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BIOLOGY UNIT 1
Revision Flash Cards

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OBSERVING CELL
STRUCTURE



· There are two types of microscopes: light
(up to X1500 and low resolution); and
electron (up to X500 000 and high
resolution).
· Resolution is how well small, close
objects can be seen separately. High
resolution produces detailed images of
cells (ultrastructure).
· Specimens need preparation…

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CELL STRUCTURE AND
FUNCTION



· Organelles; nucleus, nucleolus (makes
ribosomes), mitochondria (make ATP for
cellular energy), lysosomes (contain lytic
enzymes), chloroplasts (plant cells only),
centrioles (animal cells only, aid cell
division), cilia and flagella (beat to produce
cell movements).
· Ribosomes make proteins, rough
endoplasmic reticulum transports the
protein to…

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CELL MEMBRANES




· The fluid mosaic is a phospholipid bilayer
with scattered proteins.
· The cell surface membrane is for
transport (partially permeable) and
recognition/signalling (e.g. receptor
molecules for hormones).
· Passive transport (diffusion/facilitated
diffusion) does not use energy, while active
transport does and is against a
concentration gradient.
·…

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THE CELL CYCLE




· The life cycle of a dividing cell is the cell
cycle. It mostly involves copying and
checking genetic information. The final
small part involves mitosis which forms
two new cells.
· Cells can continue a cell cycle or they
differentiate.
· The main stages of mitosis…

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CELL ORGANISATION




· New cells produced in mitosis are
genetically identical (same chromosome
combinations) to each other and the parent
cell. Cells formed by meiosis are not
genetically identical.
· Some mitosis (e.g. bone marrow)
produces stem cells. These can
differentiate into many different cell types
(e.g. red blood cells,…

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GASEOUS EXCHANGE




· The alveolus wall is an efficient exchange
surface as it is only one cell thick. It is
moist and is highly folded for a large
surface area.
· Alveoli are supplied with a rich network
of capillaries which carry blood close to the
alveolus wall (the exchange…

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LUNG STRUCTURE AND
FUNCTION



· The trachea and bronchi have rings of
cartilage which keep them open for airflow
during ventilation.
· Smooth muscle contracts and narrows
the bronchi and bronchioles and elastic
tissue opens these airways. This controls
airflow.
· Goblet cells in the lining of the trachea,
bronchi…

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ANIMAL TRANSPORT
SYSTEMS



· Large multicellular animals have a small
surface area for their volume, resulting in a
large distance for diffusion of gases.
· They need a special transport (blood)
system to supply O2 and remove CO2,
especially if very active (e.g. birds,
mammals and fish).
· Single system…

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HEART STRUCTURE




· The left ventricle wall (thick) pumps
blood around the body. The right ventricle
wall (thinner) only has to pump blood to
the lungs.
· Atrial walls are very thin since they only
have to pump blood a short distance into
the ventricles.
· Cardiac cycle: chambers fill;…

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