bio153

Describe the morphology and lifestyle of a sponge

• sedentary suspension feeder (draw water in through side pores and out from central cavity, filter food particles in water)
• made of two cell layers, filled by the mesophyll
• good access to water so doesn't need circulatory system
• no highly differentiated tissues
• no symmetry

Why do we believe that choanoflagellates are the closest relatives to sponges?

• Choanoflagellate cells look very similar to the collar cells of sponge
• Molecular analysis also place choanoflagellate beside animal
• Some choanoflagellate have proteins to stick onto other cells to form a colony. This cells also differentiate into various cell types based on environmental cues. Scientist study these organisms to understand multicellularity

mollusca

second most diverse animal phylum (after Arthropods) with a soft body, mostly marine (some freshwater and/or terrestrial species) excreting a hard calcium carbonate shell lost/internalized in other species

What are the major features of Ecdysozoa?

• exoskeleton made of cuticle
• ecdysis

Name examples of nematodes and their importance to the human society

• caenorhabditis elegans
• importance: parasite, model organisms

Name the major groups of arthropods

- crustaceans, millipedes, insects, centipedes

Describe the major features of an arthropod body. Why do these features necessitate moulting?

• segmented body, compound eyes, fully covered in cuticle exoskeleton, jointed appendages
• exoskeleton cannot grow while the tissues do -> moult to grow

Describe the body structure of an insect

• segmented body, 3 pairs of legs, 1-2 pairs of wings

Describe the difference between incomplete metamorphosis and complete metamorphosis

• incomplete metamorphosis: gradual growth from larvae to adult through multiple moulting
• complete metamorphosis: distinct, stepwise growth from larvae to adult through pupal stage

Name the two major classes of Deuterostomes. Name some organisms who belongto these groups of animals

• echinoderm (sea stars, sea urchin), chordate

Describe the four derived traits of Chordata

• notochord
• dorsal, hollow nerve cord
• pharyngeal slits or clefts
• post-anal tail

notochord

longitudinal, flexible rod found between the digestive tube and the nerve cord (skeletal support for body, not calcified-hardened "skeleton"), in vertebrates, backbone develops around embryonic notochord

nerve cord

nerve cord of chordate embryo develops from a specific surface of the ectoderm (neural plate) that rolls and internalizes into a neural tube (dorsal to notochord), develops into brain/spinal cord

pharyngeal cleft

chordate embryos have arches and grooves that form along the outer surface of the pharynx developing into slits for some chordates, differentiate to form various muscles/tissues in humans

pharyngeal slit

allow water to pass through the body without passing through the entire digestive tract, how many invertebrate chordate feed themselves, develops into the gill slits of fish

What are the similarities and differences between a lamprey and a shark?

• similarities: vertebrate, cartilage skeleton
• differences: jaws

Cartilage skeleton

composed of extracellular matrix proteins like collagen

What are the major groups of lobe-finned fish who exist on Earth today?

• coelacanths, lung fish, tetrapod
  1) Coelacanths - "living fossil" believed to remain unchanged from ancestral shape for ~400 million years
  2) Lung Fish - fish with lungs as means for gas exchange, in addition to gills
  3) Tetrapod's - lung fish sister group adapted to land life with muscular, pectoral, and pelvic fins of lobe-finned fishes that evolved into limbs with digits

What is the difference between amphibians and their sister group, replies/mammals?How did this difference allow reptiles and mammals to adapt better to a terrestrial life?

• dual life stage (terrestrial and aquatic) vs terrestrial (contain specialized membranes to live on land)

Describe the difference between an ectotherm and an endotherm. Give a couple ofexamples of each type of organisms.

• use environment to regulate body temp vs use metabolic activity to regulate body temp

what are the major traits of mammals?

• amniotes that have hair, milk, endothermic, larger brain/ body

Name the three major groups of mammals

• monotreme, marsupial, eutherian

marsupial

embryo develops inside female body, nurtured by placenta, child born very early in development, nourished in mothers pouch with most extant marsupials living in Australian region, opossums, kangaroos, koalas, etc

eutherian

more-complex placenta than marsupials with various life forms/habitats, wide variety of tooth size/shape adapted for chewing many different foods, longer pregnancies, embryonic development within uterus, eat wide food range, tooth variety reason for success

Describe how digestive system of marsupial and placental mammals have evolved to adapt to their various foods and lifestyles

• carnivores: Need to eat large when they can, long intervals between feeding -> Large, expandable stomachs are common
• herbivores: Vegetation is more difficult to digest rather than meat because of cell walls -> Herbivores and omnivores have longer alimentary canals relative to body size, as compared to carnivores -> Longer digestive tract furnishes more time for digestion and more surface area for absorption of nutrients
• Mutualistic gut microbiome is especially important in herbivores: Many herbivores host various mutualistic bacteria and protists in fermentation chambers of their alimentary canals
• ruminants mix their food with mutualistic microbes in their multiple stomachs and regurgitate/re-chew them before full digestion

What are the defining traits of a primate? The defining traits of apes?

• Primates
• Three groups: Lemurs, lorises and bush babies; Tarsiers; Anthropoids: monkey, apes
• Earliest known primates were tree dwellers
• All primates have thumbs that is separate from other gingers to easily grasp branches
• All monkey and apes have fully opposable thumb
• Eyes on one side of the face -> better depth of perception
• Large brain, short jaws, flat face
• Well developed parental care and complex social behavior
• Apes:
• Usually taller than monkeys
• No tail
• Only gibbons and orangutans are primary arboreal
• No bipedal locomotion

what are humans

• 0.2 millions years old
• bipedal locomotion
• Language, symbolic thought, artistic expression, manufacture and use of complex tools
• Reduced jawbone, jaw muscles, shorter digestive tract