Date | May 2010 | Marks available | 4 | Reference code | 10M.2.SL.TZ1.7 |
Level | Standard level | Paper | Paper 2 | Time zone | Time zone 1 |
Command term | Explain | Question number | 7 | Adapted from | N/A |
Question
Plants are a diverse group of eukaryotic organisms. Describe the different characteristics of the bryophyta, filicinophyta, coniferophyta and angiospermophyta.
Plants store carbohydrate in the form of starch. Explain the reasons for starch being digested by the human digestive system.
Compare the structure of prokaryotic and eukaryotic cells.
Markscheme
(At least one characteristic from each group is needed for maximum credit.)
bryophyta have no roots / only have rhizoids;
bryophyta have simple leaves/stems / only a thallus;
bryophyta produce spores in capsule;
byrophyta are nonvascular;
bryophyte exhibit (pronounced) alternation of generations / a significant gametophyte generation;
filicinophyta have roots, stems and leaves;
filicinophyta (often) have divided/pinnate leaves;
filicinophyta produce spores in sporangia/spores on the undersides of leaves;
filicinophyta exhibit alternation of generations;
filicinophyta have primitive vascular tissue / no true xylem and phloem;
coniferophyta have woody stems;
coniferophyta (often) have narrow leaves/needles/scales;
coniferophyta produce seeds in cones/unenclosed seeds;
angiospermophyta have flowers;
angiospermophyta have ovules in ovaries;
angiospermophyta produce seeds (with hard coats) in fruits;
starch is a large molecule;
large molecules/starch cannot be absorbed by the intestine/villi/epithelial cells;
glucose produced by digestion of starch can be absorbed;
starch/glucose is a useful source of energy;
starch is not used in humans;
glucose is stored as glycogen not starch;
starch is not soluble/could not be transported by blood;
(In the table below, information from both boxes on same line is needed for 1 mark.)
Differences [max 4]:
Similarities: (Award 1 mark for any combination of two different items [max 2])
cytoplasm/plasma membrane/contains DNA/contains ribosomes
Examiners report
Only a few candidates could mention more than one distinguishing characteristic for each plant group. Within this category, there were a few elite candidates who earned maximum or close to maximum marks. They wrote comprehensive answers, full of detailed knowledge. For example, in terms of reproduction, they stated that bryophyta produce spores in capsules, that filicinophyta produce spores on the undersides of leaves (in sporangia), that coniferophyta produce seeds in cones or that angiospermophyta produce seeds in fruits.
That starch is useful for energy was the only idea candidates seemed to know about starch. Few candidates realized that starch molecules are large and must be digested to the size of glucose before being absorbed in the intestines of humans.
There were some good attempts to distinguish the types of cells, but all points were not described to gain full marks. Sometimes diagrams were drawn with no differences pointed out. There was general confusion about bacteria having a cell wall while eukaryotes not having it.