Biology SP2

SEMESTER 2 TRIAL EXAMINATION 2021

SECTION A [15 marks]

1C
2C
3C
4D
5A

6C
7B
8D
9A
10 B

11 A
12 A
13 D
14 C
15 D

1

SEMESTER 2 TRIAL EXAMINATION 2021

SECTION B [15 marks]

NO ANSWER SUB-TO TOTAL
16(a) TAL
(b)(i) Definition of pollination: 1
Transfer of pollen from anther to stigma 1 1
(ii) X: embryo sac 1 1
Through stigma, style, ovary wall, micropyle. 1
(c)(i) [Must travel through ovary wall to bottom before going into 1
(ii) micropyle] 1
Oviduct / fallopian tube 1 2
(d) P1: (Acrosome / Y) contains enzymes [Y is not an enzyme ] 1
P2: which hydrolyse / dissolve / breakdown / digest / softens the 1
zona pellucida / jellycoat 1 7
P1: Formation / growth of tube 1
P2: nucleus travels (along a tube / channel / pathway) into the egg
/ ovule 1
P3: enzymes are produced which allow a tube to grow / which
digests a path Any 1
TOTAL

17(a) Circle both regions – 1 mark 1

Draw and label all 3 1
disulphide bond - 1
mark

(b) 4 antigens 2
(c) Immunoglobulin D / IgD
(d) P1: Antibodies combine with antigens / pathogen / toxin /virus 11
11
/bacteria/microbe 1
P2: Bind at antigen binding region
P3: Each antibody is specific to antigen 1 4 max
P4: Antibody act with antigen in specific way to destroy antigen 1 8
P5:opsonin/precipitation/agglutination/neutralisation/complement 1
system 1
Any 4

TOTAL

2

SEMESTER 2 TRIAL EXAMINATION 2021

SECTION C [30 marks] ANSWER SUB-TO TOTAL
NO TAL

18(a) 3 components of lymphatic system:
1. Lymph/lymphatic fluid
All 3 1
2. Lymphatic vessels

3. Lymphatic/lymphoid organs

(b) 4 lymphoid organs: Function 1+1
Organ Filter pathogens from lymph 1+1
Filter antigens from air and food 1+1
Lymph node Filter antigens from blood 1+1 8 max
Tonsils Site for maturation of T lymphocytes
Spleen
Thymus gland

(c) Movement of fluid between blood and interstitial fluid 1
P1:(blood) hydrostatic pressure and osmotic pressure are 1
responsible for fluid movement 1
P2:Net pressure is calculated using the formula: (HP blood + OP
intrerstitial )fluid – (HP interstitial fluid + OP )blood 1
P3:(blood) hydrostatic pressure is higher than the osmotic 1
pressure at the arterial end of a capillary//when the (calculated) 1
net pressure is positive
P4:This forces plasma out of the capillary into interstitial space 1
P5:Forming interstitial/tissue fluid 1
P6:(blood) hydrostatic pressure is lower than osmotic pressure 1
at the venous end of a capillary// when the (calculated) net
pressure is negative 6 max
P7:This draw fluids from interstitial space into the blood 15
P8:More fluid leaves the blood than returns//90% of the
(interstitial) fluid is returned to the blood (capillary)
P9:Remaining fluid will enter lymphatic system//10% enter
lymphatic system

19(a) Impulse transmission across synapse TOTAL
P1:Impulse/action potential arrives at the end of axon/synaptic 1
knob
P2:Trigger the uptake of Ca2+ from the synaptic cleft/synapse 1
1

3

SEMESTER 2 TRIAL EXAMINATION 2021 1 7 max
1 8 max
P3:Stimulate synaptic vesicles/vesicles containing 1
neurotransmitter/vesicles of neurotransmitter to move toward 1
the presynaptic membrane 1
P4:Synaptic vesicles fuse/bind to with presynaptic membrane 1
P5:Neurotransmitters move/diffuse across the synaptic cleft 1
P6:Neurotransmitter binds with receptors on post-synaptic
membrane 2/0
P7:Trigger the sodium channels to open
P8:Sodium ions diffuse into post-synaptic neurone 2/0
P9:Post-synaptic membrane depolarised
P10:Impulse generated 2/0
2/0
(b) Differences between mechanism of action of steroid and 2/0
2/0
non-steroid 2/0

Steroid Non-steroid

P1:Permeability Easily pass through Cannot pass
towards target and enter target cell
cell membrane through, thus

P2:Formation of cannot enter cell
hormone-receptor
complex Hormone binds to Hormone binds to

receptor in receptor in the

cytoplasm/nucleus plasma

membrane/

outside cell

P3:Hormon-recep The complex The complex
tor complex activates the genes
activation activates adenylyl
No Production of
P4:Production of cAMP cyclase in the
cAMP
No Activation of membrane
P5:Activation of protein kinase
protein kinase Adenylyl cyclase
No Cascade effect
P6:Cascade effect converts ATP to

P7:Transcription cAMP
and translation
cAMP activates

protein kinase in

the cytoplasm

Cascade effect

occurs to amplify

the effect of

hormone

Involve both No Transcription
Transcription and
translation and translation

TOTAL 15
Any 2
20(a) 2 hormones involved in menstrual cycle:

Hormone Role Site of
production

4

SEMESTER 2 TRIAL EXAMINATION 2021

P1:GnRH Stimulates anterior pituitary Hypothalamus 3/0
gland to secrete FSH and LH
3/0
20(a) 3/0
3/0
Hormone Role Site of 3/0
production
P2:FSH Promotes development of
follicles and one will become Anterior
Graafian follicle pituitary
Promotes secretion of oetrogen
from the developing follicles in
the ovary

P3:LH Induces ovulation Anterior
Stimulates formation of corpus pituitary
luteum and production of
oetrogen and progesterone

P4:Oestrogen Repair of endometrium Developing 6 max
follicles/
P5:Progestero Development of endometrium corpus luteum
ne
Corpus luteum

(b) Hormonal regulation of parturition in humans 1
P1:At the end/third trimester/38-40 weeks of pregnancy, the
progesterone level decreases 1
P2: causes uterine contraction
P3:Making the wall of the cervix more flexible 1
P4:Oxytocin produced by the (foetus and the mother’s) 1
posterior pituitary
P5:(oxytocin) stimulates uterine contraction 1
P6:(oxytocin)/corticosteroid (also) stimulates the placenta to
secrete prostaglandins 1
P7:Stimulate powerful/enhanced/strong uterine contraction 1
P8:This strong contraction causes (physical and emotional)
stress 1
P9:Stimulates more oxytocin and prostaglandins to be released 1
P10:This is a positive feedback mechanism

9 max
5

SEMESTER 2 TRIAL EXAMINATION 2021

TOTAL 15

6