Life 103 Exam 1

1) Phylogeny:

a. How are species distinguished and categorized?

Based on shared genetic ancestry

b. Phylogenetic Trees

i. How are they constructed?

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ii. How are they interpreted?

c. Endosymbiotic Theory

This theory posits that certain organelles in eukaryotic cells, such as mitochondria and chloroplasts, originated as free-living prokaryotes that were engulfed by ancestral eukaryotic cells. Over time, these prokaryotes became integral parts of the host cells, leading to a mutually beneficial relationship.

2) Bacteria & Archaea:

a. General structure/function of prokaryotic cells

Prokaryotic cells are single-celled organisms that lack a nucleus and membrane-bound organelles, characterized by their simple structure.

b. Different nutritional strategies

Chemoautotroph- a microorganism that uses chemical energy to convert carbon dioxide into organic compounds

Photoautotroph- Organism makes own carbon from light energy

Chemoheterotroph- Organism gets carbon from other living things

Photoheterotroph- obtain energy from light but acquire carbon from organic sources

c. Horizontal Gene Transfer 

The incorporation of genetic material from one organism to another without reproduction, occurring via transformation, transduction, or conjugation.

3) Protists & Algae:

a. 4 Eukaryotic Supergroups (general characteristics)

Excavata- have an excavated groove

SAR- Stramenopiles:hairy flagella Alveolates:membrane bound sacs Rhizarians:amoebas

Archaeplastida- red and green algae

Unikonts- animals and fungi

b. Protist Importance 

Protists play vital roles in ecosystems, including as primary producers, decomposers, and as part of the food chain.

4) Fungi:

c. Compare/Contrast with Animals and Plants

Fungi, animals and plants are all eukaryotic. Fungi have cell walls made of chitin, while plants have cell walls made of cellulose. Fungi are heterotrophic like animals, but digest from the outside in. 

d. General Life Cycle

In fungi, the haploid stage is the dominant phase. Two haploid gametes fuse to form a diploid zygote, which develops into a sporophyte through multiple rounds of mitosis. The sporophyte produces haploid spores through meiosis, which then develop into gametophytes. The gametophytes produce gametes, and the cycle repeats.

5) Bryophytes & Ferns:

a. General structure/function

They are usually bottom feeders, non-vascular with rhizoids to anchor them to the ground. 

a. Derived Traits of Land Plants

Sporopollenin to prevent zygotes from desiccation

Alternation of generations

Multicellular with dependent embryos

Walled spores produced in sporangia

Multicellular gametangia (reproductive structures) angechonia produces eggs, antheridia produces sperm

Apical meristems (regions of fast mitosis for growth from roots and shoot tips)

b. Gametophytes vs. Sporophytes

Gametophyte refers to the haploid phase of the life cycle where sex cells (gametes) are produced, while a sporophyte is the diploid phase which produces spores through meiosis

6) Gymnosperms:

a. Gametophytes vs. Sporophytes

the sporophyte is the dominant, visible plant body that produces spores, while the gametophyte is the reduced, less visible phase that produces gametes (sex cells)

b. Spores vs. Seeds

Seed have an embryo (sperm+egg) encased in a protective coat, while spores are unicellular units that develop into an organism under specific conditions. 

Xylem transports water and dissolved minerals from the roots to the leaves

Phloem transports nutrients produced by photosynthesis from the leaves to roots