IB Biology HL 1
Unit 1: Cells, Fall 2015
Topic 1.1 Introduction to Cells
Essential Idea: The evolution of multicellular organisms allowed cell specialization and cell replacement.
Nature of Science: Looking for trends and discrepancies- although most organisms conform to cell
theory, there are exceptions. (3.1) Ethical implications of research – research involving stem cells is
growing in importance and raises ethical issues. (4.5)
Understandings:
1. According to the cell theory, living organisms are composed of cells.
2. Organisms consisting of only one cell carry out all functions of life in that cell.
3. Surface area to volume ratio is important in the limitation of cell size.
4. Multicellular organisms have properties that emerge from the interaction of their cellular
components.
5. Specialized tissues can develop by cell differentiation in multicellular organisms.
6. Differentiation involves the expression of some genes and not others in a cell’s genome.
7. The capacity of stem cells to divide and differentiate along different pathways is necessary in
embryonic development and also makes stem cells suitable for therapeutic uses.
Applications and Skills:
1. A: questioning the cell theory using atypical examples, including striated muscle, giant algae, and
aseptate fungal hyphae.
2. A: Investigation of functions of life in Paramecium and one named photosynthetic unicellular
organism.
3. A: Use of stem cells to treat Stargardt’s disease and one other named condition.
4. A: Ethics of the therapeutic use of stem cells from specially created embryos, from the umbilical
cord blood of a new-born baby and from an adult’s own tissues.
5. S: Use of a light microscope to investigate the structure of cells and tissues, with drawing of cells.
Calculation of the magnification of drawings and the actual size of structures and ultrastructures
shown in drawings or micrographs (Practical 1)
Topic 1.2 Ultrastructure of Cells
Essential Idea: Eukaryotes have a much more complex cell structure than prokaryotes.
NOS: Developments in scientific research follow improvements in apparatus – the invention of the
electron microscope lead to greater understanding of cell structure (1.8)
Understandings:
1. Prokaryotes have simple cell structure without compartmentalization.
2. Eukaryotes have a compartmentalized cell structure.
3. Electron microscopes have a much higher resolution than light microscopes.
Application and Skills:
1. A: Structure and function of organelles within exocrine gland cells of the pancreas and within
palisade mesophyll cells of the leaf.
2. A: Prokaryotes divide by binary fission.
3. S: Drawing of the ultrastructure of prokaryotic cells based on electron micrographs
4. S: Drawing of the ultrastructure of eukaryotic cells based on electron micrographs.
5. S: Interpretation of electron micrographs to identify organelles and deduce the function of
specialized cells.
Topic 1.5 The Origin of Cells
EI: There is an unbroken chain of life from the first cells on Earth to all cells in organisms alive today.
NOS: Testing the general principles that underlie the natural world: the principle that cells only come
from pre-existing cells needs to be verified.
Understandings:
1. Cells can only be formed by division of pre-existing cells.
2. The first cells must have arisen from non-living material.
3. The origin of eukaryotic cells can be explained by the endosymbiotic theory.
Applications:
1. Evidence from Pasteur’s experiments that spontaneous generation of cells and organisms does
not now occur on Earth.
Vocabulary:
Cell theory
Metabolise
Excrete
Respond
Homeostasis
Magnification
Differentiate
Differentiation
Pluripotent
Totipotent
Multipotent
Prokaryotic
Eukaryotic
Cell wall
Plasma membrane
Chromosome
Ribosome
Cytoplasm
Flagellum
Pili
Eukarytotic
Organelle
Practice Work: (Practice may be added or deleted)
 Read Ch. 1: 1.1 pg. 4-11, 1.2 pg. 12-24, 1.5 pg. 38-40
 Exercises: pg. 11 (1-4), pg. 26 (6-11), pg. 40 (19-20)
 Challenge Yourself pg. 14 (5), pg. 39 (14)
 Microscope Practice 1 and 2
 Surface Area Activity
 Magnification Practice
 Stem Cell Activity
 Cell Drawings
 Paramecium and Chlorella Lab
 Unit Review
Practice Work Due: Thursday, October 15
Assessment Dates: Paper 1 and Paper 2 Thursday, October 15
Nucleus
Nuclear envelope
Nucleolus
Endoplasmic reticulum
Vesicle
Cisternae
Golgi apparatus
Mitochondrion
Lysosome
Chloroplast
Vacuole