Molecular Orbitals and Period 2 Diatomic Molecules (Sections)
Draw a picture that shows all three 2p orbitals on one atom and all three 2p orbitals on another atom.
(a) Imagine the atoms coming close together to bond. How many π bonds can the two sets of 2p orbitals make with each other?
(b) How many p bonds can the two sets of 2p orbitals make with each other?
(c) How many antibonding orbitals, and of what type, can be made from the two sets of 2p orbitals?
Midterm 3 Study Guide Animal Diversity and Evolution notes 3 Domains 1. Bacteria 2. Eukarya 3. Archaea Eukaryan Diversity -protists -plants -fungi -animals Choanoflagellates sister group of animals Metazoans another name for animals There are more animals than any other group. 70% of them are insects (number of species) Prokaryotes have been around longer than animals What are animals 1. Multicellular 2. Ingestive heterotrophs 3. Move under volition 4. Lack cell walls, but have extracellular matrix 5. Unique, specialized cells: muscle and nerve cells 6. Sexual reproduction 7. 2n dominant 8. Flagellated sperm, non-motile egg 9. Most have larval stage 10. Cells organized into tissues 11. Conserved genes control development (hox genes) 12. Zygote undergoes cleavage, forms blastula gastrulation I-Clicker question: Nearly all animal phyla evolved in which era A: Cambrian Eumetazoa true tissues Metazoa basal node -sponges are most primitive Origin of multi-cellularity -choanoflagellates are the unicellular sister group to animals -similar to sponges Origin of bilateral symmetry, nervous system, and cephalization -cephalization to form a head -sponge has no symmetry -radial symmetry flower -bilateral symmetry ability to form a head. Example beetles Echinoderms -sea stars have pentaradial symmetry but their larvae have bilateral symmetry Bilateral symmetry -nervous system is located at the head which aids in directionality -become effective predator and consumer Bilateria -genetic mechanism that is responsible for bilateral symmetry and cephalization Embryonic tissue -diplobastic 2 tissue layers -triploblastic 3 tissue layers Origin of coelom -animals are tubular Acoelomate doesn’t have a coelem Coelomate coelom lies within the mesoderm Pseudo coelomate false coelom. Has a body cavity that is touching both the mesoderm and endoderm I-Clicker Q: Do jellyfish have a coelom A: No Protostome and deuterostome development Protostome means “first mouth” -Spiral and determinate cleavage -First hole that develops is the mouth Deuterostome means “second mouth” -Radial and indeterminate cleavage -Fate of cell not yet determined -First hole that is formed is the anus Deuterostome evolved once, protostome evolved a few times Deuterostome -humans -Chordata -Echinodermata -Hemichordata Almost everything else is a protosome Origin of Segmentation -all animal groups show segmentation -hox genes common genes for segmentation Benefit of segmentation -different parts of the body can specialize for different functions Invertebrates I Notes Big 9 Animal phyla 1. Porifera (sponges) a. Habitat mostly marine b. Motility sessile c. Diet filter feeding 2. Cnidaria a. Habitat mostly marine b. Motility motile and sessile c. Diet Predatory and filter feeder d. Diversity more than 10,000 species 3. Platyhelminthes (flat worm) a. Habitat moist habitats b. Motility motile c. Diet predator or parasite d. Diversity 25,000 species 4. Mollusca a. Habitat marine, fresh water, terrestrial b. Motility motile and sessile c. Diet predatory, filter feeder, or detrivores d. Diversity 85,000 species 5. Annelida a. Habitat marine, fresh water, terrestrial b. Motility motile and sessile c. Diet predator or parasite 6. Nematoda (most abundant) a. Habitat all habitats b. Motility motile c. Diet parasite or free-living d. Diversity 15,000 species 7. Arthropoda a. Habitat Marine, fresh water, terrestrial b. Motility Motile c. Diet several forms d. Diversity millions 8. Echinodermata (starfish) a. Habitat marine b. Motility motile c. Diet filter feeders 9. Chordata a. Habitat Land, marine, fresh water b. Motility motile c. Diet Lots of forms of feeding Majority of species are found in water, but the most divers (the big 9) are found on land Week 10 Notes Invertebrates II (Lophotrochozoa) Monophyletic group shared ancestry Paraphyletic group exclude a descendent Polyphyletic group includes group of different ancestors Clade monophyletic group I-Clicker question: Where did triploblastic tissue arise Hermichordata Where did deuterostome development arise Deuterstomia Where did bilateral symmetry arise Bilateria 3 Major clades of Bilateria 1. Deuterstomia 2. Lophotrocozoa 3. Ecdysozoa Lophotrocozoa -united by molecular characters -most divers body plans -largest number of phyla 1. Platyhelminthes- flat worms a. Acoelomate b. Flat bodies for a greater surface area to volume ration c. Gas exchange across body surface d. Gastrovascular cavity (not a tube) e. Majority are parasitic, some are free-living f. Have more than one host g. Definitive host used for sexual reproduction h. Intermediate hosts where larvae grow 2. Mollusca a. More than 85,000 species b. Second to arthropods c. Soft body and hardened shell of calcium carbonate d. Shared body plan e. Radula f. 80% are snails and slugs g. Cephalopods are neurologically advanced h. Some are toxic i. Most endangered group 3. Gastropods a. Snails and slugs b. Marine, fresh water, terrestrial c. Mantle what secretes calcium carbonate 4. Bivalves a. Clams, mussels, oysters b. Marine and freshwater c. Have 2 shells d. Foot helps them move and keep in place 5. Cephalopods a. Octopus, squid, nautilus b. Camouflage and chromophores c. Reduced mantle d. Advanced eye, behavior, and intelligence 6. Mollusks a. Most endangered b. Recently discovered that they make the world’s strongest material c. Have visceral, mass and foot Annelida (segmented worms) -chaetae bristles mad of chitin -predators 1. Marine worms a. Errantians-> mobile predators b. Sedentarians sessile 2. Leeches a. Secrete anesthetics and hirudin 3. Earth worms a. Move nutrients and aerate soil b. Common in North America but aren’t native Invertebrates III Exdysozoa Loveifera Priapula Nematoda Arthropods Ecdysozoa most diverse animal group -external covering -ecdysis molt with growth 1. Nematoda-round worms a. 15,000 species b. Important in decomposition c. Motile d. Cdenorhaloditis elgans i. 1 mm long, simple ii. 959 cells, all mapped used in research 2. Arthropoda a. Most diverse b. Most successful of all animal phyla Myriapods -most ancient lineage -may have been the first to colonize land Trilobites -extinct Crustaceans and insects -insects are a group within Crustacea Characteristics of Arthropod -segmented body abdomen, thorax, head/ cephalon -spiders the head and thorax are compined -they have paired limbs -hardened exo-skeleton and chitin. Exo-skeleton also acts as muscle attachment -jointed appendages -open circulatory system -have a heart, but don't have vessels -hemolymph circulates through hemocoel Insects are most divers -most are beetles Chelicerata (spiders, mites, scorpions) -chelicerae feeding appendages. Some are modified to inject venom -cephalothorax -abdomen -4 pairs of walking legs -pedipalps modified limbs with several function on the cephalothrax Crustacea (crabs, shrimp, copepods, barnacles, amphipods etc) -many pairs of walking legs -antennae evidence that insects and crustacea are related -cephalon, thorax, abdomen -most numerous animals on Earth -highly variable characteristics Barnacles -evolutionary constraints -sessile -modified legs filter feed -sexually reproduce through intermittent organ Insecta (beetles, butterflies, ants, bees, cockroaches, flies etc) -abdomen, thorax, head -antennae -wings for true fligh -3 pairs of walking legs -metamorphosis Insect open circulation -have a heart and body cavity -vessels feed fluid through the body -hemolymph carry nutrients -Tracheae and tracheoles -holes on the outside of the body where oxygen enters -oxygen enters the tracheae pathways that travel through the body -Oxygen moves via diffusionreason why insects are small -Giant Weta is the biggest living insect Insects used to be bigger for the oxygen content of the air changed Vertebrates I (Chordate Evolution to amniotes) Deuterstomia -Echinodermata -Hemichordata -Chordata Echinodrms -stargish, sea urchins, sea cucumbers -7,000 species Chordates -65,000 species -notochord- rod in embryo becomes spine in vertebrates -dorsal hollow nerve cord- cephize head region -pharyngeal slits elements that support the gills that eventually become jaws -post and anal tail anus comes before the tail Amniotes -Reptiles -Mammalia Tetrapods -Amphibia -Reptile -Mammalia Cephalochordata -simple -bury itself in sediment -use mouth to feed -does have the ability to move Urochordata -marine -pulls water in and filters the food products -larvae have all charactrisics of chordates Vertebrates -have complex body plan due to the duplication of Hox genes -spinal cord surrounds bony vertebrae -notochord disappears in development but is present during the embryonic stage Gnatostomes (jawed mouth) -have jaws -incomplete mineralized skeleton -gene duplication -lateral line system -enhanced smell and vision -jaws arose from support structure for pharyngeal slits Osteichtyes (majority of vertebrates) bony fish -ossified means mineralized -they have a complete ossified endoskeleton -modified lungs Actinopterygii -most diverse of the vertebrate group and ray finned fishes -inhabit all aquatic habits and there are 30,000 species Lobe –Fins (sacropterygii) -lobed fins with bony and muscular support Tetrapods -4 limbs with digits -adults lack gills -vertebrae in neck= head movement -the pelvic girdle is fused to the spine Amphibia -more diverse than mammals -5,000 species of frogs and toads -700 species of salamanders and newts -200 species of caecilians. Also, caecilians can lactate Amniotes -have an amniotic egg that has specialized extraembryonic membranes that are sometimes shelled -ventilate with rib cage Reptilia -diverse -more than 20,000 species -scales composed of keratin -shelled eggs on land -internal fertilization -ectothermic and endothermic Birds, snakes, etc Vertebrates II: Mammals and metabolic trade-offs Amniotes -Reptilia and Mammalia -have the extraembryonic membrane to prevent eggs from drying out (desiccation) -this gave them the ability to colonize land Majority of reptile lineage are diapsids 3 Major groups of Mammals (also evolved froma therapsid ancestor) 1. Monotremes a. 5 species b. Don’t have nipples, lactate by sweating c. Platypuses 2. Marsupials a. Short gestation. b. Baby is born in early development c. 300 species d. Kangaroos and opossum 3. Eutherental/ Placenta a. Majority of development in gestation b. 5,000 species Most mammals are rodents and ¼ of mammal diversity comes from bats Characteristics of Mammalia -hair -no other animal group has hair -made of kertin -complex anatomy -found on all mammals in some point of their development -vibrissae whiskers -young a fed milk from modified sweat glands -exceptions are that it is found in pigeons and caecilians -large amounts of parental investment in young -gestation is more expensive than gestation Mammal characteristics -3 bones responsible for sound (malleus, incus, and stapes). Reptiles only have 1 ear bone -the dentary makes up the lower jaw -Majority of mammals, rely on sound and smell rather than sight. Primates tend to use sight more than sound and smell. -have hair and mammary glands Mammal Evolution -mammals evolved from synapsid reptiles -Plesiosaurs evolution of homoeothermy -was around before dinosaurs -able to maintain body temperature Thermoregulation Endotherm generates metablic heat Ectotherm uses environmental heat Homeotherm constant temperature Poikilotherm variable temperature Trends of mammals -increase in brain size -increase in muscle mass and muscle number -Nocturnal habits -metabolically expensive -need more food for brain and muscle development -These trends help lead to a more efficient predator for getting and consuming food Heterodonty modified teeth that increase the efficieny in processing food Secondary palate -breathe and eat at the same time -most other vertebrates, besides crocodiles, can’t do this Mammals are endothermic homeotherms -mammals that hibernate can be poikilotherm The most diverse animal phyla have colonized terrestrial habitats. Most animal phyla are found in marine habitats Amniotes have reduced their reliance on water in their reproductive cycle Body Structure and Function Natural selection acts on heritable variation to favor the most successful solutions to these challenges An adaptation may show its function. Example variety of beak shapes and sizes on birds determine their diet. Embryonic tissue develops into 4 main types of tissue 1. Connective tissue 2. Nervous tissue 3. Muscle tissue 4. Epithelial tissue Cell structure endoplasmic reticulum and Golgi apparatus Hydrodynamics is a physical constraint of the environment. Therefore, organisms that have little to know relation have similar body types, such as dolphins and sharks. This is also known as convergence evolution. Phylum Review Metazoa -multi-cellular -digestive heterotrophs Eumetazoa -true tissues Bilateria -cephalization -bilateral symmetry -tripoblastic Lophotrochozoa, Ecdysozoa, and Deuterostomia are all made up of phyla that share molecular characteristics Form and Function continued Vertebrates and flight -evolved four times: insects, pterosaurs, birds, bats -Physical constraints -flight membranes -hollow bones -small bodies Pterodactyl elongate single digit Birdfuse distal bony elements and feathers Batelongate four digits Locomotion -Adaptations for locomotion work off of the tetrapod body plan 2 patterns for form and function -Body size and surface area -homeostasis Body size and Surface area If you’re large, you need more food, take longer to mature, lose heat and water more slowly, and reproduce slowly If you’re small, you need less food, short time to mature, loose heat and water quickly, and reproduce quickly Metabolic Rate -oxygen consumption per unit time measures metabolic activity -metabolic rates vary with activity -a mouse would need more to eat than a horse for metabolic rate Body mass and life expectancy -small animals liver shorter and large animals live longer -Exceptions bats and naked mole rats As volume increases, surface area decreases Increase surface area by… 1. Flattening 2. Folding 3. Branching Salmon hatchlings oxygen exchange occurs across skin and gills. When they get older and bigger, they no longer exchange oxygen across skin Gills -increase surface area -interstitial fluid cover cells Regulating Internal Environments: Homeostasis and Thermoregulation Conformers when the environmental temperature changes, so does the body temperature Regulators- as environmental temperature changes, the body temperature stays the same Homeostasis maintain internal temperature independent of external environment Thermoconformers do not operate equally at all temperatures, they still have an optimal range of metabolic activity that is influenced by the external environment Acclimation -organisms can adjust to gradual environmental changes Homeostasis is maintained by -set point -stimulus -sensor/control center -response Negative feed back response is to minimize effect maintain homeostasis Positive feed back amplify effect not used in homeostasis Circadian rhythm temperature varies daily Homeotherm and ectotherm environment does not vary deep sea fish Poikilotherm and ectotherm amphibians, turtles, spiders Endotherm and homeotherm mice and birds Endotherm and Poikilotherm fish and bees Mechanisms for heat exchange Conduction: direct contact between solids Ex snakes sun bathing on rocks Convection: direct contact between gas or liquid Ex A dessert hare has big ears that have lots of blood vessels Radiation: No direct contact Ex Cormorant open wings to soak up sun Evaporation: high heat of vaporation Ex dogs pant and people sweat Heat flows from areas of high heat to low heat Generate and Retain heat 1. Insulation. Seen mostly in aquatic animals and endothermic homeotherms 2. Behavioral heat absorption bask in sun and sunbathe on rocks 3. Circulation system Circulatory Vasodilation and vasoconstriction move blood to surface to either be heated or cooled Countercurrent heat exchange -keep core of body warm by letting surface body become cold -Arteries and veins are located near each other -Warm blood leaves the core of body, and when it comes to extremities it becomes cold. But since arteries and veins are near each other, when the blood returns to the body it warms back up Heat production -Shivering and non-shivering thermogenesis -non-shivering relies on brown fat tissue, which gets burned for heat -some ectotherms, like snakes and bees, use shivering to generate heat Thermoregulation and Energy Conservation -Torpor: decreased physiological activity -tend to be small endotherms, such as birds and mammals that are active with high metabolic rates Hibernation: physiological activity decreases seasonally Aestivation: summer hibernation that’s often facultative -set point decreases accompanied by periodic arousals Adaptive heterothermy: endothermic animals’ body temperature changes due to environmental stress (like hibernation, aestivation, torpor etc) All mammals are endothermic, most homeothermics, and some heterothermic Diet and Digestion All animals are ingestive heterotrophs Amino acids: protein synthesis Fatty acids: fatty acid synthesis Vitamins: Organic compounds Minerals: inorganic compounds 3 Classes of Organic molecules 1. Carbohydrates 2. Proteins 3. Lipids