Question 17N.2.SL.TZ0.06
| Date | November 2017 | Marks available | [Maximum mark: 15] | Reference code | 17N.2.SL.TZ0.06 |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Describe, Explain, Outline | Question number | 06 | Adapted from | N/A |
Reproduction in eukaryotes can be sexual or asexual.
Describe the origin of eukaryotic cells according to the endosymbiotic theory.
[4]
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]
Explain how hormones are used to control the human menstrual cycle.
[8]
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]
Outline natural methods of cloning in some eukaryotes.
[3]
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