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A2 Human Biology Unit 8
Text questions
| P163/Q1 |
Neonate, infancy, childhood, puberty,
adolescence; |
|
| P164/Q2 |
Body mass fluctuates during the course of a
day; |
|
| P167/Q3 |
Fig. 8.6 on page 166: a cross-sectional
study, because the plotted values represent the mean
values; |
|
| P170/Q4 |
Thyroxin stimulates the rate of metabolism:
rate of respiration increased → more ATP produced
(ATP needed for synthesis of proteins/organic
molecules) → higher rate of growth. |
|
| P172/Q5 |
Ageing: reduction in the rate of cell
division. Recovery from injury: damaged tissues need
to be rebuilt, hence more time needed for full
recovery. |
|
| P173/Q6 |
Fat is a poor conductor of heat. An increase
in the amount of stored fat → lower heat loss →
lower BMR necessary to maintain constant body
temperature; |
|
| P174/Q7 |
Exercise will slow down the processes which
lead to a drop in the amounts of neurotransmitter
produced by neurones. This is because organelles
responsible for synthesis of neurotransmitter remain
active and keep producing
neurotransmitter/organelles do not degenerate due to
being dysfunctional/unused. |
|
| P175/Q8 |
Hormonal theory of ageing: number of
hormone-secreting cells drops → less hormones (= less FSH) produced; |
|
| P176/Q9 | Probability of errors taking place during DNA replication may be higher in an oxidised DNA → altered sequence of nucleotides/mutations (page 176 paragraph 1: the Gene Mutation Theory of ageing). |
Assignment
| P178/Q1 | a) | March'94 (from "menstruation" - blue
graph); |
| b) | Symptoms of menarche are easily observable. |
|
| P178/Q2 | By then all the necessary
adaptations/development of the reproductive system
(mammary glands, myometrium, endometrium), as well
as, muscular - skeletal system (increased diameter
of the pelvic girdle) would have taken place (→
table 8.3,p.169); |
|
| P178/Q3 | a) | April'95 |
| b) | Corpus luteum produces oestrogen/
progesterone; an abrupt increase in progesterone
concentration of progesterone evident in April'95. |
|
| P179/Q4 | Differences in age at menarche may be
down to chance and not to genetical relationship. |
|
| P179/Q5 |
|
|
| P179/Q6 | a) | Smaller difference in age at
menarche in identical (monozygotic) twins is caused
by their identical genotypes. |
| b) | Non-twin sisters have a higher difference in
age at menarche then di-zygotic twin sisters. It is
because environmental factors acting on di-zygotic
twin sisters are very similar, which is not the case
with non-twin sisters. |
|
| P180/Q7 | a) | Over the years a pattern has
emerged, which shows that in recent years menarche
occurs earlier then many years ago. |
| b) | Similar mean age of menarche for rural
populations in Poland, Romania & India (at 14.5
years); in South Africa the mean age of menarche in
rural population takes place later (15 years). The
mean age of menarche in urban population is lowest
in India (12.7 years) and highest in South Africa
(13.4 years). |
|
| P180/Q8 | Towns: continuous illumination with
artificial light → more GnRF released by
hypothalamus → pituitary gland: gonadotrophins (FSH
→ ovaries → oestrogen → LH → ovulation. Rural
children spend more energy in physical activity than
urban children → accumulation of fat reduced in
favour of muscle tissue development (→ muscle/fat
ratio is higher) → delayed menarche. Total energy
intake in rural diets lower than that of urban diets
→ muscle/fat ratio higher → delayed menarche. |
Examinations
| P180/Q1 | a) |
211mm + (2yrs x 8.5mm/yr) = 228mm |
| b) |
Increased growth rate of the pelvis in the girl
occurred earlier (by app. 2 yr.) and is higher than
in the boy. |
|
| c) |
Steroid sex hormones (testosterone/oestrogen)
together with growth hormone stimulate the growth of the pelvic girdle. |
|
| P181/Q2 | a) |
130cm + (1yr x 5cm/ye) = 135cm |
| b) |
Curve A represents results of a longitudinal
study; curve B represents results of a
cross-sectional study. |
|
| c) |
(i) The rate of growth for the supine length
would be a little bit greater than that of the
height. (ii) The peak of the curve would be
shifted to the left, because the highest mean rate
of growth |
