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Welcome back!. Please put your prelab out on your desk for a stamp. If you have your permission slip AND $10, get those out, too. Please read the entire board. Thanks!. Salinity Lab. Seeds only germinate under certain conditions. Terrestrial seeds do not germinate in salty water. Duh.
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Welcome back! • Please put your prelab out on your desk for a stamp. • If you have your permission slip AND $10, get those out, too. • Please read the entire board. • Thanks!
Salinity Lab • Seeds only germinate under certain conditions. • Terrestrial seeds do not germinate in salty water. Duh. • So when is this a real problem? • Continuous irrigation with ground water increases Ca2+ and Mg+ ions in topsoil • Ike storm surge brought salt water 20 miles inland creating super salty conditions in marshes • Madagorda Bay – salinity levels threatened by decision to hold back more river water for cities
Salt water solution • 10% by volume • How can you dilute to desired salinity?
Today: • Get in assigned lab groups • Compare prelab plans • Determine procedure for group • Get teacher approval of plan • Set up lab (should be done by _____) • Write your hypothesis (pick a specific %NaCl solution)
Writing your hypothesis • Purpose: What level of salinization will cause mung bean seed germination to change visibly? • Hypothesis • Which two magic words? • Must be SPECIFIC • Yours can be different from your lab groups’ • Write it now
How will we measure germination? • Must be consistent among and between groups. • Process of germination: • Seed absorbs water and swells • Seed coat cracks open (green on mung beans) • Rootlet emerges • Cotyledons emerge (first proto leaves)
Coastlines experience two high and two low tides per day. • As the tide goes out, some water is left behind in sandy depressions or in areas around rocks.
Observations? • Inferences?
Starfish are keystone predators which prey on mussels, increasing diversity. (Dominant mussel cannot out-compete others.)
The mussel is pulled apart • Tubefeet pull the mussel apart. The stomach is inverted out of the starfishes mouth, and the mussel is digested and absorbed.
Range of tolerance: • Range of chemical or physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally.