Понимание структурно-смысловых связей в тексте

Biology means the study of life and it is the science which investigates all living things. Even in the days before recorded history, people knew and passed on information about plants and animals. Prehistoric people survived by learning A ______. Farming would not have developed if they had not begun to understand that animals could produce food like milk and eggs.

The ancient Egyptians studied the life cycle of insects and understood the part that insects and pollen played in the life cycle of plants. The ancient Mesopotamians even kept animals in B ______. The ancient Greeks, too, were greatly interested in understanding the world around them. Aristotle recorded his observations of plants and animals, and his successor, Theophrastus, wrote the first books on plant life, C ______.

Modern biology really began in the 17th century. At that time, Anton van Leeuwenhoek, in Holland, invented the microscope and William Harvey, in England, described the circulation of blood. The microscope allowed scientists to discover bacteria, D ______. And new knowledge about how the human body works allowed others to find more effective ways of treating illnesses.

In the middle of the 19th century, unnoticed by anyone else, the Austrian monk Gregor Mendel, created his Laws of Inheritance, beginning the study of genetics E ______. At the same time, while travelling around the world, Charles Darwin was formulating the central principle of modern biology-natural selection as the basis of evolution.

In the 20th century, biologists began to recognize how plants and animals live and pass on their genetically coded information to the next generation. Since then, partly because of developments in computer technology, there have been great advances in the field of biology, F ______.

1. who were very dangerous
2. that is such an important part of biology today
3. which made a very important contribution to the study of botany
4. which plants were good to eat and which could be used for medicine
5. what were the earliest zoological gardens
6. which led to an understanding of the causes of disease
7. which is an area of ever-growing knowledge