Tag Archives: form 3 biology exam

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CRE FORM 3 END TERM EXAMS PLUS ANSWERS FREE

ULTIMATE ACHIEVERS ACADEMY

Name___________________________________________________AdmNo:__________

Date__________________________________________Sign______________

END OF TERM  EXAMINATION 

FORM THREE

CHRISTIAN RELIGIOUS EDUCATION

TIME 2 ½ HRS

Instructions to candidates:

  1. This paper consists 6 questions
  2. Answer any 5 questions in the answer booklet provided.
Questions 1 2 3 4 5 6
Marks            

 

QUESTIONS

  1. a) State 7 teachings from the Genesis stories of creation. (7mks)
  2. b) Outline 4 differences between the traditional African view of evil and biblical concept of sin. (8mks)
  3. c) Explain how human beings fail to carry out the responsibilities given to them by God. (5mks)
  4. a) List down the teachings of Amos on social justice and responsibility.  (7mks)
  5. b) State 7 ways God would punish Israel
  6. c) How can Christians assist the church leaders to perform their duties effectively. (6mks)
  7. a) Outline the teachings of Jeremiah on judgment and punishment (7mks)
  8. b) Identify 6 symbolic acts of Jeremiah on Judgment and punishment (6mks)
  9. c) What evidences from the book of Jeremiah show that he was a true prophet of God. (7mks)
  10. a) Describe the birth of Jesus.   Luke 2: – 7 (6mks)
  11. b) State the activities that took place when Jesus was born (8mks)
  12. c) Outline the significance of the actions that took place during the birth of Jesus (6mks)
  13. a) Outline Jesus teachings on watchfulness and readiness.  Luke 12: 35 – 38 (7mks)
  14. b) List down he Jewish practices that Jesus condemned. Luke 11: 37 – 54; 121: 1 – 3  (7mks)
  15. c) Mention ways in which Christians today observe the Sabbath (6mks)
  16. a) Explain how unity of believers is expressed in the symbol of the bride. (7mks)
  17. b) Identify 7 factors that caused disunity in the early church at Corinthians (7mks)
  18. c) Give 6 factors that have contributed to national unity in Kenya (6mks)

CHRISTIAN RELIGIOUS EDUCATION

FORM THREE MARKING SCHEME

  1. a) Teaching from the Genesis stories of creation
    1. .God is the creator of everything on earth
    2. Human being are co-creators with God
  • Man and women are equal before God
  1. Human beings are superior to the rest of creation.
  2. Marriage is blessed by God.
  3. Work and leisure are instituted by God.
  • Human being should devote one day a week to worship God.
  • The environment is God gifted for human beings to export and their own benefits.
  1. Human life is God given and sacred.

7 x 1 = 7mks

b). Difference between traditional Africa views of evil and biblical concept of sin.

  1. The biblical account emphasizes on personal nature of sin while Africa emphasizes more on the social nature and consequences of evil.
  2. In the bible sin is punished in the next life while Africa believe that punishment of sin is here on earth.
  • In the bible sin does not leave human beings doomed forever but they are offered escape route and a message of hope through Christ death and resurrection whereas African society offer a final solution to evil.
  1. In the bible people are born sinners while in African society a child is born free from evil
  2. Bible teaches that sin in caused by mans thoughts and deeds while African society believe that evil is caused by evil spirits.
  3. In the bible there is eternal punishment for sinners while traditional African communities believe that punishment is here on earth.

4  x 2 = (8mks)

  1. c) Ways in which human beings fail to carry out responsibilities given to them by God.
  2. Carrying out abortion
  3. By using contraceptives
  • Practicing celibacy/failing to marry
  1. Through deforestation
  2. Failing to prevent soil erosion
  3. Failing to worship him/filling to observe the Sabbath
  • Mining and excavation leading to open ground
  • Polluting the environment
  1. Murder
  2. Sexual immorality
  3. a) Teachings of prophet Amos on social justice and responsibility
  4. The poor were sold for silver and a a pair of sandals as payment of debt.
  5. The rich women of Samaria lived in excessive luxury at the expense of the poor.
  • The rich exploited the farmers by taking an excessive share of their harvest,
  1. The rulers lived in magnificent houses.
  2. The merchants exploited the poor by selling to them poor quality goods and using false scales.
  3. The rulers were arrogant, trusted in material possessions and indulged in wine.
  • The judges were corrupt and took bribes from the rich.
  • Excessive drinking was wide spread and the Nazirites were forced to drink.
  1. Those who spoke the truth were hated.
  2. The accused told lies in law courts
  3. There was sexual immorality and temple prostitution.
  • There was misuse of garments taken as pledges.
  • There was robbery with violence.

7  x 1 = 7mks)

  1. b) Ways through which God would punish Israel
  1. Invasion by a foreign nation
  2. Destruction of places of worship
  • Attack by epidemics
  1. God would send an eclipse
  2. They would be taken to exile
  3. God would send an earth quake to destroy their houses.
  • The rich who oppressed the poor would not enjoy their wealth.

7  x 1 = 7mks

  1. c) How Christians can assist church leader perform their duties
  2. giving financial/material help
  3. Advising counseling them on various issues
  • Encouraging them in their work
  1. Participating fully in church activities/functions
  2. Giving tithes/offerings faithfully
  3. Praying for them
  • Respecting them
  • Practicing/obeying the word of God
  1. Defending them against unfair criticism
  2. Providing training opportunities for them.

6  x  1 =  6mks)

  1. a) Teachings of Jeremiah on judgment and punishment
  2. God was going to punish the people for their sins against God.
  3. God judges people by looking into their hearts.
  • Divine judgment would be fall the people of Judah as a group
  1. God would execute judgment by means of political and historical events.
  2. Gods punishment was unavoidable.
  3. The purpose of Gods punishment is to correct the sinner.
  • God gave the people a chance to repent before he punished them
  • Gods judgment is universal
  1. Gods judgment is real.

7  x 1 = 7mks)

  1. b) Symbolic acts of Jeremiah on judgment and punishment
  2. the wearing of the linen waist cloth
  3. the wearing of the wooden ox yoke.
  • Jeremiahs personal life.
  1. Remolding of the clay by the potter.
  2. The parable of the wine jars/wineskins
  3. The vision of the two baskets of figs

6 x 1 = 6mks)

  1. c) Evidences from the book of Jeremiah that shows that he was a true prophet.
  2. What he prophesied came to pass.
  3. He received his call from God
  • He was prayerful
  1. His messages came from God.
  2. He mediated between God and the people.
  3. He condemned social evils in Israel.
  • He lived according to the covenant way of life
  • He faced stiff opposition and rejection from the people
  1. He obeyed Gods command e.g Not to marry.

 

  1. a) The birth of Jesus Luke 2 : 1 – 27
  2. in those days Caesar Augustus issued a decree that a census should be taken of the entire Roman world.
  3. Everyone went to their own town to register.
  • Joseph also went from Nazareth to Bethlehem because he belonged to the house of David.
  1. He went to register with Mary who was expecting a child.
  2. While they were there she gave birth to her first born, a son.
  3. She wrapped him in cloths and laid him in a manger.

6   x  1 +  6mks)

  1. b) Activities that took place when Jesus was born. Luke 2 : 8  – 20

 

  1. There were shepherds looking after their flocks nearby at night
  2. An angel of the Lord appeared to them.
  • The glory of the lord shone around them and they were terrified.
  1. The angle told them not to be afraid for he had brought good news to them.
  2. The told them that a savior had been born.
  3. He gave them a sign: They will find a baby wrapped in cloths and lying in a manger.
  • Suddenly a great company of heavenly hosts appeared with the angels singing
  • When the angels disappeared, the shepherds left for Bethlehem.
  1. They found Joseph, Mary and the baby as they were told.
  2. They told them what the angel had told and they were amazed.
  3. Mary treasured up all these things and pondered them in her heart.
  • The shepherds returned glorifying God.

 

8  x  1 = 8mks)

 

  1. c) significance of the actions that took place during the birth of Jesus.
  2. Jesus birth in Jerusalem fulfilled Micah’s prophecy
  3. The census helped to know payment of taxes and those to join the army
  • Jesus being born in a stable and lain in a manger shows that he was humble
  1. The angles reporting the news to the shepherds shows that Jesus is a good shepherd.
  2. The angels singing in heavens showed that Jesus is indeed the son of God.
  3. The shepherds visiting Mary and Joseph confirmed the message of the angel.

6 x 1 = 6mks)

 

 

  1. a) Jesus teachings on watchfulness and readiness Luke 12: 35 – 48
  2. believers should be dressed for his coming
  3. They should keep their lamps burning
  • They should be awake/alert.
  1. Those who are found waiting will be blessed
  2. They should be prepared at all time since they don’t know the time for his coming.
  3. Believers should continue working until Christ comes back.
  • The servants who mistreat fellow workers will be punished
  • Those who do not do what is required of them will receive a severe beating.
  1. Believers are expected to respond to God according to how much they have received from him.
  2. Those who do wrong out of ignorance will receive a lesser beating/punishment

7  x 1  = 7mks)

  1. b) Jewish practices that Jesus condemned. Luke 11: 37 – 54, 12 : 1 – 3
  2. Cleaning the outside while the inside was not holy/dirt
  3. They gave tithes according to the law but failed to practice love, mercy and justice
  • They loved the high seats in the synagogue to be noticed as righteous people
  1. Scribes and teachers of the law failed to make people understand the interpretations of the law of God
  2. They attended to their animals on Sabbath day but failed to do so to human life.
  3. They loved money a lot.
  • They prayed with pride in their hearts.
  • They were a stumbling block to those who would be sincere
  1. They loved to be greeted with respect in the market places

 

 

7  x 1 =   7mks)

 

 

  1. c) Ways in which Christians observe the Sabbath
  2. Christians attend church services
  3. They read the scriptures
  • They listen to the word of God from the preachers
  1. They give offerings and pay tithes
  2. They visit the sick and preach to them
  3. They retrain from work and spend time with their families.’
  • They help the less fortunate in the society

 

6  x  1 =  6mks)

 

 

  1. a) How unity of believers is expressed in the symbol of the bride.
  2. The bride represents Christians
  3. The bride groom represents Jesus.
  • Christians as the bride should be pure.
  1. Gods relationship with his people is perfect and lasts eternally.
  2. Christians should be committed to Christ as the bride is committed to the groom
  3. The church is loved by Christ as the bride is loved by the bride groom.
  • Christians will be taken to a new home where they will live with Christ forever.

 

7  x 1 = 7mks)

  1. b) Factors that caused disunity in the early church
  2. Eating of the meat offered to the idols
  3. Dispute over church leadership
  • Misuse of spiritual gifts
  1. The abuse of the Lord’s supper
  2. Misunderstanding of the covering of the head during worship
  3. Rampant cases of sexual immorality
  • Disputes over marriage and divorce
  • Setting disputes in civil courts.
  1. Misunderstanding of the resurrection of the body/dead

 

  1. c) Factors that have contributed to national unity in Kenya
  2. The constitution
  3. The national assembly
  • The national anthem
  1. The presidency
  2. Religion
  3. National language
  • Education
  • Common currency
  1. Sports. 6  x  1 =  6mks)
Teachers' Resources

BIOLOGY FORM 3 END TERM EXAMS PLUS ANSWERS FREE

Name____________________________________Class_______________AdmNo:__________

Date__________________________________________Sign_______________

END OF TERM EXAMINATION

FORM THREE

 

BIOLOGY

TIME: 2 HOURS

INSTRUCTION TO THE CANDIDATES.

  • Write your name and admission number in the spaces provided
  • Sign and write the date of examination in the spaces provided
  • Answer all questions in section A and In section C, answer questions 11 (compulsory) and either 12 or 13 in the spaces provided.
  • Answer all the questions in the spaces provided.
  • Candidates should answer all the questions in English.

FOR EXAMINERS USE ONLY

Question/section Maximum score Candidates score
Section A 40

 

  
Section B 40

 

  
Total score 80

 

 

  

 

SECTION A:                                                                                                                                       (34MKS)

Answer all the questions

  1. a) What is transpiration                                                                                                                     1mk

………………………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. b) Give the importance of transpiration in green plants                         3mks

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. Name three mechanisms that hinder self-fertilization in green plants                                             3mks

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. Name two classes of phylum Arthropoda that has cephalothorax                                                    2mks

………………………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. a) Give two roles of testes in humans                                                                                                2mks

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. b) Name two organs that produce the hormone progesterone in female                         2mks

………………………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. a) Give two reasons why an electron microscope cannot be used to view live specimens                   2mks

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

 

 

  1. b) State the function of eye piece tube in a light microscope                         1mk

………………………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. Name the organelle that is involved in each of the following                                                          2mks
  1. manufacture of lipids

…………………………………………………………………………………….

  1. formation of lysosomes

………………………………………………………………………………………………………………

 

 

 

Process X

 

 

Large fat droplets                                                        small fat droplets

 

  1. a) Name process X                                                                                                                 1mk

 

………………………………………………………………………………………………………………………

  1. State the significance of the process named above       2mks

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. State the use of the following apparatus used in collection of specimens.                          3mks
  1. pooter…………………………………………………………………………………………………………………………………………………………………………………………………………..
  2. Baittrap

……………………………………………………………………………………………………………………………………………………………………………………………………..

  1. Fishnet

……………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. The diagram below shows how gaseous exchange occurs across the gills of a fish
  1. According to the diagram, water and blood flows in opposite directions across the gills
  2. Give the term used to describe the flow                                                               1mk

……………………………………………………………………………………..

  1. Explain the advantage of the flow named above             2mks

……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… ……………………………………………………..

  1. What difference would be observed if water and blood flowed across the gills in the same direction 2mks

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….. ………………………………………………………

  1. Name two organs in man which displays the flow system named in a) i) above                                      2mks

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..

  1. How are the gill rakers found in the gills of a fish adapted to perform their function                         1mk

…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

 

 

 

 

  1. The temperature of a person was taken before during and after bath. The results are shown in the graph below

 

 

 

37

36                         Before                                                after

Temps                                                                     during

 

35

Time in minutes

 

  1. Explain why the temperature decreased during the bath                                                               3mks

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. What changes occurred in the skin that enabled the body temperatures to return back to normal .4mks

……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. Name the specific part of human brain that controls body temperature                                        1mk

………………………………………………………………………………………………..

 

 

 

 

 

 

SECTION B : Answer question 11(compulsory) and either Question 12 or 13.

  1. In an experiment, a mixture of starch and salivary amylase solution was uniformly mixed in a beaker. 5ml of the mixture was drawn using a syringe and transferred into a visking tubing after which both ends were tightly tied ensuring there is no leakages. Six such viskingtubings were prepared. They were rinsed with distilled water on the outside then transferred at once to water bath maintained at 370c in a beaker. From time 0 and every 5 minutes interval, one visking tubing was removed from the water bath and analyzed for starch. At the same time, the contents of the water bath in the beaker were also analyzed for reducing sugars for each time intervals.

The table below shows the results

 

Timer in minutes Concentration of the food substances
  Starch in the visking tubing mg\L Simple sugars in the beaker mg/L
0 100

 

 0
5 92

 

 8
10 66

 

 34
15 36

 

 64
20 16

 

 84
25 8

 

 88

 

 

 

 

 

  1. Using a suitable scale represent the data on the grid provided below 8mks

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. At what time was there an equal concentration of starch and simple sugars    1mk

…………………………………………………………………………………….

  • Using the graph paper indicate the times when the concentrations of starch and simple sugars were 70mg/L                                                             2mks

………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. Why was the temperature maintained at 370c                         2mks

………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. Name the enzyme that was used in the experiment                   1mk

……………………………………………………………………….……………………………

  1. State and explain the results that will be observed if the water in the beaker was tested for starch 3mks

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

  1. What are the digestive roles of saliva in the mouth                                                                  3mks

……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….

  1. a) Describe the structural features of the leaves that decreases the rate of transpiration in plants     10mks

 

  1. b) Describe the mechanism of transport of carbon IV oxide in the mammalian blood             10mks
  2. a) What is pollution                2mks
  3. b) Describe various causes and effects of air pollution and for each cause state its control method

18mks

…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

 EXAM MARKING SCHEME

231/1

MARKING SCHEME

  1. a) transpiration is the process by which plants lose water inform of water vapor to the atmosphere through the stomata or lenticels.
  2. b)
  • brings about turgor in plants
  • helps to remove excess water especially to the aquatic plants
  • serves to cool plants in hot environment
  • helps in transport of mineral salts/ions and water in the plant
  • protandry
  • progyny
  • heterostyly
  • monoecious/ dioecius
  • incompatibility/self sterility
  • arachnida
  • crustacea
  1. a)
  • secretion of androgens/testosterone rej. Hormone
  • manufacture of sperms/male gametes rej. Gamete alone
  1. b)
  • ovary
  • placenta
  1. a)
  • specimen is mounted in a vacuum
  • specimen is illuminated by beam of electrons which would kill cells
  • dyes used are obtained from heavy metals which are toxic to cells
  1. b)
  • hold the eye piece lens( in position)

 

  1. a) smooth endoplasmic reticulum
  2. b) golgi bodies /apparatus
  3. a) emulsification
  4. b) used to increase surface area for enzymatic activity
  5. a) used for sucking small animals from rock surfaces or bark of trees eg ants
  6. b) for attracting and trapping small animals eg rats
  7. c) used for trapping small fish and other small aquatic aninmalseg crabs
  8. a) i) counter current flow
  9. ii) it maintains a steep concentration gradient hence increases the efficiency of oxygenation of the blood as well as diffusion of carbon iv oxide from the blood to water,.
  10. b) the diffusion gradient would be low leading to low rate of gaseous exchange; equilibrium between water and blood would be reached ; beyond which no further diffusion can take pklace
  11. c)
  • kidney/ nephron
  • placenta
  1. d) its rake like/ saw like/teeth like to trap solid particles (which may damage delicate gills filaments)
  2. a) heat was lost by conduction/ convection fro the body/skin to cold water; the cooler blood leaving the skin enter the general circulation cooling the body
  3. b)
  • vasocontriction thus less blood flowing to the skin surface reducing heat loss;
  • sweating stops
  • shivering
  1. c) hypothalamus

11.a)  plotting – 2mks

Scale – 2mks

Labelling- 1mk

Identifying curves- 2mks

Curve -1mk

  1. b) i) 12.5min ± 0.5
  2. ii) starch; 16min ± 5

reducing 9.5 min ±  0.5

iii) to provide a suitable optimum temperature for the activity of the enzymes

  1. c) amylase( salivary/pancreatic) ; diastase
  2. d) brown color of iodine is retained; because starch is still absent; the starch molecules are too larhe and cannot pass through the tiny poress of the visking tubing membrane into the water in the beaker

OWTTE

  1. e) saliva contains salivary amylase ; that breaks down starch into maltose; and bicarbonate ions that provides a suitable alkaline ph for the activity of salivary amylase during digestion

12 a)

  • Leaves are modified into spines/ thorns ; to reduce surface are over which transpiration can occur
  • Shed their leaves during dry seasons; to reduce surface area exposed to the atmosphere
  • Leaves have thick waxy cuticle; to minimize rate of cuticular transpiration
  • Some of leaves with hinge cells hence can roll or fold to reduce rate of transpiration by exposing fewer stomata to the environment hence reducing chances of transpiration
  • Have sunken stomata which accumulates moisture in substomatal spaces hence low diffusion gradient thus reducing transpiration rate
  • Have reduced number of stomata hence low rate of transpiration since the surface area for water loss is reduced
  • Some have reversed stomatal rhythm to prevent excessive water loss by transpiration
  • Have parenchyma cell in swollen leaves for storage of water eg cactus
  1. b)
  2. i) a weak carbonic acid in the red blood cells/ bicarbonate ions;

carbon iv oxide on entering the red blood cells reacts with water forming carbonic acid; this process is usually enhanced by catalytic activity of enzyme carbonic anhydrase in the red blood cells; being unstable, the carbonic acid dissociates to hydrogen ions and bicarbonate ions; which acts as buffer; the bicarbonate ions diffuses into the blood plasma and transported to the lungs; on reaching the lungs, they undergo chemical processes(accept explanation of the process) resulting to the formation of the carbon iv oxide which is then exhaled

  1. ii) when physically dissolved in plasma/ weak carbonic acid in blood plasma

carbon iv oxide is transported when physically dissolved in plasma to form a weak carbonic acid; the weak carbonic acid being unstable, dissociates to form hydrogen ions bicarbonate ions/ hydrogen carbonate ions; the hydrogen carbonate ions are transported to the lungs ; where they dissociates to water and carbon iv oxide ; from where carbon iv oxide is exhaled; the hydrogen ions remains in the blood plasma and are mainly secteted into the kidney tubules for excretion when in excess; this method is slow and hence inefficient

iii. when bound to haemoglobin in red blood cells

carbon iv oxide binds to the haemoglobin to form carbominohaemoglobin; being somewhat stable it does not dissociate and carbon iv oxide is transported in thuis form from tissues to lungs; because of high partial pressure of oxygen in the lungs the haemoglobin detaches from the carbon iv oxide; and picks up oxygen; the free carbon iv oxide is then exhaled out of the body .

 

  1. a) pollution is the release of substance or forms of energy; in quantities whose effect is harmful or unpleasant to organisms
  2. b) Sulphur based chemicals( Sulphur iv oxide, hydrogen sulphide)

produced by industries, decomposing organic matter and fumes; affects gaseous exchange ; makes acidic rain and damage leaves affecting photosyntheasis

control method– titration, dissolution and use of chemicals to remove harmful gases

smoke and fumes ; produced in areas with heavy industries, motorvehicles and contain carbon ii oxide; carbon ii oxide combines with haemoglobin to form stable carboxyhaemoglobin which is a respiratory poison; affects visibility;

control– factories should be erected far away from residential areas

dust– produced from cement, gfactories and quarries; it settles on leaves limiting photosynthesis  and causes poor visibility

control– government to enact laws on environmental pollution

sound/ noise– produced by machines aeroplanes  and heavy vehicles and affects heasring in animals

control– ear muffs should be used in industries and jua kali workshops that generates noise

aerosols– consist of fire particles, suspended gases in hebicides, insecticides and sprays; they contain copper metal- when copper is inhaled causes irritation and respiratory diseases, depletion of ozone layer and its non- biodegradable

control– used biological methods of pests control

oxides of nitrogen( nitrogen ii oxide, nitrogen iv oxide)

produced from burning petroleum fules and industries

nitrogencmpounds dissolves in rain water to form acidic rain , its carcinogenic; causes poor visibility on road users

control – use of public means of transport