IB BIOLOGY COMPREHENSIVE TEST
PAPER 2026 QUESTIONS AND CORRECT
ANSWERS GRADED A+
●● Compare the processes of spermatogenesis and oogenesis. [8 marks].
Answer: a. both produce haploid cells / both produce
(mature/male/female) gametes
b. both have mitosis at start/in epithelium / both involve mitosis and
meiosis;
c. both have cell growth before meiosis;
d. both involve differentiation (to produce a specialised gamete);
Oogenesis:
a. eggs/ova produced in the ovaries
b. process starts during development of embryo/fetus
c. meiosis breaks occur in prophase I/ prophase II/ metaphase II
d. cytoplasm split unequally / larger cell and smaller cells
e. one cell/egg (per meiosis) / some become polar bodies
f. one gamete (usually) at a time/per month/per menstrual cycle
g. timing of release: on about Day 14/in middle of menstrual cycle/at
ovulation
h. stops at menopause
,Spermatogenesis:
a. sperm (atozoa) produced in the testes
b. process starts during puberty/adolescence
c. no breaks in meiosis
d. equal division of cytoplasm
e. four sperm (per meiosis) / all cells become sperm
f. many/far more/(hundreds of) millions daily/at a time gametes
produced
g. timing of release: continuously (from testis) / by
ejaculation/intercourse
h. goes on (throughout adult life/until death)
●● Describe the consequences of the potential overproduction of
offspring. [5 marks].
Answer: a. more (offspring) than the environment can support / carrying
capacity reached
b. increased mortality/lower life expectancy/more deaths;
c. competition (for resources) / struggle for survival;
d. food/mates/nest sites/territory/other example of resource shortage /
example
of greater need;
e. variation between members of population / example of variation;
,f. better adapted more likely to survive / converse; (reject Lamarckian
statements such as those who adapt survive)
g. better adapted reproduce / pass on (favourable) genes/traits / converse;
h. natural selection / (survival of fittest) leads to evolution
●● Outline the processes that occur during the first division of meiosis.
[6 marks].
Answer: a. (consists of) prophase, metaphase, anaphase and telophase;
b. chromosome number halved/reduced/(diploid) to haploid;
c. homologous chromosomes pair up/form a bivalent/synapsis in
prophase; d. crossing over between non-sister chromatids/chromatids of
different homologues;
e. nuclear envelope breaks down (at end of prophase/start of metaphase);
f. tetrads/bivalents/homologous pairs move to/align on equator/cell
centre/on
metaphase plate in metaphase; (accept homologous chromosomes
without
pairs if pairing has already been described)
g. attachment of spindle fibres/microtubules to
centromeres/kinetochores;
h. (homologous) chromosomes separate/pulled to opposite poles in
anaphase;
i. nuclear envelopes reform/do not reform (because of meiosis II) in
telophase; Accept the above points in a series of annotated diagrams.
, Reject answers with single chromatids forming pairs in metaphase or
separating or moving to opposite poles in anaphase.
●● Prior to cell division, chromosomes replicate. Explain the process of
DNA replication in prokaryotes. [8 marks].
Answer: a. DNA replication is semi-conservative;
b. each (molecule formed) has one new strand and one from parent
molecule;
c. helicase uncoils DNA;
d. helicase separates the two strands by breaking hydrogen bonds
between
bases; (reject unzips as an alternative to uncoils but accept as alternative
to
separates if breakage of hydrogen bonds is included)
e. RNA primase adds primer / primase adds (short) length of RNA;
f. DNA polymerase III binds to/starts at (RNA) primer;
g. DNA polymerase (III) adds nucleotides/bases in a 5' → 3' direction;
h. bases according to complementary base pairing / A-T and C-G;
i. (leading strand) built up continuously (towards the replication fork);
j. (lagging strand) built up in pieces/short lengths/Okazaki fragments;
k. DNA polymerase I removes RNA/primers and replaces them with
DNA;
l. ligase seals gaps between nucleotides/fragments/makes sugar-
phosphate
PAPER 2026 QUESTIONS AND CORRECT
ANSWERS GRADED A+
●● Compare the processes of spermatogenesis and oogenesis. [8 marks].
Answer: a. both produce haploid cells / both produce
(mature/male/female) gametes
b. both have mitosis at start/in epithelium / both involve mitosis and
meiosis;
c. both have cell growth before meiosis;
d. both involve differentiation (to produce a specialised gamete);
Oogenesis:
a. eggs/ova produced in the ovaries
b. process starts during development of embryo/fetus
c. meiosis breaks occur in prophase I/ prophase II/ metaphase II
d. cytoplasm split unequally / larger cell and smaller cells
e. one cell/egg (per meiosis) / some become polar bodies
f. one gamete (usually) at a time/per month/per menstrual cycle
g. timing of release: on about Day 14/in middle of menstrual cycle/at
ovulation
h. stops at menopause
,Spermatogenesis:
a. sperm (atozoa) produced in the testes
b. process starts during puberty/adolescence
c. no breaks in meiosis
d. equal division of cytoplasm
e. four sperm (per meiosis) / all cells become sperm
f. many/far more/(hundreds of) millions daily/at a time gametes
produced
g. timing of release: continuously (from testis) / by
ejaculation/intercourse
h. goes on (throughout adult life/until death)
●● Describe the consequences of the potential overproduction of
offspring. [5 marks].
Answer: a. more (offspring) than the environment can support / carrying
capacity reached
b. increased mortality/lower life expectancy/more deaths;
c. competition (for resources) / struggle for survival;
d. food/mates/nest sites/territory/other example of resource shortage /
example
of greater need;
e. variation between members of population / example of variation;
,f. better adapted more likely to survive / converse; (reject Lamarckian
statements such as those who adapt survive)
g. better adapted reproduce / pass on (favourable) genes/traits / converse;
h. natural selection / (survival of fittest) leads to evolution
●● Outline the processes that occur during the first division of meiosis.
[6 marks].
Answer: a. (consists of) prophase, metaphase, anaphase and telophase;
b. chromosome number halved/reduced/(diploid) to haploid;
c. homologous chromosomes pair up/form a bivalent/synapsis in
prophase; d. crossing over between non-sister chromatids/chromatids of
different homologues;
e. nuclear envelope breaks down (at end of prophase/start of metaphase);
f. tetrads/bivalents/homologous pairs move to/align on equator/cell
centre/on
metaphase plate in metaphase; (accept homologous chromosomes
without
pairs if pairing has already been described)
g. attachment of spindle fibres/microtubules to
centromeres/kinetochores;
h. (homologous) chromosomes separate/pulled to opposite poles in
anaphase;
i. nuclear envelopes reform/do not reform (because of meiosis II) in
telophase; Accept the above points in a series of annotated diagrams.
, Reject answers with single chromatids forming pairs in metaphase or
separating or moving to opposite poles in anaphase.
●● Prior to cell division, chromosomes replicate. Explain the process of
DNA replication in prokaryotes. [8 marks].
Answer: a. DNA replication is semi-conservative;
b. each (molecule formed) has one new strand and one from parent
molecule;
c. helicase uncoils DNA;
d. helicase separates the two strands by breaking hydrogen bonds
between
bases; (reject unzips as an alternative to uncoils but accept as alternative
to
separates if breakage of hydrogen bonds is included)
e. RNA primase adds primer / primase adds (short) length of RNA;
f. DNA polymerase III binds to/starts at (RNA) primer;
g. DNA polymerase (III) adds nucleotides/bases in a 5' → 3' direction;
h. bases according to complementary base pairing / A-T and C-G;
i. (leading strand) built up continuously (towards the replication fork);
j. (lagging strand) built up in pieces/short lengths/Okazaki fragments;
k. DNA polymerase I removes RNA/primers and replaces them with
DNA;
l. ligase seals gaps between nucleotides/fragments/makes sugar-
phosphate
