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Plants Ms. Luaces Honors Biology.

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Presentation on theme: "Plants Ms. Luaces Honors Biology."— Presentation transcript:

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!

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