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1. BIO 111 Lecture 8
Hierarchy in Biology: order & organisation
 Announcements:
 TUTORIALS – start this week, Thursday or Friday, 2
or 3 pm.
 Read your notes on the scientific method and
Pages 10-14 of Sadava et al be ready to discuss
and answer questions in the tutorial.
 LAB SESSIONS – all those who cannot make it to
morning lab sessions, please register with Dr Pipedi
for a Monday session (3-6pm)
 “Lazy people take food in their hand but don’t even
lift it to their mouth”

2. Learning objectives
 Given so many different types/forms of
living things, are there ways of reducing
apparent chaos into some form of
simplified order?
 Is life and living organisms organized in
a particular manner?
 What are the guiding principles in
ordering life and living organisms?

3.  Biology can be visualized as a hierarchy
of units, ordered from the smallest to
the largest.
 The organism is the central unit of
study in biology.
 To understand organisms, biologists
study life at all levels of organization.

4. Biologists study life at different
levels
 Biology can be visualized as a hierarchy of units that
include
 Atoms;
 Molecules;
 Cells;
 Tissues;
 Organs;
 Organisms;
 Populations;
 Communities;
 Biosphere.

5. Levels/Grades of organization.

6. Levels of organisation

7. Different levels

8. Uniqueness of each level
 Each level of biological organization has its
emergent properties.
 e.g., Molecules have properties not found in
the component atoms;
 organelles have properties not found in the
individual molecules of which they are
composed.
 Cells have properties not found in the
individual organelles of which they are
composed.

9. 1. Atomic Level
 Lowest level usually studied in
chemistry.
 e.g. oxygen, hydrogen, carbon,
nitrogen, phosphorus, copper, iron,
etc..
 The kind, quantity, arrangement of
these atoms greatly influences
biological structure and function.

10. Molecular Level
 Atoms join to make molecules.
 Certain types of large molecules are
found in all living systems.
 These are responsible for many
biological structures and functions
 e.g. proteins, carbohydrates, lipids,
phosphates, nucleic acids, hormones,
enzymes, etc

11. Cellular Level
 The cell is the basic building block of
life,
 It has sub-components
 cytoplasm, organelles, genetic material,
etc,
 Organelles – mitochondria, golgi bodies,
chloroplasts, vesicles etc
 Some whole organisms exist at cellular
level – called unicellular
 Amoeba, Euglena, Paramecium etc

12. Cell Differentiation
 Multicellular organisms have
 Many cells
 Some cells specialize for specific
jobs/functions
 Nerve cells, muscle cells, blood cells,
secretory cells, protective cells

13. Tissue Level
 Tissues are groups of cells with similar
and coordinated functions.
 e.g. muscle, blood, xylem, epithelium,
nervous, epidermal etc

14. Organ Level
 Several different tissues are usually
joined to form larger units called organs
 e.g. leaf, brain, flower, ovary, pancreas,
kidney, lungs.
 Organs perform specific functions
 Leaf – photosynthesis, gas exchange
 Roots – water & mineral absorption
 Heart - heart pumps blood (some say it
loves!!)

15. Organ System Level
 Several organs “work” together to achieve a
common purpose (s)
 digestive, transport, communication, movement,
sensory, nervous, endocrine, reproductive,
excretory, eye, ear,
 Same organ may be part of several systems
 tongue, liver, leaf, heart, breast

16. Organism Level
 An organism is a recognizable self
contained individual
 Some are made up of only one cell =
unicellular: cell level
 Others are made up tissue: tissue level
 others are made up of organs & organ
systems: organ & organ system level

17. Population Level
 A group of many organisms of the same
species
 Organisms of the same species living in
the same area & capable of breeding
together

18. Community Level
 Several populations (different species)
living in the same area (place) in which
they interact in on or more ways
 All the populations living and interacting
within a particular geographic area
make up a biological (or biotic)
community.

19. Ecosystem Level
 An ecosystem is the living organisms in
a community together with their
nonliving or abiotic environment
 Ecosystem may vary in size from a
small drop of water to a whole ocean!

20. Biome Level
 A very large, general biotic community
such as
 Terrestrial (land) biomes
 Freshwater biomes
 Marine biomes

21. Some Terrestrial Biomes
 Tundra Taiga/boreal forests
 Montane grasslands and shrublands
 Temperate coniferous forests
 Tropical and subtropical coniferous forests
 Temperate broadleaf and mixed forests Mediterranean forests,
woodlands, and scrub
 Tropical and subtropical moist broadleaf forests
 Tropical and subtropical dry broadleaf forests
 Temperate grasslands, savannas, and shrublands
 Tropical and subtropical grasslands, savannas, and shrublands
 Deserts and xeric shrublands
 Flooded grasslands and savannas
 Riparian Wetlands

22. Biosphere Level
 The biosphere is the global sum of all
ecosystems.
 ALL biomes on earth constitute the
Biosphere and exchange energy among
each other.

23. Therefore?
o Biology can be studied at several
levels
o We have biochemists, microbiologists,
physiologist, cell biologists, forest
scientists, ecologists etc
o Which level fascinates you most?

24. Classification of organisms
o a the systematic categorization of organisms
into a coherent scheme.
o is a system which is used to organize and codify
all life on Earth.
o allows scientists to examine the relationships
between various organisms
o to construct evolutionary trees
o to explore the origins of life on Earth
o to explore the relationship of modern organisms
to historical examples.

25. Hierarchy in classification

26. Therefore?
o Biological classification is called
TAXONOMY
o It a systematic way of grouping living
organisms based on similarities of common
features
o There are 8 levels – usually 7 levels are
used
o Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
o Did King Philip Come Over For Good Soup