Biology : Chapter 1 : The Science of Life
Transcript of Biology : Chapter 1 : The Science of Life
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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!
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