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Biology IGCSE Revision
Chapter 01: Life Processes
-

All Living Organisms are composed of cells
The simplest organisms = Single Celled
: More complex ones = Plants, Animals = Multicellular Organisms
➔ Complex Organisms have different types of cells which are SPECIALISED for a specific
function

THE LIFE PROCESSES
1
...
Nutrition
: If PLANT = Making own food through photosynthesis
: If ANIMAL = Eating other organisms
3
...
Control
: Focusing on INTERNAL conditions
5
...
Movement
: If PLANT = Slow growth movements
: If ANIMALS = Movement of muscles
7
...
Excretion
: Process of getting rid of toxic, waste products
CELL STRUCTURE
Nucleus

Cell Membrane
Cytoplasm
Mitochondria

Name

CYTOPLASM

Photo

In Animal Cell

YES

In Plant Cell

Function

YES

It’s the living material that makes up a cell
...
It is
made up of many different structures, and many are too small to be seen on
a microscope
...


Name

NUCLEUS

Photo

In Animal Cell

YES

In Plant Cell

Function

YES

The largest organelle in a cell, and nearly every cell has one (exceptions are
xylem, red blood cells)
...


Name

MITOCHONDRION

Photo

In Animal Cell

YES

In Plant Cell

Function

YES

This is in the organelle that is found in all living cells
...
They carry out some reactions
for respiration and most energy from respiration is released from
mitochondria
...

It is NOT a barrier, the membrane can choose certain chemicals to pass into
and out of the cell = it is SELECTIVELY PERMEABLE
...
This is
because they can absorb light energy to photosynthesise
...


CELL WALL

Photo

In Animal Cell

Function

NO

In Plant Cell

YES

This layer is non-living, and surrounds the cell membrane
...
Cellulose helps keep the
shape of the cell, which means when water is absorbed, the internal pressure
rises, giving the cells more support
...


Name

VACUOLE

Photo

In Animal Cell

NO

In Plant Cell

Function

YES

MATURE Plant Cells have a vacuole
...
It’s filled with CELL SAP, which has dissolved sugars,
mineral ions and other solutes
...

: Enzymes = Proteins = Biological Catalysts
: Can take part in one reaction, then can catalyse more reactions
- They control the reactions within the cell
- Each cell has HUNDREDS of different enzymes
: Each one can focus on a certain reaction
- How activity of cell is controlled
: GENES >>> Proteins (ENZYMES) >>> CATALYSES Reactions
: Everything cell does depends on enzymes made
- Are NEEDED because
: At normal temperatures (e
...
Human = 37°C) reactions would be TOO SLOW
ENZYMES: LOCK AND KEY
- We can have many different enzymes because of huge VARIETY in SHAPE + STRUCTURE
: Enzymes = Proteins = Protein Molecules have many different shapes
- SUBSTRATE = The MOLECULE the enzymes acts on
- ACTIVE SITE = An AREA on the surface of an enzyme where REACTION TAKES PLACE
- SUBSTRATE + ACTIVE SITE = LOWERS the Activation Energy for reaction to start = take place
more easily

FACTORS AFFECTING ENZYMES
1
...
)

-

37°C = OPTIMUM TEMPERATURE
As temperature rises towards 37°C, rate of reaction speeds up
: The heat breaks down the protein
From 40°C upwards = heat DESTROYS the enzyme
: Like boiling an egg >>> The clear liquid becomes a white solid = caused by denaturing

2
...
g
...
g
...
g
...
Using a syringe, Put 5cm3 of STARCH SUSPENSION in a boiling tube
2
...
Fill a beaker with water (at 20oC), and place BOTH tubes in the beaker for five minutes
: Record the temperature of both solutions
4
...
Using a syringe, place a drop of iodine on each spotting tile
6
...
Repeat this every 30 seconds for 10 minutes
8
...
0-8
...
5-9
...
5-10
...
0-5
...
0-6
...
0-10
...
0 minutes

0
...
0-10
...
0-1
...
0-3
...
5-10
...
0-7
...
5-8
...
5-10
...
g
...
g
...
MUSCLE Cells
-

YEAST EQUATION
Glucose ---------->
C6H12O6 ---------->

Carbon Dioxide +
6CO2
+

: Produces ETHANOL
➔ Good for Beer and Wine
➔ CO2 from this is good for baking bread

Ethanol
(+ some energy)
2C2H5OH (+ some energy)

-

MUSCLE EQUATION
Glucose ---------> Lactic Acid
C6H12O6 ---------> 2C3H6O3

(+ some energy)
(+ some energy)

: Produces LACTIC ACID
➔ Can give people pain => constant production of the acid causes cramps
➔ People need to rest to allow the oxygen (from OXYGEN DEBT) to oxidise the acid
EXPERIMENT 2: The Production of Carbon Dioxide by Small Living Organisms
- Hydrogencarbonate Indicator Solution can tell us if CO2 is present
: It’s normally ORANGE but turns to YELLOW when CO2 is present
➔ Smallest difference makes colour change

1
...
Use a stopper to block any CO2 from the atmosphere influencing the results
3
...
Put each living organism in each boiling tube
: Be careful not to let too much air in
5
...
Gather some peas, and split them equally in half
2
...
Soak the other ones in water for 24 hours, this will make sure they are germinating
4
...
Rinse each set of peas TWICE, to get rid of any bleach in the peas
6
...
Put a thermometer in the flask, and put cotton wool at the bottom, to hold the thermometer in
place
: The cotton wool can absorb the CO2 produced from respiration
: CO2 is denser than air, so it will sink to the bottom of the inverted flask
8
...
Measure the temperature after two days, and compare to previous results
RESULTS
Before

After TWO Days

Flask with Boiled Peas

21oC

21 oC

Flask with Germinating Peas

21oC

24 oC

MOVEMENTS OF MATERIALS IN AND OUT OF CELLS
- From Cell Respiration, we knew there has to be a way cells can
: GET RID OFF SUBSTANCES (e
...
Carbon Dioxide)
: TAKE THEM IN (e
...
Glucose, Oxygen)
- Three main ways this happens:
1
...
Osmosis
3
...
g
...
g
...
g
...
g
...
), into the millions = MITOSIS
- Cell Division = Zygote >>> EMBRYO
: Certain cells will become specialised for certain functions = DIFFERENTIATION
- Different cells develop DEPENDANT on where they are
: e
...
NERVE CELL in the SPINE, or EPIDERMAL CELL on the (outer layer of the) SKIN
➔ NERVE CELL has AXON to carry nerve impulses
➔ SPERM CELL has a TAIL so it can swim to egg

SPERM CELL
NERVE CELL

CELLS, TISSUES and ORGANS
Organelle >>> Cell >>> Tissue >>> Organ >>> Organ System >>> Organism
e
...
Nucleus >> Nerve Cell >>> Nervous Tissue >>> Brain >>> Central Nervous System >>>
Human
-

Cells with a SIMILAR Function that are grouped together = TISSUE
: e
...
Muscle Tissue, Blood Tissue
Many Tissue with a SIMILAR Function that are grouped together = ORGAN
Different Organs working together = ORGAN SYSTEM
: e
...
Digestive System, Respiratory System, Circulatory System, Excretory System



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