SMART NOTE
CHAPTER 1 - THE WORLD THROUGH OUR SENSES
1. Sensory Organs
1. Sensory Organs
2. Pathway from stimulus to response
stimulus -> receptors -> nerves -> brain -> nerves -> effectors -> response
3. Sense of touch is sense that is sensitive towards the touch, pain, pressure, cold and heat.
4. The skin of human is divided into two layers, dermis and epidermis.
5. Types of receptors :
– Pain receptor
– Heat receptor
– Pressure receptor
– Cold receptor
– Touch receptor
6. Sense of smell is the sense that can detect stimuli produced by chemicals.
7. The sensitivity of nose depends of two factors:
– The strength of the smell
– The presence of mucus
8. The sense of taste is the sense that can detect stimulus produced by flavoured chemicals.
9. The tongue is the sensory organ for taste.
10. The tongue enables us to detect sweet, salty, sour, and bitter.
11. The surface has many taste buds.
12. The sense of hearing is the sense that can detect source of sound produced by vibrating object.
13. The function of each part of the ear
a) Pinna – collects and directs sound wave into ear canal
b) Ear canal – directs sound waves to the eardrum
c) Eardrum – vibrates and transfers sound waves to the ossicles
d) Ossicle – intensify the vibration
e) Eustachian tube – balances air pressure
f) Oval window – transfer sound vibration from the middle ear to inner ear
g) Cochlea – convert sound vibrations into nerve impulse
h) Semicircular canals – detect position and movement of head to keep us stay balance
i) Auditory nerves – transfer impulses from the cochlea to the brain
14. The sense of sight is the sense that can detect light stimulus
15. The function of each part of the eye
a) Sclera – maintains the shape of eyeball , protects the eyeball
b) Cornea – allow light to enter the eye , focuses light onto the retina
c) Choroid – supplies oxygen and nutrients to the eye, absorbs and prevent internal light reflection in the eye
d) Conjunctiva – protects the cornea
e) Iris – determines the colour of the eye, controls the size of the pupil
f) Pupil – allows light to enter the eye and controls the size of the pupil
g) Lens – refracts and focuses light onto the retina
h) Ciliary muscle – changes the thickness of the lens
i) Suspensory ligament – supports and holds the lens
j) Vitreous homour – maintains the shape of the eyeball
k) Aqueous humour – refracts and focuses light entering the eye
l) Retina – detects light stimulus and changes it into impulse
m) Optic nerves – transmit nerve impulses from the retina to the brain
16. Light is a form of energy that can be detected by our eyes.
17. Light travels in a straight line.
18. Light can be reflected, refracted, dispersed.
19. The rate of reflected light by a surface depends on the colour and nature of the surface.
20. When light travels at an angle through a medium of different density, the light will be deflected. This deflection is known as refraction of light.
21. Defects of vision and corrections
>Short-sightedness
– Near object are seen clearly
– Distant objects look blur
– Eyeball is too long or big
– Eye lens is too thick
– Image is formed in front of the retina
– Wear glasses with concave lens
>Long-sightedness
– Distant objects are seen clearly
– Near objects look blur
– Eyeball too short or small
– Eye lens is too thin
– Image is formed behind the retina
– Wear glasses with convex lens
22. Defects of the eye include blindness, colour blindness, astigmatism and blurred vision.
23. Colour blindness is a hereditary defect.
24. Astigmatism is a problem of hazy vision caused by irregular surface of the cornea. Astigmatism can be corrected with a cylindrical lens or through surgery.
25. Optical illusion occurs when the brain cannot interpret nerve impulses received properly.
26. The blind spot is the place where the optic nerves leave the eyeball.
27. The stereoscopic vision is a vision using both eyes at the front of the head.
28. Advantages of the stereoscopic vision :
– Sees three-dimensional pictures of object
– Enables more accurate estimation of distance and position
29. Monocular vision is a vision by animals with eyes at the side of the head
30. Advantages of the monocular vision :
– Have a wide vision field
– Cannot estimate distance accurately
31. Sound is produced by the vibrations of objects and is a form of energy carried in the form of waves.
32. Sound can be transferred through solids, liquids, gases.
33. Sound cannot be transferred trough a vacuum.
34. Sound can be reflected or absorbed by the surface of an abject.
35. Surface that are smooth, even and hard are good sound absorbers and produce weak echo.
36. Plants cannot move from one place to another but can move towards a stimulus.
37. The movements of plants are influenced by stimuli such as light, gravity, water, chemical substances and contact with external objects.
38. Tropism is the growth in parts of a plant in response towards or away from an external stimulus.
39. Growth of a part of a plant towards an external stimulus is known as positive tropism while growth away from an external stimulus is known as negative tropism.
40. Tropism involves tips of shoots and roots of plants.
41. Types of tropism :
a) Phototropism
b) Geotropism
c) Hydrotropism
d) Thigmotropism
42. Phototropism is the response of a plant towards light stimulus.
43. Geotropism is the response of plants toward gravitational pull.
44. Hydrotropism is the response of plants toward water.
45. Thigmotropism is the response of plants towards touch.
46. Shoots of plants show :
– Positive phototropism
– Negative phototropism
47. Roots of plants show :
– Positive phototropism
– Positive geotropism
48. Tendrils of plants show :
– Positive thigmotropism
– Negative hydrotropism
stimulus -> receptors -> nerves -> brain -> nerves -> effectors -> response
3. Sense of touch is sense that is sensitive towards the touch, pain, pressure, cold and heat.
4. The skin of human is divided into two layers, dermis and epidermis.
5. Types of receptors :
– Pain receptor
– Heat receptor
– Pressure receptor
– Cold receptor
– Touch receptor
6. Sense of smell is the sense that can detect stimuli produced by chemicals.
7. The sensitivity of nose depends of two factors:
– The strength of the smell
– The presence of mucus
8. The sense of taste is the sense that can detect stimulus produced by flavoured chemicals.
9. The tongue is the sensory organ for taste.
10. The tongue enables us to detect sweet, salty, sour, and bitter.
11. The surface has many taste buds.
12. The sense of hearing is the sense that can detect source of sound produced by vibrating object.
13. The function of each part of the ear
a) Pinna – collects and directs sound wave into ear canal
b) Ear canal – directs sound waves to the eardrum
c) Eardrum – vibrates and transfers sound waves to the ossicles
d) Ossicle – intensify the vibration
e) Eustachian tube – balances air pressure
f) Oval window – transfer sound vibration from the middle ear to inner ear
g) Cochlea – convert sound vibrations into nerve impulse
h) Semicircular canals – detect position and movement of head to keep us stay balance
i) Auditory nerves – transfer impulses from the cochlea to the brain
14. The sense of sight is the sense that can detect light stimulus
15. The function of each part of the eye
a) Sclera – maintains the shape of eyeball , protects the eyeball
b) Cornea – allow light to enter the eye , focuses light onto the retina
c) Choroid – supplies oxygen and nutrients to the eye, absorbs and prevent internal light reflection in the eye
d) Conjunctiva – protects the cornea
e) Iris – determines the colour of the eye, controls the size of the pupil
f) Pupil – allows light to enter the eye and controls the size of the pupil
g) Lens – refracts and focuses light onto the retina
h) Ciliary muscle – changes the thickness of the lens
i) Suspensory ligament – supports and holds the lens
j) Vitreous homour – maintains the shape of the eyeball
k) Aqueous humour – refracts and focuses light entering the eye
l) Retina – detects light stimulus and changes it into impulse
m) Optic nerves – transmit nerve impulses from the retina to the brain
16. Light is a form of energy that can be detected by our eyes.
17. Light travels in a straight line.
18. Light can be reflected, refracted, dispersed.
19. The rate of reflected light by a surface depends on the colour and nature of the surface.
20. When light travels at an angle through a medium of different density, the light will be deflected. This deflection is known as refraction of light.
21. Defects of vision and corrections
>Short-sightedness
– Near object are seen clearly
– Distant objects look blur
– Eyeball is too long or big
– Eye lens is too thick
– Image is formed in front of the retina
– Wear glasses with concave lens
>Long-sightedness
– Distant objects are seen clearly
– Near objects look blur
– Eyeball too short or small
– Eye lens is too thin
– Image is formed behind the retina
– Wear glasses with convex lens
22. Defects of the eye include blindness, colour blindness, astigmatism and blurred vision.
23. Colour blindness is a hereditary defect.
24. Astigmatism is a problem of hazy vision caused by irregular surface of the cornea. Astigmatism can be corrected with a cylindrical lens or through surgery.
25. Optical illusion occurs when the brain cannot interpret nerve impulses received properly.
26. The blind spot is the place where the optic nerves leave the eyeball.
27. The stereoscopic vision is a vision using both eyes at the front of the head.
28. Advantages of the stereoscopic vision :
– Sees three-dimensional pictures of object
– Enables more accurate estimation of distance and position
29. Monocular vision is a vision by animals with eyes at the side of the head
30. Advantages of the monocular vision :
– Have a wide vision field
– Cannot estimate distance accurately
31. Sound is produced by the vibrations of objects and is a form of energy carried in the form of waves.
32. Sound can be transferred through solids, liquids, gases.
33. Sound cannot be transferred trough a vacuum.
34. Sound can be reflected or absorbed by the surface of an abject.
35. Surface that are smooth, even and hard are good sound absorbers and produce weak echo.
36. Plants cannot move from one place to another but can move towards a stimulus.
37. The movements of plants are influenced by stimuli such as light, gravity, water, chemical substances and contact with external objects.
38. Tropism is the growth in parts of a plant in response towards or away from an external stimulus.
39. Growth of a part of a plant towards an external stimulus is known as positive tropism while growth away from an external stimulus is known as negative tropism.
40. Tropism involves tips of shoots and roots of plants.
41. Types of tropism :
a) Phototropism
b) Geotropism
c) Hydrotropism
d) Thigmotropism
42. Phototropism is the response of a plant towards light stimulus.
43. Geotropism is the response of plants toward gravitational pull.
44. Hydrotropism is the response of plants toward water.
45. Thigmotropism is the response of plants towards touch.
46. Shoots of plants show :
– Positive phototropism
– Negative phototropism
47. Roots of plants show :
– Positive phototropism
– Positive geotropism
48. Tendrils of plants show :
– Positive thigmotropism
– Negative hydrotropism
CHAPTER 2 - NUTRITION
1. Classes of food
– Carbohydrates
– Proteins
– Fats
– Vitamins
– Water
– Fibre
– Minerals
2. Carbohydrates are compounds made up of carbon, hydrogen and oxygen.
3. Ration of hydrogen to oxygen is 2:1
4. Carbohydrates are formed from simple molecules known as simple sugars.
5. Carbohydrates can be divided into three types based on the number of simple sugars in the molecules:
a) Monosaccharide [ made up of one unit of simple sugar ]
Example – glucose, fructose, galactose
b) Disaccharide [ made up of two units of simple sugars ]
Example – lactose, maltose, sucrose
c) Polysaccharide [ made up of many units of simple sugars ]
Example – starch, glycogen, cellulose (fibre)
6. Starch food such as bread, rice, potatoes.
7. Sugary food such as honey, fruits, sugar cane, milk.
8. Cellulose such as those found in the plant cell walls.
9. Function of carbohydrates :
a) To supply energy
b) As stored food in animal and plant cells
10. Food test for carbohydrates :
a) The presence of starch can be tested by iodine solution. When the iodine is dripped onto a starch solution, the solution changes to dark blue or blue-black.
b) The presence of glucose, galactose, lactose and maltose can be tested with Benedict’s solution or Fehling’s. When Benedict’s solution is heated gently in a water bath, glucose solution for two minutes, the solution changes colour gradually from light blue to green, yellow, orange, and finally a brick-red precipitate is formed.
11. Proteins are nutrients containing carbon, hydrogen, oxygen and nitrogen. Some proteins also contain sulphur and phosphorus.
12. The basic unit of proteins is amino acid.
13. Function of protein:
a) For the growth of the body
b) For formation of new cells
c) To synthesise other protein compounds
d) To provide energy
14. Test for proteins:
a) The test for the presence of proteins in food samples is known as Million’s test.
b) A red coagulation is formed when food containing proteins is heated together with Million’s reagent.
15. Fats are compounds that contain carbon, hydrogen and oxygen.
16. The ration of hydrogen to oxygen is more than 2 : 1.
17. The basic unit of fats is fatty acids combined with glycerol.
18. Function of fats:
a) As a rich source of energy
b) As a heat insulator
c) As a solvent for vitamin A, D, E, and K.
d) Prevent the loss of water.
19. Test for fats:
a) The test for the presence of fats in food samples is known as the alcohol – emulsion test.
b) A few drops of ethanol are added to a very small amount of fats and mixture is shaken vigorously to dissolve fats. An equal amount of distilled water is added. A cloudy white (milk-like) emulsion indicates the presence of fats or oils.
20. Vitamins are organic compounds that contain carbon and hydrogen. Some vitamins also contain oxygen, nitrogen, cobalt, and zinc.
21. Minerals are inorganic substances present in the form of ions.
22. Fibre is the part of food that cannot be digested by our body.
23. Fibre is made up of cellulose that exists as the main building material in the plant cell walls.
24. Fibre is important to encourage peristalsis in intestines and ensure the smooth movement of food substances as well as facilitate defecation.
25. The lack of fibre can cause faeces to store in the large intestines for a long period time. It is difficult to get rid of faeces that have turned dry and hard in the large intestines, this condition is called constipation.
26. Water makes up about three quarters or 70% of our body weight.
27. Function of water:
a) As a solvent for chemicals
b) As a transport medium
c) To regulate and maintain body temperature
d) To regulate pressure of body fluids
e) As lubricant to reduce friction between joints of bones
f) To assist smooth peristalsis.
g) As moist substance in cells, tissues and internal organs.
28. Water is expelled from the body through physiological processes such as perspiration, respiration, urination and defecation.
29. Factors that determine a person’s balanced diet:
a) Age
b) Body size
c) Sex
d) Occupation
e) Climate
f) State of health
30. The amount of energy in food is known as calorie.
31. Calorie is defined as the amount of heat needed to increase 1g of water by 1°C at 1 atmospheric pressure.
32. The SI unit to measure the amount of energy in food is joule (J).
33. A balanced diet is important to:
a) Maintain optimum health of the body
b) Ensure body growth
c) Repair and replace old or damaged tissues
d) Ensure sufficient energy for the body according to its needs
34. Diet imbalance in the long run causes a person to contract deficiency disease. This condition is known as malnutrition.
35. Digestion is a process of breaking down large or complex food molecules into simpler and smaller soluble molecules that are readily absorb by the body.
36. Digestion in the body is carried out by specific system known as the digestion system.
37. The digestive system breaks down carbohydrates into glucose, proteins into amino acids and fats into fatty acids and glycerol.
38. Digestion is said to take place if food is found in the alimentary canal.
39. The passage of food in the alimentary canal is as follows:
Mouth → oesophagus → stomach → small intestine → large intestine → rectum → anus
40. Physical digestion involves the break down of large pieces of food into smaller pieces by physical action of chewing and grinding by the teeth.
41. Saliva softens the food particles and shapes them into a lump called bolus.
42. Chemical digestion is the process of breaking down complex food into simpler form by chemical means.
43. Chemical digestion in the alimentary canal occurs in the mouth, stomach and small intestine
44.There are three types of digestive enzymes:
a) Amylase to break down starch.
b) Protease to break down proteins.
c) Lipase to break down fat.
45. When the food enters the stomach, the stomach wall will secrete gastric juice that contains hydrochloric acid, proteases and water.
46. The small intestine secretes enzymes to complete the digestion of food and absorption of digestive products.
47. The small intestine is made up three parts. They are duodenum, jejunum and ileum.
48. In the duodenum, chime is mixed with two types of secretions, bile from the gall bladder and pancreatic juice from the pancreas.
49. Bile is a yellow-greenish liquid produced by the liver and stored in the gall bladder.
50. Bile is directed into the duodenum from the gall bladder via the bile duct.
51. Bile does not contain enzyme. It is alkaline because it contains sodium hydrogen carbonate salt. Bile neutralizes acids in the stomach and provides an alkaline medium for the action of enzymes from the pancreatic juice and small intestine.
52. Bile also emulsifies fats that are it breaks up fats into smaller droplets by reducing the surface tension of fat droplets. This process is known as breakdown of fats or emulsion. This aims to increase the surface area of fats for the action of enzymes as well as accelerate the digestion of fats.
53. Function of enzymes in the pancreatic juice:
a) Pancreatic amylase breaks down starch into maltose.
Pancreatic
Starch -----------------> Maltose
b) Lipase breaks down fats into fatty acids and glycerol.
Lipase
Fat ---------------> Fatty acids + Glycerol
c) Protease breaks down proteins into polypeptides.
Protease
Proteins --------------> Polypeptides
54. Function of enzymes in intestinal juice:
a) Protease breaks down polypeptides into amino acids.
b) Lipase breaks down fats into fatty acids and glycerol.
c) Maltase breaks down maltose into glucose.
d) Sucrose breaks down sucrose into fructose and glucose.
e) Lactose breaks down lactose into galactose and glucose.
55. Vitamins and minerals are not digested in the alimentary canal as they exist in their simple original forms.
56. Products of digestion, vitamins and minerals will be absorbed into the bloodstream through the walls of the small intestine by diffusion. This process is known as absorption.
57. The small intestine has special adaptability characteristics to increases its efficiency in the process of absorption.
58. Villi increase the surface area to speech up the absorption process. The surface area for absorption is about 40m².
59. Villi also contain many blood capillaries and lacteals to increase the absorption of products of digestion.
60. Undigested substances such as fibre will be converted into faeces before being expelled from the anus by defecation.
61. Food must be handled with care to prevent food poisoning and to retain nutrients.
1. Classes of food
– Carbohydrates
– Proteins
– Fats
– Vitamins
– Water
– Fibre
– Minerals
2. Carbohydrates are compounds made up of carbon, hydrogen and oxygen.
3. Ration of hydrogen to oxygen is 2:1
4. Carbohydrates are formed from simple molecules known as simple sugars.
5. Carbohydrates can be divided into three types based on the number of simple sugars in the molecules:
a) Monosaccharide [ made up of one unit of simple sugar ]
Example – glucose, fructose, galactose
b) Disaccharide [ made up of two units of simple sugars ]
Example – lactose, maltose, sucrose
c) Polysaccharide [ made up of many units of simple sugars ]
Example – starch, glycogen, cellulose (fibre)
6. Starch food such as bread, rice, potatoes.
7. Sugary food such as honey, fruits, sugar cane, milk.
8. Cellulose such as those found in the plant cell walls.
9. Function of carbohydrates :
a) To supply energy
b) As stored food in animal and plant cells
10. Food test for carbohydrates :
a) The presence of starch can be tested by iodine solution. When the iodine is dripped onto a starch solution, the solution changes to dark blue or blue-black.
b) The presence of glucose, galactose, lactose and maltose can be tested with Benedict’s solution or Fehling’s. When Benedict’s solution is heated gently in a water bath, glucose solution for two minutes, the solution changes colour gradually from light blue to green, yellow, orange, and finally a brick-red precipitate is formed.
11. Proteins are nutrients containing carbon, hydrogen, oxygen and nitrogen. Some proteins also contain sulphur and phosphorus.
12. The basic unit of proteins is amino acid.
13. Function of protein:
a) For the growth of the body
b) For formation of new cells
c) To synthesise other protein compounds
d) To provide energy
14. Test for proteins:
a) The test for the presence of proteins in food samples is known as Million’s test.
b) A red coagulation is formed when food containing proteins is heated together with Million’s reagent.
15. Fats are compounds that contain carbon, hydrogen and oxygen.
16. The ration of hydrogen to oxygen is more than 2 : 1.
17. The basic unit of fats is fatty acids combined with glycerol.
18. Function of fats:
a) As a rich source of energy
b) As a heat insulator
c) As a solvent for vitamin A, D, E, and K.
d) Prevent the loss of water.
19. Test for fats:
a) The test for the presence of fats in food samples is known as the alcohol – emulsion test.
b) A few drops of ethanol are added to a very small amount of fats and mixture is shaken vigorously to dissolve fats. An equal amount of distilled water is added. A cloudy white (milk-like) emulsion indicates the presence of fats or oils.
20. Vitamins are organic compounds that contain carbon and hydrogen. Some vitamins also contain oxygen, nitrogen, cobalt, and zinc.
21. Minerals are inorganic substances present in the form of ions.
22. Fibre is the part of food that cannot be digested by our body.
23. Fibre is made up of cellulose that exists as the main building material in the plant cell walls.
24. Fibre is important to encourage peristalsis in intestines and ensure the smooth movement of food substances as well as facilitate defecation.
25. The lack of fibre can cause faeces to store in the large intestines for a long period time. It is difficult to get rid of faeces that have turned dry and hard in the large intestines, this condition is called constipation.
26. Water makes up about three quarters or 70% of our body weight.
27. Function of water:
a) As a solvent for chemicals
b) As a transport medium
c) To regulate and maintain body temperature
d) To regulate pressure of body fluids
e) As lubricant to reduce friction between joints of bones
f) To assist smooth peristalsis.
g) As moist substance in cells, tissues and internal organs.
28. Water is expelled from the body through physiological processes such as perspiration, respiration, urination and defecation.
29. Factors that determine a person’s balanced diet:
a) Age
b) Body size
c) Sex
d) Occupation
e) Climate
f) State of health
30. The amount of energy in food is known as calorie.
31. Calorie is defined as the amount of heat needed to increase 1g of water by 1°C at 1 atmospheric pressure.
32. The SI unit to measure the amount of energy in food is joule (J).
33. A balanced diet is important to:
a) Maintain optimum health of the body
b) Ensure body growth
c) Repair and replace old or damaged tissues
d) Ensure sufficient energy for the body according to its needs
34. Diet imbalance in the long run causes a person to contract deficiency disease. This condition is known as malnutrition.
35. Digestion is a process of breaking down large or complex food molecules into simpler and smaller soluble molecules that are readily absorb by the body.
36. Digestion in the body is carried out by specific system known as the digestion system.
37. The digestive system breaks down carbohydrates into glucose, proteins into amino acids and fats into fatty acids and glycerol.
38. Digestion is said to take place if food is found in the alimentary canal.
39. The passage of food in the alimentary canal is as follows:
Mouth → oesophagus → stomach → small intestine → large intestine → rectum → anus
40. Physical digestion involves the break down of large pieces of food into smaller pieces by physical action of chewing and grinding by the teeth.
41. Saliva softens the food particles and shapes them into a lump called bolus.
42. Chemical digestion is the process of breaking down complex food into simpler form by chemical means.
43. Chemical digestion in the alimentary canal occurs in the mouth, stomach and small intestine
44.There are three types of digestive enzymes:
a) Amylase to break down starch.
b) Protease to break down proteins.
c) Lipase to break down fat.
45. When the food enters the stomach, the stomach wall will secrete gastric juice that contains hydrochloric acid, proteases and water.
46. The small intestine secretes enzymes to complete the digestion of food and absorption of digestive products.
47. The small intestine is made up three parts. They are duodenum, jejunum and ileum.
48. In the duodenum, chime is mixed with two types of secretions, bile from the gall bladder and pancreatic juice from the pancreas.
49. Bile is a yellow-greenish liquid produced by the liver and stored in the gall bladder.
50. Bile is directed into the duodenum from the gall bladder via the bile duct.
51. Bile does not contain enzyme. It is alkaline because it contains sodium hydrogen carbonate salt. Bile neutralizes acids in the stomach and provides an alkaline medium for the action of enzymes from the pancreatic juice and small intestine.
52. Bile also emulsifies fats that are it breaks up fats into smaller droplets by reducing the surface tension of fat droplets. This process is known as breakdown of fats or emulsion. This aims to increase the surface area of fats for the action of enzymes as well as accelerate the digestion of fats.
53. Function of enzymes in the pancreatic juice:
a) Pancreatic amylase breaks down starch into maltose.
Pancreatic
Starch -----------------> Maltose
b) Lipase breaks down fats into fatty acids and glycerol.
Lipase
Fat ---------------> Fatty acids + Glycerol
c) Protease breaks down proteins into polypeptides.
Protease
Proteins --------------> Polypeptides
54. Function of enzymes in intestinal juice:
a) Protease breaks down polypeptides into amino acids.
b) Lipase breaks down fats into fatty acids and glycerol.
c) Maltase breaks down maltose into glucose.
d) Sucrose breaks down sucrose into fructose and glucose.
e) Lactose breaks down lactose into galactose and glucose.
55. Vitamins and minerals are not digested in the alimentary canal as they exist in their simple original forms.
56. Products of digestion, vitamins and minerals will be absorbed into the bloodstream through the walls of the small intestine by diffusion. This process is known as absorption.
57. The small intestine has special adaptability characteristics to increases its efficiency in the process of absorption.
58. Villi increase the surface area to speech up the absorption process. The surface area for absorption is about 40m².
59. Villi also contain many blood capillaries and lacteals to increase the absorption of products of digestion.
60. Undigested substances such as fibre will be converted into faeces before being expelled from the anus by defecation.
61. Food must be handled with care to prevent food poisoning and to retain nutrients.
CHAPTER 3 - BIODIVERSITY
1. A classification system is required to group living things methodically because of their large number and types.
2. Animals can be divided into vertebrates and invertebrates.
3. Vertebrates :
– With backbones
– Main support is endoskeleton which consists of bones.
4. Invertebrates :
– Without backbones
– Main support is exoskeleton and fluid pressure
5. Vertebrate can be divided into five groups, namely fish, amphibians, reptiles, birds and mammals.
6. The characteristics of vertebrates are as follows :
1. A classification system is required to group living things methodically because of their large number and types.
2. Animals can be divided into vertebrates and invertebrates.
3. Vertebrates :
– With backbones
– Main support is endoskeleton which consists of bones.
4. Invertebrates :
– Without backbones
– Main support is exoskeleton and fluid pressure
5. Vertebrate can be divided into five groups, namely fish, amphibians, reptiles, birds and mammals.
6. The characteristics of vertebrates are as follows :
7. Invertebrates are animals without backbones.
8. Plants can be classified according to their common characteristic.
9. Classification of plants by common characteristics:
a) Grow on land b) Grow in water c) Woody stem d) Shrub
e) Flowering f) Non-flowering g) Have seeds h) Have spores
i) Net-veined leaves j) Parallel-veined leaves
10. Plants can be divide into flowering and non-flowering
11. Flowering can be divided into two groups, the monocotyledons and the dicotyledons.
12. Cotyledon is the main seed leaf for the germination of new seedlings.
13. Cotyledon contain starch as food for the seeds that are unable to make their own food
14. Monocotyledons
– Seed has one cotyledon
– Fibrous root system, which consists of many roots of equal size
– Leaves have parallel veins
– Stem is non-woody and soft
– Example : wild grass, orchid, maize, sugarcane, palm trees, paddy
14. Dicotyledons
– Seed has two cotyledons
– Tap root system, which consists of small roots that branch out of one main root
– Leaves have net veins
– Stem is woody and hard
– Examples: rose tree, bougainvillea, angsana tree, balsam plant, guava tree
15. Non – flowering need to reproduce through spores.
Interdependence among living organisms and the environment
16. Ecology is the study of relationship between living things as well as the relationship between living things and the
environment.
17. Species is a group of organisms that have common characteristics that can breed among themselves to produce fertile
offspring.
18. Population is a group of organisms of the same species living in the same habitat.
19. A community consists of several types of interdependent populations of organisms living together in one habitat.
20. Habitat is the natural are where an organism lives and reproduces.
21. Organism obtains food and protection from their habitats.
22. All organisms living in a habitat interact to maintain the balance in the habitat.
23. Ecosystem is made up of organisms that interact with one another as well as with non-living things in their surroundings.
24. Living organisms are interdependent. Examples of interdependence between living things are:
a) Supply of gases
b)Sources of food
c) Shelter
25. Living things and non-living things interact with one another to maintain a balanced ecosystem.
26. Interaction is important for the survival of living things.
27. There are different types of interactions, such as prey-predator, symbiosis and competition.
28. Predators are organisms that hunt and eat other organisms for food.
29. Preys are organisms hunted by the predators for food.
30. Symbiosis is any close relationship or interaction between two organisms of different species.
31. Examples of symbiosis are:
– Commensalism
→A relationship in which one organism [the commensal] benefits and the other [the host] is not affected.
– Mutualism
→A relationship in which both organisms benefit.
– Parasitism
→A relationship in which one organism benefits but the organism that is harmed is the host.
→The organism that benefits is the parasite and the organism that is harmed is the host.
→The parasite lives on or inside its host body and obtains nutrients from the host.
32. Competition takes place when organisms living in the same area compete to obtain common needs such as shelter, water,
mate, minerals, food, or light.
33. Competition occurs when the common needs in an ecosystem are limited.
34. The stronger organism will dominate an area and the smaller or weaker one will be eliminated or die.
35. Biological control is a method to control the number of a pest organism [prey] by using its predator.
36. Biological control is better compared to chemical control [use of pesticides] because it is non-toxic and does not harm other
organism which is not pests.
37. Organisms can be classified as producers, consumers and decomposer according to their relationships in term of sources
of food.
38. Producers are organisms that can manufacture their own food
39. Green plants are known as producers because they can make their own food by using carbon dioxide, water and energy
from sunlight.
Light +chlorophyll
water + carbon dioxide--------------------------> glucose + oxygen
40. Consumers are organism that obtain food from other organisms
41.Consumers are usually animals cannot make their own food.
42.Consumers can be divided into three types:
a) Primary consumers
b)Secondary consumers
c) Tertiary consumers
43. Primary consumers are consumers that feed directly on plants and are normally herbivorous animals or omnivorous
animals.
44. Secondary consumers are consumers that feed on primary consumers.
45. Tertiary consumers are consumers that feed on secondary consumers.
46. Decomposers are microorganisms that break down tissues of dead organisms into simpler substances.
47. Scavengers feed on dead plants and animals and break them down into smaller parts.
48. A food chain shows the relationship between food and organisms in an ecosystem.
49. A pyramid of numbers shows the number of organisms at each stage of a food chain.
50. Photosynthesis is a process in which green plants manufactures food from carbon dioxide and water in the presence of
sunlight and chlorophyll.
51. Oxygen cycle is the continuous process of taking and returning oxygen into the atmosphere.
52.Carbon cycle is the continuous cycle of taking and returning carbon in the form of carbon dioxide to the atmosphere.
8. Plants can be classified according to their common characteristic.
9. Classification of plants by common characteristics:
a) Grow on land b) Grow in water c) Woody stem d) Shrub
e) Flowering f) Non-flowering g) Have seeds h) Have spores
i) Net-veined leaves j) Parallel-veined leaves
10. Plants can be divide into flowering and non-flowering
11. Flowering can be divided into two groups, the monocotyledons and the dicotyledons.
12. Cotyledon is the main seed leaf for the germination of new seedlings.
13. Cotyledon contain starch as food for the seeds that are unable to make their own food
14. Monocotyledons
– Seed has one cotyledon
– Fibrous root system, which consists of many roots of equal size
– Leaves have parallel veins
– Stem is non-woody and soft
– Example : wild grass, orchid, maize, sugarcane, palm trees, paddy
14. Dicotyledons
– Seed has two cotyledons
– Tap root system, which consists of small roots that branch out of one main root
– Leaves have net veins
– Stem is woody and hard
– Examples: rose tree, bougainvillea, angsana tree, balsam plant, guava tree
15. Non – flowering need to reproduce through spores.
Interdependence among living organisms and the environment
16. Ecology is the study of relationship between living things as well as the relationship between living things and the
environment.
17. Species is a group of organisms that have common characteristics that can breed among themselves to produce fertile
offspring.
18. Population is a group of organisms of the same species living in the same habitat.
19. A community consists of several types of interdependent populations of organisms living together in one habitat.
20. Habitat is the natural are where an organism lives and reproduces.
21. Organism obtains food and protection from their habitats.
22. All organisms living in a habitat interact to maintain the balance in the habitat.
23. Ecosystem is made up of organisms that interact with one another as well as with non-living things in their surroundings.
24. Living organisms are interdependent. Examples of interdependence between living things are:
a) Supply of gases
b)Sources of food
c) Shelter
25. Living things and non-living things interact with one another to maintain a balanced ecosystem.
26. Interaction is important for the survival of living things.
27. There are different types of interactions, such as prey-predator, symbiosis and competition.
28. Predators are organisms that hunt and eat other organisms for food.
29. Preys are organisms hunted by the predators for food.
30. Symbiosis is any close relationship or interaction between two organisms of different species.
31. Examples of symbiosis are:
– Commensalism
→A relationship in which one organism [the commensal] benefits and the other [the host] is not affected.
– Mutualism
→A relationship in which both organisms benefit.
– Parasitism
→A relationship in which one organism benefits but the organism that is harmed is the host.
→The organism that benefits is the parasite and the organism that is harmed is the host.
→The parasite lives on or inside its host body and obtains nutrients from the host.
32. Competition takes place when organisms living in the same area compete to obtain common needs such as shelter, water,
mate, minerals, food, or light.
33. Competition occurs when the common needs in an ecosystem are limited.
34. The stronger organism will dominate an area and the smaller or weaker one will be eliminated or die.
35. Biological control is a method to control the number of a pest organism [prey] by using its predator.
36. Biological control is better compared to chemical control [use of pesticides] because it is non-toxic and does not harm other
organism which is not pests.
37. Organisms can be classified as producers, consumers and decomposer according to their relationships in term of sources
of food.
38. Producers are organisms that can manufacture their own food
39. Green plants are known as producers because they can make their own food by using carbon dioxide, water and energy
from sunlight.
Light +chlorophyll
water + carbon dioxide--------------------------> glucose + oxygen
40. Consumers are organism that obtain food from other organisms
41.Consumers are usually animals cannot make their own food.
42.Consumers can be divided into three types:
a) Primary consumers
b)Secondary consumers
c) Tertiary consumers
43. Primary consumers are consumers that feed directly on plants and are normally herbivorous animals or omnivorous
animals.
44. Secondary consumers are consumers that feed on primary consumers.
45. Tertiary consumers are consumers that feed on secondary consumers.
46. Decomposers are microorganisms that break down tissues of dead organisms into simpler substances.
47. Scavengers feed on dead plants and animals and break them down into smaller parts.
48. A food chain shows the relationship between food and organisms in an ecosystem.
49. A pyramid of numbers shows the number of organisms at each stage of a food chain.
50. Photosynthesis is a process in which green plants manufactures food from carbon dioxide and water in the presence of
sunlight and chlorophyll.
51. Oxygen cycle is the continuous process of taking and returning oxygen into the atmosphere.
52.Carbon cycle is the continuous cycle of taking and returning carbon in the form of carbon dioxide to the atmosphere.
CHAPTER 4- INTERDEPENDENCE AMONG LIVING ORGANISMS AND THE ENVIRONMENT
1. A habitat is a natural living place of certain plants of animals.
2. It is the place where an organism obtain its food, shelter, protection and reproduces.
3. A species is an organism that have the same shape and structure and can breed together.
4. Monkeys, rats, cats and elephants are examples of different species of organism.
5. A population is a group of organism (animals or plants) of the same type (species) that live together in a habitat.
6. For example
a) a population of monkey on three
b) a population of lion in a grassland
7. A community consist of several types of animals and plants population that live together and interact with one another in a
habitat.
8. For example:
a) a pond community consists of fish, plant, tadpole and insert populations. These organisms interact with each other.
b) a grassland community consists of herbivorous and carnivorous animals, trees and grass that interact with one another.
9. Living things interact with each other and with non-living things in order to survive.
10. The interaction between living things and non-living things lead to balance in an ecosystem.
11. The interaction between living things and non-living things is shown below
a. aquatic plants obtain mineral salts from the soil in the pond.
b. Aquatic animals depend on aquatic plants to supply oxygen for the process of respiration.
c. Aquatic plants depend on aquatic animals to obtain carbon dioxide for photosynthesis.
d. Small fish and tadpoles eat aquatic plants.
e. Big fish eat small fish.
f. Kingfishers eat fish
g. Lotus, duckweed, water hyacinths and land plants obtain sunlight for the process of photosynthesis.
12. Interaction between living things and non-living things is important as it maintains
a. balance in the environment (the number and types of living thing within the environment remain the same)
b. balance in the oxygen and carbon dioxide content within the environment remain the same)
13. The organisms in a community interact with one another to obtain food, shelter, transport and many other necessities.
14. This interaction helps ensure that an ecosystem survives.
15. There are different kinds of interaction in nature
a. Prey-Predator
b. Symbiosis e.g. commensalism, mutualism, parasitism.
c. Competition
14. A predator is an organism that kills and eats another organism.
15. A prey is the organism that is eaten.
16. A predator usually has special physical characteristics such as sharp claws and fangs or beaks, with which to kill its prey.
17. Predators are carnivores and prey may be carnivores or herbivores.
18. Other examples are
a) a tiger (predator) eats chickens(prey)
b) an eagle (predator) eats rabbits (prey)
19. In symbiosis, different organisms live together in a close relationship.
20. One organism always benefits by receiving food, a place to stay and shelter. The other organism may benefit, be at a
disadvantage or is not affected.
21. Commensalisms is a relationship between two organisms which are not same species. One organism benefits from the other
and is called the commensal. This second organism is not adversely affected by the relationship and is called the host.
a) Example of plants that live on trees to obtain sunlight are: the money plant, the staghorn fern
b) Example of animals: remora fish and shark
22. Parasitism is another type of interaction between two organisms. Only one organism benefits (parasite). The others
organism is negatively or adversely affected (host).
a) stem borers and oil palm leaves
b) Aphids and trees
23. A parasite may live outside the body (ectoparasite) or inside the body (endoparasite) of another living organisms (host).
24. Mutualism is an interaction between two different organism that live together in which both organisms benefit. It can be
between two animals, two plants or one animals and one plant. They obtain nutrition and shelter from each other.
a) sea anemone and hermit crab
b) Ox peckers eat the leeches and ticks that feed on buffaloes.
25. Competition occurs when organism compete for the same basic resources.
26. Plants compete to obtain water, sunlight, minerals and living space.
27. Animals compete to obtain water, food, living space and mates for reproduction.
a) Flowering plants compete with weeds to obtain water and mineral salts.
b) Lions a pride compete for food
c) Plants in a tropical rainforest compete for basic needs. Taller trees obtain sunlight more easily.
28. Biological control is a method in which a predator, which is a natural enemy to a certain pest, is used to control the
population of that pest in a area.
29. Biological control is usually used in agriculture to control populations of pests without the use of pesticides.
30. The predator-prey interaction is applied in biological control.
31. Biological control has many advantages as compared to using pesticides.
a) does not pollute the environment
b) does not kill other pests because natural enemies are used
c) is cheap and safe to use.
32. For example
a) owls and snakes eat rats
b) fire ants eat aphids on leaves
33. Two types of interaction used in biological control are
a) parasitism – where the parasite destroys crops
b) predator-prey – eventually removes the pest.
34. Producers are all green plants that make food through photosynthesis.
35. Consumers are animals that eat plants or other animals.
36. Decomposers are organisms that decompose dead organisms (animals or plants) and change them into simple
substances.
37. Examples of decomposers are bacteria and fungi.
38. A food chain is an energy link showing how energy in food is passed from plants (producers) to animals
(consumers).
Paddy ---> rat ---> bird ---> eagle
39. When the organism in a food chain die, they are decomposed by decomposers such as fungi and bacteria, into
simple minerals.
40. A food web consists of several food chains that are interlinked.
41. The organisms in a food web interact with each other.
42. A pyramid of numbers shows the number of organism at each link of the food chain.
43. From the base of the pyramid to the top
a) the number of organisms decrease
b) the size of the organisms increase
c) more energy is lost
44. Photosynthesis is a process that occurs in green plants, in which food is made from water and carbon dioxide in the
presence of chlorophyll and sunlight.
45. Light energy is used to convert carbon dioxide and water into glucose, a simpler sugar and carbohydrate. More complex
sugars are formed from glucose.
46. The equation below shows the process of photosynthesis:
47. The glucose produced is brought to other parts of the plant to be
a) oxidized through the process of respiration to provide energy
b) stored as starch, if in excess
48. Photosynthesis is important to maintain the equilibrium of an ecosystem.
49. The importance and role of photosynthesis are:
a) supplies food to animals
b) removes carbon dioxide from the atmosphere.
c) Enables green plants to make their own food.
d) Regulates equal and maintains carbon dioxide content in the atmosphere.
e) Increases oxygen content in the atmosphere; this gas is used by organisms for respiration as well as in the
process of combustion, rusting and decomposition.
50. Natural gas cycles maintain the content of gases in the air.
51. The carbon and oxygen cycles are two natural gas cycles.
52. The carbon cycle is the circulation of carbon dioxide on Earth. It involves the use and return of carbon dioxide to the
air.
53. These processes take place continuously.
54. The carbon cycle maintains the content of carbon dioxide in the air.
55. The processes that release carbon dioxide into the air include:
a) respiration and breathing
b) combustion
c) decomposition
56. The oxygen cycle is the circulation of oxygen on Earth. It involves the end return of oxygen to the air. These
processes take place continuously.
57. The oxygen cycle maintains the content of oxygen in the air.
58. The processes that use oxygen include:
a. respiration and breathing
b. combustion
c. decomposition
d. rusting
59 Photosynthesis is the only process that releases oxygen into the air.
60. Human beings have a very close relationship with the ecosystem.
61. Human beings are a part of the ecosystem that depend on living and non-living things for survival.
62. Human beings interact with the ecosystem to obtain needs and to lead comfortable lives.
63. We obtain our needs in many ways. At the same time, we also disturb the balance of nature.
64. Human activities bring about an imbalance and decline in the ecosystem.
65. Human activities that destroy the balance of nature are
a) Forestry/logging
b) Industry
c) Housing
d) Fishing
e) Agriculture
f) Construction
g) Mining
66. Human activities cause pollution and have raised the following environmental issues:
a) the greenhouse effect
b) the thinning of the ozone layer
c) acid rain
67. The greenhouse effect occurs because a layer of carbon dioxide in the atmosphere prevents a portion of heat from
escaping to outer space.
68. The greenhouse effect raises Earth’s temperature. This is known as global warning. This phenomena causes
changes in the weather the world over.
69. Climatic change as a result of global warming causes the melting of icebergs in both poles. The sea level
increases and this results in the flooding of low-lying coastal areas.
70. The ozone layer absorbs ultraviolet rays and prevents them from reaching the Earth.
71. Chemicals such as chlorofluorocarbons (CFCs) are used in the manufacture of aerosol sprays, refrigerators and air
conditioners. These chemicals are pollutants that break down ozone molecules in the ozone layer.
72. As a result, the ozone layer has thinned and ultraviolet affected human health by causing:
a) skin cancer
b) cataracts
c) the immune system to function improperly.
73. Gases such as sulphur dioxide and nitrogen dioxide dissolve in rainwater and form acid rain.
74. Acid rain can,
a) destroy the habitats of living things
b) lower the soil pH value and make it unstable for plants.
75. Managing environmental pollution can save our Earth.
76. The following are steps we can take to reduce environmental pollution.
a) use unleaded petroleum
b) make nuclear testing illegal.
c) Create special places to burn rubbish.
d) Stop the use of chlorofluorocarbons (CFCs) by replacing it with hydrochlorofluorocarbons (HCFCs)
1. A habitat is a natural living place of certain plants of animals.
2. It is the place where an organism obtain its food, shelter, protection and reproduces.
3. A species is an organism that have the same shape and structure and can breed together.
4. Monkeys, rats, cats and elephants are examples of different species of organism.
5. A population is a group of organism (animals or plants) of the same type (species) that live together in a habitat.
6. For example
a) a population of monkey on three
b) a population of lion in a grassland
7. A community consist of several types of animals and plants population that live together and interact with one another in a
habitat.
8. For example:
a) a pond community consists of fish, plant, tadpole and insert populations. These organisms interact with each other.
b) a grassland community consists of herbivorous and carnivorous animals, trees and grass that interact with one another.
9. Living things interact with each other and with non-living things in order to survive.
10. The interaction between living things and non-living things lead to balance in an ecosystem.
11. The interaction between living things and non-living things is shown below
a. aquatic plants obtain mineral salts from the soil in the pond.
b. Aquatic animals depend on aquatic plants to supply oxygen for the process of respiration.
c. Aquatic plants depend on aquatic animals to obtain carbon dioxide for photosynthesis.
d. Small fish and tadpoles eat aquatic plants.
e. Big fish eat small fish.
f. Kingfishers eat fish
g. Lotus, duckweed, water hyacinths and land plants obtain sunlight for the process of photosynthesis.
12. Interaction between living things and non-living things is important as it maintains
a. balance in the environment (the number and types of living thing within the environment remain the same)
b. balance in the oxygen and carbon dioxide content within the environment remain the same)
13. The organisms in a community interact with one another to obtain food, shelter, transport and many other necessities.
14. This interaction helps ensure that an ecosystem survives.
15. There are different kinds of interaction in nature
a. Prey-Predator
b. Symbiosis e.g. commensalism, mutualism, parasitism.
c. Competition
14. A predator is an organism that kills and eats another organism.
15. A prey is the organism that is eaten.
16. A predator usually has special physical characteristics such as sharp claws and fangs or beaks, with which to kill its prey.
17. Predators are carnivores and prey may be carnivores or herbivores.
18. Other examples are
a) a tiger (predator) eats chickens(prey)
b) an eagle (predator) eats rabbits (prey)
19. In symbiosis, different organisms live together in a close relationship.
20. One organism always benefits by receiving food, a place to stay and shelter. The other organism may benefit, be at a
disadvantage or is not affected.
21. Commensalisms is a relationship between two organisms which are not same species. One organism benefits from the other
and is called the commensal. This second organism is not adversely affected by the relationship and is called the host.
a) Example of plants that live on trees to obtain sunlight are: the money plant, the staghorn fern
b) Example of animals: remora fish and shark
22. Parasitism is another type of interaction between two organisms. Only one organism benefits (parasite). The others
organism is negatively or adversely affected (host).
a) stem borers and oil palm leaves
b) Aphids and trees
23. A parasite may live outside the body (ectoparasite) or inside the body (endoparasite) of another living organisms (host).
24. Mutualism is an interaction between two different organism that live together in which both organisms benefit. It can be
between two animals, two plants or one animals and one plant. They obtain nutrition and shelter from each other.
a) sea anemone and hermit crab
b) Ox peckers eat the leeches and ticks that feed on buffaloes.
25. Competition occurs when organism compete for the same basic resources.
26. Plants compete to obtain water, sunlight, minerals and living space.
27. Animals compete to obtain water, food, living space and mates for reproduction.
a) Flowering plants compete with weeds to obtain water and mineral salts.
b) Lions a pride compete for food
c) Plants in a tropical rainforest compete for basic needs. Taller trees obtain sunlight more easily.
28. Biological control is a method in which a predator, which is a natural enemy to a certain pest, is used to control the
population of that pest in a area.
29. Biological control is usually used in agriculture to control populations of pests without the use of pesticides.
30. The predator-prey interaction is applied in biological control.
31. Biological control has many advantages as compared to using pesticides.
a) does not pollute the environment
b) does not kill other pests because natural enemies are used
c) is cheap and safe to use.
32. For example
a) owls and snakes eat rats
b) fire ants eat aphids on leaves
33. Two types of interaction used in biological control are
a) parasitism – where the parasite destroys crops
b) predator-prey – eventually removes the pest.
34. Producers are all green plants that make food through photosynthesis.
35. Consumers are animals that eat plants or other animals.
36. Decomposers are organisms that decompose dead organisms (animals or plants) and change them into simple
substances.
37. Examples of decomposers are bacteria and fungi.
38. A food chain is an energy link showing how energy in food is passed from plants (producers) to animals
(consumers).
Paddy ---> rat ---> bird ---> eagle
39. When the organism in a food chain die, they are decomposed by decomposers such as fungi and bacteria, into
simple minerals.
40. A food web consists of several food chains that are interlinked.
41. The organisms in a food web interact with each other.
42. A pyramid of numbers shows the number of organism at each link of the food chain.
43. From the base of the pyramid to the top
a) the number of organisms decrease
b) the size of the organisms increase
c) more energy is lost
44. Photosynthesis is a process that occurs in green plants, in which food is made from water and carbon dioxide in the
presence of chlorophyll and sunlight.
45. Light energy is used to convert carbon dioxide and water into glucose, a simpler sugar and carbohydrate. More complex
sugars are formed from glucose.
46. The equation below shows the process of photosynthesis:
47. The glucose produced is brought to other parts of the plant to be
a) oxidized through the process of respiration to provide energy
b) stored as starch, if in excess
48. Photosynthesis is important to maintain the equilibrium of an ecosystem.
49. The importance and role of photosynthesis are:
a) supplies food to animals
b) removes carbon dioxide from the atmosphere.
c) Enables green plants to make their own food.
d) Regulates equal and maintains carbon dioxide content in the atmosphere.
e) Increases oxygen content in the atmosphere; this gas is used by organisms for respiration as well as in the
process of combustion, rusting and decomposition.
50. Natural gas cycles maintain the content of gases in the air.
51. The carbon and oxygen cycles are two natural gas cycles.
52. The carbon cycle is the circulation of carbon dioxide on Earth. It involves the use and return of carbon dioxide to the
air.
53. These processes take place continuously.
54. The carbon cycle maintains the content of carbon dioxide in the air.
55. The processes that release carbon dioxide into the air include:
a) respiration and breathing
b) combustion
c) decomposition
56. The oxygen cycle is the circulation of oxygen on Earth. It involves the end return of oxygen to the air. These
processes take place continuously.
57. The oxygen cycle maintains the content of oxygen in the air.
58. The processes that use oxygen include:
a. respiration and breathing
b. combustion
c. decomposition
d. rusting
59 Photosynthesis is the only process that releases oxygen into the air.
60. Human beings have a very close relationship with the ecosystem.
61. Human beings are a part of the ecosystem that depend on living and non-living things for survival.
62. Human beings interact with the ecosystem to obtain needs and to lead comfortable lives.
63. We obtain our needs in many ways. At the same time, we also disturb the balance of nature.
64. Human activities bring about an imbalance and decline in the ecosystem.
65. Human activities that destroy the balance of nature are
a) Forestry/logging
b) Industry
c) Housing
d) Fishing
e) Agriculture
f) Construction
g) Mining
66. Human activities cause pollution and have raised the following environmental issues:
a) the greenhouse effect
b) the thinning of the ozone layer
c) acid rain
67. The greenhouse effect occurs because a layer of carbon dioxide in the atmosphere prevents a portion of heat from
escaping to outer space.
68. The greenhouse effect raises Earth’s temperature. This is known as global warning. This phenomena causes
changes in the weather the world over.
69. Climatic change as a result of global warming causes the melting of icebergs in both poles. The sea level
increases and this results in the flooding of low-lying coastal areas.
70. The ozone layer absorbs ultraviolet rays and prevents them from reaching the Earth.
71. Chemicals such as chlorofluorocarbons (CFCs) are used in the manufacture of aerosol sprays, refrigerators and air
conditioners. These chemicals are pollutants that break down ozone molecules in the ozone layer.
72. As a result, the ozone layer has thinned and ultraviolet affected human health by causing:
a) skin cancer
b) cataracts
c) the immune system to function improperly.
73. Gases such as sulphur dioxide and nitrogen dioxide dissolve in rainwater and form acid rain.
74. Acid rain can,
a) destroy the habitats of living things
b) lower the soil pH value and make it unstable for plants.
75. Managing environmental pollution can save our Earth.
76. The following are steps we can take to reduce environmental pollution.
a) use unleaded petroleum
b) make nuclear testing illegal.
c) Create special places to burn rubbish.
d) Stop the use of chlorofluorocarbons (CFCs) by replacing it with hydrochlorofluorocarbons (HCFCs)
CHAPTER 5 - WATER AND SOLUTIONS
1. Water is a colourless, odourless and tasteless liquid.
2. Water exists in three states, which are solid (ice), liquid
(water) and gas (steam).
3. Water can change from one state to another.
4. The changes in the state of water occur at specific
temperature.
5. The temperature of a substances remains constant, that
is it does not rise or drop, during the change of state.
6. The density of water is 1 g per cm3
. 1 cm
3
of water has a
mass of 1 gram. For example, 50 cm
3
of water has a
mass of 50 g.
7. Water is a poor conductor of heat.
1. Water is a colourless, odourless and tasteless liquid.
2. Water exists in three states, which are solid (ice), liquid
(water) and gas (steam).
3. Water can change from one state to another.
4. The changes in the state of water occur at specific
temperature.
5. The temperature of a substances remains constant, that
is it does not rise or drop, during the change of state.
6. The density of water is 1 g per cm3
. 1 cm
3
of water has a
mass of 1 gram. For example, 50 cm
3
of water has a
mass of 50 g.
7. Water is a poor conductor of heat.