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Nature^71

FIND OUT MORE. Algae 87 • Animals 96–97 • Planet Earth 36–37 • Fungi 86 • Microorganisms 85 • Plants 88–89

DO ALL PLANTS HAVE A ONE-YEAR LIFE CYCLE?

Annual plants, such as sunflowers, live and die within

one year, but their seeds survive the winter. Biennial

plants, such as carrots, flower and produce seeds in

their second year and then die. Perennial plants,

including oak trees, live for several years – some

flower yearly, some only once in their life cycle.

1. Seed
   germinates and
   a root and shoot
   appear
   2. Leaves
   form and a
   stem grows


2. Seeds
   are scattered as the
   flower withers


3. Reproduction
   occurs and the flower
   produces seeds

ANIMAL (LION) PLANT (RHODODENDRON) FUNGUS (MUSHROOM) PROTIST (PROTOZOA) MONERAN (BACTERIA)

2 THE FIVE KINGDOMS

The photographs below illustrate

one species from each of the five kingdoms.

WHAT ARE THE FIVE KINGDOMS OF LIVING THINGS?

Organisms are divided into five kingdoms. Monerans

include simple, single-celled organisms such as

bacteria. Protists are mostly single-celled and include

protozoa and algae. Fungi include mushrooms and

moulds. Plants include flowers, trees, and ferns.

Animals include lions, lizards, and lice.

HOW DOES CLASSIFICATION WORK?

Organisms are sorted into groups ordered by size. The

smallest, the species, contains organisms that breed

together. Related species form a genus; several genera

make a family. Linked families form an order; several

orders make a class. A phylum contains a few classes.

Phyla make up the largest group, the kingdom.

Scientists use classification to name living

organisms. They sort them into groups by

looking for any similarities or differences

that indicate how closely related they are.

Chordata (chordates) – mostly vertebrates,

such as birds and mammals.

Animalia (animals) – organisms made of

many cells that obtain energy from food.

Mammalia (mammals) – vertebrates that

have hair and feed their young with milk.

Carnivora (carnivores) – hunting mammals

that have gripping, cutting teeth.

Felidae (cats) – carnivores with sharp claws

that can be retracted (drawn in).

Panthera (big cats) – large cats that roar,

including lions, leopards, and tigers.

Panthera tigris (tiger) – big cat with a

striped coat, found in Asia.

CLASSIFYING A TIGER

1 PLANT LIFE CYCLE

The life cycle of this sunflower is completed in one

growing season. Each seed contains an embryo

plant and its food store, and germinates (sprouts)

in the spring. The young plant grows rapidly,

developing first a stem and leaves and then

flowers. In summer, the flowers produce seeds,

which fall to the ground ready to sprout next year.

3. Flower
   begins to form and
   upward growth slows

WHICH ORGANISMS LIVE LONGEST?

Elephants can live to the age of 70, and humans can

live for more than 100 years. Some giant tortoises live

for more than 150 years, but certain plants live for

much, much longer. The Californian bristlecone pine

tree is thought to live to 4,900 years old, and the

Californian creosote bush may be 12,000 years old.

Every living thing goes through a sequence

of changes called its life cycle. Initially it

grows and develops, gradually changing

shape and getting larger. Once it is fully

mature, it reproduces. Finally, it dies, and

is replaced by its offspring.

LIFE CYCLES

CLASSIFICATION

KINGDOM

PHYLUM

CLASS

ORDER

FAMILY

GENUS

SPECIES

PANTHERA TIGRIS 2

A species name has two parts – generic

(Panthera) and specific (tigris).

life on Earth