A LEVEL BIOLOGY A (SNAB): PAST PAPER 1
& GRADING GUIDE THE NATURAL
ENVIRONMENT AND SPECIES SURVIVAL
ALL ASSESSMENT & LEVEL-BY-LEVEL
MARK SCHEME COMPREHENSIVE STUDY
GUIDE 2026 FULL QUESTIONS AND
SOLUTIONS GRADED A+
◍ Stage 3- Fertility transition/ industrial.
Answer: The death rate remains low and the birth rate decreases, so
population growth slows
◍ Density.
Answer: Number of individuals per unit area or volume; dynamic property
resulting from processes that add and remove individuals from the
population
◍ Ocean currents influence climates by.
Answer: Heating or cooling overlying air masses that pass across the
land/coast of continents
◍ Exploitation.
Answer: Any interaction where one species benefits by feeding on another
species
◍ Define adaptions.
Answer: Inherited structures, functions, or behaviors that help organisms
survive and reproduce
,◍ Behavioral isolation.
Answer: Species may be separated from one another by differences in
behavior
◍ How is birth rate influenced by age? How does it differ from wealthy to
poor countries?.
Answer: The difference between the birth rates of poor and wealthy
countries can be largely attributed to differences in the age at which women
bear children. Women in poorer countries typically have children at a
younger age than do women in wealthier nations.
◍ Define independent variable.
Answer: The variable that is changed (manipulated) in the experiment
◍ Define environmental resistance.
Answer: Occurs when factors such as limited resources slow population
growth
◍ What is the scientific method?.
Answer: ObservationAsk a Question Literature ReviewHypothesis- must be
feasible by observation and experimentationPrediction- ("if___, then____"
statement)Experiment (Test)Results-state whether your hypothesis is
supported or rejected
◍ Define GPI.
Answer: Genuine progress indicatorMeasures the sustainability of a
country's human and environmental resources. GPI is the GDP plus or
minus the economic value of positive or negative impacts on the
environment.
◍ What are the 3 ( there are 4) principles of ecosystem function?.
Answer: 1. Matter and energy are neither created nor destroyed 2.
Ecosystems are always open to gains and losses of matter and energy3.
Ecosystems are self-regulated by interactions among their living and
nonliving components4. Ecosystem change is inevitable and essential
, ◍ Temperate Grassland.
Answer: 30-100cm & highly seasonal; below -10°C in winter, up to 30°C in
summer
◍ Define fitness.
Answer: Reproductive success
◍ How is a new species formed? Describe the process.
Answer: 1) Single interbreeding population 2) Population divided by barrier;
subpopulations isolated 3) The two populations evolve independently,
diverge in their traits 4) Populations reunited when barrier removed, but
now different enough that they don't interbreed
◍ Regulating services.
Answer: The ways that ecosystems control important conditions and
processes, such as climate, the flow of water, and the absorption of
pollutants
◍ Define Natural selection.
Answer: Individuals in a population that are most fit survive and leave more
offspring, causing their adaptations to become more common. Individuals
that are less fit leave fewer offspring, so their features become less common
or cease to exist.
◍ Fundamental niche.
Answer: Where a species could theoretically occupy based on the range of
conditions in which it grows & reproduces
◍ Disruptive selection.
Answer: Refers to situations in which individuals with genetic traits that fall
at the extreme ends of the range are more likely to survive than individuals
with average traits
◍ Chapter 5.
Answer: Human Population Growth
◍ Directional selection.
& GRADING GUIDE THE NATURAL
ENVIRONMENT AND SPECIES SURVIVAL
ALL ASSESSMENT & LEVEL-BY-LEVEL
MARK SCHEME COMPREHENSIVE STUDY
GUIDE 2026 FULL QUESTIONS AND
SOLUTIONS GRADED A+
◍ Stage 3- Fertility transition/ industrial.
Answer: The death rate remains low and the birth rate decreases, so
population growth slows
◍ Density.
Answer: Number of individuals per unit area or volume; dynamic property
resulting from processes that add and remove individuals from the
population
◍ Ocean currents influence climates by.
Answer: Heating or cooling overlying air masses that pass across the
land/coast of continents
◍ Exploitation.
Answer: Any interaction where one species benefits by feeding on another
species
◍ Define adaptions.
Answer: Inherited structures, functions, or behaviors that help organisms
survive and reproduce
,◍ Behavioral isolation.
Answer: Species may be separated from one another by differences in
behavior
◍ How is birth rate influenced by age? How does it differ from wealthy to
poor countries?.
Answer: The difference between the birth rates of poor and wealthy
countries can be largely attributed to differences in the age at which women
bear children. Women in poorer countries typically have children at a
younger age than do women in wealthier nations.
◍ Define independent variable.
Answer: The variable that is changed (manipulated) in the experiment
◍ Define environmental resistance.
Answer: Occurs when factors such as limited resources slow population
growth
◍ What is the scientific method?.
Answer: ObservationAsk a Question Literature ReviewHypothesis- must be
feasible by observation and experimentationPrediction- ("if___, then____"
statement)Experiment (Test)Results-state whether your hypothesis is
supported or rejected
◍ Define GPI.
Answer: Genuine progress indicatorMeasures the sustainability of a
country's human and environmental resources. GPI is the GDP plus or
minus the economic value of positive or negative impacts on the
environment.
◍ What are the 3 ( there are 4) principles of ecosystem function?.
Answer: 1. Matter and energy are neither created nor destroyed 2.
Ecosystems are always open to gains and losses of matter and energy3.
Ecosystems are self-regulated by interactions among their living and
nonliving components4. Ecosystem change is inevitable and essential
, ◍ Temperate Grassland.
Answer: 30-100cm & highly seasonal; below -10°C in winter, up to 30°C in
summer
◍ Define fitness.
Answer: Reproductive success
◍ How is a new species formed? Describe the process.
Answer: 1) Single interbreeding population 2) Population divided by barrier;
subpopulations isolated 3) The two populations evolve independently,
diverge in their traits 4) Populations reunited when barrier removed, but
now different enough that they don't interbreed
◍ Regulating services.
Answer: The ways that ecosystems control important conditions and
processes, such as climate, the flow of water, and the absorption of
pollutants
◍ Define Natural selection.
Answer: Individuals in a population that are most fit survive and leave more
offspring, causing their adaptations to become more common. Individuals
that are less fit leave fewer offspring, so their features become less common
or cease to exist.
◍ Fundamental niche.
Answer: Where a species could theoretically occupy based on the range of
conditions in which it grows & reproduces
◍ Disruptive selection.
Answer: Refers to situations in which individuals with genetic traits that fall
at the extreme ends of the range are more likely to survive than individuals
with average traits
◍ Chapter 5.
Answer: Human Population Growth
◍ Directional selection.
