Chapter Fifteen: The Diversity of Life 15.1 Taxonomy and Systematics 15.2 Algae and Fungi
Investigation 15B What is mold and how does it grow on bread? Bread Mold
15.2 Evolution of sexual reproduction The first prokaryotic cells appeared about 3 billion years ago. Prokaryotic cells reproduce asexually by splitting in two. Asexual reproduction does not allow for genetic variation unless a mutation occurs.
15.2 Evolution of sexual reproduction About 1 billion years ago, the first eukaryotic cells appeared. Eukaryotic cells evolved the ability to reproduce sexually. Organisms that reproduce sexually produce more genetic variation among their offspring.
15.2 Evolution of sexual reproduction Sexual reproduction increases genetic variation and leads to new species.
15.2 Protista The Kingdom Protista, often called protists, contains many groups that evolved separately. Scientists categorize the many groups under three main types.
15.2 Algae Algae are photosynthetic protists that are plant-like in many ways. Kelp is a good example of multicellular algae.
15.2 Algae Some multicellular algae, such as Ulva, follow a pattern of reproduction called alternation of generations.
15.2 Fungi Originally classified as plants, fungi (singular fungus) do not make their own food. Yeast, mushrooms, molds, and are examples of organisms in the Kingdom Fungi.
15.2 Fungi Fungi do not eat their food as animals do. Instead, they release digestive enzymes into their surroundings. The enzymes break down organic material and the fungi absorb the nutrients directly into their cells.
15.2 Fungi Some fungi live in symbiotic relationships with algae, bacteria, or plants. In those relationships, both the fungi and the other organism benefit. Lichens are made of two organisms—a fungus, and a green algae or cyanobacteria.
15.2 Fungi All fungi are made up of thread-like filaments called hyphae. The cells that make up the hyphae sometimes contain two, three, or even more nuclei. The hyphae form a cottony mass of threads called a mycelium.