Plants
Characteristics of Plants
Eukaryotic
Cell walls that contain cellulose
Autotrophic
Plants can carry out photosynthesis, converting
sunlight energy into chemical energy
light
light
Roles of Plants Producers
Foundation of ecosystems due to their ability to photosynthesize
Produce chemical energy that can be taken in by other organisms for use
Medicinal Uses
Discovery of chemical compounds that can be used as natural remedies
Nutrient Cycles
Cycling of nutrients in an ecosystem (e.g. carbon, nitrogen, oxygen, etc.)
Pollution clean-up
Able to clean up soil through bioremediation where plants absorb pollution such as metals from the environment
Evolution of plants
The ancestor of modern-day plants were aquatic organisms similar to green algae.
Adaptations that allowed plants to live on land include the following:
Development of lignin
Ability to stand upright and grow tall for sunlight
Development of vascular tissue
Ability to transport nutrients, waste, and water
Development of seeds
Formation of an embryo
Strategies to reduce water loss
Strategies to disperse reproductive structures without water currents
Plant Alternation of Generations
Alternation of generations – Life cycle that
alternates between diploid and haploid forms
Most plants have both a diploid phase and a
haploid phase in their life cycle
Diploid generation
Sporophyte that produces haploid spores
Haploid generation
Gametophyte that produces haploid gametes
Concept Check
What key characteristics do plants share?
Describe four adaptations plants developed that
allowed them to grow on land.
A plant life cycle shows alternation of generations.
Describe the alternation of generations of a plant.
List the differences between the sporophyte and
gametophyte plant generations.
Major Groups of Plants
Green Algae – Modern Relatives of Plant Ancestors
Green Algae – Modern Relatives of
Plant Ancestors
Ancestry – Closest living relative of plant ancestors
Habitat – shallow fresh water, e.g. edges of ponds
and lakes
Life cycle - do not undergo an alternation of
generations
Structure – Different from photosynthetic plant-like
protists because they have cell walls and
photosynthetic pigments that are identical to plants
Mosses and Relatives – Seedless Non-vascular plants
Mosses and Relatives – Seedless
Non-vascular plants
Group known as bryophytes which can be classified
as a type of non-vascular plant
Ancestry – Modern relatives of first group to diverge
from the ancestral algae ancestors with the
development of lignin
Habitat – moist environments
Life cycle – Spend most of their life cycle in the
gametophyte generation. Sperm are flagellated
and swim through water to reach eggs.
Structure – Low growing due to the lack of rigid
support structures. No stems or seeds.
Ferns and Relatives – Seedless Vascular Plants
Ferns and Relatives – Seedless
Vascular Plants
Ancestry – Modern relatives of first plants
demonstrating vascularization which is the
formation of tubes to carry fluid throughout an
organism
Habitat – moist environments
Life cycle – Spend most of their life cycle in the
sporophyte generation. Sperm are flagellated and
swim through water to reach eggs.
Structure – Have vascular tissues connecting the
roots to the shoots. This helps transport water and
dissolved nutrients throughout the plant.
Gymnosperms -Seed Plants
Gymnosperms -
Seed Plants
Ancestry – Modern relative of first plants that have
seeds, which are plant embryos.
Habitat – diverse land habitats
Life cycle – highly developed sporophyte
generation and a gametophyte generation that
produces male gametophytes in the form of pollen
grains (can travel through dry environments)
Structure – Have a gametophyte generation that
grows off the sporophyte generation (e.g. cones on
a pine tree). Seeds are not enclosed (‘naked’).
Angiosperms –Flowering Plants
Angiosperms –
Flowering Plants
Ancestry – Modern relative of first plants that have enclosed seed. Also known as flowering plants. Evolution coincides with the rise of mammals.
Habitat – diverse land habitats
Life cycle – highly developed sporophyte generation and a gametophyte generation that produces male gametophytes in the form of pollen grains (can travel through dry environments)
Structure – Gametophytes of angiosperms develop within the flowers of sporophytes. Flowers attract insects and animals for reproduction and seed dispersal. Fruits, ripened ovaries of flowers, are also produced which aid in dispersal.
Plant Kingdom
Highly organized
tissues
Vascular tissues
Dispersed by seeds
Seeds enclosed
Angiosperms (flowering
plants)
Seeds not enclosed
Gymnosperms
(conifers)
Dispersed by spores
Ferns
No vascular tissues
Bryophytes
(mosses)
No highly organized
tissues
Green algae
Concept Check
What are the major group (or phyla) of plants?
What are characteristics of these phyla?
What advantages does vascularization provide to
plants?
What advantage does the seed provide?
What is the most effective reproductive and seed-
dispersal structure in the plant kingdom?