Bio al 2002

Topics: Osmosis, Osmotic pressure, Allele Pages: 49 (5573 words) Published: October 19, 2014
2002 AL Biology marking scheme
Paper 1 Section A
Terms with *, mark deduction for wrong spelling.
Alternatives and correct answers not listed in this document should be accepted.) Marks
1 .1/2 mark for each correct answer
Column 1
E
earthworm
B
jellyfish
F
starfish
D
clam
2.

(2)

Concepts for mark allocation

worn-out organelles are enclosed by membrane forming vacuoles (1) worn-out organelles are enclosed by lysosomes (3)

lysosome releases hydrolytic enzymes into the vacuoles to digest the organelles (1) •
digested materials are recycled for resynthesis (1)
Page total 5

3. (a)

corals obtain nutrients (1/2) and O 2 (1/2) from zooxanthellae for growth /respiration (1)
colour conferred to corals attracts prey (1)
zooxanthellae obtains protection / shelter from the corals (1) coral provides a stable living environment for zooxanthellae (1) zooxanthellae obtains CO2 (1/2) and NH 4+ (1/2) / nutrients from the corals for photosynthesis (1) / growth

(Bonus (I): NH4+ is toxic to coral, zooxanthellae can help to remove this substance from the coral.)

(b)

max. 2

max. 2

+bonus = 1
(max.=4)
(poss. max. = 5)

zooxanthellae stop contributing to the corals as they stop photosynthesis in darkness (1),
compete with corals for 02 when they respire (1) / acquire nutrients from corals

(2)

Or
produce metabolic wastes e.g. C02 that lowers pH which is harmful to corals produce toxic substances (1)
(accept other reasonable negative impact on corals)
(6)
Page total = 6
Poss. Page total = 7
4.
A
C
D
0

Name of fish
Key sequence
Squalus mitsukurii ('/2)
lb, 3a
(1)
Lethrinus haematopterus (V2)
lb, 3b, 4b (1)
Cleisthenes herzensteini (1/2)
la, 2b
(1)
'/2 mark for underlining the scientific names of all fish

41/2
U = 1/2
(5)
Page total = 5

1

Marks
5.

specimen 1 (1/2)
(N.B. If matching of specimen is wrong, no mark even if reason is correct.) Reasons : (accept other correct observable biological features) •
absence of vascular bundle in stem section A (1)

presence of capsule and no flower in specimen 1 (1)
(Also accept answer by elimination.)

2

(max. 2)
6.

4.5 L (1)
*intercostal (1/2) and *diaphragm (1/2) / *respiratory (1/2) increased (1)

(3)

Page total = 5
7.

(a) G = animal tissue (1) / animal and plant tissue (1) / omnivorous carnivorous (1) H = plant tissue (1) / herbivorous (1)
(b)

(2)

Any two : (2 marks each)

the 4-chambered stomach contains microorganisms / protozoa / bacteria (1) to assist digestion of cellulose-rich food (1)

the relatively long small intestine (1) allows for more thorough digestion / absorption (4)
of digested food (1)

enlarged caecum houses microorganisms / bacteria / protozoa (1) for fermentation /digestion of cellulose (1)
Page total = 6

8.
Adaptive skeletal feature for locomotion
Forelimb of
penguin

Forelimb of
seagull

stronger bones for muscle attachment (1) / big surface area for muscle attachment / stronger 2 bones to provide better support
so that continuous strong propulsive force required for swimming can generated (1) Or
fusion of bones to provide rigidity for greater propulsive force for swimming (1) thinner / slender bones / reduce no. of bones to reduce weight (1) 2
to alleviate energy consumption in flight (I)/ cut down the energy consumption in flight Or
fusion of bones to provide rigidity for better adaptation for flight (1) (4)
Page total = 4

2

Marks
9.

(a)

amount of reducing sugar / maltose formed / at the end of the experiment ( 1) Benedict's test (1)

(2)

Or
• rate of disappearance of starch (1) / the concentration of starch / the amount of remaining starch at the end of the experiment
• Iodine test (1)
(b)

no / less reducing sugar / no maltose is formed compared with result A (1)

(1)

Or
No red precipitate is formed / no / little colour change (1) Or
starch disappeared more slowly in B compared with A (1) /...
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