Question 19N.2.SL.TZ0.5
| Date | November 2019 | Marks available | [Maximum mark: 15] | Reference code | 19N.2.SL.TZ0.5 |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Draw, Explain, Outline | Question number | 5 | Adapted from | N/A |
Draw a section of the Singer-Nicolson model of an animal cell membrane.
[4]
a. bilayer of phospholipids with both “tails” towards the inside «of the bilayer» ✔ This can be taken unlabeled from diagram.
b. hydrophilic/polar and hydrophobic/non-polar annotation ✔
c. cholesterol between phospholipid tails ✔
d. glycoprotein ✔
e. integral proteins/channel proteins ✔
f. peripheral proteins ✔ Allow this if it does not extend across the membrane
Elements should be clearly drawn, correctly positioned and annotated.
Outline the principles used by scientists to classify organisms.
[4]
a. use of the binomial system ✔
b. agreed/developed by scientists / OWTTE ✔
c. hierarchy of taxa used ✔ Names of the seven taxa not required.
d. three domains used/three domain names ✔ OWTTE
e. genome/DNA sequence similarities
OR
amino acid sequence of specific proteins ✔
f. species from a common ancestor are grouped together
OR
included in the same clade/branch in cladogram ✔
g. use evidence of evolutionary origin ✔ Allow example e.g. fossil record comparison
h. shared characteristics within a group
OR
similar embryonic development ✔
Explain the movement of energy and inorganic nutrients in an ecosystem.
[7]
a. autotrophs/producers/plants obtain inorganic nutrients from the «abiotic» environment ✔
b. energy provided «mainly» by sunlight ✔
c. light energy converted «to chemical energy» through photosynthesis ✔
d. photosynthesis/producers/autotrophs convert inorganic carbon/carbon dioxide and water into carbon/organic compounds ✔
e. «these» carbon compounds/foods contain/are a source of «useable» energy «for life» ✔
f. carbon compounds/energy are transferred along food chains when eaten by consumers/heterotrophs ✔ Allow OWTTE for mpf for passed up trophic levels.
g. respiration returns carbon «dioxide» to the environment ✔
h. respiration releases stored/chemical energy as ATP/heat ✔
i. energy/ATP is used to carry out life functions/synthesis/growth/movement ✔
j. energy is lost/not recycled ✔
k. nutrients are recycled / example of recycled nutrient e.g. carbon ✔
l. decomposers recycle minerals/inorganic nutrients ✔