Announcements Take out packet to be checked from last class if you did not get it stamped Work on energy do now Extra Credit due FRI 12/4 Unit 4A Test WED 12/16, THURS 12/17

Energy in Food: Producers The energy in the food we eat originates from the sun The beginning of every food chain starts with a producer Producers are known as autotrophs because they can use the energy from the sun to make glucose (photosynthesis) Plants are the main terrestrial producers.

Ancestors of the Plantae The Plantae evolved from green algae, most likely a group called the charophytes. Evidence: Cell wall structure of both is very similar DNA sequence data supports close relationship between these groups.

The transition to Land The risks: Harsh environment… Heat, drying out, damage by UV rays The rewards: Great opportunity… Plentiful CO2, sunlight, few competitors or herbivores. The importance: paved the way for other organisms: Food for herbivores; First soils!

Overcoming Challenges of life on land Avoid drying out. (Waterproof Covering) Be able to hold itself up. (Strong Cell Wall) Possess differentiated tissues because air and soil differ in composition and resources. (Roots, Stems, Leaves) Solve the problem of reproducing outside water. (Seeds)

Transition to land The ancestor of modern plants once established on land had enormous opportunities because there was no competition for sunlight or minerals and no herbivores. Selection rapidly led to a massive diversification of plants.

First Land Plants The first land plants were nonvascular plants (like mosses today) This means they didn’t have roots or stems so they could not transport water, sugars or minerals around the plant.

First Land Plants Lack of vascular tissue also limited the size of plants (since they can’t transport nutrients around the plant) and required them to live in very moist environments.

Rise of Vascular plants Once the first plants moved onto land, selection quickly led to the development of specialized roots and shoots to move water and other essentials around the plant The first vascular plants were ferns and other seedless plants.

Limits to early vascular plants Ferns reproduce with spores which are fragile and have a short lifetime Mosses and ferns need rainfall to help fertilize spores

Evolution of pollen and seeds Pollen dispersal is not limited by rainfall Seeds provide protection and nourishment for developing embryo.

Gymnosperms The first seed plants Most gymnosperms are cone-bearing plants (Conifers) Conifers with their needle-like leaves are adapted to cold dry weather so they dominate northern temperate regions.

Other Gymnosperms Ginko Cycads

Angiosperm diversification Angiosperms= flowering plants Have been enormously successful. There are now about 235,000 species in comparison to just over 700 gymnosperms.

Monocots Vs. Dicots Angiosperm are divide into 2 classes dicots (eudicot) 2 cotyledons (seed leaves) leaves with network of veins woody plants, trees, shrubs, beans monocots 1 cotyledon leaves with parallel veins grasses, palms, lilies

Flowers and Fruit Fruit Flower The key to the success of the Angiosperms has been that they have evolved flowers and fruit. Fruit Protects the seeds Animals eat the fruit and spread the seeds. Flower Bees, bats, birds, etc. are attracted to flowers by the nectar. When they visit multiple flowers they move pollen from one to the next

Flower Dissection Male Female Although flowers vary widely in appearance they have certain structures in common. Male Female