言教備
真三第張七第日五初月五年辰丙歷
WAH KIU YAT PO
報日僑華
三期星
neath the skin and in con-
3
日二月六年六七九一歷公年五十六國民華中
CO2 produced was probably
夏登僑
10.
nective tissue of most organs
( 7 marks ) (1) 1. Tight should be excluded. from the solution to prevent
Chances of children being
consumed by the green plant
rollers
are 75%
in another process which
(111)
is affected by an increase
Parent
8
gametes random crossing
1976
all
(TE) railers
F
12.
OR
中學會考生物科題解(一)
BIOLOGY I
卓唐慕儴·
Suggested answers:
(i) The function of phloem is to
carry food made in the lea- ves to other parts of the plant. By cutting a ring of bark containing phloem and removing it, food can no
Laurer be conducted down-
wards, so there would be an
accumulation of food in the region just above the ring causing it to swell- (ii) 1. Some of the food in the
phloem is conducted to the ripening fruits for storage. Thus the fruit above the ring would grow bigger while the one below would show no apparent change.
2. This is due to the con- tinued supply of food being. conducted to the fruit above the ring which would result in growth while the one low is deprived of further food supply would not“ (iii) After two days, the leaf
1b
be..
above the ring would wilt
and wither as it has been
deprived of water supply from the xylem. Its cells
have become flaccid due to loss of water from evaporat- ion and transpiration. The leaf below the ring would re-
main turgid and green since
it still has a continuous supply of water from the xylem; so it can carry out photosynthesis and still main turgid. (6 marks)
(1) X= villus
Y= blood capillary
Z= lacteal
(11) 1. Maltose is reduced to
glucose by enzyme maltase- 2. Soluble glucose pass through the epithelial cells of the villi & into the sur- rounding network of blood capillaries.
3. Hepatic portal vein con- veys all absorbed materials from the small intestine to:
the liver.
4′′ The end product of carbo- hydrate digestion is glucose which is converted in the
liver and in the muscles to glycogen and stored in the liver and muscles. Excess glucose not stored as glycogen may be converted to fat and stored in the fat cells of the adipose tissue beneath the skin and around
the omentum.
(111) 17 Lacteal convey fats“
2. Fat droplets accumulate
in certain cells which form
the adipose tissue found be-
growth of algae which might affect the mineral content of
the culture solution. Thus
the glass jar should be dar- kened by covering it up with
light-proof paper or paint- ing it black.
2. End og glass tube should b be inserted into culture sol- ution so as to enable suffi cient aeration for respirat-
ion of roots when air is bubbled in daily.
or 3. Replace glass rod for
glass tube as you may need to top up the solution regularly (ii) The seedling would be weak,
leaves would be spotted and roots poorly developed. (iii) 1
2a.
Calcium is important in the formation of cell walls
of green plants. It also aids development of root hairs.
2. Human beings need calcium in the proper formation of teeth and bones“ It also plays. an important role in the clot- ting of blood” ( 7 marks )
(1) The genotype of 2 is (It) beca ause two of her children are non rollers, thus they must have inherited a non roller gene from their father and one from their mother"
4.0/$
parents
gameles
random Crossing
tt (TC) (tc) 57 48 5.7 The genotype of (12) is (It) bec aude her mother is non roller ie. (tt) and her father must be a heterozygote since two of the four children are non rollers and two are rollers. These two rollers could only inherite one tongue rolling gene(T) so she must be a heterozygous
roller.
(11):
Tt
14
rollers
parents
gametes
roller Parent
(tt)
(tt)
nan roilers
gametes random crossing
( f children being
are
50%
parents
• gametes
random crossing
(Tt)
(TE)
F
non roller
Yoilers
TE (TE)
Toile
Parent
gametes yourdom Crossing
(tt) F1
non foller
It is not possible to determi ine the genotype of individu. al 15 though his phenotype
is that of a toller.
His father(8) is hetero-
zygous This is evident
because
grandparents are
tt and Tt. But his mother(9). may be a TT or a Tt since both these would result in an offspring being a tongue roller who is either TT or Tt Both (9) and (15) could be a homozygous of T (50%) or a heterozygous of T (50%)= (8 marks)
(1) In P, duplicated chromosomes
move to opposite poles. In Q chromatids separate at: centomere & begin to migrate (ii) 1. Daughter cells will have
haploid number of chromosomes as that of the parent cell.
2. Occurs in germ cells when
game
etes are formed. 3. Consistency of chromosomes number in the cells of suc-
cessive generation is ensured Since each gamete has only
haploid number, after ferti- lization, it would again pos- Bess diploid number, same as its parent cell” (iii) It ensures
full con-
plement of animes in
20 all somatic cells.
(1) Structure I is a stem tuber. (ii) Food stored is mainly starch. (iii) Aerial shoot has developed
from one of the buds or 'eyes' (iv) Root tuber eg. Carrot
Bulb
Onion
or Rhizome
or Corm
eg: ginger eg" Gladiolus
(or some other examples) (v) Advantages of growing a crop
of potato by using tubers are:-
Amount of food in tuber is much more than seed so it is
assured of sufficient food supply.
Time taken to grow is shorter. 3. Type of potato crop assured
since no new hereditary mat- erials could be introduced.
or 4.Easier and quicker means of
propagation since no exter- nal agencies are necessary to aid pollination or die- persal which are not in- 3a. volved in this.(7marks)
(i) Respiration
(11) Between the periods of X & Y the CO2 output decreaseB with that of an increase in light intensity, some of the
in light intensity. This is probably the process of pho- tosynthesis.
(iii)At point Y, the amount of CO2 produced is equal to the amount of CO2 used.
(iv) Between points Y & Z, the
rate at which CO, is needed. by the plant exceeds that pro- duced thus CO2 uptake has in- creased with an increase in light intensity which affects the rate of photosynthesis & thus the amount of CO2 requir- ed by the green plant. 3b7
(6 marks) (1) Hydrophytes( aquatic plants)
are adapted to their aquatic life in that they respire by means of stomata on their cutinised upper surface, which is probably floating on the surface of the water, but it can also take in O2 from the surrounding water through
the under surface.
(ii) Diagram showing surface-
view of lower epidermis of
Lear M
epidermal cells. Chloroplasts
stoma
nucleus
-Guard cells
ie uncil ・cytoplasm
3b. (iii) The blue cobalt chlo-
ride paper attached to the lower epidermis will turn to pink much more quickly than that on the upper epidermis. This is due to the fact that the abundant stoma on the lower epidermis permit more water vapour to be lost as result of transpiration. (7 marks) From the evidence given the osmotic potential of the c
cell sap of the guard cells as a result of the increase sugar content increases and thus
withdraw water from their neighbouring cells. This re- sults in an increase in tur- gor pressure in the guard cells causing them to swell. Since the inner border of the
guard cells' wall is thicker
it does not stretch as much
as the outer border. The guard cells curve away from each other and so increase the gap between them. Thus atoma is opened.( 3 marks) (i) Perspiration
3a.
(ii) The sweat glands produce sweat which are given off through sweat pores on the skin.
(iii) Sweating helps to maintain
body temperature constant be-
cause the latent heat absor-
bed by sweat as it evaporates is taken from the body and thus helps to reduce body's temperature. (3 marks)