Control of Animal Diseases

Text 4

Animal Kingdom

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All living things are divided into five kingdoms. Bacteria belong to the kingdom Monera, while the plantlike algae and animal-like protozoa are members of the Protista. The fungal kingdom includes molds, yeast, and mushrooms, and the kingdom Plantae includes all multicellular plants. The largest kingdom, however, is the Animalia. Its members range from very simple invertebrates, such as sponges, to highly complex mammals, such as whales, monkeys, and humans. Animals display some key differences that distinguish them from other living things. For example, what is the difference between a horse and grass? A horse moves around in the pasture eating grass. It trots toward you when you offer it a lump of sugar and shows pleasure when you stroke its head. The grass, however, is rooted to one place. It does not respond behaviorally to people or to the horse in any way.

Most animals move freely from place to place and can sense their surroundings; that is, they can taste, smell, hear, see, and touch. Certain simple animals, such as the corals and barnacles, spend most of their lives fastened to one spot, but they are able to swim freely when they are young. Even these rooted animals have parts that move in order to capture food. Plants, however, cannot shift around at their own will. They react to heat, light, chemicals, and touch, but their responses are involuntary and automatic, quite different from those of animals.

All living things are made up of cells of protoplasm. They may consist of a single cell, as does an amoeba, or billions of cells, as do trees and horses. The cell wall of a plant is composed of a woody material called cellulose. No true animal contains cellulose. Animal cells are bounded by a membrane composed chiefly of fat and protein.

Задание 1. Подтвердите или опровергните следующие утверждения:

1. All living things are divided into five kingdoms.

2. Bacteria belong to the kingdom Protista.

3. The kingdom Plantae includes all multicellular plants.

4. The largest kingdom is the Animalia.

5. All living things are made up of cells of protoplasm.

Задание 2. Ответьте на следующие вопросы:

1. How many kingdoms are all living things divided into?

2. What kingdom do bacteria belong?

3. What is the largest kingdom?

4. What are all living things made up of?

5. Are animal cells bounded by a membrane composed chiefly of fat and protein?

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Animal diseases are of great concern to humans for several reasons. Diseases can reduce the productivity of animals. Animals raised as food, such as pigs and beef cattle, that become ill may affect the economic well-being of many industries. Some animal diseases, known as zoonoses, can be transmitted to humans. In the wild, animal populations reduced by disease can upset the ecological balance of an area. And, in the case of pets, prevention and treatment of animal diseases help pets live long and healthy. Animal diseases are characterized as infectious and noninfectious. Infectious diseases are caused by an agent, such as bacteria or a virus that penetrates the body’s natural defense mechanisms, while noninfectious diseases are caused by factors such as diet, environment, injury, and heredity. Sometimes the cause of a disease is unknown. An animal may also experience one disease or a combination of diseases at any one time. To identify a disease, a veterinarian first determines the animal’s species, breed, age, and sex. This information helps to identify a disease because some diseases are more prevalent in certain species, or a disease may preferentially affect one sex or age group. The veterinarian then gathers a complete history of the animal and its problem. This history includes the symptoms the animal is displaying and when they first appeared, as well as whether the animal has been exposed to something new in its surroundings or to other animals. The veterinarian gives the animal a thorough physical examination, which may include measuring its body temperature, listening to its heart, checking its pulse, and feeling its abdomen and lymph nodes. The veterinarian then creates a list of possible diseases that may be making the animal sick. The list may be narrowed by running diagnostic tests such as X-rays, electrocardiograms, blood analyses, and bacterial or fungal cultures.

Задание 1. Выберите и переведите предложения, в которых описаны причины инфекционных и неинфекционных болезней.

Задание 2. Задайте вопросы к следующим предложениям, начав их с вопросительного слова, данного в скобках:

1. Animal diseases are of great concern to humans for several reasons. (Why?)

2. Animals raised as food, such as pigs and beef cattle. (What animals?)

3. Infectious diseases are caused by an agent, such as bacteria or a virus. (What diseases?)

4. The veterinarian gathers a complete history of the animal and its problem. (Who?)

Дата добавления: 2015-05-26