2019 HKDSE Biology · 2019. 11. 27. · 2019 HKDSE Biology & CS Biology Briefing Session Q7 Q8 Q9 Monday, November 25, 2019 2019 HKDSE Biology Briefing Session 1

2019 HKDSE Biology & CS Biology

Briefing Session

Q7 Q8 Q9

Monday, November 25, 2019 2019 HKDSE Biology Briefing Session 1

Q7 (a)

very good

correct type of succession shown

~ 50% provided a proper explanation

simply gave the definition of 2nd ecological succession

without referring to the given situation


Q7 (a)


Q7 (b) (i)

poor

few candidates realized that nitrogen cycle is involved

the top soil with humus containing the nitrogen compounds

mixed up the roles of the different bacteria involved

a few candidates mentioned the actions of nitrogen fixing bacteria (those in the root nodules of some plant species)

some candidates simply described the data and did not offer any explanation


Q7 (b) (i)


Q7 (b) (ii)

satisfactory

just pointed out the change in the plant composition (more herbaceous plant species than woody plant species in the early stage and increasing number of woody plant species / decreasing number of herbaceous plant species at a later stage)

gave explanations such as ‘the shading of the woody plants hindered the growth of herbaceous plants’ or ‘herbaceous plants had a faster growth rate than woody plants’, which were not related to the change in soil nitrogen content

simply described the data and did not offer any explanation

wrongly thought that woody plants became the dominant species Monday, November 25, 2019 2019 HKDSE Biology Briefing Session 11

Q7 (b) (ii)


Q8 (a)(i)


Ultrasound?

Q8 (a) (ii)

choices were given

Excellent

71% of the candidates were able to provide an elaboration of how the events in the discovery of ultrasound navigation of bats could be used to illustrate different aspects of the NOS


Q8 (a)(ii)


Q8 (a)(ii)


result

Q8 (a)(ii)


Q8 (b) (i)

very poor

did not distinguish between results and conclusions

simply described the results, e.g. ‘treatment A and treatment B resulted in the same rate of successful escape’

not aware of the purpose of including the treatment involving cutting and regluing the wing tail in the experimental design

a few candidates were able to point out that the manipulation involving cutting and gluing had no effect whatsoever on the rate of successful escape


Q8 (b) (i)


Q8 (b) (ii) & (iii)

very good

~ 55% of the candidates scored full marks in this question.

very good

~ 50% of the candidates drew a valid overall conclusion Monday, November 25, 2019 2019 HKDSE Biology Briefing Session 27

Q8 (b) (ii) & (iii)


Q8 (c)

satisfactory

failed to mention that the length of the wing tail was a genetic variation

pointed out that the moths with long wing tails have a higher chance of survival but they failed to identify predation by bats as the selection pressure


Q8 (c)


Q9 (a)

Fair

Many candidates just gave description about the decrease in the average mass of the two snails

only some of them were able to deduce the ecological relationship of the two snails (competition)

failed to deduce the effect of competition on the population of snail K


Q9 (a)


Q9 (b)

poor

had difficulty in relating the destruction of young leaves and buds to the chance of reproduction.

focused on the growth of individual plants instead of the effect on the community of the local wetland.


Q9 (b)


only affect snail K?

Q9 (b)


Q9 (c)

very poor

did not know the meaning of biotic factor and gave irrelevant answers


Q9 (c)


Q9 (c)


abiotic factor !

vague

Q9 (c)


Producer can also be invasive.

Q9 (d)

Poor

Many candidates wrote about how foreign species could be imported into Hong Kong, which was irrelevant

did not understand the meaning of invasive


Q9 (d)


Q9 (d)


wrote about how foreign species

could be imported into HK

Q9 (d)


did not understand the meaning of invasive

Documents

2019 HKDSE Biology · 2019. 11. 27. · 2019 HKDSE Biology & CS Biology Briefing Session Q7 Q8 Q9 Monday, November 25, 2019 2019 HKDSE Biology Briefing Session 1