Multicellular Organisms

Cell Teamwork:The Processes of Life

Objectives

At the end of this PowerPoint, you will be able to:• Explain the common problems that multicellular

organisms have.• Identify body systems in these organisms that

allow them to function as a multicellular organism.

• Show how these complex systems work together to carry out the vital functions of life.

CONTENTS• Body Organization• What Cells Need• Transportation of Materials• Obtaining Nutrients• Gas Exchange• Excretion• Movement• Control• Protection• Reproduction

Body Organization

• At first an organism like a human appears to be this complicated pile of organs.

•Those organs make up the organ systems of the body.

But first, let’s look at how life is organized from the bottom up.

Levels of Organization

AtomMolecule

Organelle

Cell

Tissue

Organ

Organ System

Organism

How to Be a Multicellular

Organism

Let’s look at the difficulties in being made up of more than 1 cell and how the body systems are organized to make it all work.

CONTENTS

What Cells Need

All cells, whether alone or part of a larger organism, do the same processes.

Cell

CONTENTS

Unicellular Organisms

• A protist is surrounded by water, food, and oxygen.

• Materials just diffuse in and out of the cell.

Nutrients Oxygen

Waste

Protist

What Cells Need

• Thus all cells need the same materials and…

• Excrete the same waste products.

Nitrogen (proteins)

Oxygen Gas (O2)

Nitrogen Waste

Protist

Carbon Dioxide (CO2)

Water

Diffusion – How Chemicals Move

• A protist is surrounded by water, nutrients, and oxygen.

• Materials just diffuse in and out of the cell.

Nitrogen (proteins)

Oxygen Gas (O2)

Nitrogen Waste

Protist

Carbon Dioxide (CO2)

Water

Diffusion – How Chemicals Move

• A protist is surrounded by water, nutrients, and oxygen.

• Materials just diffuse in and out of the cell.

Nitrogen (proteins)

Oxygen Gas (O2)

Nitrogen Waste

Protist

Carbon Dioxide (CO2)

Water

Transportation Needed

• In a multicellular organism, only the outermost cells can exchange materials with the outside environment.

• These organisms need a way to get materials in and out of the inner cells.

Nutrients Oxygen

Waste

?CONTENTS

Transportation Needed

• In some simple organisms like this sponge, water with nutrients just flows in and out of the organism.

Transportation: “Pipes”

In more complicated multicellular organism, there are “pipes” which transport nutrients around the body.

Plant Transportation Systems

• In plants xylem pipes carry water and nutrients up from the roots.

• Phloem pipes carry food from the leaf down to other cells.

Animal Transportation Systems

In animals, blood vessels are the pipes that transport food, oxygen, and wastes around the body.

Animal Transportation Systems

We also call this system the Cardiovascular System.

• cardio- = heart (the pump)• -vascular = vessels (the pipes)

CONTENTS

Multicellular Organisms: Obtaining Nutrients

• Multicellular organisms (except plants) need food for energy.

• They need a system to get food in and broken up for the body to use.

Food

Waste (unused food)CONTENTS

Animals: Obtaining Nutrients

Animals have a digestive system which:

• Takes in food

• Breaks the food down.

• Gets the digested food into the blood for transportation to the cells.

Because plants make their own food through photosynthesis, they:

• Do not eat and

• Do not need a digestive system.

Plants do need:

• Sunlight for energy

• Water

• Carbon Dioxide

• Nutrients

Plants: Obtaining Nutrients

Plants have organs which help them take in nutrients and to do photosynthesis:

• Roots – Absorb (take in) water and nitrogen from the soil

• Leaves – take in carbon dioxide and carry out photosynthesis

• Take in CO2

• Location of photosynthesis

• Absorb water

• Absorb nitrogen

CONTENTS

Multicellular Organisms: Gas Exchange

• Multicellular organisms need a system to get oxygen in and carbon dioxide out of the body.

Oxygen CO2

CONTENTS

Plants: Gas Exchange

Plants also need to exchange gases with the atmosphere.

For Photosynthesis:

CO2 in O2 out

For Cellular Respiration:

O2 in CO2 out

CO2 in

LEAF

O2 out In

Photosynthesis CO2 in O2 out

Plants: Gas Exchange

Plants also need to exchange gases with the atmosphere.

For Photosynthesis:

CO2 in O2 out

For Cellular Respiration:

O2 in CO2 out

CO2 in

LEAF

O2 out In

Respiration O2 in CO2 out

CONTENTS

Multicellular Organisms: Excretion

• Multicellular organisms need a system to get poisonous wastes out of the body.

WasteCONTENTS

Multicellular Organisms: Excretion

• Removing carbon dioxide (CO2) from the body is also part of excretion.

CO2 out

Excretory SystemWe sometimes combine these 2 systems under the

heading of the Excretory System.

ExcretorySystem

UrinarySystem

RespiratorySystem

= +

+

CONTENTS

Unicellular Organisms: Movement

• For a protist to move, it simply needs to move its one cell.

Protist

CONTENTS

Multicellular Organisms : Movement

• A multicellular organism can only move if every cell moves at the same time and in the same direction.

• A control system is needed for this to happen.

CONTENTS

Multicellular Organisms: Control

• A multicellular organism needs to have control systems to coordinate cells.

CONTENTS

Electrical Control: Nervous System

• Central Control – Brain and Spinal Cord• Nerves to carry messages

PLANTS

Sorry, no answer here.

Discuss this one with your group.

Chemical Control: Endocrine System

• Glands produce chemical hormones.• The blood carries these chemical messages.

That’s right. The Circulatory System

The blood is needed to transport the chemical hormones around the body.

CONTENTS

PROTECTION

• Multicellular organisms, like unicellular organisms, need protection.

• This protection or defense is the combined effort of many systems.

• Cells work together as a tissue, organs work together in a system, and the systems work together to protect the organism.

CONTENTS

PROTECTION

• Your bones and cartilage protect organs.

• Your bones make up an endoskeleton (inside).

• Many animals have an exoskeleton (outside).

The horseshoe crab’s shell is

an exoskeleton.

PROTECTION

• Your muscles aid in protection in allowing you to escape.

PROTECTION

• These 2 systems allow you to sense, react and escape danger.

PROTECTION

Organisms have skin and often other protective coverings.

PROTECTION

• The circulatory system transports the food and oxygen that you need for dealing with emergencies.

• Your blood’s ability to clot is protection from both blood loss and harmful pathogens.

PROTECTION

But the Immune System allows your body to fight off pathogens (outside invaders) that actually enter your body.

PROTECTION

An army of different types of white blood cells destroy these foreign pathogens and give you immunity (protection) from future “invasions”.

CONTENTS

PLANT PROTECTION

What are some of the organs that plants have to protect themselves?

CONTENTS

OdorSkunk Cabbage

What else can you think of?

Reproduction

• All life can reproduce because every cell has DNA.

• Most multicellular organisms reproduce sexually by combining an egg with either a sperm or pollen.

• These two half cells have 1/2 the DNA of each parent and combine to form a whole cell.

CONTENTS

Plant Reproduction

• Plants, like animals, reproduce sexually. Flowers produce pollen which fertilize eggs to create seeds.

• Either wind or insects carry the pollen to another flower.

Reproduction

• But some multicellular organisms can reproduce asexually.

• Fungi produce spores which unlike eggs, sperm, and pollen contain a complete set of DNA. Only one parent is needed.

CONTENTS