Science 8 Unit B – Section 1.0Living things share certain characteristics and

have structures to perform functions

Section 1.0 Outcomes

Describe the characteristics of living things Analyze the general structure and function of

living things Explain how living things have different

structures for similar functions Show how the body is organized into

systems

1.1 – The Characteristics of Living Things

There are many types of living things – from simple single-celled organisms to complex multicellular life forms

However, they all share 6 characteristics:

1. Living things are made of cells

Cell:

Every organism is made up of at least one cell

Every cell must come from another cell

2. Living things use energy

Organisms require energy to carry out a number of processes

The way that the energy is gathered can vary, but all living things do require energy

As well, living things require nutrients to grow Metabolism:

3. Living things respond to the environment

Every organism shows a response to various types of stimulus

Stimulus:

4. Living things grow and develop

All living things both grow and develop over their lifetime

Growth involves a simple change in size of the organism

However, many organisms develop, which means that their body shape may change drastically over time

5. Living things reproduce

All living things must come from other living things

This is known as reproduction Reproduction is not necessary for an

organism to survive, but without reproduction a species will not survive

6. Living things have adaptations for their environment

Adaptation:

Adaptations make it easier for a particular organism to survive long enough to reproduce

Viruses & Prions – Living or Not?

A virus is a strand of DNA that is wrapped within a protein shell

Viruses enter host cells and use their cellular machinery to reproduce more virus particles

Prions are proteins that interact with host cells and cause diseases

1.2 – Structure and Function

Living things need to carry out a number of tasks to survive

Some tasks are common to almost all organisms, while some tasks are specific to a few (or even a single) species

Structure vs. Function

Structure:

Function:

Different structures, same function

Some organisms use different structures to carry out the same function

Variation in Structures

Often variation in structure is due to the environment in which an organism is found

However, the variation is not caused by the environment

The variations occur through random mutations and those that give organisms an advantage are passed on

Darwin’s Finches

Each of the finches on the Galapagos islands developed over time to have a beak shape that matched the most abundant type of food on each island

This happened when birds who were born with the correct beak shapes outcompeted other birds and reproduced, passing on their beak shapes

1.3 – Organs and Organ Systems

There are a number of levels of organization within the human body

The lowest level is the individual cell Collections of similar cells make up tissues Collections of tissues that work to perform a

task are known as organs Groups of organs that carry out a similar task

are known as organ systems

Ex: The digestive system

At a cellular level, a vast number of different cells make up the digestive system

These cells form epithelial, muscle, connective, and nervous tissue

These tissues form organs such as the stomach, intestines, esophagus, and other organs

All of these organs together make up the digestive system

The Circulatory System

Structures:

Used to transport oxygen, food, and other substances

Defends the body against diseases

The Respiratory System

Structures:

Exchanges oxygen and carbon dioxide between the outside air and the blood

The Digestive System

Structures:

Breaks down food into particles that can be absorbed and transported throughout the body

The Nervous System

Structures:

Coordinates and controls the actions of all organs and organ systems

Detects, processes and responds to changes in external and internal environments

The Excretory System

Structures:

Removes chemical and gaseous wastes from the blood

The Skeletal System

Structure

Provides a movable support frame for the body

Protects soft-tissue organs

Structures:

Moves bones Moves organs that contain muscle tissue

The Muscular System

The Integumentary System

Structures:

Protects the body’s internal environment from the external environment

Sense pain, pressure, and temperature