Kingdom Plantae Key Questions 1.What do plants need to survive? 2. How did plants adapt to land? 3. What feature defines most plant life?

Characteristics of Plants. Traditionally plants have been characterized as members of the kingdom plantae.

Characteristics of Plants. You already know that trees, shrubs and grass are plants.

Characteristics of Plants. Mosses, ferns and green algae are also plants.

Characteristics of Plants. Green algae use to be classified as protists, but in recent years biologists have reclassified them as plants.

Characteristics of Plants. Plants are eukaryotes that have cell walls made of cellulose and carry out photosynthesis using chlorophyl a and b.

Characteristics of Plants. Comparison of chlorophyl a and b. Chlorophyll b molecule Chlorophyll a molecule

Characteristics of Plants. Chlorophyll a absorbs light within the violet, blue and red wavelengths while mainly reflecting green. This reflectance gives chlorophyll its green appearance.

Characteristics of Plants. Within the reaction centers of both photosystems I and II, are a pair of chlorophyll a molecules that pass electrons on to the ETC ( electron transport chain ).

Characteristics of Plants. In land plants, the light harvesting antennae around photosystem II contain the majority of chlorophyll b

Characteristics of Plants. Most plants are autotrophs, but a few are parasites or saprobes. Plants have developed a variety of adaptions to enable them to succeed as a stationary land organisms. The basic needs of plants are: 1) sunlight 2) gas exchange 3) water 4) minerals

1. Sunlight Plants use energy from sunlight to carry out photosynthesis. Every plant displays adaptations based on that need for sunlight. Photosynthetic plant organs such as leaves are typically broad and flat to maximize exposure to sunlight.

2. Gas Exchange Plants require oxygen gas to support cellular respiration. They also require carbon dioxide gas to carry out photosynthesis. During photosynthesis, plants produce more oxygen than they need, so they release the excess oxygen gas into the air.

3. Water On hot sunny days, plants can lose a lot of water to the air, just as when we sweat.

3. Water Water is also a reactant that is required for photosynthesis to occur, so it is consumed when the sun is shining.

3. Water Land plants have evolved structures that limit water loss. Other structures speed up intake of water from the ground. Stomata Root hairs

4. Minerals Plants also absorb minerals through their root system. Minerals are nutrients in the soil needed by plants

Evolution of Plants For most of Earth’s history, land plants DID NOT exist. Life was concentrated in the oceans, lakes and streams.

Evolution of Plants Photosynthetic prokaryotes like the cyanobacteria added oxygen to the planet’s atmosphere.

Evolution of Plants Fossil records indicate plants and animals originated in the water. For many years now biologist have placed green algae in the kingdom protista, however it has become clear that they are actually true plants. Evidence that green algae should be classified as plants includes: 1. They have cell walls identical to plants 2. They have photosynthetic pigments identical to plants 4. Comparison of genomes shows they are related. 3. They have reproductive cycles very similar to plants.

Evolution of Plants The first land plants. Fossil spores of land plants have been found in rocks 475 million years old.

Evolution of Plants The first land plants. The oldest fossils of plants themselves are only 50 million years old.

Evolution of Plants The first land plants. The greatest challenge for these new land plants was obtaining water, which they achieved by growing close to the ground.

Evolution of Plants The first land plants. Over time, the demands of life on land favored the evolution of plants: 1. more resistant to the drying rays of the sun 2. more capable of conserving water 3. more capable of reproducing without water

Evolution of Plants The first land plants. The appearance of land plants changed the rest of life on earth. Land plants change the environment in ways that allowed new species to evolve, new ecosystems to develope, and organic soil to build up.

Evolution of Plants The first land plants. Several groups of plants evolved from the first pioneering land species: 1. Mosses 2. Ferns 3. Cone-bearing plants 4. Flowering plants

Evolution of Plants The first land plants. Botanist today divide the plant kingdom into 5 major groups.

The Plant’s Life Cycle Land plants have a distinctive sexual life cycle that sets them apart from most other living organisms. The life cycle of land plants has two alternating phases, a diploid (2N) phase and a haploid (N) phase.

Conclusion