KCSE TOPICAL QUESTIONS & ANSWERS
EXCRETION AND HOMEOSTASIS
EXCRETION AND HOMEOSTASIS
1.1990 Q7 P1
(a) Explain why the body temperature of a healthy human being must rise up to 390C on a humid day.
(b) In an experiment a piece of brain was removed from a rat. It was found that the rat had large fluctuations of body temperature. Suggest the part of the brain that had been removed.
2. 1991 Q16 P1
(a) Explain how urea is formed in the human body
(b) Describe the path taken by urea from the organ where it is formed until it leaves the human body
3. 1992 Q4 P1
(a) Explain why sweat accumulates on a person’s skin in a hot humid environment.
(b) Name the specific part of the brain that triggers sweating
4. 1992 Q10 P1
Explain why some desert animals excrete uric acid rather than ammonia.
5. 1992 Q19 P1
Explain the part played by each of the following in homeostasis
(a) Insulin and Glucagon
(b) Antidiuretic hormone
6. 1993 Q2 P1
State the role of the following hormones in the body:
b. Antidiuretic hormone
7. 1993 Q10 P1
What osmoregulatory changes would take place in a marine amoeba if it was transferred to a fresh water environment?
8. 1994 Q2 P1
Name two components of blood that are not present in the glomerular filtrate.
9. 1994 Q3 P1
How would one find out from a sample of urine whether a person is suffering from diabetes mellitus?
10. 1995 Q17 P1
Describe how excretion takes place in
(i) Mammalian Kidneys
(ii) Green plants (5 marks)
11. 1996 Q3 P1
When is glycogen which is stored in the liver converted into glucose and released into the blood (1 mark)
12. 1996 Q21 P1
Explain how the mammalian skin is adapted to perform its functions (20 marks)
13. 1997 Q8 P1
A person was found to pass out large volumes of dilute urine frequently.
(a) Name the disease the person was suffering from
(b) Hormone that was deficient
14. 1997 Q15 P1
The equation below represent a metabolic that occurs in the mammalian liver
Amino acids →Organic compounds + urea
(a) Name the process.
(b) What is the importance of the process to the mammal?
(c) What is the source of amino acids in this process
(d) What is the difference between essential and nonessential amino acids?
15. 1999 Q11 P1
Give reasons for each of the following:
a) Constant body temperature is maintained in mammals.
b) Low blood sugar level is harmful to the body.
16. 2000 Q5 P1
State the importance of osmo-regulation in organisms
17. 2000 Q13 P1
The temperature of a person was taken before, during and after taking a cold bath. The results are shown in the graph below
(a) Explain why the temperature fell during bath
(b) What changes occurred in the skin that enabled the body temperature to return to normal?
18. 2001 Q6 P1
Adult elephants flap their ears twice as much as their calves in order to cool their bodies when it is hot. Explain.
19. 2001 Q11 P1
The diagram below represents a mammalian nephron
(a) Name the
(i) Structure labeled P
(ii) Portion of the nephron between point X and Y
(b) Name the process that takes place at point Q
(c) Name one substance present at point R but absent at point S in a healthy mammal
(d) The appearance of the substance you have mentioned in (c) above is a
symptom of a certain disease caused by a hormone deficiency. Name the
(e) State the structural modifications of nephrons found in the desert mammals
20. 2003 Q14 P1
a) Explain how marine fish regulate their osmotic pressure.
b) Explain the role of antidiuretic hormone when there is excess water in the human body.
21. Some students used a model to demonstrate the effect of sweating on human body temperature. Two boiling tubes A and B were filled with hot water. The temperature of water in the tubes was taken at the start of the experiment and then at 5 minutes interval.
The surface of tube A was continuously wiped with a piece of cotton wool soaked in methylated spirit. The results obtained are shown in the table below.
a) On the same axes, plot graphs of temperature of water in the tubes against time.
b) At what rate was the water – cooling in tube A?
c) Why was tube B included in the set up?
d) Account for the rate of cooling in tube A.
e) State two processes of heat loss in tube b.
f) What would be the expected results if tube A was insulated?
g) What would the insulation be comparable to in:
h) Name the structures in the human body that detect:
i) External temperature changes
ii) Internal temperature changes
22. 2004 Q18 P1
How is the mammalian skin adapted to its functions? (20 marks)
23. 2005 Q13 P1
The diagram below shows a section through the mammalian skin.
a) Name the parts labeled E, F and G. (3 marks)
b) State two functions in each case of substance secreted by the structures labelled.
(i) H (2 marks)
(ii) I (2 marks)
24. 2006 Q4 P1
a) Name the fluid that is produced by sebaceous glands. (1 mark)
b) What is the role of sweat in human skin? (2 marks)
25. 2006 Q7 P2
Describe how human kidney functions (20 marks)
26. 2007 Q14 P1
(a) What is the meaning of the terms
(i) Homeostatic (1 mark)
(ii) Osmoregulation? (1 mark)
(b) Name the hormones involved in regulating glucose level in blood (2 marks)
27. 2007 Q2 P2
(a) Explain what happens to excess amino- acids in the liver of humans (3 marks)
(b) Which portion of the human nephron are only found in the cortex? (3 marks)
(c)(i) What would happen if a person produced less antidiuretic hormone? (1 mark)
(ii) What term is given to the condition described in (c) (i) above (1 mark)
28. 2008 Q2 P1
State the importance of the following processes that take place in the nephrons of a human kidney
(a) Ultra filtration ( 1 mark)
(b) Selective reabsorption ( 1 mark)
29. 2008 Q11 P1
(a) What is homeostasis? (1 mark)
(b) Name three processes in the human body in which homeostasis is involved (3 marks)
30. 2009 Q17 P1
Explain why plants do not require specialized excretory organs (4 marks)
31. 2009 Q21 P1
Explain what happens in humans when concentration of glucose in the blood decreases below the normal level ( 4 marks)
32. 2009 Q8 P2
Describe the role of the liver in homeostasis in the human body (20 marks)
33. 2010 Q18 P1
Give two reasons why animals have specialized organ for excretion as compared to plants (2 marks)
34. 2010 Q19 P1
State the changes that occur in arterioles in the human skin during thermoregulation. (2 marks)
35. 2011 Q1 P1
Name two kidney diseases.(2 marks)
36.2011 Q25 P1
State one economic importance of each of the following plant excretory products.
37. 2011 Q7b P2
Explain how the human skin brings about cooling of the body on a hot day. (7 marks)
38. 2012 Q18, 19 P1
18. Why plants able to accumulate most of their waste products for long? (1 mark)
19. List four forms of diabetes mellitus. (4 marks)
39. 2012 Q2 P2
The diagram below illustrates the structure of the kidney nephron.
(a) Name the part labeled E. (1 mark)
(b) How the part is labeled F adapted to its function? (4 marks)
(c) State three physiological mechanisms of controlling the human body temperature during a cold day. (3 marks)
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