A LEVEL BIOLOGY A (SNAB): PAST PAPER 1
& GRADING GUIDE THE NATURAL
ENVIRONMENT AND SPECIES SURVIVAL
ALL ASSESSMENT & LEVEL-BY-LEVEL
MARK SCHEME FINAL TEST 2026
QUESTIONS WITH CORRECT ANSWERS
GRADED A+
◍ isotherms.
Answer: humboldt used his data to discover this concept, allowing scientists
to see patterns of life with different climates
◍ E/MSY.
Answer: extinctions per million species per year
◍ Charles Darwin.
Answer: The author of The Origin of Species and the co‑discoverer of the
theory of evolution by natural selection.
◍ Defining feature of allopatric speciation.
Answer: Geographic isolation.
◍ Sterile hybrid due to genetic incompatibility.
Answer: Mule.
◍ Which evolutionary forces can introduce new genetic variation into a
population?.
Answer: mutation and gene flow
,◍ Genetic Drift.
Answer: A change in the allele frequency of a population as a result of
chance events rather than natural selection.
◍ Sympatric speciation in fleas.
Answer: A shift to a new host (cattle) leads to habitat isolation, reproductive
isolation, prezygotic barriers, and sympatric speciation.
◍ Fossils Darwin found in South America.
Answer: Extinct giant sloth, bivalve fossils high in the Andes, a
gomphothere, and a fossilized horse.
◍ Answer to Question A.
Answer: 3
◍ Sympatric speciation.
Answer: Speciation occurring within the same geographic area, such as
Anolis lizards diversifying on the same island.
◍ Alexander von Humboldt.
Answer: Often considered the first environmentalist in Western cultural
tradition.
◍ diversifying selection.
Answer: a type of natural selection in which organisms with phenotypes at
both extremes of the phenotypic range are favored by the environment
◍ population.
Answer: A group of individuals that belong to the same species and live in
the same area
◍ Fecundity.
Answer: The potential reproductive capacity of an individual.
◍ quantitative.
Answer: type of data that uses numbers that are measured or counted
◍ Reproduction & Inheritance.
Answer: example - parents pass on genes containing similar genetic
, information (DNA)
◍ Which element is the MOST important inorganic nutrient used by plants?.
Answer: Nitrogen
◍ sympatric speciation.
Answer: The formation of new species in populations that live in the same
geographic area
◍ Phylogeny.
Answer: A proposed family tree of living things showing evolutionary
relationships.
◍ genetic drift is the effect of what.
Answer: chance
◍ Allele frequencies sum.
Answer: The allele frequencies of all alleles of a gene must add up to 1.
◍ what happens to the number of mammal species when you go from the
equator to the poles?.
Answer: decreases
◍ Lynn Margulis.
Answer: Researcher who proposed that mitochondria were once free‑living
bacteria.
◍ hypothesis.
Answer: proposed answer to a question that was informed by observations
and data
◍ what are plant and animal distributions defined by?.
Answer: abiotic and biotic factors
◍ Secondary plant compounds.
Answer: Plant chemicals that may be used to develop new drugs.
◍ qualitative.
Answer: type of data that uses senses like light, sound and smell
& GRADING GUIDE THE NATURAL
ENVIRONMENT AND SPECIES SURVIVAL
ALL ASSESSMENT & LEVEL-BY-LEVEL
MARK SCHEME FINAL TEST 2026
QUESTIONS WITH CORRECT ANSWERS
GRADED A+
◍ isotherms.
Answer: humboldt used his data to discover this concept, allowing scientists
to see patterns of life with different climates
◍ E/MSY.
Answer: extinctions per million species per year
◍ Charles Darwin.
Answer: The author of The Origin of Species and the co‑discoverer of the
theory of evolution by natural selection.
◍ Defining feature of allopatric speciation.
Answer: Geographic isolation.
◍ Sterile hybrid due to genetic incompatibility.
Answer: Mule.
◍ Which evolutionary forces can introduce new genetic variation into a
population?.
Answer: mutation and gene flow
,◍ Genetic Drift.
Answer: A change in the allele frequency of a population as a result of
chance events rather than natural selection.
◍ Sympatric speciation in fleas.
Answer: A shift to a new host (cattle) leads to habitat isolation, reproductive
isolation, prezygotic barriers, and sympatric speciation.
◍ Fossils Darwin found in South America.
Answer: Extinct giant sloth, bivalve fossils high in the Andes, a
gomphothere, and a fossilized horse.
◍ Answer to Question A.
Answer: 3
◍ Sympatric speciation.
Answer: Speciation occurring within the same geographic area, such as
Anolis lizards diversifying on the same island.
◍ Alexander von Humboldt.
Answer: Often considered the first environmentalist in Western cultural
tradition.
◍ diversifying selection.
Answer: a type of natural selection in which organisms with phenotypes at
both extremes of the phenotypic range are favored by the environment
◍ population.
Answer: A group of individuals that belong to the same species and live in
the same area
◍ Fecundity.
Answer: The potential reproductive capacity of an individual.
◍ quantitative.
Answer: type of data that uses numbers that are measured or counted
◍ Reproduction & Inheritance.
Answer: example - parents pass on genes containing similar genetic
, information (DNA)
◍ Which element is the MOST important inorganic nutrient used by plants?.
Answer: Nitrogen
◍ sympatric speciation.
Answer: The formation of new species in populations that live in the same
geographic area
◍ Phylogeny.
Answer: A proposed family tree of living things showing evolutionary
relationships.
◍ genetic drift is the effect of what.
Answer: chance
◍ Allele frequencies sum.
Answer: The allele frequencies of all alleles of a gene must add up to 1.
◍ what happens to the number of mammal species when you go from the
equator to the poles?.
Answer: decreases
◍ Lynn Margulis.
Answer: Researcher who proposed that mitochondria were once free‑living
bacteria.
◍ hypothesis.
Answer: proposed answer to a question that was informed by observations
and data
◍ what are plant and animal distributions defined by?.
Answer: abiotic and biotic factors
◍ Secondary plant compounds.
Answer: Plant chemicals that may be used to develop new drugs.
◍ qualitative.
Answer: type of data that uses senses like light, sound and smell
