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Biology for Advanced Level Secondary Schools
environment. Bacteria possessing pili sedimentation rate, i.e. how fast
include Neisseria gonorrhoeae and a particle of given size and shape
some strains of Escherichia coli, and ‘settles’ to the bottom of a solution.
Salmonella. The units of a ribosome are often
Plasmalemma Membrane that separates described by their Svedberg (s) values,
the interior parts of the cell from the which are based upon their rate of
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outside environment (the extracellular sedimentation in a centrifuge.
space) that protects the cell from its Tegument The outer covering of
environment, usually consisting of a platyhelminths, made up of an
lipid bilayer with embedded protein. epidermal layer and sometimes
Pleural membrane Thin, slippery and provided with cilia, spines and
moist membrane surrounding the glandular tissue
lungs. It has two layers; the outer Uniramia A group of arthropods
layer called parietal pleura and inner characterised by having appendages
layer visceral pleura with a space (antennae and legs) with only a
between them called pleural cavity single ramus (branch). They also
filled with pleural fluid secreted by have a single pair of antennae and
the membrane. an exoskeleton that is strengthened
Poikilothermic animals Animals whose by tanning process and made water
body temperature fluctuates with that proof by a wax layer. The group has
of the environment. Examples include three main classes: the Chilopoda
amphibians and reptiles. (centipedes), Diplopoda (millipedes)
Pseudocoelomates Animals with and Hexapoda or Insecta (insects and
a primitive (false) body cavity their relatives).
(pseudocoelum) Ureotelic organisms Animals that excrete
Repugnatorial fluid Defensive secretions urea as the primary nitrogenous
(odorous fluid) produced by animals, waste material. Examples include
such as certain insects for defence cartilagenous fish, adult amphibians,
against predators and mammals including humans.
Ribulose biphosphate (RuBP) An organic Uricotelic organisms Organisms that
substance (a 5 carbon compound) excrete uric acid, example birds and
involved in Calvin cycle which is part reptiles
of the light independent reactions of Vaccine A biological preparartion that
photosynthesis provides active acquired immunity
Schwan cells Cells in the peripheral nervous against a particular disease
system that form the myelin sheath
around a neuron’s axon. Schwan cells
are also called neurilemmocytes.
Svedberg value (s or sv) A measure
of a particle’s size based on its
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