Algae: the Simplest Green Plants

The main difference between green plants and other living things is their ability to make food - complex starch and sugar molecules from simple carbon dioxide and water. They do this by the process of photosynthesis which requires the presence of chlorophyll, the material that produces the colour in all green plants.

Algae are the simplest organisms in the plant kingdom that possess chlorophyll and can make their own food. Algae vary in size: they may consist of a single cell, or a row of cells joined together to form a filament. The largest algae consist of a plant body called a thallus, which is made of many cells and gives the plant a ribbon-like appearance. Algae live in both fresh and salt water and may swim, float or fasten themselves to a firm surface. Some of them live in the soil and a few are parasites on animals and plants. All algae possess chlorophyll, but their green colour may be masked by other pigments. This provides a way of classifying them according to colour, for instance green algae (Chlorophyceae)_, brown algae (Phaeo-phyceae) and red algae (Rhodophyceae). Algae reproduce in various ways. Sexual reproduction may occur, resulting in the formation of a new individual by the fusion of two sex cells. Sometimes asexual reproduction takes place, in which spores are produced, or a single-celled alga splits in two. Vegetative reproduction occurs when a filament or thallus breaks into two parts to form new plant bodies.

One of the most common of the single-celled green algae is Pleurocoocus, whose colonies form a green film over the shady, moist side of tree trunks. Spirogyra is a common filamentous green alga which grows in ponds and stagnant pools. A salt-water alga with a thallus body is the sea lettuce, Ulva, which is eaten in salads in some parts of the world. Diatoms are single-celled algae (Bacillariophyceae), that live in fresh in salt water. They grow in enormous numbers and make up a great part of the floating organisms called plankton, which is found in all seas and is the food supply for many aquatic animals.

Crammar exercises practice participle

Ex. 1. Translate into Russian. Pay attention to the functions of Participle I and Participle II.

1. The nature of the mutations involved is unknown. 2. The mechanisms involved are worth investigation. 3. The nature of the cells concerned has not been determined. 4. The properties of the substances involved are as yet not clearly understood. 5. The phenomenon is rather complicated and the processes involved are not yet clear. 6. The complexity of the technique involved increased considerably. 7. The rate of a reaction depends on the specific nature of the substances involved. 8. None of the authors concerned had based his experiment on the method discussed. 9. Consideration of these cases may help us to isolate the various fundamental problems involved. 10. Being organic, the chromosomes must change their form. 11. Looking through the lists of species we find that the leaves are at varying heights above the ground in the different species. 12. Being perforated by animals the soil is consequently looser. 13. Examining the cell under a microscope we could watch its division. 14. Being examined under a microscope the cell reveals its secrets. 15. Being composed of many cells an organ of a higher plant is relatively thick. 16. Having examined a new specimen the taxonomist described its characteristics. 17. Having investigated the species within these individual environments we must first try to discover the chief peculiarities in their structure. 18. Having entered via the blood vessels the dividing mesodermal cells differentiate into the micro- or mesoglial cells. 19. Having analysed the properties of the liquid we discovered that it was poisonous. 20. Having lived in that town all his life, he knew it very well.

Ex. 2. Translate into Russian. Pay attention to the functions of Participle II.

1. All of the above-mentioned investigators found a decrease in gastric mobility. 2. The reader may be referred to the book already mentioned. 3. Fungus filaments were demonstrated in all the soils examined. 4. The results obtained may be summed up in one simple statement. 5. All of the material bounded by the cell wall is referred to as protoplasm. 6. Cultivated under favourable conditions the vegetation is getting dense and luxuriant. 7. The species collected varied in their characters. 8. The data obtained confirmed the above statement. 9. The growing mass divided into two increased the surface without immediate increase in volume. 10. The fungus probably introduced by aircraft first occurred in Holland in 1958. 11. The cations tested passed through the protoplasm.

Ex. 3. Translate into Russian. Compare Complex Object and Complex Subject.

1. In moist weather the plasmodia may be found creeping about on the surface of or emerging from the various substrata within they developed. 2. The first two factors can be distinguished from the rest as having been internal, in the sense that they concerned the inherent constitution of the plant. 3. One of the foregoing theories can be regarded as convincing. 4. The two central fibers were presumed as being double, like the other nine and are shown enclosed in a membrane. 5. Using density gradient techniques, the author showed the specific fraction of Bacillis subtilis DNA as possessing an increased density. 6. I had the brakes of my car repaired at Morgan’s Garage. 7. I found a penny lying on the sidewalk. 8. I was tired, so I just watched them playing volleyball instead of joining them. 9. Kate smelt something burning in the kitchen. 10. When she ran into the kitchen, she saw fire coming out of the oven. 11. We consider matter being built up of atoms.

Ex. 4. Translate the sentences into Russian with Absolute Participle construction.

1. In a regular diploid species there are two chromosome sets, each chromosome type being represented twice. 2. The hare and the rabbit are different species of one genus, the dog, the wolf belonging to quite a different family. 3. The protoplasm is relatively homogeneous; apparently neither nucleus nor plastids being present. 4. The spores are shed when the water temperature rises to 20⁰, shedding occurring each afternoon. 5. There being a very small nucleus in the centre of the cell, the structure is wholly different. 6. Other conditions being equal, the closely packed type will have a honeycomb structure. 7. Very few families of chlorophyceae lack this structure, those that do being the more highly evolved. 8. A number of microscopists, the most eminent being F. Cohn, described a great many morphological varieties of microorganisms. 9. In each group the cells become less closely packed, with clear spaces being visible between them. 10. All have a very definite alternation of generations, with the gametophyte being the dominant phase. 11. In the present chapter will be described the process of mitosis occurring as it does in the development of the body, particular attention being given to the behaviour of chromosomes. 12. Probably these twists are among the factors permitting localized survival of relicts of these two species, both widespread in Tertiary times. 13. The procedure involved successive series of stimulations at hourly intervals, each series being continued until the response disappeared.