science 8 unit b – section 1.0 living things share certain characteristics and have structures to...
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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
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
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 Skeletal System
Structure
Provides a movable support frame for the body
Protects soft-tissue organs