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 ….

2. 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:

1. What sequence of events has the evolution of life on Earth involved?

2. What organisms appeared first on Earth?

3. How much time does our solar system exist?

4. What is creationism?

5. Why is creationism not a science?

6. What can you say about the hypothesis of spontaneous generation?

7. Aristotle believed that life started from lifeless materials, didn’t he?

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

9. How did Louis Pasteur and John Tyndall overthrow the belief that microorganisms arose spontaneously?

3) Point out the topic sentence in each paragraph.

3. LANGUAGE FOCUS

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

noun	verb	adjective
	to evolve
appearance
	to create
		scientific
cell
	to form
		dead
reproduction
	to believe
development
	to generate
organism
	to account

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

a)	b)
Development	to disappear
to permit, to let	one-celled organisms
to use	decrease
to perform	living
to show	on the one hand
Multiplication	cold
to accept	to stay
to examine	to challenge
Explanation	seldom
to originate	little known
larva

3. Complete the sentences using the text:

I. The first living things to appear….

II. With cellular specialization certain cells within the multicellular organism …..

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

IV. The creationists’ method of inquiry ….. on the Bible.

V. Scientists, on the other hand, ….

VI. ….. are often called creationists.

VII. The fact is that creationism is not a …..

VIII. ……. is known as spontaneous generation.

IX. Maggots appeared only ….

X. Until the nineteenth century people still believed …..

XI. ….. 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.

4. 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.

Дата добавления: 2015-09-03