IB Biology 2016 syllabus

1. 4. UNICELLULAR,
MULTICELLULAR & CELL
DIFFERENTIATION
1.1 – Organisms
consisting of only one cell
carry out all functions of
life in that cell

2. FUNCTIONS OF LIFE
o All organisms carry out the following functions of life, regardless of
whether they exist in unicellular or multicellular forms:
o Nutrition – obtaining food to provide energy for growth
o Metabolism – chemical reactions inside cells
o Growth – an irreversible increase in size
o Response – the ability to react to changes in the environment
o Excretion – Getting rid of waste products of metabolism
o Homeostasis – keeping the conditions inside the organism within tolerable limits
o Reproduction – producing offspring either sexually or asexually
o Viruses?

3. PRACTICAL –
INVESTIGATING THE
FUNCTIONS OF LIFE
1.1 – Investigation of
functions of life in
Paramecium and one
named photosynthetic
unicellular organism

4. 1. THE MICROSCOPE
A. Eye piece
B. Focus knob
C. Fine focus knob
D. Low power objective
E. High power objective
F. Nose piece
G. Stage
H. Micro-slide clips
I. Sub-stage condenser
J. Iris diaphragm
K. Filter holder
L. Condenser knob
M. Mirror

5. PARAMECIUM

6. CHLAMYDOMONAS

7. YOUR TURN
o Carefully read through the sheet provided “Using light microscopes”
taken from Allott.
o Complete the worksheet “Prac 2: Functions of life in unicellular
organisms”

8. 4. UNICELLULAR,
MULTICELLULAR & CELL
DIFFERENTIATION
1.1 – Multicellular organisms
have properties that emerge
from the interaction of their
cellular components
1.1 – Specialized tissues can
develop by cell differentiation in
multicellular organisms
1.1 – Differentiation involves
the expression of some genes
and not others in a cell’s
genome

9. MULTICELLULAR ORGANISMS
o Some unicellular organisms live together in colonies. Although the
cells are cooperating, they are not fused together to form a single cell
mass so are not a single organism.
o Organisms consisting of a single mass of cells, fused together, are
multicellular
o Multicellular organisms begin as a single cell which produces many
copies of itself at a rapid rate. These cells then undergo
differentiation and specialisation
o The properties of multicellular organisms arise from the interaction
of their components (their differentiated cells)
o This is sometimes summed up with the phrase: the whole is greater
than the sum of its parts

10. CELL DIFFERENTIATION
o In multicellular organisms different cells perform different functions.
This is called division of labour
o A group of specialised cells that perform the same function is called
a tissue
o By becoming specialised, the cells in a tissue can carry out their role
more efficiently than if they had many different roles
o They can develop the ideal structure for their function
o The development of cells in different ways to carry out specific
functions is called differentiation
o In humans there are 220 different, highly specialised cell types, all
of which develop by differentiation and all of which contribute to the
overall functioning of the organism in their own way

11. DIFFERENTIATION AND CELL
REPRODUCTION
o In multicellular organisms many cells have the ability to reproduce
themselves – this allows for growth and for replacement of
damaged/dead cells
o Multicellular organisms begin as a single cell which has the ability to
reproduce at a very rapid rate. The resulting cells then go through a
differentiation process to produce all the required cell types
necessary for the well-being of the organism
o Differentiation is the result of the expression of certain specific
genes but not others.
o Genes, segments of DNA, enable the production of all the different
cells in an organism. However, each cell will become a specific type of
cell depending on which genes becomes active.

12. DIFFERENTIATION AND CELL
REPRODUCTION
o Some cells cannot reproduce once they become specialised e.g.
nerve and muscle cells
o Skin (epithelial) cells can reproduce throughout their life
o Cancer cells are examples of cells that undergo extremely rapid
reproduction with very little or improper differentiation. The result is
a mass of cells (a tumour)
o There are populations of cells within organisms that retain their
ability to divide and differentiate into various cell types – stem cells
o Using the SEM to see cell differentiation

13. PRACTICAL – WET MOUNTS
OF PLANT CELLS AND
PREPARED SLIDES OF
ANIMAL CELLS
1.1 Skill – Use of a light
microscope to investigate
the structure of cells and
tissues, with the drawing
of cells

14. SOME OF THE SLIDES YOU WILL BE
LOOKING AT

15. PRACTICAL – LOOKING AT
DIFFERENTIATED CELLS
USING A LIGHT MICROSCOPE
1.1 Skill – Use of a light
microscope to investigate
the structure of cells and
tissues, with the drawing
of cells

16. SOME OF THE SLIDES YOU WILL BE
LOOKING AT

17. PALISADE MESOPHYLL CELL
o These cells are found in the upper part of the leaf, just below the upper
epidermis. They are the site of the majority of the photosynthesis
performed by the leaf.

18. XYLEM VESSEL
o Xylem vessels have become specialized for the transport of water and
mineral salts from the roots to all the other parts of the pant. They are
especially important in the supply of water to the leaf cells for
photosynthesis and in maintaining the ‘transpiration stream’.

19. PHLOEM VESSEL
o Phloem has become specialised for the transport of nutrients/sugars
produced by photosynthesis. They transport these from the leaves
(sites of photosynthesis) to every other cell in the plant that requires
these.

20. STOMATAL PORE WITH GUARD
CELLSo Most stomata are found on the undersurface of leaves (sometimes they are
on the stems).
o The hole in the centre is the stomatal pore and it allows carbon dioxide to
diffuse into the leaf for the purpose of photosynthesis. Oxygen (a waste
product of photosynthesis) and water vapour also exit the leaf via the
stomatal pores.
o On either side of the pore are the kidney shaped guard cells. They can
change shape to open and close the pore. This occurs due to changes in the
turgor of (the amount of water in) the guard cells.

21. SMOOTH MUSCLE / INVOLUNTARY
MUSCLE
o These cells are found mainly in the walls of organs like the digestive
system, the trachioles of the lungs and the walls of arteries and veins.
Smooth muscle is not under the voluntary control of the nervous system.
Their contraction is less strong than that of striped muscle but they do not
tire as easily.

22. VOLUNTARY OR STRIPED MUSCLE
o This is the type of muscle attached to the skeleton. It is capable of pulling
strongly but it does tire easily. The stripes in the muscle fibres are caused
by specialized protein filaments inside the cells which are involved in the
contraction process. Many muscle fibres are multi-nucleated (note:
exceptions to cell theory)

23. MOTOR NEURON
o Motor neurons carry impulses from the central nervous system to the
effectors (muscles or glands). The nerve cells body of the neuron is in the
white matter of the brain or spinal cord and the long thin axons will
terminate in the effector.

24. SPERM/ SPERMATOZOA
o Sperm are the male gametes. They are produced in the seminiferous
tubules of the testes. After meiosis has halved the chromosome number, the
cells differentiate into spermatozoa.

25. WHITE BLOOD CELL/ LEUCOCYTES
o There are a number of different types of white blood cell. Each performs
specific functions within the immune system. White blood cells are all larger
than red blood cells (Erythrocytes) and all have a nucleus. In some types the
nuclei are lobed.
Leukaemi
a

26. YOUR TURN
o Complete the worksheet and the practical “Prac 4 – Cell
differentiation”

27. PRACTICAL – USING
SCALES/SCALE BARS TO
CALCULATE ACTUAL SIZE OF
DIAGRAMS AND SUBCELLULAR
1.1 Mandatory Prac -
Calculation of the
magnification of drawings
and the actual size of
structures and
ultrastructures shown in
drawings or micrographs

28. YOUR TURN
o Complete the worksheet “Microscopy and Scales”