1- Cells are differentiated in the human body.
*Because each group of cells in the human body has its own function that differ from the others groups.
2- The plant cell has a fixed shape.
Because it has a cellular wall that supports it and gives the cell its shape.
3- Animal cell has not a definite shape.
*Because it hasn’t cellular wall that supports the cell and gives it its shape.
4-Cell wall is inflexible.
Because it is made of cellulose substance that is inflexible.
5-Cells of leaves in plants have green colour.
Because they contain green plastids that give the cells the green colour.
6- The heart is an organ.
Because it consists of a group of tissues that work together.
7-. Bone cells cannot perform the same function of muscle or skin cells.
*Because each type of cells in the body has a specific function.
8-Food should be chewed well.
*To help its swallowing and it is digested easily and faster.
9-When a person chews a piece of bread, it tastes sweet.
*Because saliva changes starch into sugar.
10-Bile juice has an important role.
Because bile breaks down fats and oil into small particles that dissolve in water.
11-The volume of the chest cavity increases during inhalation process.
Because during inhalation, the diaphragm contracts and moves down and rib cage moves up.
12-Exhaled air makes limewater turbid.
Because the exhaled air contains a big amount of carbon dioxide gas that makes limewater turbid.
13-Exhaled air contains more carbon dioxide gas than inhaled air.
Because during food burning inside the body cells, carbon dioxide gas is produced that comes out of the body with the exhaled air.
14-number of inhalation and exhalation increases during carrying out physical exercises.
*Because during physical exercises, the body needs more oxygen to burn more food to obtain more energy.
15-. The nose has hairs.
*To filter dust from the inhaled air.
16- The nose has blood capillaries.
To warm the inhaled air before its entrance to the lungs.
17- The nose has mucus.
To moisten the inhaled air before its entrance to the lungs.
18- You should breathe through your nose not through your mouth.
*Because the nose contains:
- Hairs to filter dust from the inhaled air.
- Mucus to moisten the inhaled air before its entrance to the lungs.
- Blood capillaries to warm the inhaled air before its entrance to the lungs.
19- Food does not enter trachea (respiratory system) during swallowing.
*Due to the presence of the epiglottis that closes the larynx during swallowing.
20-. Larynx is called the vocal organ.
Because it contains the vocal cords that produce the human voice
21-The presence of epiglottis at the top of the larynx. Larynx has epiglottis at its top.
To close the larynx during swallowing to prevent the food from entering the respiratory system.
22-Drops of water could enter the trachea when you drink quickly.
Because when you drink quickly, the epiglottis cannot close the larynx quickly, so drops of water could enter the trachea.
23- The trachea has cartilage rings in its wall.
*To be opened all the time for breathing.
24-Presence of cilia inside the trachea.
*To sweep out any foreign bodies that may enter the trachea.
25-Lungs have alveoli.
To exchange the gases during respiration.
26-The walls of the alveoli and blood capillaries are thin.
To allow the gaseous exchange between each other.
27-You should avoid contacting with sick people or using their tools.
To avoid the infection with respiratory system.
28-You should avoid exposing to cold air after having a warm bath.
To avoid catching cold.
29-We should avoid bathing in water of canals.
To avoid the infection with bilharzia worms that harm the urinary system and cause bloody urine.
30-Cosmetics must not be overused.
To keep the skin healthy.and to avoid inflammation skin
31-. We have to decrease eating spicy and salty food.
Because they harm the urinary system.
32-. The amount of urine that the human body gets rid of it changes from a day to another.
Because the amount of urine depends on:
- The body activity. - The temperature. - The amount of water drunk.
33-Formation of a layer of rust on the surface of a wet iron wire.
Due to the reaction between iron and water in the presence of oxygen gas and this is a chemical change.
34- Changing the sugar shape after heating it strongly on a burning spoon. A piece of sugar loses its properties after burning.
Because burning of sugar is a chemical change that changes the structure of sugar producing a new substance with new properties.
35-. Sugar keeps its flavour after dissolving it in water.
Because dissolving of sugar in water is a physical change,
34-• A solution is a mixture.
Because the components of the solution can be separated by simple physical means as the mixture.
35-. Calcium carbonate does not disappear when it is stirred in water.
Because calcium carbonate is from the salts that does not dissolve in water.
36-When you put a spoon of sugar in a hot cup of tea, it disappears quickly.
Because heating increases the speed of dissolution process.
37-. Drops of water are formed when exposing water vapour to a cold surface.
Due to the condensation of water vapour when touching a cold surface.
38-. You must not touch caustic soda solution before its dilution.
Because it has a burn effect on the skin.
39-Red litmus paper is used to test for alkalis
Because alkalis change the colour of red litmus paper into blue.
40-. Blue litmus paper is used to test for acids.
Because acids change the colour of blue litmus paper into red
41-Formation of a layer of rust on the surface of a wet iron wire.
Due to the reaction between iron and water in the presence of oxygen gas and this is a chemical change.
42- Changing the sugar shape after heating it strongly on a burning spoon. A piece of sugar loses its properties after burning.
Because burning of sugar is a chemical change that changes the structure of sugar producing a new substance with new properties.
43-. Sugar keeps its flavour after dissolving it in water.
Because dissolving of sugar in water is a physical change,
44-• A solution is a mixture.
Because the components of the solution can be separated by simple physical means as the mixture.
45-Calcium carbonate does not disappear when it is stirred in water.
Because calcium carbonate is from the salts that does not dissolve in water.
46-When you put a spoon of sugar in a hot cup of tea, it disappears quickly.
Because heating increases the speed of dissolution process
47-. Drops of water are formed when exposing water vapour to a cold surface.
Due to the condensation of water vapour when touching a cold surface.
48-. You must not touch caustic soda solution before its dilution.
Because it has a burn effect on the skin.
49-. Solutions of some salts do not affect the colour of red or blue litmus paper
. Because they have a neutral effect on litmus paper.
50-Melting of ice or wax is a physical change.
Because it causes a change in the shape, but not in the structure.
51- Evaporation of water is a physical change.
Because it causes a change in the shape, but not in the structure.
52- Formation of clouds and rains is a physical change.
Because it causes a change in the shape, but not in the structure.
53-Burning a piece of bread is a chemical change.
Because it causes a change in its structure producing a new substance with new properties.
54- Wood burning is a chemical change.
Because it causes a change in its structure producing a new substance with new properties.
55- Fermentation of milk is a chemical change.
Because it causes a change in its structure producing a new substance with new properties.
56-Rusting of iron is considered as a chemical change.
Because it causes a change in its structure producing a new substance with new properties.
57-. Melting of ice is a physical change, but burning a piece of wood is a chemical change.
Because melting of ice causes a change in its shape not in its structure, but burning of wood causes a change in its structure producing a new substance with new properties.
58-Smoking and using narcotics lead to the destruction of the respiratory system.
Because they damage the two lungs and also cause lung cancer.
59-The circulatory system is called the system of translocation in the human body.
Because the circulatory system is responsible for carrying digested food and oxygen gas to all the body cells and carries the wastes as carbon dioxide gas from all the body cells to the excretory system
60-The two sides of the heart are separated from each other by a wall called septum.
To prevent the mixing of blood in the two sides of the heart.
61-Blood flows from atrium to ventricle in the heart and not vice versa.
*Due to the presence of a valve that allows blood to flow from atrium to ventricle only and not in the opposite direction.
•62- Blood does not flow back to the atrium when the ventricle contracts.
*Due to the presence of a valve that allows blood to flow from atrium to ventricle only and not in the opposite direction.
63-. Heart is acting as a pump in its performance.
Because the heart pumps the blood to all the body parts.
64-The presence of a valve between each atrium and ventricle in the heart.
To allow the blood to flow from atrium to ventricle only and not in the opposite direction.
65-The speed of heartbeats increases during performing a large muscular effort.
Because we need more oxygen carried by blood to burn more food in the body cells, to produce more energy needed for physical activities.
66-The blood has a liquid form.
Due to the presence of plasma in the blood which is in the liquid form.
67-Wounds heal when there is a cut in one of the blood vessels.
Due to the presence of platelets that have a role in the blood clot process to heal the wounds.
68-The blood capillaries are very fine blood vessels.
To allow the diffusion of dissolved substances and gases from and to the body cells.
69-. Ammonia solution changes the red litmus paper to blue but lemon juice turns blue litmus paper to red.
Because ammonia solution is an alkaline substance, while lemon juice is an acid.
70-. The solution of tooth paste is acidic.
*Because it changes the colour of blue litmus paper into red.
Or because it has sour taste .
71-. Citric acid is from acids.
Because it changes the colour of blue litmus paper into red.
72-. Alkalis are used in the soap industry.
Because alkalis react with vegetable oil to form soap.
73- We can differentiate between solution of vinegar (acids) and caustic soda
. Because alkalis or caustic soda turn(s) the colour of red litmus paper to blue and acids or vinegar turn(s) the colour of blue litmus paper to red.
78- Effervescence occurs when acids (as acetic acid) react with sodium carbonate or bicarbonate.
Due to the formation of carbon dioxide gas.
79- Boiling occurs when acids react with sodium carbonate or bicarbonate
* Due to the formation of carbon dioxide gas
80-. Importance of blood platelets.
Because they have a role in the blood clot process to heal the damaged vessels and wounds.
81-Importance of white blood cells.
Because they resist the microbes which attack the body.
82-The walls of ventricles are more thicker than the walls of atria.
Because ventricles pump the blood to all parts of the body, while atria push the blood to ventricles opposite only.
83-We should do physical activity regularly.
To keep the respiratory and circulatory systems healthy.
84-We have to eat balanced diet and avoid eating fats and salts too much.
To keep the circulatory system healthy.
85-The two kidneys are the most important organs in the urinary system. Because they filter the blood from harmful substances such as urea, uric acid, excess water and salts.
86-We should avoid keeping urine in the urinary bladder.
*To avoid any precipitation of harmful substances in it.
87-We should not expose the skin to sun rays for a long period of time.
*To avoid dryness and inflammation of skin
88-Skin is an organ that has several functions.
Because it has an excretory, protection, regulation and sensation functions.
89-We should wash skin daily during the summer season.
*-To remove sweat and to open the skin pores.
90-The human skin surface contains pores.
To get rid of the sweat out of the body.
*Because each group of cells in the human body has its own function that differ from the others groups.
2- The plant cell has a fixed shape.
Because it has a cellular wall that supports it and gives the cell its shape.
3- Animal cell has not a definite shape.
*Because it hasn’t cellular wall that supports the cell and gives it its shape.
4-Cell wall is inflexible.
Because it is made of cellulose substance that is inflexible.
5-Cells of leaves in plants have green colour.
Because they contain green plastids that give the cells the green colour.
6- The heart is an organ.
Because it consists of a group of tissues that work together.
7-. Bone cells cannot perform the same function of muscle or skin cells.
*Because each type of cells in the body has a specific function.
8-Food should be chewed well.
*To help its swallowing and it is digested easily and faster.
9-When a person chews a piece of bread, it tastes sweet.
*Because saliva changes starch into sugar.
10-Bile juice has an important role.
Because bile breaks down fats and oil into small particles that dissolve in water.
11-The volume of the chest cavity increases during inhalation process.
Because during inhalation, the diaphragm contracts and moves down and rib cage moves up.
12-Exhaled air makes limewater turbid.
Because the exhaled air contains a big amount of carbon dioxide gas that makes limewater turbid.
13-Exhaled air contains more carbon dioxide gas than inhaled air.
Because during food burning inside the body cells, carbon dioxide gas is produced that comes out of the body with the exhaled air.
14-number of inhalation and exhalation increases during carrying out physical exercises.
*Because during physical exercises, the body needs more oxygen to burn more food to obtain more energy.
15-. The nose has hairs.
*To filter dust from the inhaled air.
16- The nose has blood capillaries.
To warm the inhaled air before its entrance to the lungs.
17- The nose has mucus.
To moisten the inhaled air before its entrance to the lungs.
18- You should breathe through your nose not through your mouth.
*Because the nose contains:
- Hairs to filter dust from the inhaled air.
- Mucus to moisten the inhaled air before its entrance to the lungs.
- Blood capillaries to warm the inhaled air before its entrance to the lungs.
19- Food does not enter trachea (respiratory system) during swallowing.
*Due to the presence of the epiglottis that closes the larynx during swallowing.
20-. Larynx is called the vocal organ.
Because it contains the vocal cords that produce the human voice
21-The presence of epiglottis at the top of the larynx. Larynx has epiglottis at its top.
To close the larynx during swallowing to prevent the food from entering the respiratory system.
22-Drops of water could enter the trachea when you drink quickly.
Because when you drink quickly, the epiglottis cannot close the larynx quickly, so drops of water could enter the trachea.
23- The trachea has cartilage rings in its wall.
*To be opened all the time for breathing.
24-Presence of cilia inside the trachea.
*To sweep out any foreign bodies that may enter the trachea.
25-Lungs have alveoli.
To exchange the gases during respiration.
26-The walls of the alveoli and blood capillaries are thin.
To allow the gaseous exchange between each other.
27-You should avoid contacting with sick people or using their tools.
To avoid the infection with respiratory system.
28-You should avoid exposing to cold air after having a warm bath.
To avoid catching cold.
29-We should avoid bathing in water of canals.
To avoid the infection with bilharzia worms that harm the urinary system and cause bloody urine.
30-Cosmetics must not be overused.
To keep the skin healthy.and to avoid inflammation skin
31-. We have to decrease eating spicy and salty food.
Because they harm the urinary system.
32-. The amount of urine that the human body gets rid of it changes from a day to another.
Because the amount of urine depends on:
- The body activity. - The temperature. - The amount of water drunk.
33-Formation of a layer of rust on the surface of a wet iron wire.
Due to the reaction between iron and water in the presence of oxygen gas and this is a chemical change.
34- Changing the sugar shape after heating it strongly on a burning spoon. A piece of sugar loses its properties after burning.
Because burning of sugar is a chemical change that changes the structure of sugar producing a new substance with new properties.
35-. Sugar keeps its flavour after dissolving it in water.
Because dissolving of sugar in water is a physical change,
34-• A solution is a mixture.
Because the components of the solution can be separated by simple physical means as the mixture.
35-. Calcium carbonate does not disappear when it is stirred in water.
Because calcium carbonate is from the salts that does not dissolve in water.
36-When you put a spoon of sugar in a hot cup of tea, it disappears quickly.
Because heating increases the speed of dissolution process.
37-. Drops of water are formed when exposing water vapour to a cold surface.
Due to the condensation of water vapour when touching a cold surface.
38-. You must not touch caustic soda solution before its dilution.
Because it has a burn effect on the skin.
39-Red litmus paper is used to test for alkalis
Because alkalis change the colour of red litmus paper into blue.
40-. Blue litmus paper is used to test for acids.
Because acids change the colour of blue litmus paper into red
41-Formation of a layer of rust on the surface of a wet iron wire.
Due to the reaction between iron and water in the presence of oxygen gas and this is a chemical change.
42- Changing the sugar shape after heating it strongly on a burning spoon. A piece of sugar loses its properties after burning.
Because burning of sugar is a chemical change that changes the structure of sugar producing a new substance with new properties.
43-. Sugar keeps its flavour after dissolving it in water.
Because dissolving of sugar in water is a physical change,
44-• A solution is a mixture.
Because the components of the solution can be separated by simple physical means as the mixture.
45-Calcium carbonate does not disappear when it is stirred in water.
Because calcium carbonate is from the salts that does not dissolve in water.
46-When you put a spoon of sugar in a hot cup of tea, it disappears quickly.
Because heating increases the speed of dissolution process
47-. Drops of water are formed when exposing water vapour to a cold surface.
Due to the condensation of water vapour when touching a cold surface.
48-. You must not touch caustic soda solution before its dilution.
Because it has a burn effect on the skin.
49-. Solutions of some salts do not affect the colour of red or blue litmus paper
. Because they have a neutral effect on litmus paper.
50-Melting of ice or wax is a physical change.
Because it causes a change in the shape, but not in the structure.
51- Evaporation of water is a physical change.
Because it causes a change in the shape, but not in the structure.
52- Formation of clouds and rains is a physical change.
Because it causes a change in the shape, but not in the structure.
53-Burning a piece of bread is a chemical change.
Because it causes a change in its structure producing a new substance with new properties.
54- Wood burning is a chemical change.
Because it causes a change in its structure producing a new substance with new properties.
55- Fermentation of milk is a chemical change.
Because it causes a change in its structure producing a new substance with new properties.
56-Rusting of iron is considered as a chemical change.
Because it causes a change in its structure producing a new substance with new properties.
57-. Melting of ice is a physical change, but burning a piece of wood is a chemical change.
Because melting of ice causes a change in its shape not in its structure, but burning of wood causes a change in its structure producing a new substance with new properties.
58-Smoking and using narcotics lead to the destruction of the respiratory system.
Because they damage the two lungs and also cause lung cancer.
59-The circulatory system is called the system of translocation in the human body.
Because the circulatory system is responsible for carrying digested food and oxygen gas to all the body cells and carries the wastes as carbon dioxide gas from all the body cells to the excretory system
60-The two sides of the heart are separated from each other by a wall called septum.
To prevent the mixing of blood in the two sides of the heart.
61-Blood flows from atrium to ventricle in the heart and not vice versa.
*Due to the presence of a valve that allows blood to flow from atrium to ventricle only and not in the opposite direction.
•62- Blood does not flow back to the atrium when the ventricle contracts.
*Due to the presence of a valve that allows blood to flow from atrium to ventricle only and not in the opposite direction.
63-. Heart is acting as a pump in its performance.
Because the heart pumps the blood to all the body parts.
64-The presence of a valve between each atrium and ventricle in the heart.
To allow the blood to flow from atrium to ventricle only and not in the opposite direction.
65-The speed of heartbeats increases during performing a large muscular effort.
Because we need more oxygen carried by blood to burn more food in the body cells, to produce more energy needed for physical activities.
66-The blood has a liquid form.
Due to the presence of plasma in the blood which is in the liquid form.
67-Wounds heal when there is a cut in one of the blood vessels.
Due to the presence of platelets that have a role in the blood clot process to heal the wounds.
68-The blood capillaries are very fine blood vessels.
To allow the diffusion of dissolved substances and gases from and to the body cells.
69-. Ammonia solution changes the red litmus paper to blue but lemon juice turns blue litmus paper to red.
Because ammonia solution is an alkaline substance, while lemon juice is an acid.
70-. The solution of tooth paste is acidic.
*Because it changes the colour of blue litmus paper into red.
Or because it has sour taste .
71-. Citric acid is from acids.
Because it changes the colour of blue litmus paper into red.
72-. Alkalis are used in the soap industry.
Because alkalis react with vegetable oil to form soap.
73- We can differentiate between solution of vinegar (acids) and caustic soda
. Because alkalis or caustic soda turn(s) the colour of red litmus paper to blue and acids or vinegar turn(s) the colour of blue litmus paper to red.
78- Effervescence occurs when acids (as acetic acid) react with sodium carbonate or bicarbonate.
Due to the formation of carbon dioxide gas.
79- Boiling occurs when acids react with sodium carbonate or bicarbonate
* Due to the formation of carbon dioxide gas
80-. Importance of blood platelets.
Because they have a role in the blood clot process to heal the damaged vessels and wounds.
81-Importance of white blood cells.
Because they resist the microbes which attack the body.
82-The walls of ventricles are more thicker than the walls of atria.
Because ventricles pump the blood to all parts of the body, while atria push the blood to ventricles opposite only.
83-We should do physical activity regularly.
To keep the respiratory and circulatory systems healthy.
84-We have to eat balanced diet and avoid eating fats and salts too much.
To keep the circulatory system healthy.
85-The two kidneys are the most important organs in the urinary system. Because they filter the blood from harmful substances such as urea, uric acid, excess water and salts.
86-We should avoid keeping urine in the urinary bladder.
*To avoid any precipitation of harmful substances in it.
87-We should not expose the skin to sun rays for a long period of time.
*To avoid dryness and inflammation of skin
88-Skin is an organ that has several functions.
Because it has an excretory, protection, regulation and sensation functions.
89-We should wash skin daily during the summer season.
*-To remove sweat and to open the skin pores.
90-The human skin surface contains pores.
To get rid of the sweat out of the body.
