MCAT -BIOLOGICAL AND BIOCHEMICAL
FOUNDATIONS OF LIVING SYSTEMS EXAM
WITH CORRECT ACTUAL QUESTIONS AND
CORRECTLY WELL DEFINED ANSWERS
LATEST ALREADY GRADED A+ 2025 – 2026
(*Ecology)
Convergent evolution - ANSWERS-Convergent evolution
occurs when two populations that don't share a recent
common ancestor start to resemble each other as they
adapt to the same or similar environments (e.g. a dolphin
and a fish).
(*Ecology)
Parallel evolution - ANSWERS-Parallel evolution occurs
when two related populations evolve similarly for a long
period of time as they experience similar environmental
conditions.
,(*Ecology)
Fitness - ANSWERS-An organism's total ability to pass on
traits to offspring. i.e. a combination of an organism's ability
to survive to an age where it can reproduce, and its ability
to reproduce once it gets there (fecundity)
(traits that give an organism high fitness are selected for by
natural selection. They confer survival and reproduction and
the former and latter increase fecundity)
(*Ecology)
Fecundity - ANSWERS-How easily and how often an
organism can produce offspring/ (selected for by natural
selection)
(*Ecology)
Artificial Selection ("selective breeding") - ANSWERS-Does
not occur naturally, has outside individual literally choosing
which traits in an individual will be passed on. e.g farmers
picking better crop varieties for seeds, scientist adding
genes that help with pest resistance to crops
(*Ecology)
,Population Bottleneck Effect - ANSWERS-When an
environmental stress factor wipes out a large proportion of
the population such that only a tiny fraction remains. There
are two outcomes to a bottleneck event or population stress
event: 1. Failure to adapt (extinction) and 2. Survive the
stress (recovery) For the latter, the gene pool will change
significantly and selection for new traits will occur
(*Ecology)
Inbreeding - ANSWERS-This is when individuals in a
population selectively produce offspring with a certain
smaller group within that larger population (cultural,
religion, preference reasons) .. geographical barriers are
main cause of non-human inbreeding. In inbred
populations, recessive diseased alleles generally go
unnoticed.
Asexual Reproduction vs Sexual Reproduction - ANSWERS-In
asexual, daughter cells are genetically identical to parent
cell. In sexual reproduction, offspring are genetically unique.
Asexually reproducing organisms have low genetic diversity,
Sexually reproducing organisms have high genetic diversity
(*Genetics)
, In x-linked inheritance, how are alleles distributed? -
ANSWERS-Males receive one allele from the mother (on X)
and none from the father (provides Y).
(*Genetics)
How do dominant disorders proceed across generations? -
ANSWERS-They do not skip generations
(*Genetics)
What form of transmission is characteristic of X-linked
disorders? - ANSWERS-Mother to Son transmission
(*Genetics)
What are the sources of alleles in recessive diseases? -
ANSWERS-A diseased allele must be received from each
parent in autosomal disorders and it must be received just
from the mother in X-linked disorders
(*Genetics*)
What is the allelic basis for rare recessive genetic disorders?
- ANSWERS-It is most likely X-linked. It is much more rare to
get two carriers marrying into one family i.e. autosomal
disorder
FOUNDATIONS OF LIVING SYSTEMS EXAM
WITH CORRECT ACTUAL QUESTIONS AND
CORRECTLY WELL DEFINED ANSWERS
LATEST ALREADY GRADED A+ 2025 – 2026
(*Ecology)
Convergent evolution - ANSWERS-Convergent evolution
occurs when two populations that don't share a recent
common ancestor start to resemble each other as they
adapt to the same or similar environments (e.g. a dolphin
and a fish).
(*Ecology)
Parallel evolution - ANSWERS-Parallel evolution occurs
when two related populations evolve similarly for a long
period of time as they experience similar environmental
conditions.
,(*Ecology)
Fitness - ANSWERS-An organism's total ability to pass on
traits to offspring. i.e. a combination of an organism's ability
to survive to an age where it can reproduce, and its ability
to reproduce once it gets there (fecundity)
(traits that give an organism high fitness are selected for by
natural selection. They confer survival and reproduction and
the former and latter increase fecundity)
(*Ecology)
Fecundity - ANSWERS-How easily and how often an
organism can produce offspring/ (selected for by natural
selection)
(*Ecology)
Artificial Selection ("selective breeding") - ANSWERS-Does
not occur naturally, has outside individual literally choosing
which traits in an individual will be passed on. e.g farmers
picking better crop varieties for seeds, scientist adding
genes that help with pest resistance to crops
(*Ecology)
,Population Bottleneck Effect - ANSWERS-When an
environmental stress factor wipes out a large proportion of
the population such that only a tiny fraction remains. There
are two outcomes to a bottleneck event or population stress
event: 1. Failure to adapt (extinction) and 2. Survive the
stress (recovery) For the latter, the gene pool will change
significantly and selection for new traits will occur
(*Ecology)
Inbreeding - ANSWERS-This is when individuals in a
population selectively produce offspring with a certain
smaller group within that larger population (cultural,
religion, preference reasons) .. geographical barriers are
main cause of non-human inbreeding. In inbred
populations, recessive diseased alleles generally go
unnoticed.
Asexual Reproduction vs Sexual Reproduction - ANSWERS-In
asexual, daughter cells are genetically identical to parent
cell. In sexual reproduction, offspring are genetically unique.
Asexually reproducing organisms have low genetic diversity,
Sexually reproducing organisms have high genetic diversity
(*Genetics)
, In x-linked inheritance, how are alleles distributed? -
ANSWERS-Males receive one allele from the mother (on X)
and none from the father (provides Y).
(*Genetics)
How do dominant disorders proceed across generations? -
ANSWERS-They do not skip generations
(*Genetics)
What form of transmission is characteristic of X-linked
disorders? - ANSWERS-Mother to Son transmission
(*Genetics)
What are the sources of alleles in recessive diseases? -
ANSWERS-A diseased allele must be received from each
parent in autosomal disorders and it must be received just
from the mother in X-linked disorders
(*Genetics*)
What is the allelic basis for rare recessive genetic disorders?
- ANSWERS-It is most likely X-linked. It is much more rare to
get two carriers marrying into one family i.e. autosomal
disorder
