DIVERSITY OF LIVING THINGS - PLANTS

Document Sample
DIVERSITY OF LIVING THINGS - PLANTS Powered By Docstoc
					DIVERSITY OF LIVING
     THINGS

     G9 α ∆ Ω




      PLANTS
     CROSS-SECTION OF A LEAF




http://en.wikipedia.org/wiki/Palisade_cell
CONTROLLING GAS EXCHANGE AND
WATER LOSS

For photosynthesis to occur properly there
must be a perfect balance of materials.

-Carbon dioxide gas (enters the plant
coming from the air)
-Oxygen (moves out to the atmosphere
from the leaves)
-Water vapor (moves out to the atmosphere
in a process called transpiration)
           PHOTOSYNTHESIS




http://en.wikipedia.org/wiki/File:Photosynthesis.jpg
GAS EXCHANGE IS PERFORMED BY
STOMATA

Stomata (singular: stoma) are little openings at
the bottom of leaves.

Function: Gas exchange (carbon dioxide
comes in and oxygen goes out) and water loss
by transpiration.

For photosynthesis the plant needs enough
carbon dioxide coming in through stomata but
without losing too much water.
   STOMATA




Stoma in tomato leaf shown via
colorized scanning electron          A stoma in cross-section
microscope image


http://en.wikipedia.org/wiki/Stoma
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/G/GasExchange.html
PLANT TRANSPIRATION




http://click4biology.info/c4b/9/plant9.2.htm
MECHANISMS TO AVOID WATER LOSS
IN EXCESS.

-The surfaces of leaves are covered by a
cuticle (waxy protective layer) that
prevents water loss.

-When the air is dry and/or hot the stomata
can close.

-Stomata can open at night when there is
less evaporation.
MORE MECHANISMS TO AVOID WATER
LOSS IN EXCESS.

-Some plants have adaptations, for example
in cacti the spines are modified leaves that
loses little water (because of less surface
area exposed) by evaporation.
The photosynthesis occurs in the stem.
  ADAPTATIONS TO AVOID LOSS OF
  WATER IN CACTI


                                                 The leaves have been
                                                 reduced to needles to
                                                 reduce transpiration.
                                                 The stem is fleshy in which
                                                 the water is stored.
                                                 The stem becomes the main
                                                 photosynthetic tissue.

http://click4biology.info/c4b/9/plant9.2.htm#5
PLANTS GROW THROUGHOUT THEIR
LIFETIMES

-Plants grow as long as they live.

-It occurs when cells at the tips of roots and
stems divide faster than the others.

-Plants roots and stems grow longer, thicker and
branch.

-Only stems grow leaves.
PLANTS GROW THROUGHOUT THEIR
LIFETIMES


-Leaves grow from buds produced in plant's
stems.
A bud is small protuberance on a stem or
branch, sometimes enclosed in protective
scales (modified leaves) and containing an
undeveloped shoot, leaf, or flower.
http://en.wikipedia.org/wiki/File:Plant_Buds_clasification.svg
PLANTS WITH SOFT STEMS

Some examples:

-Wildflowers

-Garden flowers

-Vegetables
PLANTS WITH SOFT STEMS

Some characteristics:

-The stems and leaves die when the
enviromental conditions are not favourable
(too cold or too dry).

-They store carbohydrates in their roots.

-If the conditions are good (heat, water,
sunlight new stems and leaves grow.
PLANTS WITH WOODY STEMS

Examples:
-Trees
-Shrubs

Characteristics:
-They have tough stems that do not die each
year.

-The stems grow thicker and longer.
-They develop a thick stem from xylem. This
is wood.

-The growing tissues in woody stems are
located near the outer surface of the stem,
right under the bark (The older part of the
plant is in the center of the trunk).
Mosses & Ferns
MOST MOSSES AND FERNS LIVE IN
MOIST ENVIRONMENTS (3.2 – 92)

Plants species adapted to life on land

-Evidences indicate that life appeared on
Earth 3.8 billion years ago.
Tiny singled-cell (unicellular organisms) and
multicellular organisms lived in watery
environments such as:




-Warm shallow seas
-Deep ocean vents (opening permitting the
escape of fumes (a liquid, a gas, or steam).
-Ponds (A still body of water smaller than a
lake).
Fossil evidence suggests that plant life did not
appear on Earth until 475 million of years ago.

The ancestors of plants were the first organisms
to move to land

Scientists believe they looked like green algae that
exist today.
Green algae and plants are autotrophs
(producers = produce their own food by
doing photosynthesis).

Their cells contain chloroplasts (where
photosyntesis is done).
THE FIRST PLANTS

The place where we are now millions of
years ago could have been a pond.

This pond contained:

-Tiny floating organisms that could
photosynthesize (the Sun provided the
light).

-Nutrients ( C, H, O, N)
The following facts occurred:

-The organisms reproduced and increased in
number.

-The pond became crowded.

-Some of the organisms were pushed to the
edges of the pond.

-After a period of dry weather the pond shrank
(became smaller in size).
-Some organisms were no longer in the water.

-The ones that survived started to live on land
and became the ancestors of the first plants.

Scientists believe this process happened in
millions of ponds during millions of years
Some differences between life on land and
life in water faced by the first plants:

Disadvantages:
-On land there is no water to support the
plants body.
-There is no water to avoid drying out.

Advantage:
-Plenty of carbon dioxide.
-Plenty of light from the Sun.
MOSSES AND FERNS

-Both probably evolved from algae that lived
in the sea and in freshwater.

-Mosses are simpler than ferns in structure.
          MOSSES




http://www.aquamoss.net/Introduction.htm
        Mosses




http://www.davidlnelson.md/Cazadero/Mosses.htm
http://www.countrysideinfo.co.uk/moss_article/page2.htm
http://www.countrysideinfo.co.uk/moss_article/page2.htm
http://www.countrysideinfo.co.uk/moss_article/page2.htm
      Leaves of moss




http://www.davidlnelson.md/Cazadero/Mosses.htm
MOSSES (SOME CHARACTERISTICS)

-Their cells have a cell wall that provides
support.

-Most cells have areas for storage of water
and nutrients (vacuoles).

-They have simple structures that function as
roots, stems and leaves.

These structures allow mosses to live on
land while algae live only in the water.
MOSSES ARE NONVASCULAR PLANTS

Mosses don't have vascular tissue (xylem
and phloem).

Water and dissolved nutrients move from cell
to cell. This process is not very efficient so
mosses can't be large.
         Mosses cells
         Water moves through cell to cell as mosses
         lack a vascular system




http://www.davidlnelson.md/Cazadero/Mosses.htm
MOSS REPRODUCTION
   MOSS REPRODUCTION
             Life cycle of a moss




http://www.sbs.auckland.ac.nz/uoa/science/about/departments/sbs/newzealandplants
         CAPSULES
   CAPSULES IN MOSSES
   SPOROPHYTES




http://www.sbs.auckland.ac.nz/uoa/science/about/departments/sbs/newzealandplants/mosses/
 FERNS ARE VASCULAR
FERNS ARE VASCULAR PLANTS
                   PLANTS
FERNS ARE PLANTS



 Consequence:
 They can grow bigger much bigger
 than mosses
FERNS REPRODUCE WITH
       SPORES
LIKE MOSSES FERNS NEED
  WATER TO REPRODUCE
FERNS REPRODUCTION
FERNS REPRODUCTION
          FERNS


                                               Trunks may reach heights of 20 m.
                                               Found in moist areas
                                               on both North and South Islands in
                                               New Zealand.
                                               (photo, John Braggins)



http://www.sbs.auckland.ac.nz/uoa/science/about/departments/sbs/newzealandplants/ferns/native-
ferns/cyatheaceae-black-silver-ferns.cfm
        FERNS




      The stipes that support the large fronds are
      thick and very tough and have a characteristic
      black appearance.
      (photo, Larry Jensen)
http://www.sbs.auckland.ac.nz/uoa/science/about/departments/sbs/newzealandplants/ferns/native-
ferns/cyatheaceae-black-silver-ferns.cfm
       FRONDS OF FERNS




http://www.sbs.auckland.ac.nz/uoa/science/about/departments/sbs/newzealandplants/ferns/
native-ferns/cyatheaceae-black-silver-ferns.cfm
These structures are clusters. They are
located on the back of the fronds.
Spores are produced here by meiosis.
http://www.sbs.auckland.ac.nz/uoa/science/about/departments/sbs/newzealandplants/ferns/
native-ferns/cyatheaceae-black-silver-ferns.cfm
COMPARING DOMINANT STAGES
   OF MOSSES AND FERNS

• In mosses the dominant stage is male and
  female plants (the ones producing sperms
  and eggs).
• In ferns the dominant stage is the spore-
  producing plant.
    COMPARING FIRST AND
   SECOND GENERATIONS IN
     MOSSES AND FERNS
In mosses and ferns:

-The first generation are the structures that
  produce sperms and eggs.

-The second generation is the structure that
  produces the spores
 MOSSES, FERNS AND OTHER
PLANTS CAN ALSO REPRODUCE
        ASEXUALLY

• Small pieces can grow into a new plant
• New plants can branch off from old ones
 Comparing sexual and asexual
         reproduction

Asexual reproduction allows plants to
spread more easily but the genetic material
is exactly the same as the parent plant.
Sexual reproduction increases genetic
diversity and the possibility of new
adaptations.
SEEDS AND SPORES ARE
   REPRODUCTIVE
    ADAPTATIONS
COMPARING SEEDS AND
     SPORES
              SPORES

A spore is a reproductive structure that is
adapted for dispersal and surviving for
extended periods of time in unfavorable
conditions.
Spores contain a single reproductive cell
Spores are produced from meiosis in
mosses and ferns.
                SEEDS
A seed is young plant (embryo) contained
in a protective coating containing nutrients.
The coating protects the embryo until the
conditions (moisture, temperature, water,
etc) are good for it grow.
SOME CHARACTERISTICS OF
   SPORES AND SEEDS
                GERMINATION


    Germination is the growing of a new plant from:
-   A spore (a new plant will grow from a single cell)
-   A seed (a new plant will grow from an embryo).
 GERMINATION IN SEEDS
An embryo can stay without growing for a
long time.

Germination is when the embryo starts to
grow.

The embryo absorbs water from the soil
 and
uses the nutrients stored.
MORE COMPARISONS BETWEEN
    SPORES AND SEEDS

• Seeds can be spread by the wind, animals
  or water.
• Spores are spread by the wind in general.
• Spores and seeds are adaptations that
  made reproduction on land possible.
                POLLEN


• Small multicellular structure containing a
  sperm cell.
                POLLEN
• They have a hard outer covering to keep
  the sperm from drying out.

• They can be carried by:
- Wind, water, animals (insects, birds,
  butterflies, bats, etc)
Tip of a tulip stamen with many grains of pollen
            POLLINATION
• The pollen grain attaches to the part of the
  plant that contains the egg.
• The sperm is released and gets to the egg.
    Life cycle of a pine tree



The reproductive structures are pinecones
                                           Mature female European
                                           Black Pine cone




http://en.wikipedia.org/wiki/File:Pinus_nigra_cone.jpg
                                      Male cone of a pine




http://en.wikipedia.org/wiki/Pine_cones
Each tree has separate male and female
cones.

Sperm and eggs are produced by meiosis in
the cones.
  Gymnosperms are Seed Plants
        “naked seed”

• Pollen and Seeds are reproductive
  adaptations;
• Seed Plants are generally better at
  reproducing in “difficult” environments, like
  dry and cold;
• GYMNOSPERMS produce seeds, but they
  are not enclosed in fruits!
                Conifers
         “most common gymnosperms”

• Are adapted to cold climates – little water
  available;
• Leaves are needle-shaped and have a
  thick cuticle (prevents water loss);
• Sugar production the whole year.
Cycads, Gnetophytes & Ginkgoes
              “Other Gymnosperms”

• These are 3 types of Gymnosperms which
  are very different from one another.




Cycadophyta      Equistella
                Cycads
• Palm-like trees from tropical areas;
• Produce Cones for Seeds;
• Many produce poisonous compounds.
            Gnetophytes
• Tropical Gymnosperms that produce
  cones;
• Chemichals are used to treat cold
  symptoms.
                Ginkgo
• Gymnosperms with fleshy seeds hanging
  from their branches;
• Often in parks and along streets;
• Seed coat produces a foul smell.
      Angiosperms

Seed Plants that produce Flowers
           and Fruits
             Angiosperms
• Most species of plants are angiosperms;
• Most trees whose leaves change color in
  the fall;
• Sperm protected in a pollen grain;
• Eggs develop into embryos that are
  enclosed within seeds;
• Male and female parts may be on the
  same plant or not.
    Flowers are the Reproductive
      Structure of Angiosperms

• Sperm and egg cells are contained in a
  flower;
• Egg cells develop in a part of the flower
  called ovary;
• Once the eggs are fertilized seeds form
  and ovary wall thichens becoming a fruit!
Plants Also Reproduce Asexually
• New shoots can grow out from the parent
  plant;
• Asexual reproduction allows plants to
  reproduce even when the conditions are
  not right for the germination of seeds.
Strawberry new shoot –
       “runner




           No Genetic Material
           Exchange! No Diversity!
Parts of a Flower
  The pollen-bearing part of a
  stamen.




the stalklike portion of a stamen,
supporting the anther.
The part of a carpel that
receives the pollen




 Extension of the carpel, which
 bears the stigma at its apex




 The enlarged lower part of the
 carpel enclosing the ovules or
 young seeds.


  The modified or expanded
  portion of the stem or axis
  that bears the organs of a
  single flower
Stigma + Style + Ovary = CARPEL




      Inside Ovary there are
      Ovules
SEPALS: One of the separate,
usually green parts forming the
calyx of a flower



PETALS: One of the often
brightly colored parts of a
flower     surrounding   the
reproductive organs
Fruit
• A Fruit is a ripened plant ovary;
• Ovaries may contain one or more seeds.
  Fleshy Fruits
“have juicy flesh”
       Dry Fruits
“have dry flesh and shell”
Animals Spread Pollen & Seeds
Animals Spread Pollen & Seeds
       Wind Pollination
A lot more pollen is produced!

				
DOCUMENT INFO