iGCSE Biology Paper 1 Specification
LEVELS OF ORGANISATION - VERIFIED ANSWER Organelles, Cells, Tissues, Organs, Systems
CELL STRUCTURES - VERIFIED ANSWER Nucleus,Cytoplasm,Cell membrane, Cell wall, Chloroplast,
Vacuole
STRUCTURE OF CARBOHYDRATES, PROTEINS & LIPIDS - VERIFIED ANSWER LARGE ,molecules made up
from smaller basic units
STARCH & GLYCOGEN - VERIFIED ANSWER From simple sugar
PROTEIN - VERIFIED ANSWER From amino acids
LIPIDS - VERIFIED ANSWER From fatty acids and glycerol
ROLE OF ENZYMES IN METABOLIC REACTIONS - VERIFIED ANSWER Enzymes lower the activation energy
of a reaction- making it faster (BIOLOGICAL CATALYST)
HOW FUNCTIONING ENZYMES ARE AFFECTED - VERIFIED ANSWER By changes in TEMPERATURE and
changes in PH
DIFFUSION - VERIFIED ANSWER The net overall MOVEMENT of particles of a GAS or SOLUTE from an
area of HIGH CONCENTRATION to an area of lower concentration DOWN the concentration gradient
OSMOSIS - VERIFIED ANSWER When WATER moves across a PARTIALLY PERMEABLE MEMBRANE, from
an area of HIGH CONCENTRATION to an area of lower concentration DOWN the concentration gradient
,ACTIVE TRANSPORT - VERIFIED ANSWER The movement of substances AGAINST a concentration
gradient/across a cell membrane, using ENERGY
MOVEMENT OF SUBSTANCES INTO AND OUT OF CELLS - VERIFIED ANSWER Can be by diffusion, osmosis
and active transport
PHOTOSYNTHESIS EQUATION - VERIFIED ANSWER Carbon dioxide + water > glucose + oxygen
6CO2 + 6H2O = C6H12O6 + 6O2
MINERAL IONS FOR GROWTH - VERIFIED ANSWER MAGNESIUM ions are needed for CHLRORPHYLL;
NITRATE ions are needed for AMINO ACIDS
RESPIRATION PURPOSE - VERIFIED ANSWER Respiration is a reaction that occurs in living things to
create energy. It breaks down glucose to release energy
AEROBIC RESPIRATION - VERIFIED ANSWER The process by which FOOD molecules are BROKEN DOWN
using OXYGEN to release ENERGY for the cells
ANAEROBIC RESPIRATION - VERIFIED ANSWER Cellular respiration in the ABSENCE of OXYGEN
AEROBIC RESPIRATION EQUATION - VERIFIED ANSWER Glucose + Oxygen > Carbon dioxide + Water +
Energy
C6H12O6 + 6O2 → 6CO2 + 6H2O (+ energy)
ANAEROBIC RESPIRATION EQUATION - VERIFIED ANSWER PLANTS: Glucose > Lactic acid + Energy
ANIMALS: Glucose > ethanol + carbon dioxide + energy
,ROLE OF DIFFUSION IN GAS EXCHANHANGE - VERIFIED ANSWER In the circulatory system oxygen enters
the blood and carbon dioxide leaves the blood via gaseous exchange. Gasses move across the walls of
alveoli to an area of lower density than they are in: Oxygen moves into the blood as there is a low
density of oxygen in the blood; Carbon dioxide moves into the lungs as it is an area of lower density.
GAS EXCHANGE IN RELATION TO RESPIRATION AND PHOTOSYNTHESIS - VERIFIED ANSWER In
photosynthesis: 6CO2 + 12H2O > C6H12O6 + 6O2 + 6H2O
So the plant takes up carbon dioxide and gives out oxygen
In respiration: C6H12O6 + 6H2O > 6CO2 + 6H2O
So the plant gives out carbon dioxide
ROLE OF STOMATA IN GAS EXCHANGE - VERIFIED ANSWER Guard cells regulate the opening and closing
of the stomata; allowing carbon dioxide and oxygen to be exchanged between the leaf and the
atmosphere. The stomata is open during the day. At night, the stomata is closed
ADAPTATION OF LEAF STRUCTURE - VERIFIED ANSWER Leaves are thin which allows gasses to diffuse
quickly through them. In addition the stomata at the bottom of the leaf allow the diffusion of gasses in
to the leaf- when a guard cell is shrunk gasses can enter the leaf
ROLE OF INTERCOSTAL MUSCLES AND DIAPHRAGM IN VENTILATION - VERIFIED ANSWER The intercostal
muscles and diaphragm control ventilation in the lungs.
When they contract the create more space in the lungs: drawing air in.
When the relax the constrict the rings: pushing air out of the lungs
ADAPTATION OF ALVEOLI FOR GAS EXCHANGE - VERIFIED ANSWER The alveoli have are thin, this allows
gasses to diffuse through them easily.
They are small and there are many of them meaning there is a large surface area through which much
gas can diffuse at once. It also meVERIFIED ANSWER there is a lot of surface in contact with the blood
stream for gasses to diffuse into.
Alveoli have a moist lining for gasses to dissolve into
, BIOLOGICAL CONSEQUENCES OF SMOKING - VERIFIED ANSWER Tar can cause cancerous mutations in
the lungs.
Smoke removes the cilia- tiny hairs- which keep the lungs clean.
Smoking also hardens the arteries, constricting the blood flow and putting strain on the heart, resulting
in coronary heart disease.
UNICELLULAR- NO NEED FOR TRANSPORT SYSTEM - VERIFIED ANSWER Unicellular organisms- including
fungi and bacteria- have a large surface area to volume ratio and they are small and so the diffusion
distance is short, meaning diffusion happens very quickly
MULTICELLULAR SYSTEM- NEED FOR TRANSPORT SYSTEM - VERIFIED ANSWER Multicellular organisms
have a small surface area to volume ratio and the distance for diffusion would be very large and so very
slow. This wouldn't support the organism; so they have developed transport systems, like the ventilation
system and the circulatory system which speed up diffusion enough to support themselves
ROLE OF XYLEM - VERIFIED ANSWER Transport nitrates, phosphates, water and other mineral salts from
the roots to other parts of the plants, like the leafs, flowers and buds.
Xylem consists of columns of hollow, dead cells. Substances are carried up the tube dissolved in water
HOW WATER IS ABSORBED BY ROOT HAIR CELLS - VERIFIED ANSWER Roots branch to increase the
surface area and to increase the chances of finding a water source. Root hairs are epidermal cells on the
surface of the root: they also increase the surface area for absorption. They absorb minerals by active
transport and water by osmosis. These substances then move to the xylem
TRANSPIRATION - VERIFIED ANSWER The EVAPORATION if water from the surface of a plant
COMPOSITION OF BLOOD - VERIFIED ANSWER Red blood cells / White blood cells / Platelets / Plasma
URINE - VERIFIED ANSWER Contains WATER, UREA and SALTS
LEVELS OF ORGANISATION - VERIFIED ANSWER Organelles, Cells, Tissues, Organs, Systems
CELL STRUCTURES - VERIFIED ANSWER Nucleus,Cytoplasm,Cell membrane, Cell wall, Chloroplast,
Vacuole
STRUCTURE OF CARBOHYDRATES, PROTEINS & LIPIDS - VERIFIED ANSWER LARGE ,molecules made up
from smaller basic units
STARCH & GLYCOGEN - VERIFIED ANSWER From simple sugar
PROTEIN - VERIFIED ANSWER From amino acids
LIPIDS - VERIFIED ANSWER From fatty acids and glycerol
ROLE OF ENZYMES IN METABOLIC REACTIONS - VERIFIED ANSWER Enzymes lower the activation energy
of a reaction- making it faster (BIOLOGICAL CATALYST)
HOW FUNCTIONING ENZYMES ARE AFFECTED - VERIFIED ANSWER By changes in TEMPERATURE and
changes in PH
DIFFUSION - VERIFIED ANSWER The net overall MOVEMENT of particles of a GAS or SOLUTE from an
area of HIGH CONCENTRATION to an area of lower concentration DOWN the concentration gradient
OSMOSIS - VERIFIED ANSWER When WATER moves across a PARTIALLY PERMEABLE MEMBRANE, from
an area of HIGH CONCENTRATION to an area of lower concentration DOWN the concentration gradient
,ACTIVE TRANSPORT - VERIFIED ANSWER The movement of substances AGAINST a concentration
gradient/across a cell membrane, using ENERGY
MOVEMENT OF SUBSTANCES INTO AND OUT OF CELLS - VERIFIED ANSWER Can be by diffusion, osmosis
and active transport
PHOTOSYNTHESIS EQUATION - VERIFIED ANSWER Carbon dioxide + water > glucose + oxygen
6CO2 + 6H2O = C6H12O6 + 6O2
MINERAL IONS FOR GROWTH - VERIFIED ANSWER MAGNESIUM ions are needed for CHLRORPHYLL;
NITRATE ions are needed for AMINO ACIDS
RESPIRATION PURPOSE - VERIFIED ANSWER Respiration is a reaction that occurs in living things to
create energy. It breaks down glucose to release energy
AEROBIC RESPIRATION - VERIFIED ANSWER The process by which FOOD molecules are BROKEN DOWN
using OXYGEN to release ENERGY for the cells
ANAEROBIC RESPIRATION - VERIFIED ANSWER Cellular respiration in the ABSENCE of OXYGEN
AEROBIC RESPIRATION EQUATION - VERIFIED ANSWER Glucose + Oxygen > Carbon dioxide + Water +
Energy
C6H12O6 + 6O2 → 6CO2 + 6H2O (+ energy)
ANAEROBIC RESPIRATION EQUATION - VERIFIED ANSWER PLANTS: Glucose > Lactic acid + Energy
ANIMALS: Glucose > ethanol + carbon dioxide + energy
,ROLE OF DIFFUSION IN GAS EXCHANHANGE - VERIFIED ANSWER In the circulatory system oxygen enters
the blood and carbon dioxide leaves the blood via gaseous exchange. Gasses move across the walls of
alveoli to an area of lower density than they are in: Oxygen moves into the blood as there is a low
density of oxygen in the blood; Carbon dioxide moves into the lungs as it is an area of lower density.
GAS EXCHANGE IN RELATION TO RESPIRATION AND PHOTOSYNTHESIS - VERIFIED ANSWER In
photosynthesis: 6CO2 + 12H2O > C6H12O6 + 6O2 + 6H2O
So the plant takes up carbon dioxide and gives out oxygen
In respiration: C6H12O6 + 6H2O > 6CO2 + 6H2O
So the plant gives out carbon dioxide
ROLE OF STOMATA IN GAS EXCHANGE - VERIFIED ANSWER Guard cells regulate the opening and closing
of the stomata; allowing carbon dioxide and oxygen to be exchanged between the leaf and the
atmosphere. The stomata is open during the day. At night, the stomata is closed
ADAPTATION OF LEAF STRUCTURE - VERIFIED ANSWER Leaves are thin which allows gasses to diffuse
quickly through them. In addition the stomata at the bottom of the leaf allow the diffusion of gasses in
to the leaf- when a guard cell is shrunk gasses can enter the leaf
ROLE OF INTERCOSTAL MUSCLES AND DIAPHRAGM IN VENTILATION - VERIFIED ANSWER The intercostal
muscles and diaphragm control ventilation in the lungs.
When they contract the create more space in the lungs: drawing air in.
When the relax the constrict the rings: pushing air out of the lungs
ADAPTATION OF ALVEOLI FOR GAS EXCHANGE - VERIFIED ANSWER The alveoli have are thin, this allows
gasses to diffuse through them easily.
They are small and there are many of them meaning there is a large surface area through which much
gas can diffuse at once. It also meVERIFIED ANSWER there is a lot of surface in contact with the blood
stream for gasses to diffuse into.
Alveoli have a moist lining for gasses to dissolve into
, BIOLOGICAL CONSEQUENCES OF SMOKING - VERIFIED ANSWER Tar can cause cancerous mutations in
the lungs.
Smoke removes the cilia- tiny hairs- which keep the lungs clean.
Smoking also hardens the arteries, constricting the blood flow and putting strain on the heart, resulting
in coronary heart disease.
UNICELLULAR- NO NEED FOR TRANSPORT SYSTEM - VERIFIED ANSWER Unicellular organisms- including
fungi and bacteria- have a large surface area to volume ratio and they are small and so the diffusion
distance is short, meaning diffusion happens very quickly
MULTICELLULAR SYSTEM- NEED FOR TRANSPORT SYSTEM - VERIFIED ANSWER Multicellular organisms
have a small surface area to volume ratio and the distance for diffusion would be very large and so very
slow. This wouldn't support the organism; so they have developed transport systems, like the ventilation
system and the circulatory system which speed up diffusion enough to support themselves
ROLE OF XYLEM - VERIFIED ANSWER Transport nitrates, phosphates, water and other mineral salts from
the roots to other parts of the plants, like the leafs, flowers and buds.
Xylem consists of columns of hollow, dead cells. Substances are carried up the tube dissolved in water
HOW WATER IS ABSORBED BY ROOT HAIR CELLS - VERIFIED ANSWER Roots branch to increase the
surface area and to increase the chances of finding a water source. Root hairs are epidermal cells on the
surface of the root: they also increase the surface area for absorption. They absorb minerals by active
transport and water by osmosis. These substances then move to the xylem
TRANSPIRATION - VERIFIED ANSWER The EVAPORATION if water from the surface of a plant
COMPOSITION OF BLOOD - VERIFIED ANSWER Red blood cells / White blood cells / Platelets / Plasma
URINE - VERIFIED ANSWER Contains WATER, UREA and SALTS
