IB Biology SL Notes

Summary:

This “IB Biology SL” is an in-depth and informative note designed to provide students with a thorough understanding of biological concepts at the standard level. The note encompasses key topics, including cell biology, which delves into the structure and function of cells, molecular biology, which explores the interactions and processes of biomolecules; and genetics, which examines the principles of heredity and gene expression. Additionally, the note covers ecology, focusing on the relationships between organisms and their environment, and human physiology, which investigates the various systems that contribute to the overall functioning of the human body. This comprehensive resource equips students with a strong foundation in biology for academic success and future pursuits in the field.

Excerpt:

IB BIOLOGY SL NOTES

Calculating Cell Size + Magnification
➔ Magnification = Image Size/Actual Size
➔ Actual Size = Image Size/Magnification
➔ 1 mm = 1000 µm
1 cm = 10 000 µm

Data processing and graphing
● Use a ruler to find values
● Never say “amount” or “size”
● When comparing – use at least 3 values on the graph, X and Y

MICROSCOPY
Light microscopes
– illuminating source is light
– living or dead organisms
– up to 1500x magnification
– image is coloured
– lower resolution

Electron microscopes
– illuminating source is a stream of electrons
– only dead organisms
– up to 300 000x magnification
– image is black and white
– higher resolution

CELL BIOLOGY
Mitosis: division of nucleus into two genetically identical daughter nuclei
➔ Prophase: the nucleus is still intact, but the envelope is gone, DNA is condensing, and centrioles (only in animal cells) begin to move
➔ Metaphase: chromosomes line up in the middle of the cell, centrioles on opposite ends of the cell, begin to produce spindle fibres/microtubules, attach to centromeres
➔ Anaphase: chromosomes move too far sides of the cell, helped by spindles
➔ Telophase: chromosomes split up + become less visible, nuclear membrane forming

IB Biology SL

➔ Interphase → G1 – S – G2
– Makes up 90% of cell cycle
– Duplication of chromosomes into two sister chromatids
– G1: protein synthesis + replication of organelles + cytoplasm…
– G0: differentiated cell
– S: DNA replication/duplication/synthesis
– G2: replication of organelles etc., preparation for division