that were left open. In these, flies had been able to lay their eggs, which then hatched into fly larvae, or maggots. The flies were unable to land on the meat in the covered jars, and no maggots appeared there. From this he concluded that maggots would arise only where flies could lay their eggs.

During the nineteenth century, Louis Pasteur and John Tyndall conducted the experiments in which they demonstrated that bacteria are present in the air, and if the air surrounding a heat-sterilized nutrient broth is bacteria-free, then the broth remains bacteria-free. Until this time, people still believed microorganisms arose spontaneously.

By the late 1870s, most scientists agreed that all organisms arose from the reproduction of preexisting organisms, and the concept of spontaneous generation had become history.

Notes to the text:

Aristotle ["xrIs'tq(V)tl]

Francesco Redi [fren'tSeskqV 'redI]

Louis Pasteur ['lu(:)Is px'stq:]

John Tyndall [dZPn tIndl]

The Bible is to be accepted. – Библию следует считать.

They happen to be creationists.- Оказывается, что они креационисты.

It wasn’t until 1668 that…. – Только в 1668 году ….

II. COMPREHENSION CHECK.

1. Say whether the following statements are true or false:

a) The first living organisms that appeared on Earth were one-celled organisms.

b) More complex, multicellular organisms came from the simplest creatures.

c) The difference between simpler and more complex organisms consists only in cell number.

d) Scientists generally agree that our solar system originated about 5.4 billion years ago.

e) The method of inquiry based on the belief that the world was created in six days is called creationism.

f) Scientists utilize only what they call the scientific method.

g) Aristotle believed in the origin of living organisms from nonliving material.

h) Francesco Redi challenged and overthrew the theory of spontaneous generation.

2. Give answers to the questions below:

a) What sequence of events has the evolution of life on Earth involved?

b) What organisms appeared first on Earth?

c) How much time does our solar system exist?

d) What is creationism?

e) Why is creationism not a science?

f) What can you say about the hypothesis of spontaneous generation?

g) Aristotle believed that life started from lifeless materials, didn’t he?

h) What experiments did Francesco Redi carry out to solve the problem of the origin of life on Earth?

i) How did Louis Pasteur and John Tyndall overthrow the belief that microorganisms arose spontaneously?

3) Point out the topic sentence in each paragraph.

III. LANGUAGE FOCUS

1. Form the derivatives of the words given in the chart below (where possible):

2. Find in the text: a) synonyms and b) antonyms to the following words and word combinations:

3. Complete the sentences using the text:

a) The first living things to appear….

b) With cellular specialization certain cells within the multicellular organism …..

c) Scientists …. that our solar system appeared some 4.5 billion years ago.

d) The creationists’ method of inquiry ….. on the Bible.

e) Scientists, on the other hand, ….

f) ….. are often called creationists.

g) The fact is that creationism is not a …..

h) ……. is known as spontaneous generation.

i) Maggots appeared only ….

j) Until the nineteenth century people still believed …..

k) ….. the concept of spontaneous generation had become history.

4. Translate the sentences into English using the vocabulary of Unit 1:

а) Вероятно жизнь на земле зародилась в форме простейших одноклеточных организмов, из которых произошли более сложные, многоклеточные организмы.

б) Простейшие одноклеточные организмы должны были добывать пищу из неорганических веществ и превращать их в органические.

в) В течение миллиардов лет произошли многочисленные изменения организмов, которые привели к возникновению растений и животных.

г) Ученые считают, что наша солнечная система образовалась 4.5 миллиарда лет назад.

д) Библия описывает, что вселенная была создана за 6 дней.

е) Метод исследования сторонников теории креационизма основывается на положениях Библии.

ж) Ученые используют научные методы, чтобы проверить гипотезы и теории и развит свои концепции и идеи.

з) Аристотель полагал, что жизнь произошла из неживой материи.

к) Франческо Реди опроверг теорию самозарождения и доказал, что все организмы возникли в результате размножения предшествующих организмов.

л) Гипотеза, касающаяся зарождения жизни из неживой материи, известна как теория самозарождения.

IV. FOLLOW-UP ACTIVITIES.

1. Discuss in pairs different theories concerning the evolution of life on Earth.

2. Write an essay about the origin of life on Earth.

ADDITIONAL TEXT

I. Read and translate the text. Be ready to fulfil the tasks that follow.

PROPERTIES OF CHEMICAL REACTIONS

An atom is the smallest particle of an element that can retain the chemical properties of that element. It is composed of a nucleus, which contains positively charged protons and neutral neutrons, around which negatively charged electrons revolve in orbits. For example, a helium atom contains 2 protons, 2 neutrons, and 2 electrons.

An ion is a positively or negatively charged atom or group of atoms. An ion which is negatively charged is called an anion, and a positively charged ion is called a cation.

Isotopes are alternate forms of the same chemical element. A chemical element is defined in terms of its atomic number, which is the number of protons in its nucleus. Isotopes of an element have the same number of protons as that element, but a different number of neutrons. Since atomic mass is determined by the number of protons plus neutrons, isotopes of the same element have varying atomic masses.

All substances are composed of matter, they have mass and occupy space. Elements and compounds constitute two general classes of matter. Elements are substances that consist of identical atoms (i.e., atoms with identical atomic numbers). This definition of an element includes all isotopes of that element. Hence O¹⁸ and O¹⁶ are both considered to be elemental oxygen. A compound is a substance that is composed of two or more different kinds of atoms (two or more different elements) combined in a definite weight ratio. This fixed composition of various elements, according to law of definite proportions, differentiates a compound from a mixture. Elements are the substituents of compounds. For example, water is a compound composed of the two elements hydrogen and oxygen in the ratio 2:1, respectively. This compound may be written as H₂O, which is the molecular formula of water. The subscript “2” that appears after the hydrogen (H) indicates that in every molecule of water there are two hydrogen atoms. There is no subscript after the oxygen (O) in the molecular formula of water, which indicates that there is only one oxygen atom per molecule of water. Hence water is a compound whose molecules are each made up of two hydrogen atoms and one oxygen atom.

II. PO ST-READING TASKS.

1. Define the following terms: atom, isotope, ion, element, compound.

2. Describe the differences between an element and a compound.

3. Talk about different constituents of matter.

UNIT 2