Classifying Life's Diversity: Biology Notes

• Study notes on classifying life's diversity, viruses, bacteria, protists, multicellular organisms like plants and fungi and the animal kingdom

Classifying Life's Diversity

• The morphological species concept classifies species based on their appearance and physical traits.
• The biological species concept classifies species based on their ability to mate and produce fertile offspring.
• The phylogenetic species concept classifies species based on having a shared common ancestor but having evolved differently.
• Binomial nomenclature is a two-name system (Genus + species) used to classify organisms.
• Taxonomy is the science of classifying organisms.
• Anatomical evidence (bone structure & physical traits), physiological evidence (internal processes like metabolism), and DNA evidence (genetic similarities) are used to show how species are related.
• Phylogenetic Trees are diagrams illustrating evolutionary relationships between species.
• The three domains of life include Bacteria (prokaryotic), Archaea (prokaryotic), and Eukarya (eukaryotic).
• The six kingdoms of life include Eubacteria, Archaebacteria, Protists, Plantae, Fungi and Animalia.
• Prokaryotic cells are simple cells lacking a nucleus.
• Eukaryotic cells are complex cells possessing a nucleus.
• Dichotomous keys are tools used to identify organisms based on a series of choices.
• Biodiversity refers to the variety of life on Earth.
• Species diversity refers to the variety of species in an ecosystem.
• Genetic diversity refers to the variety of genes within a species.
• Ecosystem diversity refers to the variety of ecosystems in a region.
• Genetic diversity is essential for species survival because it allows adaptation to environmental changes, increases resistance to diseases, and helps prevent extinction.
• The biodiversity crisis refers to the rapid loss of species due to human activities like deforestation, pollution, and climate change.

Viruses

• Viruses are not considered alive because they cannot reproduce on their own and do not grow, develop, or produce energy.
• Viruses are classified by the shape and size of their capsid and by the diseases they cause.
• In the lytic cycle (active phase) the virus injects DNA/RNA, replicates rapidly, bursts (lyse) the cell membrane, killing it and infects more cells.
• In the lysogenic cycle (dormant phase) the virus injects DNA/RNA into host, but the genetic material stays hidden and replicates when the host cells replicates.

Bacteria

• Cocci (spherical), bacilli (rod-shaped), and spirilla (spiral) are shapes of bacteria.
• Pairs of bacteria are called diplo-, clumped bacteria are staphylo-, and chains of bacteria are strepto-.
• Thermophiles thrive in heat, acidophiles thrive in acidic conditions, and halophiles thrive in salty environments.
• During binary fission (asexual reproduction) the cell elongates and DNA is replicated, the cell wall and plasma membrane divide, the two DNA copies move to opposite sides, and the cell separates.
• During conjugation (sexual reproduction), a resistant bacterium grows a conjugation bridge to connect with the sensitive bacterium and copies the resistance genes making both stronger.
• Gram-positive bacteria have a thick peptidoglycan layer and stain purple, while Gram-negative bacteria have a thin peptidoglycan layer and stain pink.
• The endosymbiotic theory says that complex eukaryotic cells evolved from simpler prokaryotic cells when a large prokaryotic cell engulfed a smaller one and established a symbiotic relationship.
• Mitochondria and chloroplasts are the strongest evidence for endosymbiosis.
• Mitochondria releases energy from sugar
• Chloroplasts uses sunlight to make sugar through photosynthesis
• Other membrane-bound organelles are thought to come from the inward folding of the cell membrane similar folds created the ER and Golgi apparatus.

Protists

• Animal-like protists are heterotrophs classified by movement via pseudopods (amoeba), flagella (flagellates), or cilia (ciliates).
• Plant-like protists perform photosynthesis using chloroplasts, including diatoms, dinoflagellates, and euglenoids.
• Fungus-like protists absorb nutrients from other organisms, living or dead.
• Paramecium move using cilia features a nucleus, and vacuoles.
• Amoeba moves using pseudopodia (false feet).

Multicellular Organisms

• Millions of years ago, plants only lived in water as algae from which they can evolve to adapt to life on land.
• Multicellular algae are called seaweeds; brown, red which is the first unicellular organism, and green.
• Algae and plants both contain chlorophylls a and b, have cellulose-based cell walls, similar genetic information, and store food as starch.
• For land survival, plants needed protection from drying out, a water transport system, and a body support system.
• Non-vascular plants (mosses, liverworts, hornworts) lack true roots, stems, or leaves and are small due to the lack of support structures.
• Vascular plants include seedless vascular plants (ferns) and seed-producing vascular plants (angiosperms and gymnosperms).
• Fungi are eukaryotic, heterotrophic, multicellular, and composed of densely packed hyphae forming a mycelium in the soil, reproducing both sexually and asexually.
• Parasitic fungi absorb nutrients from living cells from a host.
• Predatory fungi have mycelia with specialized structures for trapping prey.
• Mutualistic fungi have partnerships with other organisms, often plants and protists.
• Saprobial fungi feed on dead organisms or organic wastes.
• Zygospore fungi (mold) commonly appear on food.
• Sac fungi (yeast) are the largest group of fungi that consist of single-celled yeast that develop spores.
• Club fungi (mushrooms) are typical mushrooms.

Animal Kingdom

• Invertebrates lack a backbone, while vertebrates possess one.
• Animals are classified based on differences in structure, tissues, and organ systems.
• Ectoderm, mesoderm, and endoderm are the three body layers in animals.
• Bilateral symmetry is when an organism can be divided into equal halves, whereas radial symmetry is a circular arrangement.
• Acoelomates lack a coelom and have everything packed together.
• Coelomates have their digestive tract and other organs suspended in a fluid-filled body cavity called a coelom.
• Segmentation refers to the division of the body into sections.
• Animals can exhibit complex, fast, stagnant/stationary movement, or be sessile (unmoving).
• Most animals reproduce sexually using gametic reproduction with zygotes produced by external or internal fertilization, while some can reproduce asexually.
• Animals are multicellular, eukaryotic, lack cell walls, and are heterotrophs.
• Phylogenetic trees illustrate evolutionary relationships.