Photosynthesis: the basis of life

Green life has been steadily pumping out oxygen as a waste product of photosynthesis for millions of years. Some of the oxygen is used as a raw material for respiration, but most of it has accumulated in the atmosphere. So the very existence of our oxygen-rich atmosphere depends on the photosynthesising activities of green life.

Animals cannot make their own food. The only way they can obtain complex organic substances is by eating other organisms. These organisms ultimately depend on the ability of plants to harvest energy from sunlight to make food from carbon dioxide and water. Life on Earth is almost entirely solar powered.

The site of photosynthesis

Although, leaves are the main sites of photosynthesis in most plants, it can take place in any part that is green. These green parts have chloroplasts, which contain all the biochemical machinery necessary for the light-dependent and light-independent stages of photosynthesis.

Chloroplasts act as compartments, isolating the photosynthetic reactions from other cellular activities. Each chloroplast consists of two membranes enclosing a gelatinous matrix called the stroma. The stroma contains ribosomes, circular DNA, and enzymes used in photosynthesis. Suspended in the stroma are thylakoids. These are disk-like membrane sacs, several of which are stacked in a group to form a granum (plural grana). The space inside each thylakoid in a stack is connected with the other thylakoids in the stack, forming a continuous fluid-filled compartment called the thylakoid space. The thylakoid membranes contain photosynthetic pigments, including chlorophyll.

 

■ Glossary of essential terms for you to know

№	English term	Russian equivalent
	ingestion	прием пищи
	digestion	переваривание пищи
	alimentary canal	пищеварительный тракт
	raw	сырой
	to enable	давать возможность
	to take place	происходить
	to convert	превращать
	substrate	питательная среда
	starch	крахмал
	storage	накопление, хранение
	complex	сложный
	a waste product	продукт отхода
	entirely	полностью
	site	место
	to enclose	окружать

■ Your Essential Assignments

I. Quick check:

1. During photosynthesis, what gas is:

a. raw material

b. product?

2. Give the precise location in a typical terrestrial plant of:

a. the light-dependent stage

b. the light-independent stage of photosynthesis.

 

II. Fill in the missing words:

Term (verb)	Noun	Adjective
react	.......	.......
accumulate	.......	.......
produce	.......	.......
require	.......	.......
connect	.......	.......

III. Use monolingual English dictionary and write down what could the words given below mean:

plant, leave, ingredient, substance, raw, energy.

IV. Match these words with their definitions:

	Photosynthesis	A.	a type of solid or liquid that has particular characteristics
	Chlorophyll	B.	natural light that comes from the sun
	Substance	C.	one of several good substances such as sugar which consist of oxygen, hydrogen, and carbon and which provide your body with heat and energy
	Soil	D.	the green substance in leaves
	Respiration	E.	one of the many substances that exist in food such as meat, eggs, and beans, which help your body to grow and keep it strong and healthy
	Waste	F.	a chemical substance produced by living cells in plants and animals, that causes changes in other chemical substances without being changed itself
7.	Sunlight	G.	the production by a green plant of special substances like sugar that it uses as food, caused by the action of sunlight on chlorophyll
8.	Glucose	H.	the smallest part of a living thing that can exist independently
9.	Protein	I.	the process of breathing
	Fat	J.	things that people and animal eat
	Carbohydrate	K.	a very thin piece of skin that covers or connects parts of the body
12.	food	L.	a natural form of sugar that exists in fruit
13.	enzyme	M.	the top layer of the earth in which plants grow
14.	cell	N.	Unwanted materials or substances that are left after you have used something
15.	membrane	O.	an oily substance contained in certain foods

V. Find English equivalents to the following word combinations:

№	Russian term	English equivalent
1.	прием и переваривание пищи
2.	пищеварительный тракт
3.	вместо…
4.	сложные вещества
5.	происходит только при свете
6.	химические реакции
7.	главная пищеварительная среда
8.	производить свою собственную еду
9.	способность растений получать энергию от солнца
10.	клеточная активность
11.	состоит из двух мембран

 

VI. Give Russian equivalents to the following English terms:

№	English term	Russian equivalent
	to be rich in carbohydrates, proteins and fats
	simple ingredients
	a waste product
	raw materials
	external source of free energy
	to be supplied by sunlight
	light-dependent stage
	light-independent stage
	to form cell walls
	complex organic substances
	the main site of photosynthesis
	a fluid-filled compartment

 

VII. Find synonyms among the pool of words:

Pool of words	Synonyms
1)1.plant /2.substance /3. material /4.herb
2)1.digestion /2.energy /3.assimilation /4. power
3)1.obtain /2.act /3.connect /4.join /5.react /6.get
4)1.gather/2.enclose /3.surround /4.accumulate

VIII. Answer the following questions. Use all information given before:

1. What is plant material rich in?

2. Do plants make their food for themselves?

3. What is chlorophyll?

4. What is the role of chlorophyll?

5. What process is called photosynthesis?

6. What are two main stages in photosynthesis?

7. What is the difference between light-dependent and light-independent stage?

8. What is the main site of photosynthesis in most plants?

IX. Match the sentence halves. Make complete sentences:

⇐ Предыдущая891011121314151617Следующая ⇒

Поделиться:

Популярное:

1. If the rows built according to the basis of quality, it is called an attributive, and if by variables, the variational.