This document provides an overview of biological organization from the biosphere level down to the subatomic particle level. It outlines the key levels of organization such as ecosystems, organisms, tissues, cells, organelles, molecules and atoms. The objective is to understand the different hierarchical levels of biological structure and organization, from the largest to the smallest level. It also defines some key terms used to describe biological organization like biosphere, population, species, organ and tissue.

1. Lecture -1 (B)
Introduction to Biology
XI
Dr.Qurrat-ul-Ain
Lecturer Biology
AKUEB-MSB
3 Aug 2016

2. Objective
• Understand different levels of biological
organization.

3. • The elements which are used in formation of
various chemical compounds from which living
organisms are made are called Bio-elements.
•
Out of 92 naturally occurring chemical
compounds, only 16 are bio-elements and out of
these 16 only 6 account for 99% of the total mass
in human body.
•

5. Levels of biological
organization

6. • biosphere
• That part of earth inhabited by living organisms;
includes both the living and the nonliving
• Ecosystem
• A community together with its nonliving
surroundings

7. • Community
• Two or more populations of different species
living and interacting in the same area
• Population
• Members of one species in habiting the same
area

8. • Species
• Very similar, potentially interbreeding
organisms
• Multicellular organism
• An individual living thing composed of many
cells

9. • Organ system
• Two or more organs working together in the
execution of s specific body function
Organ
• A structure normally composed of several tissue
types that from a functional unit

10. • Tissue
• a group of similar cells that perform a specific
function
• Cell
• The unit of life
•

11. • Organelle
• A structure within a cell that performs a specific
function
• Micro-molecules and macro molecules
• A combination of atoms
•

12. • Atom
• The smallest particle of an element that retains
the properties of that element
• Subatomic particle
• Particles that make up an atom
•

13. Biome
• A biome is a large regional community primarily
determined by climate.