9th Class Biology Chapter 3 Notes
Important Notes of Chapter No.3: Biodiversity Class 9th Urdu Medium or 9th class biology chapter 3 notes written by Honorable Sir Adnan Haider Suib. These notes are very helpful in the preparation of 9th class biology chapter 3 notes for students of the 9th class Biology Urdu Medium and these are according to the paper patterns of all Punjab boards.
Summary and Contents:
Topics which are discussed in the notes are given below:
- Very Important Multiple Choice Questions (MCQs) of Chapter No.3 Biodiversity Urdu Medium
- At least 10 million kinds of organisms inhabit the Earth but less than one third of these have been
studied and catalogued (put in record) by biologists. Diversity among the Earth’s organisms is
more obvious than the fundamental unity of life. We see that all organisms share many biological
characteristics. Five principal groups of organisms are prokaryotes, protists, fungi, plants, and
animals. In this chapter we will focus on the differences among different groups of organisms. We
will also see how are organisms classified and named and what are the concerns with the existence
of biodiversity.
- Biodiversity: The term “biodiversity” has been derived from ‘bio’ and ‘diversity’. “Diversity” means variety within
a species and among species. Biodiversity is a measure of the variety of organisms present in
different ecosystems.
- The diversity of plants’ (flora) and animals’ (fauna) in a region depends on climate, altitude, soils
and the presence of other species. Biodiversity is not distributed evenly on Earth. It is richest in
the tropics. Temperate regions also have many species while there are fewer species in the polar
regions. Biodiversity found on Earth today is the result of 4 billion years of evolution. The origin of
life is not well known to science, though limited evidence suggests that until 600 million years ago,
all life consisted of bacteria and similar unicellular organisms.
- Importance of biodiversity: Biodiversity provides food for humans. A significant proportion of drugs are derived, directly or
indirectly, from biological sources. A wide range of industrial materials e.g. building materials,
fibres, dyes, resins, gums, adhesives, rubber and oil are derived directly from plants.
- Biodiversity plays important role in making and maintaining ecosystems. It plays a part in regulating
the chemistry of our atmosphere and water supply. Biodiversity is directly involved in recycling
nutrients and providing fertile soils.
- Classification - Aims And Principles:
- There is a large collection of very dissimilar forms of organisms, found on Earth. Over 1.5 million
types of animals and over 0.5 million types of plants are known to biologists and these are only
a small percentage of the total types estimated to live on Earth. They range in complexity from
small and simple bacteria to large and complex human beings. Some of them live in sea, some on
land; some walk, others fly, and still others are stationary. Each has its own way of life i.e. getting
food, avoiding unfavourable environmental conditions, finding a place to live, and reproducing its
kind. When there are so many diverse kinds of organisms, it becomes difficult to learn about the
characteristics of each.
- To study such a large collection, biologists classify the organisms into groups and subgroups and
for this task they require some system. Biological classification is a method by which biologists
divide organisms into groups and subgroups.
- Aims of Classification: The branch of biology which deals with classification is called taxonomy and the branch which deals
with classification and also traces the evolutionary history of organisms is known as systematics.
The main aims of both these branches are;
1. To determine similarities and differences among organisms so that they can be studied easily.
2. To find the evolutionary relationships among organisms.
- Basis of Classification: Classification is based on relationship amongst organisms and such relationship is got through
similarities in characteristics. These similarities suggest that all organisms are related to one another
at some point in their evolutionary histories.
However, some organisms are more closely related than others. For example sparrows are more
closely related to pigeons than to insects.