• Inclined planes.
• Single fixed pulley.

Inclined Planes.

These are tools that make work easier by increasing the effort distance.

Examples of inclined planes.

• Screw
• Screw driver.
• A road winding up a hill.
• Ladder.
• Staircase, escalators, ramps.
• Wedge

Single Fixed Pulley.

These are simple tools that make work easier by changing the direction of the force.
They are used to lift or raise load on higher surfaces.

A rope or string is put along the groove. The groove prevents the rope from slipping off.

Properties of a single fixed pulley.

• Makes work easier by changing the direction of the force.
• The effort distance and the load distance are equal.
• The effort force and load force move in opposite direction.
• The effort force and load force are equal

Uses of pulleys

1. Hoisting the flag.
2. To load or offload cargo at the ports.
3. Used in cranes

• Energy Transformation.
• Energy Conservation
  • Ways of conserving energy
  • Advantages of Renewable Energy

Energy Transformation.

The law of energy conservation statesthat, energy cannot be created or destroyed but can be changed to other forms of energy.

Energy Conservation.

Energy conservation means protecting, preserving, restoring and managing energy resources.

Ways of Conserving of Energy.

1. Using energy sparingly by:
   1. Switching bulbs off when not needed.
   2. Using public transport instead of private vehicle.
   3. Using bicycles or walking for short distance.
   4. Using vehicles with low fuel consumption.
   5. Using thermosflask and hot pots to keep food hot.
   6. Using energy saving bulbs.
2. Using energy efficient devices.
   1. Modern jiko/improvised jiko
   2. Clay cookers.
3. Using renewable forms of energy.
   Renewable forms of energy refers to forms that are inexhaustible like wind, water, sunlight, food, biogas and forests.
   Non-renewable sources of energy are those that can get exhausted when use like petrol, diesel, kerosene, natural gas

Advantages of Renewable Energy.

• Are cheap.
• Do not pollute the environment.
• Help to conserve non renewable forms of energy.
• Readily available and in abundance.

• Nutritional requirements for special groups
  • Nutritional Needs For a Pregnant or Expectant Mother
  • Nutritional Needs of Lactating or Breastfeeding Mother.
  • Nutritional Needs of Infants
  • Weaning
• Food poisoning

Nutritional Requirements For Special Groups

Nutritional Needs For A Pregnant Or Expectant Mother

• Should be rich in proteins for proper growth of baby.
• Should have carbohydratesfor properfunctioning of baby's organs and providing the mother with enough energy.
• Should be rich in vitamin D and calcium for strong bones and teeth of the baby and formation of blood cells.
• Should be rich in irons for healthy blood of the mother and foetus
• Should have fibres to improve the mother's digeston and prevention of constipation
• Should have plenty of fluids for good production of milk and maintenance of properlevel of amniotic fluid.

Nutritional Needs of Lactating Or Breastfeeding Mother.

• Should be rich in irons to replace the blood lost during birth.
• Should be rich in calcium, magnesium and phosphorus for recovery and strengthening of teeth and bones.
• Should have vitamins to protect the mother against infection.

Nutritional Needs of Infants

Infants are children below 2years.

The best food for them is breast milk as it is wholesome ie it contains all the nutrients required by the body.

Advantages of breast milk

• It is wholesome.
• It has colostrum that gives natural immunity.
• It is readily available in the right form and right temperature.
• It is free from diseases.
• It does not cause allergies.
• It is easy to digest.
• It strengthens mother-child bond.

Advantages of bottle feeding.

• Convenient when the mother has little or no milk.
• Someone else can feed the baby when the motheris away.
• Children born to HIV/AIDS mother cannot be infected through bottled milk.

Disadvantages of bottle feeding.

• Might lack some nutrients.
• Lacks colostrum.
• Not readily available.
• Children might develop allergies.
• Should have extra fluids for production of milk.

Weaning.

This is the gradual introduction of semi solids foods to an infant. It is done at the age of 4-6months. Breast feeding should continue upto 2 years. Introduce one food item at a time.

Food Poisoning.

This is an illness of the stomach caused by eating foods containing harmful substances.

Agents of food poisoning.

• Micro-organism.
• Chemicals.

Symptoms of food poisoning.

• Violent vomiting.
• Severe headache.
• Diarrhoea.
• Fever.
• Feeling weak and dizzy.
• Severe abdominal pain.
• Nausea
• Muscle paralysis.
• Constipation.

Methods of prevention food poisoning.

• Proper storage of food to avoid contamination.
• Proper preservation of food.
• Propersanitation and disposal of garbage.
• Hygienic handling of food.
• Proper cooking of food.
• Thourough washing of hands before handling food.
• Avoid buying damaged fruits and canned foods.
• Proper washing of utensils and dishes used for food

STANDARD 8, END OF TERM 1
SCIENCE
NAME....................................................SCHOOL...............................

1. The following are characteristics of clouds
   They are rain laden.
   They have a flat base,
   They are dark or grey in colour.
   They bring fine weather
   They are thick white feathery
   Which among the above characteristics describe cumulus clouds?
   1. (ii), (iv), (v)
   2. (iii), (iv). (vi)
   3. (ii)(iii).(v)
   4. (i)(iii), (iv))
2. The fusion of sex cells in human being take place in the
   1. ovary
   2. uterus
   3. oviduct
   4. testis
3. Which one of the following farm practices conserve soil and water?
   1. Terracing
   2. Building gabions
   3. Planting trees
   4. Mulching
4. The following are signs and symptoms of certain diseases.
   Skin rashes 
   Fever
   Abdominal pains
   Sore on the walls of intestines.
   The disease is LIKELY to be
   1. Bilharzia
   2. Typhoid
   3. Cholera
   4. Malaria
5. The diagram below shows a maize seed.
   
   Which one of the following statement is TRUE?
   1. Part Z is the endosperm.
   2. Part Y forms the embryo.
   3. Part W forms the shoot. 
   4. Part X store food for the young plant.
6. Which one of the following pairs of materials are opaque?
   1. Oil and mirror
   2. Wood and windscreen
   3. Skylight and paraffin
   4. Frosted glass and metal
7. The following are materials used to make a certain weather instrument.
   Metal sheets.
   Nail
   Pole
   Compass
   The weather instrument is MAINLY used to measure
   1. strength of wind
   2. amount of rainfall
   3. air temperature
   4. direction of wind
8. The following are sources of electricity EXCEPT
   1. car batteries
   2. solar panel
   3. torch bulb
   4. dynamo
9. Which one of the following materials is used as insulator?
   1. Copper wire
   2. Rubber band
   3. Iron rod
   4. Aluminium wire
10. The BEST way of controlling the spread of HIV/AIDS among the school going pupils is by
    1. being faithful to one partner.
    2. encouraging the use of condoms.
    3. visiting V.C.T. 
    4. abstaining from sex.
11. Which one of the following excretory product is NOT excreted by the skin?
    1. Carbondioxide
    2. Urea
    3. Excess water
    4. Excess salt
12. Which one of the following sexual transmitted infections is caused by virus?
    1. Syphilis
    2. Gonorrhoea
    3. Chancroid
    4. Genital herpes
13. The following are adaptation of a certain plant.
    Needlike leaves.
    Thick waxy cuticle
    Sunken stomata
    Folded leaves
    The plant growing in the same environment is also LIKELY to have
    1. large flat leaves.
    2. deep root.
    3. air sacs
    4. flexible stems
14. Which of the following pairs of plants are non green and flowerless?
    1. Algae and bacteria
    2. Fern and liverworts . 
    3. Mushroom and mucor
    4. Pine and cedar
15. The diagram below shows an experiment on change of state on matter.
    
    Which process take place at the point marked M?
    1. Evaporation
    2. Boiling
    3. Condensation
    4. Freezing
16. Which one of the following is NOT as a result of bending of light?
    1. A coin in water appear raised.
    2. Formation of images on mirrors.
    3. Swimming pools appears raised.
    4. Formation of the rainbow.
17. The following are effects of drug abuse.Which one is an economic effect?
    1. Loss of income.
    2. Accident
    3. Poor health
    4. Marital conflicts
18. Birds that feed on flesh have
    1. short, straight, thick beak
    2. strong, curved beaks
    3. flat, serrated beaks
    4. long, slender beaks
19. Which one of the following is NOT a sign of ill health in livestock?
    1. Rough coat.
    2. Reduced yields.
    3. Stunted growth
    4. Lower yields.
20. In which of the following parts of digestive system is food NOT digested?
    1. Small intestine
    2. Stomach
    3. Mouth
    4. Large intestines
21. The set up below can be used to investigate the presence of a certain component of soil.
    
    Which two components soil can be investigated by the set up shown above
    1. Water and humus
    2. Mineral particles and organic matter.
    3. Water and living organism.
    4. Ilumus and air
22. The following are examples of straight fertilizer EXCEPT
    1. Munate of potash
    2. CAN
    3. Diammonium Phosphate
    4. Double supersphosphate
23. The body require enough mineral salts for
    1. energy
    2. good health
    3. growth and repair
    4. muscle development
24. The following animals lay unfertilized eggs and live partially in water EXCEPT
    1. salamander
    2. toads
    3. crocodile
    4. news
25. Which one of the following pairs of plants have the same root system?
    1. Onions and sisal
    2. Coconut and mango
    3. Grass and beans
    4. Cowpeas and sorghum
26. Which one of the following statement is NOT TRUE about all arteries?
    1. They carry blood rich in oxygen.
    2. They carry blood away from the heart.
    3. They have thick walls.
    4. Blood pressure in them is high.
27. Which two form of energy. DOES NOT require medium for transmission
    1. Electricity and light
    2. Heat and light
    3. Sound and light.
    4. Sound and heat
28. The diagram below represent the arrangement of the parts of a lever.
    
    The lever illustrated above is LIKELY to be
    1. spade
    2. wheelbarrow
    3. claw hammer
    4. crowbar
29. Which one of the following is NOT a way of reducing friction? Using 
    1. ball bearing
    2. rubber 
    3. lubricants
    4. roller
30. The diagram below shows a food chain
    Maize → rat → snake → vultures
    Which one of the following animal is in the same level with the vultures?
    1. Duck 
    2. Goat
    3. Hyena
    4. Lion
31. The following are properties of matter
    Have definite volume
    Have definite muss.
    Change state when heated
    Occupy space.
    Which substance given below bave the above characteristics?
    1. Milk and water vapour
    2. Salt and ice
    3. Oxygen and nitrogen
    4. Water and milk
32. Which one of the following immunizable diseases are immunized at 10 weeks and immediately after birth to young infants?
    1. Polio, Tetanus, Tuberculosis
    2. Whooping cough, Tetanus, Diptheria
    3. Tuberculosis, Measles, Polio
    4. Yellow fever, Polio, Fertusis
33. The chart below represent approximate percentage of the component of air.
    
    Which portion represent the gas that is NOT used by living things?
    1. S
    2. T
    3. P 
    4. R
34. Oil and grease are used in some simple tools to
    1. reduce opposing force
    2. make them more durable.
    3. increase friction.
    4. make them more attractive.
35. Which of the following feeds provide livestock with protein?
    1. Maize germ 
    2. Lucem 
    3. Cotton seed cake
    4. Mollasses
36. One of the following is NOT in the same group as a tick. Which one?
    1. Spider
    2. Scorpion
    3. Mite
    4. Crab
37. The diagram represents a set up that was used to demonstrate a certain property of matter
    
    The aspect of matter demonstrated is that
    1. liquid expand and contract.
    2. gases expand and contract.
    3. water exert pressure
    4. air occupies space.
38. Pre-test counselling is given
    1. after the result of the test are released.
    2. after the test is done.
    3. before one takes an HIV test.
    4. before results are released to the person who is tested.
39. Which one of the following foods will help boost the immune system of the body?
    1. Egg, milk, bacon
    2. Carrot, rice, cassava
    3. Onions, spinach, tomatoes 
    4. Peas, beans, greengrams
40. When tea leaves is put in a glass of cold water and heated at the bottom, the tea leaves are observed to rise and fall. This is because tea leaves
    1. are carried by hot water which come down on cooling.
    2. and water rise when heated and come down on cooling.
    3. becomes lighter than water when heated.
    4. rise when heated and come down on cooling
41. Which one of the following is a MAJOR non living component of environment?
    1. Animal
    2. Buildings
    3. Plant
    4. Soil
42. Which one of the following is NOT a use of water in factory?
    1. Making fountains.
    2. Surfing
    3. Mixing chemicals
    4. Cleaning equipments.
43. Which one of the following activities is water conserved by re-using?
    1. Using domestic water for washing toilets.
    2. Treating sewage water.
    3. Turning off taps after use.
    4. Harvesting rain water from roofs.
44. During pregnancy period, the placenta has all the following functions EXCEPT
    1. facilitates the exchange of foods from the mother to the foetus.
    2. allow the mother's blood to mix with foetus blood
    3. facilitates the exchange of gases between the mother.
    4. allows the passage of waste from the foetus to the mother.
45. During the investigation of soil water retention all the following materials need to be the same EXCEPT
    1. size of the funnel. 
    2. time allowed for the experiment.
    3. types of soil
    4. amount of water added.
46. A flower which has long feathery stigma and loosely held anthers is also LIKELY
    1. produce nectar.
    2. have sweet scent
    3. have brightly coloured petals.
    4. produce many pollen grains
47. A beam balance is used fo
    1. comparing mass of different objects.
    2. measuring volume of objects.
    3. comparing size of different objects.
    4. measuring height of objects.
48. Study the diagram below
    
    Which pair of blood vessels above carry blood that is bright red in colour? 
    1. W.X
    2. W.S
    3. ST D
    4. T.X
49. Carnassial teeth found in the carnivorous animals are modified
    1. canine and premnolars
    2. pre molars and molars
    3. canine
    4. incisors
50. The diagram below shows a method of separating mixture
    
    The method can be used to separate
    1. coarse and fine sand
    2. salt and iron filling
    3. sugar and water 
    4. maize and beans

MARKING SCHEME

1. A
2. C
3. D
4. B
5. B
6. A
7. D
8. C
9. B
10. D
11. A
12. D
13. B
14. C
15. C
16. B
17. A
18. B
19. D
20. D
21. A
22. C
23. B
24. C
25. A
26. A
27. B
28. A
29. B
30. C
31. D
32. A
33. B
34. A
35. B
36. D
37. B
38. C
39. C
40. A
41. D
42. B
43. A
44. B
45. C
46. D
47. A
48. C
49. B
50. A

• The Meaning and Major Components of Environment
• The Meaning and Effects of Soil Pollution.
  • Effects of Soil Pollution
  • Methods of Soil Conservation
• Air Pollution
  • Major Causes of Air Pollution
  • Effects of Air pollution on Living and Non-living things
  • Ways of controlling air pollution

The Meaning and Major Components of Environment

Environment describes all the things and conditions that make up our surroundings on earth.

The major natural components of environment consist of living things and non-living things i.e. Water, Soil, Air, Plants and Animals

Water

Water is a very important component of the environment in that all living things depend on water. Water forms part of the environment for fish as fish get oxygen from the water and feed on water plants or some other fish found in the water. All other living things that live in water get oxygen from the water.

Other water sources found in the environment is a dependent for other living things on the land e.g. animals get water from rivers, lakes, rain and dams. People also use rain water for domestic purposes. They harvest the water using tanks and drums. They also
fetch water from rivers and wells.

Without water plants can not grow well. We already know that the conditions necessary for germination are: water, air and warmth. During photosynthesis, plants use water to make their own food.

Soil

Another important component of environment is soil which makes the homes of some small animals. Plants get nutrients from the soil so as they can grow well, get water from the soil through absorption and are finally held by the soil. Also soil is important to
animals in that they feed on plants that grow on the soil e.g. zebra, cows and goats. They are called herbivorous because they feed on green plants and vegetable materials that grow on the soil. Human beings cultivate the soil to produce food crops that they eat.

Many small animals live in the soil like ants, termites, moles, groundhogs and some bacteria which decompose dead plant and animal materials.

Air

One of the major components of the environment is air which all living things cannot survive without. We already know that air is a composition of many gases; oxygen which makes 21% of the air is needed for respiration.

Note that living things breath in oxygen and those animals that live in water get their oxygen from the dissolved oxygen in the water. Carbon dioxide in air is 0.03% which is used by plants in making their own food in presence of sunlight, a process called
photosynthesis. These plants give out carbon dioxide. It is from the atmosphere where the plants and animals on the land get their oxygen and those in water get theirs in the water.

Animals take in oxygen through breathing and give out carbon dioxide. On the other hand plants take in carbon dioxide during photosynthesis and give out oxygen. Leguminous plants e.g. beans, ground nuts and peas use nitrogen which makes 78% part
of the air to make proteins.

Plants

Another major component of the environment is plants. Trees provide shelter for some animals such as monkeys and insects. Animals get their food from plants either directly or indirectly. Plants do also hold soil together thus preventing soil erosion.
Plants give out oxygen to the atmosphere during photosynthesis and animals take in oxygen during breathing. Dead plants decay and decompose releasing nutrients to the soil making it fertile.

Animals

Some animals help in pollination such as bees and butterflies. They help in cross pollination of flowers in plants. Animals also help in seed dispersal. Waste matters from animals add nutrients to the plants and this way soil becomes fertile. Small animals like
bacteria decompose materials in the environment to release nutrients to the environment. Animal breath out carbon dioxide into the atmosphere which in turn is used by plants to make food.

The Meaning and Effects of Soil Pollution

Soil pollution is the presence of substances that affect the quality of the soil also known as land pollution. It affects the usual use of soil and is dangerous to the health of human beings, other animals and plants. In other words, soil pollution means making soil impure. We say that when certain substances are present in the soil they pollute it. Substances that make soil or other components of the environment impure are called pollutants (contaminant). Some of examples of such pollutants are plastics, polythene papers, fertilizer, pesticides and herbicides.

NB: Pesticides kill pests while herbicides kill weeds.

If oil is spilled on the soil it pollutes it. The following are some causes of soil pollution:

• Domestic waste disposal improperly
• Improper disposal of raw industrial waste
• Excess use of fertilizers, herbicides and pesticidesin the activities of poor agriculture
• Spilling oil on the soil
• Mining activities destroysthe soil structure and leave excessminerals on the top soil.

Effects of soil pollution

When soil is polluted, its fertility is affected and this too affects the soil productivity leading to the living components of the environment i.e. plants and animals getting affected as well.

Effects of soil pollution on plants

Dumping

Most materials such as plastics and polythene papers do not decay. If such materials are not properly dumped, they may cause damage to leaves and stems of plants when deposited on the soil as they decay. Through this way, they interfere with growth of the plants as follows:

• Absorption of water and mineral salts.
• Growth of roots of the plants since they block the roots.
• Air circulation in the soil.

Negative Effects of Soil Pollution on Animals.

Soil being homes of many small animals, such as worms, ants and termites, they are negative affected when soil is affected (polluted). Some small animals like bacteria make soil to be rich by decomposing dead vegetable and animal materials. Thisis the way humus is added into the soil making it more productive. Other small animals like earthworms and millipedes dig in the soil and this allows air and water circulation in the soil. The improved soil aeration and drainage of the soil allows the roots of the plants to penetrate into the soil easily.

The presence of oil, chemicals in the soil such as herbicides and pesticides and other harmful pollutants make it difficult for the small animals to survive and when they die the soil losesits quality and lowers productivity.

NB: Small animals in the soil improve soil air aeration and drainage.

Methods of Soil Conservation.

Animals and plants depend on soil. Plants grow on the soil while animals feed on the plants hence they need to conserve soil. To conserve soil means to protect it from losing its natural properties and productivity. There are various methods of conserving soil. This section briefly discusses these methods.

Table 3.1: Summary of the main methods used in soil conservation

Methods used in soil Conservation

1. Control use of agricultural chemicals
   Agricultural chemicals include the following: fertilizers, pesticides and herbicides. If used uncontrollably they can lead to soil pollution and even water pollution. Their use can also be harmful to crops and those who consume the crop which include animals and human beings.
   Farmers should strictly follow the manufacturer’s instructions while using the agricultural chemicals. The instructions which come with agricultural chemicals clearly advise on the following:
   • Type of the chemical to use.
   • Purpose of the chemical.
   • Direction of usei.e. the amount to use and mode of application.
   • Precautionary measures to observe.
2. Ensuring proper disposal of waste
   A lot of waste is produced by domestic and industries. Both wastes can be harmful or useful. So that soil is not polluted by these wastes it is important to have good ways of disposing them. This is called waste management.
   1. Domestic Waste
      Domestic waste means the garbage people discard from their homes. This may be of organic refuse or inorganic refuse.
      
      Organic refuse: This refers to those that can rot and includes food remains, vegetables, and fruit peelings.
      
      Inorganic refuse: This does not rot and some may take long time to decay.
      Examples of such are plastics, broken glasses, metal parts and cans. Domestic
      waste should not be dumped on the soil surface.
      
      Methods of disposing domestic waste
      Converting waste into compost manure
      A compost pit should be dug at home for all garbage that can rot e.g. food leftovers. This can be made into compost manure
      
      Using local authority service
      Waste in urban areasis deposited into the garbage bins provided by the local authorities who arrange for its collection and thereafter proper disposal.
      Table 3.2:common methods of waste disposal
      

      Method	Description
      Incinerator	this is burning the inorganic refuse at very high temperatures in a machine
      Recycling	This is the most effective method. It involve collecting waste e.g. papers, plastics, broken glasses and food cans, treating them with chemicals and reusing them to make more of the same products
      Depositing in pit latrines	Inorganic waste should be thrown into a pit latrine or buried deep in the soil. Also it can be burnt in an improvised incinerator as shown below.
      Reusing	Reusing means using an item more then once or for a different function from the one it was meant for at the beginning. Many such as cooking fat and oils, honey and jam are packed in reusable jars and cans. These can be used at home to store other products e.g. salt, sugar or small foods. Honey jars can be used as drinking glasses.

   2. Industrial Waste
      A lot of waste is produced in the industries. Such wastes include oil, contaminated acids and metal waste. Water is contaminated with chemicals, waste rubbers and waste papers. Some of these chemicals are not only hazardous to the soil but to the living component sin the environment.
      

      Method	Description
      On-site treatment	This is where waste is treated harmless at an industry at the point where it is produced. This in turn reduces the danger of polluting the environment during the transportation process to the point where it is appropriate to be disposed.
      Reusing	Some industries use some products more than once or for different function from the initially meant for e.g. commercial industries, the solvent they use such as petrol to dry clean garments is not thrown away but filtered and reused.
      Recycling	Companies that make bottles do not throw broken bottles away but recycle them to make new ones. There are other companies that buy waste paper and recycle them to make tissues e.g. toilet rolls, facial tissues and serviettes.
      Waste Exchange Programme	One industry may produce waste that can or may be needed by another industry for its raw materials. This can be considered as useful waste. To explain this lets look at furniture manufacturer where the saw dust is produced and wood shaving as waste products. These can be used by a company that manufactures papers.
      Treating hazardous waste	This is where the new methods are used to treat hazardous waste to make them non-hazardous. Harmful pollutants are destroyed so that they do not pose any danger to the environment.
      Substituting raw materials	This is the process where the raw materials that produce harmful wastes are replaced with other that produces less harmful waste.
      Changing Manufacturing process	A process or stage which produces waste during the manufacturing process may be changed or eliminated so that the waste is no longer produced.
      Incineration	This is the process of burning waste using machines such as incerators and furnaces.
      Reducing its generation	This is the best method of reducing waste. It involves simply preventing waste generation.
      Government regulations	In this, government has put in place laws to control the disposal of waste. Such control aims at preventing illegal dumping of harmful waste.

3. Avoid burning vegetable cover
   When we want to clearland for farming, we should slash or uproot the unwanted vegetations but not burning them. This is because cleared vegetation left to rot increase humus and adds nutrients to the soil.
   
   NB: Vegetation cover guards soil against exposure to the agents of soil erosion.
   
   When we burn vegetation, we kill the living organisms in the soil and no humus goes into the soil. Vegetation cover also prevents soil from agents of soil erosion such as wind, water and animals.
4. Mulching
   This is covering the soil with dead plant materials such as dry grass and leaves. This prevents excessloss of water from the soil through evaporation. This also reduces splash erosion. The mulch decays afterwards and adds humus to the soil.
5. Planting ground cover
   It is advisable to plant ground coversince land should not be left bear. Ground cover may include ground cover crops that spread out overthe soil surface and cover it. Examples of such cover crops include grass and sweet potatoes. These crops or plants hold the soil firmly with their roots helping or preventing the soil from being carried away by agents of soil erosion such as wind and rain. Cover crops also trap soil as water flows through the garden thus conserving soil.
6. Terracing
   Terraces dug along the contours on the slopes reduce the speed of run-off water. This reduces soil erosion and this way soil is conserved.
7. Planting trees
   Planting of trees can be either afforestation or re-afforestation.
8. Afforestation
   This is planting of trees in areas where none has been planted.
9. Re-afforestation
   This is planting trees where forests have been cleared. Trees are important in preserving soil:
   
   • Reduce wind erosion by breaking the wind
   • The roots hold soil particlesfirmly together. This helps the soil from being carried away by agents of soil erosion.
   • They provide shade thus reducing the amount of water evaporation.
   • They reduce the speed of running water. This reduces the strength of water to erode the soil.
   • The leaves fall off and decompose thus increasing the amount of humus in the soil.
10. Contour farming
    In this crops are planted along the contours on ridges. This helps reduce soil erosion thus conserving the soil.
11. Building gabions
    As already known, gulley erosion where running waterforms V or U - shaped channels. These gullies can be blocked by building structures called gabions across them. Gabions are heavy boxes made of wire mesh that are filled with stones. As water flows through the gabion, soil is trapped thus reducing soil erosion and repairs the soil structure.
12. Proper stocking or controlled grazing
    Farmers should keep livestock that a piece of land can hold. This is called proper stocking which leads to soil conservation. When animals overgraze they uproot the vegetable cover e.g. grass. This way the soil becomes exposed to agents of soil erosion such as wind and water.

Air Pollution

Air is an important component of the environment. Pure air is a mixture of 21% oxygen, 78% nitrogen, 0.03% carbon dioxide and 0.97% rare gases, water vapour, and dust particles. Presence of harmful substances in the air is called air pollution. The substances are called pollutants. Pollutants endanger human health and also affect other living components in the environment i.e. plants and animals. Others which arte indirectly affected by air pollution are water and soil.

Major causes of air of Pollution

1. Tobacco smoking
   This is one of the major forms of air pollution. It is normally smoked as cigarettes. In addiction to nicotine and tar, tobacco contains carbon monoxide as well which is a highly poisonous gas as it interferes with the ability of the blood to transport oxygen to the body organs. Smoke from cigarettes does not only affect the active smoker but also the passive smokeri.e. any one who inhales the cigarette smoke (polluted air) unintentionally.
2. Burning tyres and plastic materials
   The combustion of tyres and plastic materials produces harmful emissions and poisonous gases and especially when they do not completely burn. Incomplete combustion produces gases such as carbon monoxide which poses threat to humans health and to the survival of animals and plants. Similarly, carbon dioxide is a product of incomplete combustion. As we already know the normal carbon dioxide in the air is 0.03% excess carbon dioxide in the air as pollutant. Other pollutants from combustion are tiny particles of smoke and soot.
   
   Rubber and plastics when burnt produces black sooty flame and emits smoke that makes the air smoggy and also emits a foul smell. Charcoal burning is also a threatto the environment
3. Emission of Gases from Vehicle Exhaust
   Vehicles use fuels like petrol and diesel to run. The combustion of these fuels in the engine of the vehicles produces harmful gases e.g. carbon dioxide, carbon monoxide and other gases. These gases produced by vehicles contain poisonous gases then contribute to pollution of the air. Exhaust gases from vehicles thus contribute to pollution of air and especially in cities and big towns where traffic is heavy.
   
   Another harmful substance that may be contained in burning fuels is lead which is dangerousto human health.
4. Spraying Farm Chemicals
   Agricultural or otherwise farm chemicals include the following: Herbicides, Acaricides and Pesticides
   
   Farm chemicals are dissolved in water and sprayed to either crops or animals using a sprayer. As spraying farm chemical is done, wind blows some of the chemicals thus polluting the air. The person spraying the chemicals should take the following precaution measures to avoid inhaling the chemicals:
   
   • Wearing protective clothessuch as gas mask, gloves and protective coats.
   • Spraying in the same direction the wind is blowing to and not against the wind.
5. Aerosol sprays
   These are packed in cans or other containersfrom which liquid is forced out in form of a fine mist. The perfume or pesticide is dissolved in solvent which remains in the atmosphere after spraying and pollutes it. The solvent may contain harmful chemical substances which interfere with the ozone layer.
   
   NB: Ozone is a gasin the upper part of the atmosphere. It forms a protective blanket known as the ozone layer which protects the earth from harmful rays from the sun. Harmful gases result in tuning of the ozone layer. When this is depleted, the survival of human being, animals and plants is at a threat.
6. Industrial Waste Gases
   Most industries release waste gases into the air which may be harmful. Some of these industries produce excess carbon dioxide which can pollute the air. Some otherindustries produce a gas called sulphur dioxide which is also harmful. Other industries too produce dust and small particles which are harmful. These waste industrial gases must be treated so that they are made safe.

Effects of Air Pollution on Living Things and Non-Living Things

Polluted air is a threat to human, animals and plant life. Also it is dangerous to nonliving components of the environment e.g. water and soil. It corrodes materials such as corrugated iron sheets and marble.

1. Effects of air pollution on living things

   1. Effects of air pollution on plants
      In order to grow healthy, plants need clean air. Polluted air affects plants in the following ways:
      • Leaves are covered with dust particle and thus blocking the sunlight and so affecting photosynthesis, the process by which plants make their own food. Soot and dust block the stomata this may affects plants.
      • Some waste gases such as sulphur dioxide dissolve in water droplets to form acidic solutions which damage leaves of plants. Presence of these gases in the air could also lead to formation of acid rain which make the soil to be acidic thus affecting the availability of nutrients to plants. High acidity on the soil may interfere with the survival of organisms that are very important to plants growth. When absorbed through roots, acid rain interferes with proper development of plant and it may wither and die. When deposited in water sources like pond, lakes and oceans, water plants that feed on water animals are affected.
   2. Effects of air pollution on animals
      Air pollution is a threat to humans, domestic and wild animals through the following ways:
      • Causes respiratory problems. When animals inhale dust and other harmful gases, they can develop respiratory such as coughing and sneezing which may result to respiratory diseases.
      • May cause allergies resulting in coughing, sneezing, irritation of eyes and breathing problems.
      • When acid rain gets deposited into water sources like lakes, ponds, and oceans, water animals e.g. fish are affected.

2. Effects of air pollution on non living things

   • Sulphur and carbon dioxide are among gases that cause air pollution when dissolved in the rain water. They form acid rain which corrodes metals such as corrugated iron sheets and stones like marble.
   • Acid rain causes weathering of rocks.
   • The view of environment is also destroyed by smoke and smog which are a mixture of gas particles.
   • Smog destroys materials made of rubber too.
   • Dust particles soil our clothes and settle on surface of tables, window sills and furniture thus making then dirty.

Ways of Controlling Air Pollution

Air pollution is controlled in several ways: These include;

• Avoiding smoking cigarettes
• NOT burning tyres and plastic materials

Table 3.4: Air Pollution Control Measures

• Hard and soft water.
  • Advantages of hard water.
  • Disadvantages of hard water.
  • Advantages of soft water.
  • Disadvantages of soft water.
  • Types of water hardness.

Hard and soft water.

Hard water is water which contains dissolved salts ie magnesium and calcium. Mainly from sea,
oceans, boreholes, lakes and dams.

Soft water is water with no or little dissolved salt in it. Mainly rain water.

Advantages of hard water.

• Contains dissolved minerals which are good for our health.
• It has a good taste to drink.
• It is good in brewing industry.

Disadvantages of hard water.

• Wastes a lot of soap because it does not lather easily.
• It discolours teeth when drank.
• It stains clothes.
• It causes clogging and blocking of pipes.
• It forms scales or fur on boilers and hot water pipes.
• Wastes a lot of time and energy during laundry.

Advantages of soft water.

• Does not stains teeth.
• Best in laundry.

Disadvantages of soft water.

• Does not have a good taste.
• Has no minerals required by the body.

Types of water hardness.

There are two types of water hardness, namely;

• Temporary water hardness.
• Permanent water hardness.

Temporary water hardness can be removed by boiling or distillation. Permanent water hardness can be removed by adding chemicals.

NB: The process of removing the dissolved minerals from hard water is called softening.

• Adaptations of animals to their environment
  • Feeding habitats in mammals.
  • Feeding adaptations in birds
• Adaptations of Animals to Movement.
  • Adaptations to Flying.
  • Adaptations to Swimming
  • Adaptations to Hopping and Leaping.
• Signs of Ill Health in Livestock.
  • Effects of Livestock Diseases.

Adaptations of Animals to their Environment

Feeding Habitats in Mammals.

Herbivores.

These are mammals that feed on plants eg cow, buffalo, antelopes, elephants etc

They are classified into two, namely;

• Grazers- They feed on grass eg cattle, buffalo, hippopotamus
• Browers- They feed on twigs and leaves eg antelopes, girraffes, goats

Carnivores.

These are mammals that feeds on flesh only. They include; lions, dogs, cats, leopard, etc

Adaptations of carnivores.

1. They have sharp and pointed incisiors for catching and holding their prey.
2. They have long pointed and strong canines for tearing off pieces of flesh from bone, they also penetrate flesh, holding and killing the prey.
3. They have ridged, flattened premolars and molars which fit well into each, saw like on both jaws for crushing bones and flesh into small portions.
4. They have strong scissor like carnassial teeth on both jaws for slicing into flesh and cracking bones.
5. They have well spaced teeth to prevent flesh from getting stuck between teeth.

Feeding Adaptations in Birds.

Grain eaters.

These are birds which feeds on grains or seeds.
They include; chicken, doves, Turkey, pigeons,Weaver bird and quelea birds. They have a strong, short, straight, thick, blunt and cone shaped beaks for picking grains.
Their claws are adapted to scratching.

Flesh eaters.

They are know us birds of prey.
They include Hawks, eagles, kites and falcons
They have short, thick, sharp and hooked(curved) beaks for cutting and tearing flesh.
They have a sharp eyesight for spotting their prey from far.
They have strong,sharp and curved claws called talons for holding and tearing their prey.

Nectar feeders.

They feed on nectars.
Examples include; sunbird and humming bird.
They have a long slender and slight curved beak for sucking nectarsfrom a flower.

Filter feeders.

These birds filters their foods from mud.
They include; ducks, sea gulls, swans, geese, pelican and flamingo.
They have a flat, broad, strong and serrated (v-shaped) beaksfor sieving or filtering their foods
Their feet are webbed.

Adaptations of Animals to Movement.

Reasons for movement.

1. To search for food (prey).
2. To search for shelter.
3. To escape from predators.
4. To search for favouble climatic condition.
5. To seek mates for reproduction.

Adaptations to Flying.

1. They have wings which has feathers to increase surface area for flapping against air.
2. They have hollow bones to make themlight so that they can float on air
3. They have a streamlined bodiesto enable them move quickly, smoothly and easily through air.

Adaptations to Swimming

1. They have fins(pelvic, pectoral, caudal, dorsal and anal fins) which help them to move in water.
2. They have swim bladder (air bladder) which help them to control their depth during swimming.
3. They have webbed feet which act as oarsfor propelling themin water.
4. They have streamlined body which help them to move smoothely in water.
5. They have scales pointing backwards and covered with slimy substance to minimise waterresistance

Adaptations to Hopping and Leaping.

They have a powerful hind legs to enable them move forward. Some have a
short fore legs and strong hind eg kangaroo. Some also have tails for balancing.
They include; amphibians, grasshopper, locust and kangaroos.

Signs of Ill Health in Livestock.

• Stunted or retarded growth.
• Loss of weight.
• Reduced yields.
• Rough coat.
• Coughing.
• Blood or worms in stool.
• Inactive.

Effects of Livestock Diseases.

• Lowers yields.
• Lowers quality of the product.
• Diseases can be passed to human being.
• Can cause death to animals

• Adaptations of plants to their environment.
  • Plants adapted to dry area.
  • Plants adapted to wet areas.
  • Adaptations to normal soil and water conditions.

Adaptations of plants to their environment.

Adaptations are mechanisms that enable a plant to survive in a habitat. Plants habitats include:-

• Dry areas
• Wet areas.
• Normal soil and water condition

Plants adapted to dry area.

Plants that are able to survive in dry area are called xerophytes.

Examples include: Cactus, acacia, euphorbia, baobab, sisal, marram grass, pricky pears, desert
shrubs, sun dune grass, jacaranda, thorn tree, cassava, casuarinas and candelabra.

Characteristics of xerophytes.

1. They have deep and widespread root system to obtain waterfrom a wider area.
2. They have stemsthat can store water; their stems are thick, fleshy and succulent. They also have waxy cuticle to reflect sunlight which may cause overheating.
3. They have needle-like leaves which reduces water loss by transpiration and evaporation.
4. Some have few leaves to reduce water losslike acacia.
5. Some shed leaves in dry seasonsto reduce water loss eg jacaranda.
6. Some fold their leaves to trap moisture for the plant eg sun dune grass.
7. Some are covered with a thick waxy cuticle which reduces water loss through evaporation eg sisal.
8. Some become inactive during dry seasons.
9. Some have sunken stomata that are hidden in small depression.
10. Some have reversed stomatal rhythm i.e. open their stomata during the night and close during the day.
11. Some have more stomata on the lowersurface than on the upper surface to reduce water loss through evaporation.

Plants adapted to wet areas.

They are called hydrophytes.

Most they grow in equatorial forests, swamps, marshes, lakes and rivers.

They include: water lily, butter cup, mangroves, bladderwort, water lettuce, duck weed, aquatic
ferns, rice plants and water hyacinth.

Adaptations of hydrophytes.

1. They have broad or wide flat leaves which enables them to float on water and encourages water loss by transpiration eg water lily
2. They have shallow roots which reduce the rate of absorption
3. They have leafy shoots which encourages water loss by transpiration, they also have more stomatas on the upper surface than on the lowersurface
4. They have numerous stomata which remain open to allow gas absorption for photosynthesis.
5. They have flexible stemsthat cannot be broken by water currents.
6. They have thin cuticle to encourage water loss through transpiration.
7. They have air sacs to enable them to float on water.
8. They have waxy and hairy leaf surface to prevent water from standing on the leaf surface.
9. They have floating flowers to allow for the cross pollination by small animals.

Adaptations to normal soil and water conditions.

Plants which grow in normal soil and water conditions are called mesophytes.

They includes maize, beans, potatoes and bananas.

Signs of unhealthy crops.

1. Leaf discoloration.
2. Stunted or stranded growth.
3. Curled leaves.
4. Spots or streaks
5. Wilting.

Effects of crop diseases.

1. Lower yields.
2. Reduces quality of produce.
3. Reducesincome or economic loss.

• Sexually Transmitted infections (STIs)

Sexually Transmitted Infections (STIs)

These are diseases which are passed from one person to another person through sexual contact.

They are also called sexual transmitted diseases (STDs)

NB: Genital herpes and HIV/AIDS are other STIs caused by virus.

• Fertilization
  • Types of Fertilization
  • Foetal Development.
• Excretion
  • Excretory Organs (SKIL)

Fertilization

Fertilization is the fusion or union of the nuclei of the ovum and the sperm in the
oviduct/fallopian tube.

Types of Fertilization.

There are two types of Fertilization that takes place in the female's body. Namely;

• Internal fertilization- Which takes place inside the female's body, mainly in human beings,
  birds and reptiles.
• External fertization - Which takes place outside the female's body, mainly amphibians and
  fish.

Process of Fertilization in human beings

During sexual intercourse/coitus/copulation, sperms are introduced in the vagina by the penis.

Sperms swim in the semen using their tails until they reach the oviduct where they meet a
mature ovum.

Many sperms surrounds the ovum but only one penetrates the ovum, the nuclei of the sperm
and the ovum fuse to form a Zygote

After fertilization a woman becomes pregnant and this is called conception. NB: The sperms
which do not penetrate the ovum are killed.

The zygote then undergo cell division, travels down to uterus and attaches itself on the uterine walls, this is called implantation

After implantation, the zygote is called embryo 

Foetal Development.

After implantation, the embryo develops a disc-shaped organ called placenta which joins the
embryo to the mother.

At 6weeks the embryo has formed most of the important body organs such as the
lips, nose, arms, ears, eyes, feet and toes.

At 8weeks(2months), the embryo is called foetus. The foetus is surrounded by the amnion which
contains a fluid called amniotic fluid.

Functions of the placenta

• Exchange of carbon dioxide and oxygen between the mother and the foetus.
• Supply food from the mother's blood to the foetus.
• Production of hormones that maintains pregnancy.
• Facilitates transfer of waste productsfrom the foetus to the mother's blood.

Functions of the umbilical cord.

• Joins the foetus to the placenta.
• It is a passage for oxygen, food and carbon dioxide.

Functions of the amniotic fluid.

• It acts as a shock absorber to protect the foetus against physical injuries.
• It keeps the foetus warm.
• It prevents the foetus from drying.
• It lubricates the foetus for easy movement.

NB: Gestation period takes nine months or 36 to 40weeks or 280days in human beings, this is
the period between conception and birth.

Signs of pregnancy.

• Menstruation stops.
• The breast becomes larger, tender and sensitive.
• Increased frequency of urination.
• Craving for some foods.
• In later stage, expectant mothers experience some slight backaches.
• Heartburns.
• The abdomen enlarges.
• Breathlessness,tiredness and increased pulse rate.
• Movement of the foetus is felt.
• Morning sickness or nausea.

Birth process.

It is also called parturition.

When the foetus is fully developed, the head faces downwards and is positioned directly above the
cervix.

Stages in the birth process.

• The uterus walls contract causing labor pain.
• The cervix widens.
• Amnion burst and amniotic fluid flows out of the vagina.
• The baby is pushed out through the vagina with the head first.
• Breathing is induced by pinching of patting the baby.
• The umbilical cord is tied and cut, this prevents loss of blood from the mother and the baby also separates the baby from the mother.
• The placenta is expelled from the body. The expelled placenta is called afterbirth.

Excretion

This is the removal of waste productsfrom the body.

Excretory Organs (SKIL)

There are 3 main excretory organs, namely;

• Skin
• Lungs
• Kidneys.

Waste products removed by these organs are;

• Excess water.
• Excess salt.
• Urea.
• Carbon dioxide.
• Lactic acid.

Water, salt, urea and lactic acid forms sweat

Water, urea and salt forms urine.

Order of urine.

Kidney----->Ureter----->Bladder----->Urethra.