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Chapter 2: Intro to Multicellular Organisms
Levels of Organization
Unicellular vs. Multicellular
In single-celled, one cell performs ALL functions.
In multi-cellular, different cells perform different functions. › They are specialized to do specific jobs.
Multicellular Kingdoms
Almost all multi-cellular organisms belong to the plant, fungi, and animal kingdoms.
Levels of Organization
Begins with the cell.
Cells that perform the same job join together to form tissue.
The tissues join together to make an organ, and organs that work together form an organ system.
Organ Systems lead to Organisms
Different organ systems have specific purposes in an organism. › Nervous: respond to environment› Muscular: movement and heat› Respiratory: inhale O2 and exhale CO2› Circulatory: delivers O2 in blood and
remove CO2 in blood› Digestive: breaks down food
Chapter 2: Intro to Multicellular Organisms
Adaptations and Reproduction
Adaptation
An adaptation is any inherited characteristic that increases the change of an organism’s survival and reproduction. › Getting energy › Shape/structure of body› Behavior
Adaptation
When an organism reproduces an offspring with a unique trait, it is considered an adaptation if it is helpful/advantageous.
Adaptation Examples - Fox
Fennec fox: desert fox; large ears keep it cool and fur color helps it blend.
Arctic fox: cold north; small ears, legs, and nose reduce heat loss; winter coat is thicker and white.
Red fox: grasslands/woodlands; body fur helps it blend with its surroundings.
Adaptation
Adaptations result in diversity through sexual reproduction. › The DNA in the offspring is not the same as
the DNA in the parent.
Review…
Meiosis produces gametes (1n/haploid) cells, containing only one copy of DNA.
When male and female gametes are joined, fertilization occurs and the DNA from both parents are combined to form the new offspring.
Review…
Most multicellular organisms reproduce by sexual reproduction; some can reproduce asexually (one parent).
Budding– second organism grows off parent; identical DNA.
Chapter 2: Intro to Multicellular Organisms
Plants are Producers
The Sun’s Energy
Chemical energy is the form of energy that all organisms use to carry out life functions.
Plants capture light energy and convert it into chemical energy through ---
Photosynthesis
Plants take in water + CO2 + sun energy
Turn it into glucose (sugar) and oxygen
Mostly take place in the leaves, which are green because of…? › Chloroplasts
Autotrophs
Plants are also called autotrophs, which means “self-feeder”.
Algae and some bacteria/protists are also able to use photosynthesis. › Plants are a different type of producer
because they have specialized cells to story energy excess energy is stored as starch.
Releasing Stored Energy
When plants need to release energy, the starch is broken down and cellular respiration occurs.
Adapting to Environments
Leaves, stems, and roots allow plants to live on land.
Grass: deep roots, produce seeds quickly, and can grow in various areas.
Adapting to Environments
Trees: cannot survive in harsh conditions, but different types of trees can survive in different areas.
› Coniferous: (pine) do better is cold climates; needle-shaped leaves stay green.
› Deciduous: (maple) need long growing season and loses leaves in cold temps.
Adapting to Environments
Protection: some plants have adaptations that prevent them from being eaten. › Mustard: odor› Poison Ivy/Oak: harmful chemicals › Nicotine: poison
Adapting to Environments
Specific Needs: › Venus Fly Trap: leaves fold to capture
insects; fluids given off by the leaves break down the body, and nutrients are given off to the plant.
Chapter 2: Intro to Multicellular Organisms
Plants Respond to their Environment
Responding to Environments
Plants can respond to a stimulus: something that produces a response from an organism. › Gravity, touch, and light
Responding to Gravity
Plants respond to gravity and have a sense of up and down.
Responding to Touch
Some plants have special stems called tendrils.
These plants grow in close contact with another object to help raise it closer to the sunlight.
Responding to Light
Stems and leaves grow toward light because they have a special hormone: chemical substance that is produced in one part of the organism and creates a reaction.
Auxin
Responding to Light
Step 1: sunlight stimulates production of auxins at the tip of the stem.
Step 2: auxin moves to cells on dark side.
Step 3: cells with auxin grow longer cells, causing them to bend to light.
Responding to Seasonal Changes
Shorter daylight (fall/winter) means less time to capture sunlight.
Many plants go into dormancy, causing them to temporarily stop growing.
Trees and other plants can survive the winter, and grow leaves back. Other plants must be replanted every year.
Responding to Seasonal Changes
Seasons can also affect reproduction: short day plants vs. long day plants.
Chapter 2: Intro to Multicellular Organisms
Animals are Consumers
Consumers & Heterotrophs
Animals are consumers: organisms that need to get energy from another organism.
Heterotrophs: organisms that feed on other organisms.
Obtaining Food
Simple feeding: filtering food from environment.
Complex feeding: searching for food and/or capturing food.
Types of Consumers
Herbivores: plants/algae
Carnivores: other animals
Omnivores: plants and animals
Processing Food
Digestion is the process that animals use to break down food.
Digestion uses physical and chemical activity.
Processing Food
Some animals, like sponges, can take in food particles directly into their cells.
Jellyfish have a single opening in their bodies to take in food and expel wastes.
Most animals have a tube-like system- mouth at one end, waste released at the other end.
Releasing and Storing Energy
Animals obtain energy through cellular respiration.
Most animals take in water through their digestive system.
The oxygen needed for cell. resp. is brought into the body in different ways.
Bringing in Oxygen
Insects: spiracles – tiny openings in body
Fish: gills – oxygen in water
Others, like humans, take in oxygen through the lungs.
Interacting with the Environment
For most animals, muscle and skeletal systems provide movement and support.
Nervous systems allow animals to sense and respond to stimuli. › Light, sounds, odors, temp, hunger, thirst,
etc.
Behavior
Behavior: any observable response to a stimulus.
Some behaviors are inherited (spiders spinning a web), and others are learned.
Individual Behavior
Often meet basic needs – food, water, shelter.
Respond to environment
Animals of the Same Species
Social behaviors
Parents and offspring
Behaviors for attracting mate
Working together or being competitive › Hunting in packs/competing for space
Animals of the Different Species
Competition: The search for food. Predator: animal that hunts other
animals.› Running fast, hunting abilities
Prey: animal that is being hunted. › Escaping predators, hiding, running in
packs.
Animals of the Different Species
Cooperation: tickbirds remove ticks from the skin of an impala.
This is symbiosis – it benefits both animals.
Seasonal Changes
Migration: the movement of animals to a different region in response to environment.› Monarch butterflies, birds
Hibernation: sleeplike state that lasts for an extended time period.› Frogs, turtles, fish, insects, etc.
Chapter 2: Intro to Multicellular Organisms
Fungi are Decomposers
Decomposers
Break down the complex carbon compounds that are part of living matter.
They are heterotrophs.
Decompose bodies of plants/animals, fallen leaves, shed skin, and animal droppings.
Characteristics of Fungi
Most multicellular (except yeast)
Nucleus and thick cell wall
No specialization
Has reproductive body and network of cells called a hyphae.
Hyphae
A mass of hyphae is called a mycelium.
Hyphae – just one cell thick.
Cells release chemicals to break down materials around them.
Sexual Reproduction of Fungi
A spore is a single reproductive cell that can grow into a new organism.
A single mushroom can make a billion spores, which are spread through the air by wind.
Asexual Reproduction of Fungi
Hyphae can break and new mycelium can form – like budding.
Yeast can have a simple cell division or budding.
Mushrooms
A single mushroom is a part of a much larger mycelium.
Some are edible, some are poisonous (toadstool).
The cap produces spores; the cap and stalk are filled with hyphae.
Molds Mold that we commonly see is the
spore-producing part of fungus.
Hyphae grow into the food.
Used to make cheese (Penicillium) and soy sauce (Aspergillus).
Molds Can cause disease (athlete’s foot).
Can treat disease (Penicillin).
Reproduce with spores, mostly through the moving air. › Pilobolus shoots a spore-containing cap up
to two meter away because of pressure.
Yeasts Single-celled
Moist environments and surfaces
Some grow on human skin, which can cause disease.
Makes bread rise
Helpful Bacteria The main decomposers on Earth.
releasing nutrients of decaying materials into the soil.
This helps the plant that the hyphae is surrounding.
Lichen Single-celled algae
Can live just about anywhere
Harmful Bacteria Many produce toxins – harmful
chemicals
The potato famine in Ireland.
Some fungus is used for medicines – penicillin. › Prevents bacteria from reproducing
successfully.
