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Glossary – Unit 2
Key area 2.1 Cells tissues and organs.
Word
Multicellular
Organisms
Cell Specialisation
Tissue
Histology
Histopathology
Organ
Organ System
Definition
A living thing made of more than one cell
When cells become differentiated to carry out a
particular function
A group of similar cells which carry out the same
function
The study of cells and tissues of plants and animals
The study of cells and tissues to diagnose and monitor
diseases
A group of differentiated tissues that work together
to carry out a particular function e.g. heart and lungs
A group of organs that work together to carry out a
particular function e.g. circulatory, respiratory and
digestive
Key area 2.2 – Stem Cells and meristems
Word
Definition
Stem cell
Unspecialised cell capable of dividing into cells that
can develop into different cell types
Embryonic Stem
Found in embryos and have the potential to divide and
Cells
become nearly any cell type in the body
Adult Stem Cells
Found in tissues and organs and can divide and
differentiate into different cell types
Meristem
Localised region of actively dividing cells in plants
Ethical issue
A moral dilemma
Key area 2.3a – Control and communication: Nervous system
Word
Definition
Cerebrum
Large folded part of the brain that controls conscious
responses, memory, thought, intelligence and emotions
Cerebellum
Medulla
Stimuli
Sensory Strip
Motor Strip
Central Nervous
System (CNS)
Neurone
Sensory Neurone
Relay Neurone
Motor Neurone
Effectors
Nerve impulse
Reflex arc
Part of the brain that controls balance and
coordination of movement
Part of the brain which controls breathing, heart rate
and peristalsis
Changes in the environment detected by receptor cells
that trigger a response in an organism
Area of the cerebrum that deals with all incoming
information from the senses
Area of the cerebrum that sends information to
muscles of the body that we control by conscious
thought
Part of the nervous system made up of the brain and
spinal cord
Nerve cell that is specialised to transmit electrical
impulses
Nerve cell that transmits electrical impulses from a
sense organ to the CNS
Nerve cell that transmits electrical impulses from
sensory neurones to motor neurones
Nerve cell that carries electrical impulses from the
CNS to effectors such as muscles or glands
The muscles or glands that make the appropriate
response
Electrical signals which travel along nerve cells
Synapse
Pathway of information from a sensory neuron through
a relay neuron directly to a motor neurone
The gap between two neurones
Neurotransmitters
Chemicals which are released to effect a change
Synaptic cleft
The area a neurotransmitter has to cross to continue
to the next neurone
Cell that can detect stimuli inside or outside of the
body
Organ of the central nervous system of mammals
where vital functions are coordinated
Part of the CNS of a mammal that runs within its
backbone
Receptor cell
Brain
Spinal cord
Key area 2.3b – Control and communication: Endocrine system
Word
Definition
Endocrine system
Gland that produces and releases a hormone directly
into the blood
Hormones
A protein released by an endocrine gland into the
blood to act as a chemical messenger
Insulin
A hormone produced by the pancreas, responsible for
triggering the conversion of glucose into glycogen in
the liver
Glucagon
A hormone produced by the pancreas, responsible for
triggering the conversion of glycogen into glucose in
the liver
Diabetes
A condition where the sufferer cannot control glucose
levels in their body
Glands
A group of cells that produce and secrete chemicals
into the body
Pancreas
The organ responsible for the production of digestive
enzymes and the hormones insulin and glucagon
Glycogen
Animal storage carbohydrate located in the liver and
muscle tissues
Liver
A large organ with many important functions including
a role in blood glucose control
Target organ
An organ with receptor molecules on its cell surface
that recognise a specific hormone
Key area 2.4 – Reproduction
Word
Definition
Reproduction
The production of new members of a species
Sexual reproduction
Reproduction which requires the use of sex cells
Asexual
reproduction
Zygote
Reproduction which does not require sex cells
Gametes
Sex cells containing haploid chromosome number
A fertilised egg cell
Haploid
Sperm cell
A cell which only contains half the normal amount of
chromosomes (23 in humans)
A cell which contains the full chromosome complement
(46 in humans)
Male sex organs in animals responsible for the
production of sperm
A gamete produced in the testes of male animals
Ova (singular Ovum)
Female gametes produced by ovaries in animals
Ovaries
Fertilisation
Female sex organs in animals responsible for the
production of ova
When ova are released at regular intervals from the
female ovaries
The fusion of gametes
Oviduct
The site of fertilisation of an ova by a sperm cell
Pollination
The transfer of pollen grain from anther to stigma,
usually by wind or an animal pollinator
The male reproductive organs of a flower
Diploid
Testes
Ovulation
Stamen
Pollen grain
Stigma
The structure produced in the anthers of a flower
that contains the male gamete
Where pollen lands during fertilisation
Ovules
The female gamete of plants
Key area 2.5 – Variation and inheritance
Word
Definition
Variation
Differences in characteristics that can be seen
between individual members of a species
Discreet
Variation that is clear cut and observable as
(discontinuous)
categories
variation
Continuous variation Variation where a characteristic can have any value in
a range
Ploygenic
Inheritance determined by the interaction of several
genes acting together
Gene
A small section of DNA that codes for the production
of a particular protein
Alleles
Different versions of the same genetic characteristic
Genetics
The study of variation and inheritance
Phenotype
The visible characteristics of an organism that occur
as a result of its genes
The alleles that an organism has for a particular
characteristic
Form of a gene that is expressed in the phenotype,
whether it is homozygous or heterozygous
An allele of a gene that only shows in the phenotype if
the genotype is homozygous for that allele
Describes a genotype in which the two alleles for the
characteristic are the same
Describes a genotype in which the two alleles for the
characteristic are different
Genotype
Dominant alleles
Recessive allele
Homozygous
Heterozygous
Key area 2.6a – The need for transport in plants
Word
Definition
Transpiration
The evaporation of water through the stomata of
leaves
Xylem
Narrow, dead tubes with lignin in their walls for the
transport of water and minerals in plants
Phloem
Vessels in plants that transport sugars
Photosynthesis
Stomata
Guard cells
Lignin
Minerals
Process carried out by green plants to make their own
food using light energy
Tiny pores in the leaf epidermis that allow gas
exchange
Found on either side of a stoma; they control gas
exchange in leaves by controlling opening and closing
of the stoma
Carbohydrate material lining the xylem vessels and
providing strength and support
Nutrient ions essential for healthy growth
Root hair cell
Spongy mesophyll
Vascular tissue
A specialised cell that increases the surface area of
the root epidermis to improve the uptake of water and
minerals
Plant leaf tissue with loosely packed cells and air
spaces between them to allow gas exchange
Plant tissue composing of phloem and xylem that
transports minerals in a plant
Key area 2.6b – The need for transport in animals: circulation
Word
Definition
Circulatory system
Consists of the heart, blood vessels and the blood
they contain
Heart
Muscular organ that pumps blood around the body
Blood vessels
Artery
Vein
Capillaries
Plasma
Haemoglobin
Valves
Structures which allow blood to be transported
around the body
General name for a blood vessel that carries blood
away from the heart
General name for a blood vessel that transports blood
to the heart
Tiny blood vessels with walls one-cell thick where
exchange of materials occurs
The liquid part of blood that carries many substances
such as sugars, salts, amino acids, proteins, vitamins,
water, carbon dioxide and urea.
Pigment in red blood cells that transports oxygen as
oxyhaemoglobin
Structures in veins that prevent backflow of blood
Aorta
Pulmonary artery
Pulmonary vein
Vena cava
Ventricle
Atria
The main artery that carries oxygenated blood away
from the heart in mammals
Artery carrying deoxygenated blood from the heart
to the lungs
Vein carrying oxygenated blood to the heart from the
lungs
Vein carrying deoxygenated blood to the heart from
the body systems
Lower chambers of the heart that receive blood from
the atria and pump it into the arteries
Upper chambers of the heart which receive blood
from veins
Key area 2.6c The need for transport in animals: gas exchange
and nutrient absorption
Word
Alveoli
Definition
Tiny sacs in lungs that form the gas exchange surface
Cartilage
Flexible tissue forming C-shaped rings in the trachea
to keep the airways open
Hair-like structures lining the trachea that move
mucus with trapped bacteria away from the lungs
The breakdown of large, insoluble food molecules into
smaller, soluble ones
Central vessel in the villi responsible for the
absorption of fats
Organs responsible for gas exchange
Cilia
Digestion
Lacteal
Lungs
Lymph
Mucus
Peristalsis
Liquid that circulates within a mammals body,
transporting the products of fat digestion from the
lacteals
Sticky substance lining the trachea and bronchi,
trapping dust and bacteria
Waves of muscular contraction responsible for the
movement of food through the intestines
Villi
Gas exchange
Carbohydrate
Fats
Proteins
Finger-like projections of the small intestine lining
providing a large surface area for the digestion of
food
The movement of molecules such as oxygen and carbon
dioxide
A substance such as sugar, starch or glycogen,
containing the elements carbon, hydrogen and oxygen
A substance which is used as an energy source and for
insulation, made from fatty acids and glycerol
A substance composed of chains of amino acids
containing the elements carbon, hydrogen, oxygen and
nitrogen
Key area 2.7 – Effects of lifestyle choices on human transport
exchange systems
Word
Definition
Lifestyle choice
Decisions on lifestyle that impact on an individual’s
health
Diet
The food and drinks which a person consumes
Obesity
Heart attack
Tobacco
Exercise
Alcohol
A condition where a person is heavily overweight which
often puts strain on their organs
A blockage to the coronary artery
Smoking increases the risk of developing heart
disease
Healthy activities which improve circulation and blood
flow to muscles
Heavy drinking can lead to an increase in blood
pressure which increases the risk of having a heart
attack or stroke