По специальности «Зоотехния»

 

The Theory of Natural Selection

In the 1800s, Charles Darwin, a British naturalist, developed the theory of natural selection in his book “On the Origin of Species by Means of Natural Selection”. Darwin had the opportunity to travel around the world as the naturalist on a British survey ship. Wherever Dar­win visited, he saw a large number of different kinds of plants and animals and noted how well they were adapted to their particular situations.

He determined that there were several factors that could interact together to allow for natural selection:

4. Individuals within a species showed variation; some of the variations were very useful and others were not. For example, individual animals that are part of the same species show different colour variations. Some colours make the animal more conspicuous while others are less conspicuous.

5. Organisms within a species typically produce many more offspring than can survive. This means that here is not enough suitable habitat for all of the offspring to grow to maturity. A pair of rabbits may have three to four litters of offspring each sum­mer with several young in each litter.

6. Because of the excess number of individuals, there is a struggle for survival. Individuals within the population must compete with each other for food, space, mates, or other requirements that are in limited supply.

Great horned owls and other large owls typically produce two young at a time, but if food is in short supply, the larger of the two young will get the majority of the food.

6. Because of variation among individuals, some would have a greater chance of surviving and reproducing than others. The competition for resources often results in the less fit individuals dying; therefore, they do not get a chance to reproduce themselves. Even if they do not die, they may mature more slowly and not be able to repro­duce as many times as the more fit members of the species.

7. As time passes and each generation is subjected to the same kind of process, there will be an increase in the percentage of individuals showing the favorable variations and a decrease in those having unfavorable variations. The species will become better adapted to its environment.

 

Задание 1. Закончите предложения:

1. Charles Darwin developed the theory of ….

2. Individuals within a species showed ….

3. Organisms within a species typically produce ….

4. Individuals within the population must compete with each other for ….

5. The competition for resources often results in ….

 

Задание 2. Прочитайте примеры естественного отбора из текста.

Modern Veterinary Care

The zoo veterinarian attends to the needs of every animal in the zoo habitat, from the tiniest shrew to the largest elephant, monitoring diet, dental health, and even reproduction. Zoo veterinarians perform blood tests, vaccinations, routine examinations, and even surgery. They manage endangered species to encourage successful mating and reproduction. For pandas, which are solitary in the wild, this might involve isolating individuals during the non-breeding season, and then bringing a pair together to mate when the time is right.

Veterinarians employed in regulatory medicine are responsible for controlling or eliminating certain diseases and protecting the public from animal diseases that can affect people. As food inspectors, they identify diseased livestock and unsafe meat and poultry. Regulatory medicine veterinarians also prevent foreign diseases from entering the country by enforcing quarantines and inspecting animals. They supervise interstate shipments of animals, test for the presence of diseases, and manage campaigns to prevent and eradicate diseases that threaten animal and human health such as tuberculosis, undulant fever, and rabies. Some public health veterinarians evaluate the safety of food processing plants, restaurants, and water supplies. Those in environmental health programs study and evaluate how various pesticides, industrial pollutants, and other contaminants affect human and animal populations. Other public health veterinarians are epidemiologists (specialists who study the cause and incidence of diseases). Public health veterinarians employed in government and private laboratories provide important diagnostic and testing services. They might, for example, inspect beef to insure that it does not contain E. coli bacteria or chicken to insure that it is free of Salmonella bacteria.

 

Задание 1. Соедините две части предложения:

1. The zoo veterinarian … 2. Food inspectors … 3. Regulatory medicine veterinarians … 4. Epidemiologists … 5. Some public health veterinarians…

1. identify unsafe meat and poultry. 2. study the cause and incidence of diseases. 3. perform blood tests, vaccinations, routine examinations. 4. evaluate the safety of food processing plants. 5. manage campaigns to prevent and eradicate diseases that threaten animal and human health.

 

Задание 2. Ответьте на вопрос:

What are the duties of public health veterinarians?

 

 

History of Microbiology

Microbiology began with the development of the microscope in the

17th and 18th centuries. By 1680 the Dutch scientist Anthony van Leeuwenhoek had produced a simple hand-held device that allowed scientists to view a variety of microbes – which Leeuwenhoek called “animalcules” – in stagnant water and in scrapings from teeth.

In the late 1700s Edward Jenner conducted the first vaccinations, using cowpox virus to protect people against smallpox. Later an altered form of the rabies virus was used to protect against the dreadful disease rabies. Vaccines remain the major means of protection against most viral infections.

Modern microbiology had its origins in the work of the French scientist Louis Pasteur – considered the father of microbiology – who developed methods of culturing and identifying microbes. During the second half of the 19th century, he and his contemporary Robert Koch provided final proof of the germ theory of disease. Pasteur was the first to propose that microbes cause chemical changes as they grow. Koch derived a central principle of modern microbiology, known as Koch’s Postulate that determines whether a particular germ causes a given disease.

Pasteur and his contemporaries developed pure culture methods for the growth of microbes. Another great advance in pure culture methods came in the late 19th century, when microbiologists discovered that each kind of microbe preferred a certain medium for optimal growth. In 1929 Alexander Fleming observed that molds can produce a substance that prevents the growth of bacteria. His discovery, an antibiotic is called penicillin, was later isolated and produced commercially to protect people against the harmful effects of certain microorganisms. Today several kinds of penicillin are synthesized from various species of the mold Penicillium and used for different therapeutic purposes. In the 1940s microbiology expanded into the fields of molecular biology and genetics. Viruses were found to be simple microbes that could be studied quantitatively, and they themselves were used to study the nature of deoxyribonucleic acid, or DNA Scientists found that DNA could be removed from living cells and spliced together in any combination. They were able to alter the genetic code dictating the entire structure and function of cells, tissues, and organs.

 

Задание 1. Соотнесите имя ученого с его вкладом в науку:

1. Anthony van Leeuwenhoek 2. Edward Jenner 3. Louis Pasteur 4. Robert Koch 5. Alexander Fleming

1. provided final proof of the germ theory of disease. 2. produced a simple hand-held device that allowed scientists to view a variety of microbes. 3. conducted the first vaccinations. 4. observed that molds can produce a substance that prevents the growth of bacteria. 5. developed methods of culturing and identifying microbes.

Задание 2. Перескажите текст на родном языке.

Animal Kingdom

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. Закончите предложения:

1. Plants react to heat, light, chemicals, and touch, but their responses are…

2. The largest kingdom Animalia ranges from…

3. All living things are made up of…

4. Certain simple animals spend their lives…

 

Задание 2. Используя материал текста, ответьте на вопросы:

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

2. What is the largest kingdom?

3. How do animals sense their surroundings?

4. Do plants react to their surroundings?

5. All living things are made up of cells of protoplasm, aren’t they?

Control of Animal Diseases

Animal diseases are of great concern to humans for several reasons. Diseases can reduce the productivity of animals used to produce food, such as hens and dairy cows. 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 can be transmitted to humans, and control of these types of diseases, known as zoonoses, is vital to public health. 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 lives, enhancing the companionship shared by a pet and its human owner. 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 (a doctor who treats animals) first determines the animal’s signalment – its 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. Once the disease is identified, the doctor develops a treatment plan for the animal.

 

Задание 1. Ответьте на вопросы по тексту:

1. Why are animal diseases of great concern to humans?

2. Can animal diseases upset the ecological balance of an area?

3. What are two types of animal diseases?

4. What information helps to identify a disease?

5. When does the doctor develop a treatment plan for the animal?

 

Задание 2. Опишите действия ветеринарного врача по постановке диагноза болезни животного.

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