The Organization of Life

Section #3:The Diversity of Living

Things

Imposing Order on Diversity

• Scientists like to group and organize life on earth based on different characteristics

• Scientists can then make connections and comparisons between the diversity of life

Th

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f Life

BACTERIA

• microscopic• single-celled organisms• usually have cell walls• lack nuclei• reproduce by dividing in half• found in every habitat on Earth

Role of Bacteria

• break down the remains and waste material of other organisms to return nutrients to the soil

• recycle mineral nutrients like nitrogen and phosphorus

• convert nutrients into a form that others can use them

FUNGI

• have nuclei• cell wall• no chlorophyll• absorb food & nutrients from

their surroundings• also play a role in the break

down of dead materials

PROTISTS

• diverse group • most are one-celled

microscopic organisms like amoebas, diatoms, plasmodium

• some are plant-like, including algae

PROTISTS

• from an environmental standpoint – the algaealgae are the most important protists because of their ability to make their own food from the sun’s energy

• algae (from seaweed to pond scum) are the initial source of initial source of foodfood in most ocean & freshwater ecosystems

PLANTS

• multi-cellular• make their own food (photosynthesis)• have a cell wall• most live on land• roots underground collect water &

minerals from the soil• leaves collect sunlight and gases

from the atmosphere

Vascular Tissue

• system of tubes that carry water & food to the rest of the plant

• this tissue also provides a “skeletal” system so plant can grow upwards

Vascular Tissue

LOWER PLANTS

• mosses, ferns, club mosses• have no vascular tissue• cannot grow very large • have swimming sperm• must live in damp places

GYMNOSPERMS

• pine trees + other evergreens• a.k.a. conifers• cone-bearers• woody plants that can live in drier

environments because they use pollen to protect & transport sperm

• needle-like leaves lose little water

ANGIOSPERMS

• flowering plants• produce seeds in fruit• pollen is carried by wind, insects, birds or animals• seeds are dispersed by animals & birds• source of food for most land animals +

provide a wide range of building materials & fibers for humans

ANIMALS

• many-celled• cannot make their own food • no cell wall• bodies are soft & flexible• some have developed skeletons –

either internal or external• most are more mobile than plants

INVERTEBRATES

• lack backbones• some live attached to a hard

surface in the ocean & act as filter-feeders

• only move during larvae stage• examples = corals & mollusks

INSECTS

• insects are most abundant & successful because of – waterproof shell– move quickly– reproduce quickly– some can fly– small size allows them to hide

easily and find habitats almost anywhere

VERTEBRATES

• have backbones• examples = fish, amphibians,

reptiles, birds, mammals

Discussion:

• What are some possible ways that each group of vertebrates has adapted to increase survival compared to the other groups?

•mobility•temperature regulation•reproduction•Habitat (food, niche, competition)