1. Write down whether the following statements are true or false. Give extensive answers.

1. By practicing division of labour bees can obtain an adequate food supply.

2. All females in a colony lay fertile eggs.

3. The drones help worker-bees to build combs and collect food.

4. Honey is affective in the treatment of some diseases.

5. All the cells in a wax comb are of the same size.

6. The queen lays two kinds of eggs: unfertilized and fertilized.

7. The building of combs is the most difficult part of the community’s life.

8. Insects possess intellect and the power of reason.

9. Visiting one flower after another, bees insure cross-pollination.

2. Complete the sentences using the text and translate them into Russian.

1. The combs which are not occupied by eggs and larvae serve ….

2. The grubs in smaller cells are fed on … whereas the queen larva is given ….

3. The duties of the bees within the colony depend on … .

4. Chains of reflex actions which are interconnected and take place in a strict succession are called ….

5. … are all males and the largest bees in the colony except … .

6. … does not fly in search of nectar or pollen.

7. … do all the work in the beehive.

8. Mouth-parts of bees have been modified to serve purposes … .

9. The nectar is taken into …and moves to. Then it is mixed with … and changed into … .

10. The honey is used as … for the whole colony.

3. Answer the following questions on the text in written form.

1. Where do bees live?

2. What are the main functions of the queen?

3. Why don’t worker-bees lay eggs?

4. What are their functions?

5. What do the drones do?

6. In what way have workers’ mouth-parts been modified?

7. What are the stages of making honey?

8. What is the life-cycle of honey-bees?

9. What is the distribution of work of worker-bees within the colony?

10. How did the French naturalist Fabre prove that bees can’t think and their behavior is instinctive?

4. Translate a passage into Russian in written form. Text 21 class crustacea. Fresh-water crayfish

The Fresh-water Crayfish lives on the beds of rivers, lakes, and fresh-water ponds, where it crawls about on its long, jointed legs. It swims swiftly backwards, by powerful strokes of its tail.

The Crayfish feeds on small animals and the decaying corpses of bigger ones, to which it is attracted by their odour.

Structure

Unlike the insects, the body of the Crayfish is divided into only two sections: the cephalothorax and the abdomen.

The cephalothorax is covered with a carapace und carries two pairs of antennae (long and short), compound eyes, mouth-parts, and ten segmented legs. The first pair of walking legs which carries huge claws is very big.

Unlike the cephalothorax, the abdomen consists of segments. It is flexibly connected with the cephalothorax and can be bent underneath. Each segment of the abdomen carries a pair of short dovetailed appendages. The abdomen ends with flattened, solid appendages, the uropods. The last uropod carries the anus.

Body Cover

The body of the crayfish is protected by a chitinous exoskeleton, which is thicker and harder than that of the May-beetle. It contains considerable quantities of lime and is an excellent armour. The muscles are attached to the inside of the exoskeleton, controlling the action of the animal's legs, antennae and other organs.

The chitinous cover is rigid, it cannot stretch. Therefore, the process of growth is linked with periodic moultings.

When alive, the crayfish is commonly the colour of its environment. The colour may be varied a good deal by the action of the pigment chromatophores found in the chitinous cover: red, dark blue, green or brown. When the animal is thrown into boiling water all these pigments are destroyed, except the red one. That is why boiled crayfish is always red.

The muscles under the axoskeleton are covered by a thin epithelium, the hypodermis which secretes a new layer of chititl each time the animal moults.

Nutrition

The crayfish catches its food with the nippers of its first pair of walking legs, and the 6 pairs of hard plates - the jaws and the maxillipeds are used to hold and crush it.

In the gastric mill the food is further ground by tooth-like bodies ("ossicles") and is later digested by the liver juice. Digestion continues in the upper end of the intestine, where the food is absorbed.

Breathing System

Living in running water, the crayfish breathes with gills, delicate, feather-like frills situated in special cavities inside the lateral walls of the protective carapace.

Water carrying dissolved oxygen, penetrates through special openings, which lie at the base of the cephalothorax, enters the gill cavities, and moves over the gills. The current is caused by swift movements of the maxillipeds.

Circulatory System

The circulatory system of the crayfish consists of a heart and blood vessels. The heart, which lies on the dorsal side of the body, is shaped like a small bag. Vessels lead away from it conveying the animal's blood to all parts of the body. This type of circulatory system is known as an open blood system, and is the same as that of the arthropods.

Excretion

Wastes are withdrawn from the body by the green glands, thin-walled greenish bladders found in the front part of the cephalothorax.

Reproduction

The sexes are separate. The female ovaries produce immense quantities of eggs. When matured, they are passed out of the body along short oviducts. Fertile eggs stick to the abdominal appendages of the mother. When they hatch the young also cling to them until they are big enough to tend for themselves.

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