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

concentration, factor, intensity, light, wavelength, vegetation.

IV. Match these words with their definitions:

	photosynthesis	A.	connected with the outside of a surface
	investigation	B.	the amount of space that a substance or object contains or fills
	light	C.	the production by a green plant of special substances like sugar that it uses as food, caused by the action of sunlight on chlorophyll
	factor	D.	the process of making chemical reaction quicker by adding a catalyst
	external	E.	a small bush with several woody stems
	internal	F.	one of the possible different forms of an atom of a particular element
7.	supply	G.	an official attempt to find out the reasons for something such as a crime, accident or scientific problem
8.	catalysis	H.	the energy from the sun, a lamp, a flame etc. that allows you to see things
9.	limiting	I.	inside something
	shrub	J.	a chemical substance produced by living cells in plants and animals, that causes changes in other chemical substances without being changed itself
	to measure	K.	preventing any improvement or increase in something
12.	volume	L.	one of several things that influence or cause a situation
13.	enzyme	M.	an amount of something that is available to be used
14.	velocity	N.	to find the size, length, or amount of something using standard units
15.	isotope	O.	the speed at which something moves in a particular direction

V. Find English equivalents to the following word combinations:

№	Russian term	English equivalent
1.	точное измерение
2.	используется растениями для дыхания
3.	внешние и внутренние факторы
4.	может быть продемонстрировано
5.	прямо пропорционально чему-либо
6.	изменения в температуре
7.	ограничивающий фактор
8.	наименее благоприятный
9.	приводит к увеличению
10.	в ответ на
11.	оптимальный уровень

VI. Give Russian equivalents to the following English terms:

№	English term	Russian equivalent
	the rate of photosynthesis
	produced per unit time
	compensation point
	light intensity
	concentration of photosynthetic pigments
	a heavy isotope of oxygen
	sun plants and shade plants
	to be sensitive to temperature
	to be driven by light
	to be similar to
	have little effect on the reactions
	under natural conditions

VII. Find synonyms among the pool of words:

Pool of words	Synonyms
1)1.external/2.limit/3.outer/4.internal/5.inner/6.end-point
2)1.rate/2.measure/3.degree/4.level/5.proportion/6.position
3)1.factor /2.strength /3.component /4.intensity
4)1.improvement /2.isolated /3.separated /4.development

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

1. How can the rate of photosynthesis be measured?

2. What is the compensation point?

3. What is the compensation point related to?

4. Is photosynthesis affected by external and internal factors?

5. What do external factors include?

6. What do internal factors include?

7. What is the effect of light intensity, carbon dioxide level, temperature on the rate of photosynthesis?

8. What does the law of limiting factors state?

IX. Match the sentence halves. Make complete sentences:

1.	The rate of photosynthesis can be measured as	A.	lght intensity, the wavelength of light, carbon dioxide levels, temperature, wind velocity, and water and mineral supplies.
2.	The compensation point is usually related to	B.	to light intensity.
3.	Photosynthesis is affected by many factors,	C.	tpe and concentration of photosynthetic pigments, enzyme and water content, and leaf structure, and position.
4.	External factors include	D.	its rate at any given moment is limited by the factor at its least favourable value and by that factor alone.
5.	Internal factors include	E.	both external (in the environmental) and internal (inside the plant).
6.	The rate of photosynthesis is directly proportional	F.	because these are driven by light, not heat.
7.	Changes in temperature have little effect on the reactions of the light-dependent stage	G.	the volume of carbon dioxide taken in by a part per init time, or as the amount of carbohydrate produced per unit time.
8.	When a physiological process depends on more than one essential factor being favourable,	H.	a particular light intensity or carbon dioxide level.

X. Read and translate the short text without any dictionary:

Fact of life: The atmosphere contains less than 0.04 per cent carbon dioxide, yet each year plants make more than 200 billon tones of carbon compounds from this meagre supply of carbon dioxide.

XI. Food for thought:

Seaweeds grow on rocky shores, in zones with different species growing at different heights above the low-tide mark. Suggest how the light compensation point of seaweeds at the low-tide mark differs from that of seaweeds close to the high-water mark.