Life Sciences Grade 12 Final Revision Document of 2023
Question 2
Give the correct biological term for each of the following descriptions. Write only the term next
to the question numbers.
DESCRIPTION TERM
2.1 A gland whose secretions are transported through blood streams.
2.2 A system that is responsible for chemical coordination in the body.
2.3 A hormone that stimulates ovulation in humans
2.4 The process of maintaining a constant internal environment in the human
body
2.5 A gland whose secretions are transported through ducts.
2.6 A hormone that stimulates mammary gland to produce milk.
2.7 A hormone that is responsible for osmoregulation in the body.
2.8 Specialized cells in the pancreas that secretes insulin and glucagon.
2.9 A hormone responsible for secondary sexual characteristics in males
2.10 A hormone that is responsible for maintaining salt balance in the blood.
2.11 A gland that secretes FSH and LH in females.
2.12 Chemical messengers produced by endocrine glands.
2.13 A gland located in the neck that secretes thyroxin hormone.
2.14 A hormone that controls the metabolic rate in the body.
2.15 A hormone that increases the blood glucose level in the body.
2.16 A hormone that lowers the blood glucose level in the body.
2.17 Promotes the secretions of hormones produced by thyroid glands.
2.18 A mechanism that detects imbalances and restores balance in the internal
environment
2.19 A hormone responsible for growth and development in the body.
2.20 The part of brain that controls body temperature
2.21 Groups of cells in the pancreas that secrete insulin and glucagon
2.22 The homeostatic process whereby temperature is controlled in the body
(22 x 1) (22)
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Life Sciences Grade 12 Final Revision Document of 2023
Question 3
Indicate whether each of the descriptions in COLUMN I applies to A ONLY, B ONLY, BOTH A
AND B or NONE of the items in COLUMN II. Write A only, B only, both A and B or none next
to the question number.
Column I Column II
3.1 The hormone that is in excess in a person that grows A: ADH
abnormally tall B: Thyroxin
3.2 A hormone that controls the salt content in a human body
A: Aldosterone
B: Adrenalin
3.3 The state of the blood vessels in the skin of a human A: Dilated
when the environmental temperature is high B: Constricted
3.4 May cause a decrease in the pH of the blood A: excess carbon dioxide
B: excess glucose
3.5 Acts both as an endocrine and exocrine gland A: Adrenal
B: Pancreas
(5x2) (10)
Question 4
The diagram below represent human endocrine system
4.1 Identify parts A and D (2)
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Life Sciences Grade 12 Final Revision Document of 2023
4.2 Write down the LETTER and the NAME of the part that
(a) Produces the hormone glucagon (2)
(b) Produces a hormome that controls the growth of long bones (2)
(c) Produces an iodine-containing hormone (2)
(d) Produces a hormone that is involved in the re-absorption of some salts by the
kidneys (2)
4.3 State TWO similarites between hormones and nerves with regard to their
functions. (2)
(12)
Question 5
The diagram below shows the interaction between two endocrine glands.
5.1 Name the type of interaction that occurs between hormone A and gland B. (1)
5.2 Identify:
(a) Glands B (1)
(b) Hormone A (1)
(c) Hormone C (1)
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Life Sciences Grade 12 Final Revision Document of 2023
5.3 Name the disorder that results when gland B is overstimulated and becomes
enlarged. (1)
5.4 Which hormone (A or C) will be expected to be high in the blood of the person
with the disorder named in QUESTION 5.3? (1)
(6)
Question 6
The diagram below represents a part of the human skin
6.1 (1)
6.2
(3)
6.3
(2)
(6)
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Life Sciences Grade 12 Final Revision Document of 2023
Question 7
The diagram below shows parts of the skin that are involved in thermoregulation.
7.1 Give TWO reasons why part A is classified as an exocrine gland. (2)
7.2 Describe the role of skin receptors in thermoregulation. (2)
7.3 Explain why structure B dilates on a hot day. (2)
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Life Sciences Grade 12 Final Revision Document of 2023
Question 8
The diagrams below show the human kidney and human brain.
8.1 Name the hormone secreted by gland C that has an effect on:
(a) Long bones (1)
(b) Mammary glands in the breasts (1)
8.2 During an emergency situation, gland A releases a hormone that prepares the
body for a 'fight or flight' response by stimulating an increase in breathing rate
and heart rate. This increase leads to increased energy production in the
skeletal muscles and an increase in blood carbon dioxide levels.
(a) Name the hormone secreted by gland A in an emergency situation. (1)
(b) Explain how an increase in breathing rate and heart rate results in
increased energy production in skeletal muscles. (4)
8.3 Describe how part B is involved in carbon dioxide homeostasis (4)
(11)
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Life Sciences Grade 12 Final Revision Document of 2023
Question 9
Read the extract below.
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Life Sciences Grade 12 Final Revision Document of 2023
9.1
(1)
9.2
(3)
9.3 (3)
9.4
(4)
(11)
Question 10
The table below shows the average rate of blood flow to the skin at different
environmental temperatures.
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Life Sciences Grade 12 Final Revision Document of 2023
10.1
(1)
10.2
(2)
10.3
(3)
10.4
(4)
10.5
(2)
(12)
Question 11
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Life Sciences Grade 12 Final Revision Document of 2023
11.1
(2)
11.2
(1)
11.3
(4)
11.4
(2)
(9)
Question 12
The graphs below show the effects of eating many small meals and eating fewer large
meals on blood glucose and insulin concentrations in a normal person.
The arrows on the graphs below indicate when meals were eaten. The normal blood
glucose concentration is 100 mg/dl.
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Life Sciences Grade 12 Final Revision Document of 2023
12.1
(1)
12.2
(5)
12.3
(4)
(10)
Question 13
13.1 Describe the negative feedback mechanism that occurs when thyroxin
levels in the blood are high (5)
13.2 A person has a medical condition that results in the under-secretion of
thyroxin.
Explain why this person will gain weight if the thyroxin levels remain
continuously low in the blood (3)
(8)
Question 14
14.1 Name the hormone that is secreted the
dangerous situation. (1)
14.2 State THREE effects that the hormone in QUESTION 13.1 has on the body. (3)
14.3 Describe the homeostatic control of blood glucose levels in a person who
consumed a drink with large amount of sugar (5)
(9)
Question 15
Describe how the human body maintain the carbon dioxide concentration in the blood
when it rises above normal limits. (7)
Question 16
Describe the role of different glands of the endocrine system in providing the body with
extra energy during a dangerous situation. (9)
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Life Sciences Grade 12 Final Revision Document of 2023
Question 17
The diagram below shows the homeostatic control of blood glucose levels.
17.1 Identify:
(a) Gland A (1)
(b) Hormone C (1)
17.2 A certain disorder causes decreased production of hormone B.
(a) Explain how this will affect the blood glucose levels. (3)
(b) Name the disorder. (1)
17.3 Scientists have been investigating the use of adrenalin as a treatment for
people who cannot produce hormone C.
Explain why this treatment may work. (3)
Question 18
Wearing a face mask is recommended to reduce the spread of the coronavirus. There are
some concerns about the efficiency of breathing when wearing a face mask.
Scientists investigated the effect of wearing face masks on carbon dioxide levels in blood.
They:
Obtained permission from 150 healthy volunteers, aged 30, to participate in the
investigation
blood
Asked the participants to:
o Sit still for 10 minutes without wearing a face mask
o Sit still for 10 minutes while wearing a face mask
o Exercise for 10 minutes without wearing a face mask
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Life Sciences Grade 12 Final Revision Document of 2023
o Exercise for 10 minutes while wearing a face mask
Allowed a 15-minute interval between each 10-minute phase
Recorded the carbon dioxide levels at the end of each 10-minute phase
Ensured that the face mask covered the nose and mouth
18.1 Identify the:
(a) Independent variable (1)
(b) Dependent variable (1)
18.2 State TWO factors that were taken into consideration in the selection of the
participants. (2)
18.3 Give ONE reason why the results at the end of this investigation may be
considered reliable. (1)
18.4 Explain why scientists allowed a 15-minute interval between each phase. (2)
18.5 Give a reason why the carbon dioxide levels were measured while
participants were sitting still. (1)
18.6 Describe the homeostatic control of carbon dioxide when it is high in blood (7)
(15)
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