1. Plants
Ms. Luaces
Honors Biology

2. 2.2 – Properties of Water
Water is a neutral molecule and found over 75% of Earth’s surface
However, water is polar (a molecule in which the charges are unevenly distributed)

3. 2.2 – Properties of Water
Polar molecules like water can attract each other – known as hydrogen bonding
This accounts for many of waters special properties

4. 2.2 – Properties of Water
Cohesion: attraction between molecules of the same substance
Why drops of water form beads and why there is such a thing as surface tension
Adhesion: attraction between molecules of different substances
Causes the capillary action that draws water out of roots up into a plants stems and leaves

5. 2.2 Properties of Water
Water also has a high heat capacity – takes a large amount of heat to cause the molecules to move faster
This is why cells don’t overheat as they are carrying out the bodies processes – the water is drawing the heat out (sweat!)

6. Chapter 22: Plants
Plants have adapted so well to many environments that they dominate much of the surface of the planet
Include trees, shrubs, mosses, and even green algae!

7. 22.1 – Characteristics of Plants
Plants are:
Kingdom Plantae
Multicellular
Eukaryotes
Have cell walls with cellulose
Autotrophs (photosynthesis)

8. 22.1 – Characteristics of Plants
The lives of plants center on the need for sunlight, gas exchange, water and minerals
Sunlight: required for photosynthesis so they’ve developed broad, flat leaves
Gas exchange: require carbon dioxide and have to let go of oxygen, so they’ve developed special parts to deal with this
Water and minerals: required for photosynthesis and survival, so they’ve evolved structures that limit water loss and increase the intake of water and nutrients upwards from the soil

9. 22.1 – The History & Evolution of Plants
Ancestors of land plants were water-dwelling without leaves and roots: today’s algae
At first, algae was in Protista, but because they have cell walls and do photosynthesis, they are classified as plants

10. 22.1 – The History & Evolution of Plants
Over time, the demands of life on land favored the evolution of plants more resistant to the drying rays of the sun, more capable of conserving water, and more capable of reproducing without water.

11. 22.2 Seedless Plants
Algae: any photosynthetic eukaryote other than a land plant
Mostly aquatic
Absorb moisture and nutrients directly from their surroundings
One of the first plants to evolve billions of years ago
Can form colonies – how first plants probably arose

12. 22.2 Mosses and other Bryophytes
Bryophytes: higher degree of cell specialization and one of the first plants to become established on land.
Characteristics:
Live in damp places with plenty of water
Lack vascular tissue (roots and stems) and lignin, and therefore cannot support a tall plant body
Include mosses, liverworts, and hornworts

13. 22.2 Vascular Plants
Tracheophytes (vascular plants): have a transport system with true vascular (roots and stems) tissue
Characteristics:
Contain cells called tracheids (water conducting cells)
Contain xylem (carries water from the roots) and phloem (transports solutions of nutrients and carbs)

14. 22.2 Vascular Plants Vascular plants are split up into 2 categories:
Seed Plants: the majority of plants on earth
Seedless plants: ferns, mosses and horsetails

15. Let’s Practice!
Study Workbook A Pgs. 17 #1-4 and Pgs SKIP #4-6
Work with a buddy – one sheet of paper
Question AND Answer
You’ve got 40 minutes!!

16. 22.3 Seed Plants
Each and every seed contains a living plant ready to sprout as soon as it encounters the proper conditions for growth
A seed is a plant embryo and a food supply, encased in a protective covering

17. 22.3 The Importance of Seeds
Unlike mosses and ferns, the gametes of seed plants do not need standing water for fertilization
Adaptations that allow seed plants to reproduce without standing water include:
a reproductive process that takes place in cones or flowers
the transfer of sperm by pollination
the protection of embryos in seeds

18. 22.3 Seed Plants Gymnosperms Angiosperms
Bear seeds directly on scales of cones
Male gametophyte is in pollen grain
Pollen is carried by wind
Flowering plants
Bear their seeds in flowers inside a layer of tissue to protect the seed
Male gametophyte also in pollen grain
Pollen is carried by animals

19. 22.3 Seed Plants
Embryos can remain in dry conditions for weeks or even years because of the tough seed coat that surrounds and protects it

20. 22.4 Flowering Plants
Angiosperms (flowering plants) are the most recent in evolution of plants
Contain ovaries, which surround and protect seeds
Attract animals such as bees to carry pollen to other flowers

21. 22.4 Flowers & Fruits
Fruit contains one or more ovaries with seeds inside the walls
Helps to disperse the seeds, especially when eaten by an animal
Increase the range the plants inhabit (over hundreds of km)

22. 22.4 Angiosperm Classification
Classified according to the number of seed leaves (cotyledons) in their embryos
One seed leaf – monocots
Two seed leaves – dicots
** Recent classification has shown dicots go into a variety of different categories, and have been expanded
**Figure is a good reference!