Page 17 - 11-Bio-1 Introduction

1. Introduction eLearn.Punjab

However even in the case of productive theory the testing goes on. In fact many scientists take it as
a challenge and exert even greater efforts to disprove the theory. If a theory survives this skeptical
approach and continues to be supported by experimental evidence, it becomes a scientific law. A
scientific law is a uniform or constant fact of nature, it is virtually an irrefutable theory. Biology is
short in laws because of elusive nature of life.

Examples of biological laws are Hardy-Weinberg law and Mendel’s laws of inheritance. You will learn
about them in later chapters. You can see that laws are even more general than theories and afford
answers to even more complex questions, therefore there are relatively a few laws in biology.

BIOLOGY AND THE SERVICE OF MANKIND

The science of biology has been helping mankind in many ways in increasing food production; in
combating diseases and in protecting and conserving environment. Biological advances in the field
of food and health have resulted in high standard of living.

Plant production has been tremendously increased by improving existing varieties and developing
new high-yield and disease - resistant varieties of plants and animals used as food.

Plant and animal breeders have developed, through selective breeding, using the principles of
genetics, new better varieties of wheat, rice, corn, chicken, cow and sheep. Poultry breeders have
developed broilers for getting quick and cheap white meat. Genes for disease resistance and other
desirable characters are introduced into plant, using the techniques of genetic engineering. Such
transgenic plants (plants having foreign DNA incorporated into their cells) can be propagated
by cloning (production of genetically identical copies of organisms/cells by asexual reproduction)
using special techniques such as tissue culture techniques etc. Plant pathogenic fungi and insect
pests of crops which weaken the plants and reduce the yield had traditionally been controlled
by using chemical fungicides and insecticides (pesticides). Use of these chemicals poses toxicity
problems for human beings as well as environmental pollution. Moreover, there are chances of
insects becoming resistant to the effect of these chemicals. Biological control (control by some
living organisms) eliminates all such hazards. In biological control, pests are destroyed by using
some living organisms that compete with or even eat them up. An aphid that attacks walnut tree is
being controlled biologically by a wasp that parasitizes this aphid.

17 V: 1.1