UNIT 4 DAY 5 - OUR FAMILY TREE Flashcards
1
Q
chordates are defined by possession of the following 4 derived characters
A
- dorsal hollow nerve chord –> transmits information across the body
- notochord –> stiff but flexible rod, supports the body
- pharyngeal sites –> food particles in water are collected here as they pass from mouth through slits and out again
- post anal tail –> muscle in tail provides propulsion
2
Q
original chordate possessed
A
- one set of hox genes –> controls head to tail organisation during development
3
Q
living example of chordate
A
- amphioxus
- buried in sand
- amphioxus sedentary filter-feeders
- sister group of craniates –> active hunters
4
Q
craniates
A
- buried in sand
- amphioxus sedentary filter-feeders
- sister group of craniates –> active hunters
5
Q
craniates are defined by possession of the following derived characters
A
- sense organs: (nose, eyes, inner ears), products of the outgrowth of the front end of dorsal hollow nerve cord
- brain: evolved in front part of the nerve to process the information coming from sense organs and to send instructions to the muscles
- skull: a sensitive equipment needed for protection
- neural crests: skull comes from new embryonic tissue derived from the neural tube
6
Q
craniates
A
- need more genes to control early development, became available when gene duplications arose by mutations
- entire set of Hox genes were duplicated
- have high metabolic rate –> need more efficient ways of extracting oxygen from water and delivering this oxygen to the body
7
Q
craniates delivering oxygen
A
- pharyngeal slits of amphioxus, used to filter food particles from water evolved into pharyngeal gill slits, instead extract oxygen from water by diffusion to capillary bed
- 2 chambered heart delivers oxygenated blood via circulatory system to capillary beds, when oxygen diffused from blood into body cells
8
Q
living example of craniates
A
hagfish
9
Q
vertebrates derived characteristics
A
- improvements in skeleton and gills
- vertebral column replaces notochord –> surrounds and protects dorsal, hollow nerve cord
- different set of developmental genes (DIx genes) are duplicated
10
Q
vertebrate groups that are still alive
A
- hagfish
- lampreys
- gnathostomes
11
Q
Gnathostomes derived characteristics
A
- jaws, with teeth
- 2 sets of paired fined (stability in swimming)
- second duplication of hox genes
- lateral line
12
Q
cartilaginous fishes
A
skeleton made from cartilage
13
Q
Bony “fishes” derived character
A
- possession of a lung
14
Q
living example of bony “fish”
A
polypterus
15
Q
ray-finned fish derived traits
A
- possession of a swim bladder
- an organ of buoyancy
- swim bladder lost connection to esophagus air can’t be added by gulping with the mouth
- gas secreted into it via circulatory system
