Introduction
Date: 2015-10-07; view: 544.
Cyclical process
Unit 8 Linear relationships (3)
Exercise 2. Fill in the missing remarks.
Exercise 1. Each of the phrases in A can be answered by a phrase in B. Match the phrases.
| A | В |
| 1. Can Dr Blackmore see me some time tomorrow? 2. Before lunch is not good. He'll be out of the office. 3. When can we meet? 4. Would 3 o'clock be convenient for you? | a. How about later in the afternoon? b. It's all the same to me. I'm absolutely free. c. Do you think you could make it a little earlier? d. No, I'm afraid not. He won't be available until the day after tomorrow. |
A: __
B: Mr Green can't see you at 11 o'clock on Monday.
A: __
B: No, I'm sorry, on Tuesday he has a meeting in the morning. Is the afternoon possible?
A: __
B: Thank you.
In the previous unit you learned how to write up a linear process, i.e. a process that consists of a series of stages and which has a beginning and an end. A natural process is more likely to be cyclical than linear. In a cyclical process there is no clear beginning or end, so that the cycle is continuously repeated. The diagram below should make the difference between the two types of process clear.
1. A linear process
| Input | Step1 .--. | Step 2 , , , - > i- - U | etc | Output | ||||
2 . A cyclical process
 |
stage
stage
 |
stage
stage
A cyclical process is described in much the same way as a linear process except that it is not always clear where the cycle begins.
Task 1
This flow diagram illustrates the nitrogen cycle. Nitrogen is essential for human, animal and plant life, and over 90% of the Earth's supply exists as a gas in the atmosphere. The diagram shows how nitrogen is provided to living organisms and then returned to the atmosphere. Below the flow diagram is a list of sentences describing the stages in the cycle. The sentences are not in an acceptable sequence. Using the flow diagram as a guide, match the sentences with the stages in the flow diagram to produce a text in acceptable sequence.
|
 
|
| Fixation by lightning |
| Gaseous |
| Denitrification |
1. Lightning contributes some nitrogen, in the form of nitrates, to the soil.
2. This gaseous nitrogen is returned to the atmosphere.
3. When animals eat the plants, the nitrogen they contain is synthesized into protein. *
4. When plants or animals die, proteins are decomposed by bacteria into amino acids which are in turn broken down into ammonium.
5. But at the source of most nitrogen is bacteria on plants, which 'fix' the nitrogen into ammonia.
6. The nitrates in the soil are absorbed by plant roots.
7. Some of the nitrates are degraded into nitrogen gas in the denitrification process.
8. The ammonium is broken down into nitrites.
9. The ammonium resulting from decomposition returns to the nitrite - nitrate - protein cycle.
10. The nitrites are converted into nitrates by soil bacteria.
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