Download Chapter 20-Fungi and Plants

Chapter 20-Fungi and Plants
Section 1- Fungi
Section 2 – Early Land Plants
Section 3 – Seed Plants
Section 1-Fungi
• Characteristics of Fungi
– All Fungi are heterotrophs– fungi are not green so
they don’t contain chlorophyll or make food from
sunlight. They get their food from their
surroundings.
– The bodies of multicellular fungi are made of
filaments. These filaments are long strings of
individual cells called hyphae. Each cell is
separated by a wall with holes called a septa. The
holes allow the cytoplasm and nuclei to flow from
cell to cell. As the hyphae grow, they branch and
form a tangle mass called a mycelium.
– Cell walls of fungi contain chitin. This is the same
material found in the exoskeleton of insects and
other arthropods. Chitin is more resistant to
decomposition by bacteria than is the cellulose of
plants.
– Fungi digest food outside their bodies. Fungi get
food from both living and dead animals and
plants. As the hyphae spread through a food
source, they secrete enzymes that break down
organic matter. The hyphae then absorb the
nutrients. The mycelium of a fungus may have
many meters of hyphae.
– Most fungi reproduce by spores. The only parts of
a fungus you can see are its reproductive
structures. Most of the hyphae are woven inside
the food source. Mold or mildew produce clusters
or short strings of tiny, beadlike spheres on the
tips of hyphae. These tiny structures are
reproductive cells called spores. A fungal spore
can develop into a new individual.
 Spores can withstand dry conditions and a wide
range of temperatures. Some can be carried by air
currents. Some are sticky and cling to animals for
transport. If a spore lands on a food source with
enough moisture, the spore rapidly grows a
hypha.
Section 2- Early Land Plants
• Characteristics of plants
– Photosynthetic
– Cell walls made of polysaccharide called cellulose
– Many types of cells arranged in tissues
• Most plants have vascular tissues
– To grow large, must have internal tubes called
vascular tissue that transport water and nutrients
– Vascular plants are roses, houseplants, grasses,
oak trees and ferns
• Nonvascular plants – do not have vascular tissue so must
transport water and nutrients by osmosis and diffusion.
– Must live in wet environments
– They need a film of water to reproduce so sperm can swim
to egg
– They are relatively small – most are less than 1 in tall
– Most are anchored by a root-like structure called a rhizoid.
– The leaf-like structure are only one or two cells thick
– Water enters through pores on the undersurface where it
is not covered by cuticle.
– Mosses are the most widespread nonvascular plants. They
can grow in dense carpets on the forest floor.
– The gametophyte is the dominant form of the nonvascular
plants
Section 3 – Seed Plants
• The most important feature of plants with
seeds is that plants could now exist in dry
environments.
• Seed plants have woody tissues which allow
plants to grow tall and compete for sunlight.l
• Seed plants have a more complex vascular
tissue that lets water and nutrients be carried
to the new heights.
• Seed plants also no longer need water to
reproduce – the use pollen, cones, or flowers
and seeds.
• Seeds are able to survive unfavorable
conditions. Each seed contains an embryo,
baby plant, and stored nutrients the embryo
uses as it begins to grow.
• The structure of the seed that stores the
nutrients is called the cotyledons. The seeds
are either a monocotyledon (one seed leaf) or
a dicotyledon (two seed leaves).
• The hard outer seed coat covers the embryo
protecting it from physical injury or drought.
A seed can lie dormant for years and still grow
into a healthy plant.
• Special features on seeds include hooks,
feathery projections, or winglike projections.
These are all characteristics that help to move
seeds from place to place.
• Gymnosperms: Plants with naked seeds
• The seeds do not develop within a fruit
• Most seeds form in a cone, which are clusters
of scales or modified leaves
• The most familiar gymnosperms are firs,
pines, junipers, redwoods, and spruces