BIOLOGY
LS1001
2023-24 : AUTUMN
SECTION 3/ SLOT TA
Lecture 2
Introduction to Biology in Engineering
Dr Monalisa Mishra
Department of Life Science
NIT Rourkela
Characteristics, Origin, Hierarchy, and
Classification of Life Forms
2
Outlines
1. Characteristics of Living Things
2. Diversity and Complexity of Life Forms
Levels of Organisation of Life
Classification of Organisms
Taxonomy
Linnaeus’s Classification and Binomial Nomenclature Systems
Characteristics of Living Things
 Cellular organization – made up of cells
 Nutrition
 Respiration
 Movement
 Excretion
 Growth (size and number)
 Reproduction
 Homeostasis
 Adaptation
 Respond to the environment
# Homeostasis
Maintaining the same state
Homeo = same, steady
Stasis = state
Examples:
 Water balance inside and outside of cell
 Human body temperature
 Blood pH is tightly regulated (7.40).
 Pancreatic hormones work to regulate blood glucose.
 Cells function best when these are in balance
# Adaptation
Changing to meet the needs of the environment
Examples:
Bird migration ? - behavioral adaptation
food, nesting places
Human body temperature - physiological adaptation
Hibernation ?- physiological adaptation
(conserve energy to survive adverse weather conditions
or lack of food; Frog)
# Respond to Environment
• Stimulus - a change in the environment
– Eg. light, heat, pH, vibration, smell, etc.– earthworms respond to all
of these.
• Response - reaction to the change.
– Eg. pupils get smaller.
• Essential for any organisms to–
–
–
–
–
Escape predators
Find food
Move to light
Move away from toxins
Find a mate
In summary, living organisms:
 are composed of cells (Cellular Organization)
 are complex and ordered (Ordered Complexity)
 respond to their environment (Sensitivity)
 can Grow, Develop and Reproduce
 obtain and use energy (Energy Utilization)
 maintain internal balance (Homeostasis)
 allow for Evolutionary Adaptation
Levels of Organisation of Life
Classification of Organisms
Unicellular (Amoeba, bacteria, protozoa, and yeast) and
multicellular (animals, plants, fungus)
Prokaryotes (most primitive organisms) and eukaryotes
Autotrophs (synthesise their own food), heterotrophs (cannot
synthesise their own food), and lithotrophs (uses inorganic
compounds, nitrifying/iron-oxidizing bacteria)
Aminotelic (aquatic animals including fishes),
Ureotelic
(mammals, adult amphibians, sharks, and marine cartilaginous
fishes), and Uricotelic (birds, insects, land snails, many reptiles)
Taxonomy (classification system)
Two-kingdom classification by Carolus Linnaeus
based on the mode of their nutrition and mobility
Animalia (unicellular protozoans and multicellular animals)
Plantae (remaining organisms)
Limitations:
No clue about the evolutionary relationships between animals and plants,
Viruses were not included
Grouped unicellular and multicellular organisms together
No separate classification for the prokaryotes
Did not classify some organisms such as lichens, euglena, slime mould, etc., that
have unconventional characteristic features
Taxonomy (classification system)
Three-kingdom classification by Ernst Haeckel
Animalia
Plantae
Protista (protozoa, microbes)
Limitations:
Placed nucleated and enucleated organisms together under Protista
Four-kingdom classification by Herbert F. Copeland
Animalia
Plantae
Protista
Monera —prokaryotes (bacteria and archaea)
Limitations:
Fungi was included under plantae
Taxonomy (classification system)
Five-kingdom classification by Robert H. Whittaker
Animalia - multicellular consumers
Plantae - multicellular producers
Protista - unicellular eukaryotes
Monera —prokaryotes (bacteria and archaea)
Fungi - multicellular decomposers
Taxonomy (classification system)
Six-kingdom and Three Domain classification by Carl Woese
based on their differences in rRNAs
Linnaeus’s Classification and Binomial Nomenclature
System
 Carolus Linnaeus proposed this hierarchical
classification system and binomial nomenclature
system to organise and name the organism.
 He is known as ‘Father of Taxonomy’
 In binomial nomenclature system,
scientific name of each organism
consists of two parts represented
with Latin words, first genus and
then species
 Always written in italics with first
letter of genus in capital letter only.
E.g., Homo sapiens
Human
Model Organisms
 Model organisms serve as a proxy for understanding the biology of humans
and human diseases
 Model organisms possess unique characteristic features such as easy
maintenance in the lab and short generation times
 These organisms that share many genes with humans
(E.g., mouse and human genomes are ~85% identical; Fruit fly and
human are 60% identical; Yeast has ~23% genes homologs in human)
Mouse (Mus musculus)
Yeast (Saccharomyces cerevisiae)
Fruit fly (Drosophila melanogaster)
Worms (Caenorhabditis elegans)
Zebrafish (Danio rerio)
Escherichia coli