Seaweeds

Lesson 10

1. Read the following words and word combinations:

Chlorophyceae

Phaeophyceae

Rhodophyceae

Chlamydomonas

Sargassum

temperature

cytoplasm

haploid

potassium

iodine

polysaccharides

world-enormous

phycobilins

2. a) Cover the right column and read the English words. Translate them into Russian and check your translation.

b) Cover the left column and translate the Russian words back into English.

shingle or sandy beaches sporeling salinity chlorophyll lineage pyrenoid mannitol carotenoid

берег, покрытый галькой или песком молодой спорофит соленость хлорофилл происхождение, родословная пиреноид маннит, маннитол каротиноид

3. Read the words and put down their Russian equivalents:

a mixture of polysaccharides ________________

sporelings of the larger seaweeds ____________

singlecelled autotrophs ____________________

sugar mannitol ___________________________

colour drains ____________________________

be torn away _____________________________

huge numbers ____________________________

shingle or sandy beaches ___________________

the bulk of the plant cover __________________

in nuance of colour and rhythm of pattern ______

aquatic food chains ________________________

4. Find suffices of the following words. Determine part of the speech.

Usually, larger, sandy, division, distribution, rocky, beautiful, aquatic, earliest, integral, primary, producer, division, tropical, variety, visible, mixture, commercially, fertilizer, useful, alginic, stabilizer, emulsifier.

5. Arrange antonyms in pairs and translate them into Russian:

a) large, minimize, left, complex, frequently, variable, benefit, equality, wide, important

b) constant, simple, seldom, maximize, inequality, small, narrow, right, unimportant, disadvantage.

6. Master the following words.

Chlorophyceae – зеленые водоросли

Phaeophyceae – бурые водоросли

Rhodophyceae – красные водоросли

heterotrophic plant - гетеротроф

autotrophic plant - автотрофное растение

red algae - красные или багряные водоросли, багрянки (Rhodophyceae)

kelp - бурая водоросль, (преим. ламинария)

7. Put down the English for:

тем не менее

глазное пятно

чашевидный

органелла

крахмал

калий

8. Give the four forms of the following verbs:

to simplify, to form, to get, to develop, to run, to tear, to find, to write, to make, to give, to like, to have, to identify, to move.

9. Read and translate the text.

Seaweeds divide into Chlorophyceae (Greens), Phaeophyceae (Browns) and Rhodophyceae (Reds). This division by colour is a good guide to the groups described in the following pages. The colour drains from many types of seaweed when they have been torn away by storms.

Most seaweeds grow on rocks or shells or on other seaweeds. Usually no large ones are found on shingle or sandy beaches, where wave action moves the particles and so prevents the spores or sporelings of the larger seaweeds from developing. Different kinds of rock and their slope, the salinity of the water and its temperature also influence the distribution of seaweeds.

About 700 species of seaweeds have been recognized round the coasts of Britain. Nevertheless seaweeds as a whole are not such a difficult group that many of the common species which make up the bulk of the plant cover on a rocky shore cannot be recognized in the field.

Seaweeds are certainly not easy to identify but in nuance of colour and rhythm of pattern they are beautiful plants and worth closer study then they usually receive.

Algae are an ancient group, and whether classified as plants or protests, they are believed to have been the ancestors of the other aquatic and land plants. The earliest organisms on earth, 3.5 billion years ago, were most likely anaerobic heterotrophs, but eventually, these organisms gave rise to singlecelled autotrophs that produced their own food molecules through photosynthesis.

Huge numbers of algae inhabit the oceans and form an integral part of most aquatic ecosystems. Unicellular algae are primary producers in nearly all aquatic food chains.

Some ancient green algae growing in an ocean inter or in a freshwater pond were probably the ancestors of the lineage from which all land plants evolved more than 400 million years ago. Today, there are 7000 species of green algae in the division Chlorophyta.

Individual cells of green algae usually have a single nucleus, but some species have cells containing many nuclei in one large mass of cytoplasm.

The best-known green alga is Chlamydomonas. This common organism lives in moist soils and freshwater pools, and each haploid cell tends to contain a single large cup-shaped chloroplast; sometimes an eyespot, or stigma; and starch-producing organelles called pyrenoids.

Most of the 4000 or so species of red algae in the division Rhodophyta are small, delicate marine organisms that live in shallow or deep tropical waters.

Red algae have a variety of pigments that absorb well all wavelengths of visible light. These pigments, called phycobilins, include the red phycoerythrin and the blue phycocyanin and enable some red algal species to live as the deepest photosynthesizers. Red algae contain chlorophyll and carotenoids.

Many brown algae are fairly small, but the division Phaeophyta also includes the giants of the algal world-enormous kelps that can reach 100 m in length. Sargassum, however, is found in warm tropical seas and sometimes forms huge floating masses.

Brown algae store food reserves in the form of laminarin, a mixture of polysaccharides, lipids, and the sugar mannitol, and many species concentrate the important nutrients nitrogen, potassium, and iodine from the surrounding water. People sometimes farm kelps commercially for human food, livestock, and fertilizer and extract useful materials such as alginic acid as a stabilizer, emulsifier, and waterproofing substance.

10. Answer the questions:

1. What types of seaweed do you know?

2. Where does most seaweed grow?

3. Are Seaweeds plants?

4. Why Algae are the ancestors of the other aquatic and land plants?

5. What forms an integral part of most aquatic ecosystems?

6. Can you describe green algae?

7. What is the best-known green alga?

8. How long can the world-enormous kelps be?

9. Why do people sometimes farm kelps commercially?

10. Why do you study seaweeds?

11. Find the corresponding words and word combinations.

Brown algae	фикобилин
mixture of polysaccharides	удобрение
singlecelled autotrophs	хлоропласт, имеющий форму чашки
alginic acid	смесь полисахаридов
fertilizer	сахарный маннит
phycobilins	домашний скот
cup-shaped chloroplast	Бурые водоросли
the sugar mannitol	гаплоидная клетка
livestock	альгиновая кислота
haploid cell	одноклеточные автотрофы

12. Pair work. Speak on the topic “Seaweeds”.

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