Biology Now, 2e

Animal-like protists are consumers. Fungus-like protists are decomposers. Plant-like protists are photosynthetic.

Diplomonads,

others

Brown algae,

diatoms, others

Ciliates,

others

Euglenoids,

others

The kingdom Protista is an artificial grouping defined

by what members of this group are not: protists are

not plants, animals, fungi, bacteria, or archaeans.

Most protists are single-celled

and microscopic, and they can

swim with the help of one or

more flagella, or by waving a

carpet of tiny hairs called cilia.

Although most protists are harmless, the

best-known ones are pathogenic, like

Plasmodium vivax, the protist that causes malaria.

Bryophytes (mosses and liverworts)

Ferns

Angiosperms

Plants are multicellular autotrophs

and mostly terrestrial. Because plants

are producers, they form the basis of

essentially all food webs on land.

Plants have a waxy covering,

known as the cuticle, that

covers their above-ground

parts. A waxy cuticle holds in

moisture—an important

adaptation to life on land.

Gymnosperms were the first plants to

evolve pollen, a microscopic structure

that contains sperm cells, which freed

them from a dependence on water for

fertilization. Gymnosperms were also

the first to evolve seeds, which can be

disseminated so they will not compete

with the mother plant for sunlight, or

for water and nutrients in the soil.

Gymnosperms

Flowering plants, or

angiosperms, are dominant and

the most diverse group of

plants on our planet. The keys

to the success of angio-

sperms are the flower, a

structure that evolved through

modification of early plant

reproductive organs, and the

fruit, a fleshy ovary wall that

protects and helps disperse the

seeds inside it.

Protista

Protista

Plantae

Forams,

others Red algae

Green

algae

Common ancestor

of the Eukarya

Common ancestor

of plants and the

green algae

The evolutionary history of the protists

remains unresolved.

Figure 14.9

The four kingdoms of the domain Eukarya

Q1: What group of organisms shares the most recent common ancestor with plants?