| Date | November 2017 | Marks available | 4 | Reference code | 17N.2.SL.TZ0.06 |
| Level | Standard level | Paper | Paper 2 | Time zone | TZ0 |
| Command term | Describe | Question number | 06 | Adapted from | N/A |
Question
Reproduction in eukaryotes can be sexual or asexual.
Describe the origin of eukaryotic cells according to the endosymbiotic theory.
Explain how hormones are used to control the human menstrual cycle.
Outline natural methods of cloning in some eukaryotes.
Markscheme
a. mitochondria and chloroplasts are similar to prokaryotes
b. «host» cell took in another cell by endocytosis/by engulfing «in a vesicle»
Allow “taking in” in place of “engulfing”
c. but did not digest the cell/kept the «ingested» cell alive
OR
symbiotic/mutualistic relationship «between engulfed and host cell»
d. chloroplasts and mitochondria were once independent/free-living «organisms»
e. DNA «loop» in chloroplast/mitochondrion
f. division/binary fission of chloroplast/mitochondrion
g. double membrane around chloroplast/mitochondrion
h. 70s ribosomes «in chloroplast/mitochondrion»
Award up to [2] for evidence from mpe to mph
[Max 4 Marks]
a. FSH stimulates the development of follicles
b. follicles produce estrogen
c. estrogen stimulates the repair of the uterus lining
d. estrogen stimulates LH secretion
e. LH causes/stimulates ovulation
f. LH causes/stimulates the development of the corpus luteum
g. corpus luteum secretes progesterone
h. progesterone causes/stimulates thickening of the uterus lining
OR
prepares uterine lining for implantation
OR
maintains the endometrium
i. progesterone/estrogen inhibits the secretion of LH/FSH
j. falling progesterone levels at the end of the cycle allow FSH production/menstruation
k. negative/positive feedback «control» described correctly
l. LH/FSH are pituitary hormones
[Max 8 Marks]
a. clones are genetically identical organisms
OR
group of cells derived from a single parent cell
b. asexual reproduction in plants such as tubers/runners/bulbs
Allow other verifiable examples of plants
c. common in non-vertebrates such as budding in hydra
Allow other verifiable examples of invertebrates
d. budding in yeast/fungi
Allow other verifiable examples of fungi
e. identical twins «in humans» are clones because they originate from
the same cell
