Science 8 Unit B – Section 1.0 Living 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