Yara Khnaizer 9S
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Life Processes
 Life processes are the actions that are needed to help us determine if an organism is
alive or not
 All living things must follow every single one of the life 7 life processes (MRS GREN) to be
considered alive
Movement
The action of changing position or place. Living organisms do this to look
for food and shelter, and to escape from danger
Respiration
Chemical reaction to release energy from molecules
Sensitivity
To detect and respond to changes in the environment (stimuli). This can
be an internal reaction or an external one
Growth
Increase in the number of cells
Reproduction Process to replicate cells or make more of the same species of organism.
It can be through: giving birth, laying eggs, or asexual reproduction
Excretion
Removal of metabolic waste products. Excretion gets rid of unwanted
substances
Nutrition
Taking in and using food to be provided with energy
Cells and levels of organization
 A cell is the basic unit of life and the smallest unit of a living organism
 Larger structures such as tissues and organs are made from billions of cells
Largest < - - - - - - - - - Smallest
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A tissue is a group of similar cells working together to perform a similar function
An organ is a group of tissues working together to perform a similar function
An organ system is a group of organs working together to perform a similar function
An organism is when a group of organ systems work together to form a living
being/thing
Level of
organisation
Definition
Example in
plants
Example in
animals
Cells
The smallest unit of an organism
Palisade cell
Red blood
cells
Tissues
A group of cells with a similar structure
and function, which all work together to
do a particular job
Leaf
epithelium
Stomach
lining
Organs
Made from a group of different tissues,
which all work together to do a particular
job
Leaves
Kidney
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Organ
system
Made from a group of different organs,
which all work together to do a particular
job
Photosynthetic
system
Digestive
system
Organism
group of organ systems working together
to form an individual plant, animal, or
single-celled organism
Daffodil
Human
Inside the cell
 The little structures inside cells are called organelles and they each have different jobs
that they perform within the cells
 You can see them by using microscopes – sometimes the smaller organelles need more
powerful microscopes called electron microscopes
 Organelles all have different functions which we need to keep track of:
Organelle/structure Function
Size info
Nucleus
Contains genetic material (DNA) – controls cell the largest
activity, how they grow and how they work
organelle in animal
cells
Cytoplasm
Watery/gel substance – where most chemical Takes up most of
reactions take place
the cell – fills in
space
Cell Membrane
Surrounds the cell under the cell wall –
Surrounds the cell
controls what enters and leaves the cell
Mitochondria
Carry out aerobic respiration – release of
Very small and
energy (from glucose)
need electron
microscope
Ribosomes
Where protein is made in protein synthesis –
Extremely small
site of protein synthesis
and can only be
seen with electron
microscope
Cell Wall
The outer layer of a cell – helps give the cell
Surrounds the cell
structure and shape – strengthens the cell
Vacuole
Contains cell sap – used as storage
Big – can take from
30-80% of a (plant)
cell
Chloroplasts
Site of photosynthesis – makes/provides food Very small and
(for plants) – contains chlorophyll which is
need electron
green and helps absorb sunlight energy which microscope
is needed in photosynthesis
 Which organelles are in a cell depends on the type of cell and their role
 Specialized cells are cells that have a specific role – they have organelles that help them
carry out their role
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Cell type
How is it specialised?
What does it do?
Has a thin layer of tiny
moving hairs called cilia
Move mucus,
which contains
trapped bacteria
and dust, out of
the airways (i.e.
trachea)
Ciliated cell
Red blood cell
Sperm cell
Contains haemoglobin, a
pigment that carries oxygen.
Does not contain a nucleus
which increases the volume
of haemoglobin in the cell
Very flexible so it can move
through narrow blood
vessels
Has an acrosome which
contains digestive enzymes
to break through the egg cell
membrane
Has a tail to help it swim to
the egg (ovum)
Contains many mitochondria
to provide lots of energy
Transport oxygen
from the lungs to
the body tissue
for aerobic
respiration
Carry genetic
information from
the father to the
egg during sexual
reproduction
Root hair cell
Has a long, thin extension
which provides a large
surface area for absorption
to happen
Absorb water
and minerals
from the soil
Contains lots of chloroplasts
for photosynthesis
Contains large permanent
vacuole for sap
Collects sunlight
using chlorophyll
Used for
photosynthesis
Palisade cell
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Nerve cell (neurone)
They are long, so that they
communicate with distant
parts of the body. They also
have branched endings
called dendrites. These
connect with many other
neurones.
Carry electrical
impulses
between
different parts of
the body
Egg cell (Ovum)
Used for
fertilization
The cell is large to store food
(fusing sperm
and energy. It contains a
and egg cells
great cell membrane to
together).
control what can enter and
Contains a
leave.
haploid nucleus
to contain DNA.
 Eukaryotic cells (complex cells) have their DNA surrounded by a membrane (have a
nucleus)
 Prokaryotic cells don’t have their DNA surrounded by a membrane – the DNA is “floating
around” (no nucleus)
Classification
 Classification involves grouping together organisms based on their common
characteristics. We do this to help us categorize new species, and to learn more about
the ancestry of similar organisms
 There are 6 groups of organisms
o Animals
o Plants
o Protoctists
o Bacteria
o Fungi
o Virus (not classified as living)
Animals
• Animals are multicellular organisms.
• Their cells contain a nucleus, cell membrane and cytoplasm. They don’t contain
chloroplasts and can’t photosynthesise
• Most animals have nervous coordination which means they can respond to their
surroundings e.g. humans jump/scream when they are scared
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• They can usually move around from one place to another
• They store carbohydrates in the form of glycogen i.e. they convert soluble glucose into
insoluble glycogen for storage in the body
• Examples:
o Mammals e.g. humans
o Insects e.g. mosquito
Average animal cell structure
Plants
•
•
•
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•
Plants are multicellular
They have chloroplasts so they can photosynthesise
Their cells have cell walls and are made of cellulose
Plants store carbohydrates as sucrose or starch
Examples:
o Cereals e.g. maize
o Legumes e.g. peas/beans
• Formula/equation for photosynthesis:
Average plant cell structure
Differences between plants and animals
Organelle/structure
Nucleus
Cytoplasm
Cell Membrane
Mitochondria
Ribosomes
Cell Wall
Vacuole
Chloroplasts
(Diagram on next page)
Plant
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Animal
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X
X
X
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Ribosomes
Different organelles included in
both cells
Protoctists
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Family name: Protoctista
Unicellular microscopic organisms
Some have chloroplasts for photosynthesis like plant cells (example: chlorella)
Others don’t have chloroplasts and are more like animal cells (example: amoeba)
Some Protoctists are pathogenic (they are pathogens and can cause diseases)
o Example: Plasmodium – Protoctist that causes the disease malaria and is spread by
mosquitoes.
 Examples:
o Amoeba
o Plasmodium
o Chlorella
Bacteria
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Unicellular microscopic organisms
Some have chloroplasts for photosynthesis like plant cells
Others don’t have chloroplasts and are more like animal cells
Most are decomposers (they feed off other organisms)
The structure of a bacteria is quite different from other cells
o The circular chromosome is the main DNA
o Bacteria are prokaryotic (they do not have a nucleus, so the DNA floats around in the
cytoplasm)
o The plasmid is a separate section of DNA and is mostly used in reproduction
o The flagellum is a ‘tail’ that helps the bacteria swim and helps it to move.
 Examples:
o Streptococcus pneumonia
o lactobacillus bulgaricus
o pneumococcus
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Yara Khnaizer 9S
Fungi
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They don’t contain chloroplasts and can’t carry out photosynthesis
They store carbohydrates as glycogen (like animals)
They are Eukaryotic and have their DNA surrounded by a membrane (have a nucleus)
Can be unicellular (yeast) or multicellular (mucor – common mushroom)
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The multicellular organisms have a body called a mycelium
It is made up of hyphae and contain lots of nuclei
Hyphae are thread-like structures made of cells and cell tubes (tubes made of cells)
The cells that form hyphae have cell walls, but instead of cellulose cell walls, these ones
are made of chitin
 A mycelium is a group of hyphae strings together and beneath the ground
 Most feed by saprotrophic nutrition
o The fungi detect large insoluble molecules on the outside
o They then secrete (release) extracellular enzymes on the outside onto the molecules
o The enzymes break down (digest) the insoluble molecules into soluble molecules
o These molecules are absorbed
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Viruses
 They are classified as
o Non-living
o Parasitic (or parasites) because they damage the host they use to survive
o Pathogens
 Viruses are a group don’t follow the seven life processes and can’t do these processes
independently
 When viruses reproduce, they do so by infecting the cells of living organisms and trick
those cells into making copies of same virus – they don’t reproduce on their own, and
need a host cell
 They infect all types of living organisms
Virus reproducing
in host cell
 Unlike other groups, viruses are not cells – they are small particles that contains parts
like cells and have very varied sizes and shapes
 They contain genetic material as either DNA or RNA
 Viruses don’t have a cell wall or cell membrane (as they are not cells) and instead they
have a protein coat on the outside
 An example in plants includes:
o Tobacco Mosaic Virus (TMV) which stops the production of chloroplasts and leads to
discoloration as chloroplasts are used in chlorophyll production
 Examples in humans include:
o HIV (human immunodeficiency virus) which causes the disease known as AIDS
(acquired immunodeficiency syndrome) and suppresses the immune system
o Influenza which is a virus that causes the flu and is a respiratory condition that
affects the nose, throat and upper lungs – produces a fever
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Yara Khnaizer 9S
Definitions
Word
Organelle
Eukaryotic cells
Prokaryotic cells
Multicellular
Unicellular
Secrete
DNA
RNA
Definition
Organised or specialised structures within a living cell
Have their DNA surrounded by a membrane (have a nucleus)
Don’t have their DNA surrounded by a membrane – the DNA is
“floating around” (no nucleus)
Containing multiple cells
Containing a single cell
To release
Deoxyribonucleic acid – the molecule that carries genetic instructions
in all living things
Ribonucleic acid – plays a central role in turning genetic information
into your body's proteins