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• What is Biology?• Characteristics of Life• Classification of Living Organisms

Chapter 1The Science of Life

Overview and Learning Outcome

1.1 : What is Biology

1.2 : Characteristics of Life

1.3 : Classifying Living Organisms

Definition of biology, biologist and organisms

State the characteristics of life

Understand why biologists classify organisms

State how biologists classify organisms

The word ‘biology’ comes from the Greek term bios, which means life

The Greek term logos means knowledgeScientists who study living things are called biologistsBiologists use the term ‘organisms’ to refer to a living

thing

Biology is the science of life. It involves the study of living things and the theories that describe the world of life

1.1 : What is Biology?

1.1 : Key Ideas

1. The study of science of life is called biology

2. Biologists are scientists who study living things

3. Organism is the term used to refer to a living thing

It is not easy to give an exact definition of the term ‘life’

However, observations and experimentations have shown that all living organisms carry out certain activities

We say these activities are characteristics of living organisms, or in other words, these activities are the

1.2 : Characteristics of Life

CharacteristicsOf Life

Cells Nutrition Respiration Excretion Growth and Development Movement Reproduction Sensitivity Adaptibility

1.2 : Characteristics of Life

All organisms are made of simple units called cellsThe cells of an organism carry out activities necessary for

the organism to stay aliveWe will be learning more about cells in Chapter 2

*** Non-living things are not made up of cells ; they are made up of atoms

Cells

The cell (from Latin cella, meaning "small room") is the basic structural, functional, and biological unit of all known living organisms. Cells are the smallest unit of life that can replicate independently, and are often

called the "building blocks of life".

All organisms need energy to stay aliveThey also need materials to make the living matter in the cells

of their bodiesNutrition is the process by which organisms take in food and

convert it into new protoplasmOrganisms gain the energy and materials they need from their

food

Nutrition

Living organisms require energy to perform activities such as growing and moving

Living organisms gain energy through the process of respiration Respiration is the oxidation of food substances to release energy for cell

activities All organisms respire In both plants and animals, organic food substances such as

carbohydrates and fats are used to store energy This energy is set free when these substances are broken down through

respiration into carbon dioxide and water

Respiration

Respiration

A chemical reaction takes place when glucose is broken down during respiration

Numerous other chemical reactions occur in the cells of a living organism

Since these chemical reactions take place in living cells, they are called metabolic reactions.

Metabolism is the sum of all the biochemical reactions that take place within the cell

Excretion

Some metabolic reactions produce waste substances that are useless or even harmful to the organism

These substances must be removed The process by which the organism removes metabolic

waste products is called excretion The substances that are to be removed are called

excretory products Carbon dioxide, water, mineral salts and nitrogenous

waste are all excretory products

Excretion

Most animals have special organs for removing their excretory products

Living organisms are open systems continually receiving and disposing both energy and materials – this process is basic to their continued existence. If it stops or breaks down, the organism dies

Excretion

Disposal of liquid waste from human body is done by the excretory system. The system consisting of two kidneys, two ureters, one urinary bladder, and one urethra performs the work of collecting, storing and removing all the liquid waste products from the body.

Kidney Diseases Ureteral Diseases Urinary Bladder Diseases Urethral Diseases

Diseases Related to the Excretory System

Growth is a permanent increase in the mass and volume of an organism when absorbed food is converted into living matter

Some of the new matter formed is used to repair worn out parts of the cell

The rest is added to the original living matter and this increases its size

Growth and Development

Development may make an organism more complex or even change its form

The body of an organism can change and become larger in size

It can also become more complex This kind of growth is characteristic of

living organisms

Growth and Development

Growth and Development

Movement is a characteristic of organismsThe movement of organisms is independent of external forcesMost animals are able to move from place to anotherSuch motion is called locomotionSome animals do not have the power of locomotion, however,

they can still move parts of their bodiesMost plants are unable to carry out locomotion but parts of the

plants are always moving slowly

Movement

Self-powered motion by which a whole organism changes its location through walking, running, jumping, crawling,  swimming or flying.

Locomotion does not include actions that are not powered by the organism, for example, drifting

Locomotion

All living organisms are able to reproduceIn reproduction, some characteristics are passed

on from the parents to their offspringThis is because genetic information is passed on

from the parents to their offspringOrganisms are mortal, thus reproduction is

necessary for a species to survive

Reproduction

Animals and plants are sensitive to changes in their environment

They can detect and react to these changes in ways which are beneficial to them

A change in the environment or an external influence causes the organisms to react in a predictable way

Such a change or external influence is called stimulus

The reaction of an organism to a stimulus is known as a response

This response of living organisms to a stimulus is termed sensitivity or irritability

Sensitivity

Living organisms are able to adjust and adapt to changes in their environment

Adaptation is any characteristic of an organism that improves its chances of surviving in its environment

Can be classified into structural adaptation or behavioural adaptation or physiological adaptation

Adaptability

Anatomical adaptations are physical features such as an animals shape. Behavioural adaptations can be inherited or learnt and include tool use, language and swarming behaviour. Physiological adaptations include the ability to make venom; but also more general functions such as temperature regulation.

Eg :

Adaptations to surviving in extreme conditions :

Anatomical (Structural) : Grow thicker fur (cold climates)

Behavioural : To come out only at night to avoid high temperatures (hot climates)

Physiological : Temperature Regulation

Learn More About : Adaptability

Read more about adaptability at http://www.bbc.co.uk/nature/adaptations

Some of the characteristics of living organisms can be found in certain non-living matter

For example, a motorcar can move and give off waste products when its fuel is burnt

It also has a well-organised and complex structureHowever, machines do not reproduce and they do not growAll the characteristics of life must be considered when

distinguishing between a living organism and a non-living matter

Understanding the differences between a living organism and a non-living matter

1.2 : Characteristics of Life (Summary)

Cells- Building blocks of life

Nutrition- Process by which

organisms take in food and convert it into new

protoplasm

Respiration- Oxidation of food

substances to release energy for cell activities

Excretion- Process by which organisms remove metabolic wastes

products

Growth and Development- Permanent increase in the mass and volume of

an organism when absorbed food is

converted into living matter

- - Make an organism more complex and even

change its form

Movement- Movement of organisms

is independent of external forces

Reproduction- Process which is

necessary for a species to survive

Sensitivity- Response of living

organisms to a stimulus

Adaptability- Process by which

organisms adjust and adapt to changes in their

environment

• The characteristics of life are as follows1. Organisms are made up of cells2. Organisms gain energy and the materials

needed to make the living matter for their bodies, through the process of nutrition

3. Organisms respire. Respiration releases energy through breakdown of food substances such as glucose

4. Organisms remove metabolic waste products through excretion

5. Organisms grow. The growth of an organism is a permanent increase in the

mass and volume of the organism6. Organisms can move by themselves in a

directed and controlled way7. Organisms reproduce their own kind8. Organisms are able to detect and

respond to changes in their environment. This is called sensitivity

9. Organisms adapt to increase their chances of survival

• All the characteristics of life must be considered when distinguishing between a living organism and non-living matter

1.2 : Key Ideas

There are millions of living organisms on Earth.

In order to study them, biologists group living organisms according to their similarities and differences

This is called classification The system of classification used

today was developed by the Swedish naturalist, Carolus Linnaeus

1.3 : Classifying Living Organisms

Swedish botanist, physician, and zoologist, who laid the foundations for the modern biological naming scheme of binomial nomenclature (formal system of naming species of living things by giving each a name composed of two parts)

For example, homo sapiens is the scientific term for humans Homo is the genus Sapiens is the species

Carolus Linnaeus

What systems could be used to classify organisms?

Organisms can be grouped according to properties that are meaningful to humans

This type of classification is called artificial classification

However, this type of classification is not useful to biologists, as it does not show any natural relationships between the

organisms in a group Biologists use a system of

classification called natural (biological) system of classification

Such a system is based on similarities and differences between organisms

This system is easy to refer to when identifying organisms

Classifying Living Organisms

Biological System of Classification

In a natural system classification, organisms are classified according to a graded scale or hierarchy

The resemblance between organisms becomes much closer as we go down the scale of classification

For instance, it is easy to distinguish one family from another

It is also fairly easy to separate different genera but different species may be more difficult to differentiate

Biological System of Classification

Kingdoms of Living Organisms

The common name given to an organism may vary in different parts of the world

This can cause confusion Carolus Linnaeus used Latin to give 2 names to each organism This naming system is called the binomial system The 1st name refers to the genus which the organism belongs and it starts

with a capital letter The 2nd name is the species name and it starts with a small letter Both genus and species names are italicised or underlined

Binomial System of Naming Species

For example, domestic cat

First Name : (genus) : Felis

Second Name : (species) : domestica

Therefore, its scientific name is Felis domestica

Binominal System of Naming Species

We classify organisms according to their similarities and differences

The natural classification is hierarchical, with each level in the hierarchy having a specific label

Starting from the largest group, the order is as follows :Kingdom > Phylum > Class > Order > Family > Genus >

Species

1.3 : Key Ideas

All living organisms are capable of 1. Excretion and Respiration2. Locomotion and Excretion3. Photosynthesis and Reproduction4. Respiration and Locomotion

Test Yourself!

All living organisms are capable of 1. Excretion and Respiration2. Locomotion and Excretion3. Photosynthesis and Reproduction4. Respiration and Locomotion

Test Yourself!

Ans : 1

Below is a list of groups Carolus Linnaeus used to classify organisms

Rearrange the groups in an hierarchy, beginning with the largest group

Test Yourself!

OrderGenus

KingdomClass

PhylumFamilySpecies

Answer :Kingdom > Phylum > Class > Order > Family > Genus > Species

Test Yourself!

We will learn about cells in the next chapter

Remember to read about cells so as to speed up the teaching and understanding process!

Next Chapter