OCR a level biology Exam Questions And
Answers Verified 100% Correct
Cyclic AMP (cAMP) - ANSWER Secondary messenger released inside cells to activate
a response
Cyclic changes - ANSWER Rhythmic changes, such as tides, day length, and
fluctuations in predator and prey species
Dark band - ANSWER In stritated muscle also known as the A band which shows the
length of the mysoin filaments; there is some overlap with the actin filaments within this
band.
Death phase - ANSWER Population size is decreasing as cells are dying faster than
new ones are formed
Decomposers - ANSWER Living organisms that feed on waste or dead organic matter
Deflected succession - ANSWER When succession is stopped or interfered with such
as by grazing or when a lawn is mowed
Depolarisation - ANSWER Where inside of a cell becomes less negatively charged
compared with the outside
Descending limb - ANSWER Part of loop of Henle that carries fluid from proximal
tubule into medulla
Diabetes Mellitus - ANSWER Condition where blood glucose concentration cannot be
controlled effectively
Dihybrid - ANSWER Involving 2 gene loci
Directional changes - ANSWER Non cyclic changes, in one direction only, such as
coastal erosion
Directional selection - ANSWER type of natural selection that occurs when
environmental change favours a new phenotype and so results in a change in the
population mean
Discontinuous variation - ANSWER Genetic variation producing discrete phenotypes-
2 or more non overlapping catergories
DNA ligase - ANSWER Enzyme that catalyses joining of sugar and phosphate groups
within DNA
,DNA sequencing - ANSWER Technique that alows genes to be isolated and read
Dry mass - ANSWER Amount of biomass remaining after removal of all water.
Ecosystem - ANSWER Community of animal, plants and bacteria integrated with the
physical and chemical environment
Ectotherm - ANSWER Organism that relies on external sources of heat to maintain
body temperature
Effector - ANSWER Cell tissue or organ that brings about response
Electrofusion - ANSWER Application of electric field to recipient cell to make it more
receptive to vector carrying novel gene
Electrophoresis - ANSWER Process to separate proteins or DNA fragments of
different sizes
Electroportion - ANSWER Process of introducing vector with novel gene into
cell;
pulse of electricity makes recipient cell more
porous
Endoctrine glands - ANSWER Ductless glands which hormones are released
directly
into blood
Endocrtrine system - ANSWER Communication system involving hormones as
signalling molecules
Endotherm - ANSWER Organism that uses heat from metabolic reactions to maintain
body temperature
Epistasis - ANSWER Interaction of non linked gene loci where one masks or
suppresses the expression of another.
Ethanal - ANSWER AKA acetaldehyde CH3CHO
Ethanol - ANSWER ethyl alcohol C2H5OH
Excitatory post synaptic potential EPSP - ANSWER Small post synaptic potential that
makes the neurone more likely to fire an action potential
Excretion - ANSWER Removal of metabolic waste from body
, Exergonic - ANSWER Biochemical reactions that release energy
Exocrine glands - ANSWER Glands that secrete substances into ducts
Exon - ANSWER Coding, or expressed region of DNA; nucleotide sequence within a
gene that remains in the final mRNA transcribed from that gene
First messengers - ANSWER Hormones that act as signalling molecules outside the
cell that bind to plasma membrane and initiate effect inside cell
Founder effect - ANSWER When small sample of original population establishes a
new area; its gene pool is not as diverse as that of the parent population
Frameshift - ANSWER Alternation to base sequence of length of DNA due to an
insertion or deletion of nucleotide base.
Gas chromatography - ANSWER Technique where sample is vaporised in presence of
gaseous solvent and passed into long tube that is lined with absorption agent. Each
substance dissolves differently in gas and stays in gas phase for unique, specific time,
called retention time.
Eventually substance comes out of gas and is absorbed onto agent lining tube.
Analysed to make chromatogram.
Gene locus - ANSWER Position of gene on pair of homologous chromosome
Gene pool - ANSWER All allele and genes within a breeding population
Generator potential - ANSWER Change in potential across the receptor membrane
Genetic bottleneck - ANSWER Sharp reduction in size of population due to
environmental catastrophes or human activities which reduces genetic diversity. As
population expands it is less diverse than before.
Genetic modification - ANSWER Manipulating genome of organism
Genotype - ANSWER Genetic makeup of organism
Geotropism - ANSWER Directional growth response, made by plants to gravity
Germ line gene therapy - ANSWER Gene therapy by inserting functional allele into
gametes or zygotes
Glomerular filtration rate - ANSWER Rate at which fluid enters nephrons
Answers Verified 100% Correct
Cyclic AMP (cAMP) - ANSWER Secondary messenger released inside cells to activate
a response
Cyclic changes - ANSWER Rhythmic changes, such as tides, day length, and
fluctuations in predator and prey species
Dark band - ANSWER In stritated muscle also known as the A band which shows the
length of the mysoin filaments; there is some overlap with the actin filaments within this
band.
Death phase - ANSWER Population size is decreasing as cells are dying faster than
new ones are formed
Decomposers - ANSWER Living organisms that feed on waste or dead organic matter
Deflected succession - ANSWER When succession is stopped or interfered with such
as by grazing or when a lawn is mowed
Depolarisation - ANSWER Where inside of a cell becomes less negatively charged
compared with the outside
Descending limb - ANSWER Part of loop of Henle that carries fluid from proximal
tubule into medulla
Diabetes Mellitus - ANSWER Condition where blood glucose concentration cannot be
controlled effectively
Dihybrid - ANSWER Involving 2 gene loci
Directional changes - ANSWER Non cyclic changes, in one direction only, such as
coastal erosion
Directional selection - ANSWER type of natural selection that occurs when
environmental change favours a new phenotype and so results in a change in the
population mean
Discontinuous variation - ANSWER Genetic variation producing discrete phenotypes-
2 or more non overlapping catergories
DNA ligase - ANSWER Enzyme that catalyses joining of sugar and phosphate groups
within DNA
,DNA sequencing - ANSWER Technique that alows genes to be isolated and read
Dry mass - ANSWER Amount of biomass remaining after removal of all water.
Ecosystem - ANSWER Community of animal, plants and bacteria integrated with the
physical and chemical environment
Ectotherm - ANSWER Organism that relies on external sources of heat to maintain
body temperature
Effector - ANSWER Cell tissue or organ that brings about response
Electrofusion - ANSWER Application of electric field to recipient cell to make it more
receptive to vector carrying novel gene
Electrophoresis - ANSWER Process to separate proteins or DNA fragments of
different sizes
Electroportion - ANSWER Process of introducing vector with novel gene into
cell;
pulse of electricity makes recipient cell more
porous
Endoctrine glands - ANSWER Ductless glands which hormones are released
directly
into blood
Endocrtrine system - ANSWER Communication system involving hormones as
signalling molecules
Endotherm - ANSWER Organism that uses heat from metabolic reactions to maintain
body temperature
Epistasis - ANSWER Interaction of non linked gene loci where one masks or
suppresses the expression of another.
Ethanal - ANSWER AKA acetaldehyde CH3CHO
Ethanol - ANSWER ethyl alcohol C2H5OH
Excitatory post synaptic potential EPSP - ANSWER Small post synaptic potential that
makes the neurone more likely to fire an action potential
Excretion - ANSWER Removal of metabolic waste from body
, Exergonic - ANSWER Biochemical reactions that release energy
Exocrine glands - ANSWER Glands that secrete substances into ducts
Exon - ANSWER Coding, or expressed region of DNA; nucleotide sequence within a
gene that remains in the final mRNA transcribed from that gene
First messengers - ANSWER Hormones that act as signalling molecules outside the
cell that bind to plasma membrane and initiate effect inside cell
Founder effect - ANSWER When small sample of original population establishes a
new area; its gene pool is not as diverse as that of the parent population
Frameshift - ANSWER Alternation to base sequence of length of DNA due to an
insertion or deletion of nucleotide base.
Gas chromatography - ANSWER Technique where sample is vaporised in presence of
gaseous solvent and passed into long tube that is lined with absorption agent. Each
substance dissolves differently in gas and stays in gas phase for unique, specific time,
called retention time.
Eventually substance comes out of gas and is absorbed onto agent lining tube.
Analysed to make chromatogram.
Gene locus - ANSWER Position of gene on pair of homologous chromosome
Gene pool - ANSWER All allele and genes within a breeding population
Generator potential - ANSWER Change in potential across the receptor membrane
Genetic bottleneck - ANSWER Sharp reduction in size of population due to
environmental catastrophes or human activities which reduces genetic diversity. As
population expands it is less diverse than before.
Genetic modification - ANSWER Manipulating genome of organism
Genotype - ANSWER Genetic makeup of organism
Geotropism - ANSWER Directional growth response, made by plants to gravity
Germ line gene therapy - ANSWER Gene therapy by inserting functional allele into
gametes or zygotes
Glomerular filtration rate - ANSWER Rate at which fluid enters nephrons
