Lecture 12 bi 101

Class Overview

• Focus on cells in the context of organisms: monarch butterflies and milkweed.

• Exam 2 scheduled for Thursday, November 14th.

  • 24-hour exam window on Moodle.

  • Individual exam format: 1.5 hours once started.

Class Adjustments

• Received feedback on course structure; will slow down lectures to improve engagement and understanding.

• Encourage light note-taking; full notes can be made using recordings available on Moodle.

Environmental Context

• Changes in environment noted:

  • Reduction in sunlight hours and drop in temperatures with the season.

  • Reminder for self-care as winter approaches; importance of mental and physical well-being.

Exam Preparation

• Introduced study guide for Exam 2; use of interactive discussions to identify confusing topics.

• Discussed strategies for prioritizing study time and tackling difficult concepts.

Monarch Butterflies

• Monarchs as a case study for cellular functions:

  • Unique migration patterns; travel up to 3,000 miles.

  • Declining populations due to habitat loss and climate change.

  • Significant lifecycle differences, with multiple generations per year.

• Importance of milkweed as a habitat and food source.

Migration Patterns

• Two main populations in North America:

  • East of the Rockies (overwinter in Florida and Mexico).

  • West of the Rockies (overwinter in California and Baja California).

  • Migration driven by environmental cues and needs for food sources.

Factors Affecting Monarch Populations

• Decline linked to:

  • Habitat destruction.

  • Climate change and increased temperatures.

  • Increased pesticide use.

• Discussion on the ecological importance of butterflies:

  • Pollination and ecological balance.

Photosynthesis in Milkweed

• Overview of photosynthesis process:

  • Light reactions and Calvin cycle explained.

  • Roles of water, light, and carbon dioxide in producing glucose.

Uses of Glucose in Plants

• Milkweed utilizes glucose for:

  • Cellular respiration to produce ATP.

  • Structural support (cell walls).

  • Nectar production for feeding butterflies.

Nectar Composition

• Nectar contains glucose, sucrose, and fructose:

  • Production processes discussed including hydrolysis and dehydration synthesis.

• Monarch butterflies convert sucrose in nectar to glucose using enzymes.

Mutualistic Relationship

• Monarchs and milkweed are in a mutualistic relationship:

  • Pollination and food source dependence highlighted.

• Speculation on extinction implications:

  • Extinction of either species could lead to detrimental effects on the other.

Conclusion

• Emphasis on interconnectedness of ecosystems, highlighting relationships between organisms, including photosynthesis and respiration.