Download Science4CE Biology notes

Specialised cells
Specialised cells are adapted to carry out a
specific role in an organism, that no other types of
cell perform. Here are some examples:
Nerve cells: carry impulses
(signals) from the brain or spinal
cord to other parts of the body.
Cells, tissues and organs
A group of similar cells form a tissue e.g.
muscle cells form muscle tissue
A collection of organs
working together form
an organ system e.g.
the muscle system
A collection of organ
systems form an
organism e.g. a human
A collection of tissues forms an organ
e.g. the heart
Sperm cells: the male gametes
(or reproductive cells) of an
animal. Designed to fertilise the
egg.
Organs
Palisade cells: found on the top
side of a leaf and packed with
chloroplasts, these plant cells are
designed for photosynthesis.
Red blood cells: contain
haemoglobin to absorb and carry
oxygen around the body.
Muscle cells: made of fibres
which can contract or relax to
cause movement.
CELLS & CELL FUNCTIONS
Organs are made up of different tissues which when
put together in a structured way, carry out a specific
process in an organism.
An organ system is a group of organs working
together to perform a complex process in an
organism.
Some organisms have multiple organ systems to
carry out the major functions for survival, whilst other
organisms just need certain organs.
Root hair cells: found in the
roots of a plant and designed to
increase the surface area for
greater absorption of water and
minerals.
Fertilisation
Fertilisation is the fusion of male and female gametes (sex
cells).
When gametes fuse, the first cell of a new organism is
created (the zygote).
In living things that reproduce sexually, fertilisation is part of
the process of reproduction.
Examples of human organ systems include:
circulatory system (moving blood around the body),
respiratory (for taking in oxygen and removing CO2),
nervous (sending impulses to and from the brain),
excretory (removing toxic waste), reproductive
(producing offspring), digestive (for breaking down &
absorbing food), endocrine (hormone production)