unit 7 Flashcards
(93 cards)
1
Q
what is air
A
a mixture of gases
2
Q
what is air made up of?
A
78% nitrogen, 21% oxygen, 0.9% noble gas (mainly argon), 0,07% water vapour and other, 0.03% carbon dioxide
3
Q
put a burning splint into a test tube with oxygen. what happens to the burning splint?
A
burns more brightly
4
Q
put a glowing splint into a test tube with oxygen. what happens to the glowing splint?
A
relights
5
Q
property of oxygen
A
can support burning
6
Q
add a few drops of hydrogencarbonate indicator to a test tube with carbon dioxide. what happens to the indicator?
A
turns from red to yellow
7
Q
add a few drops of limewater to a test tube with carbon dioxide. what happens to the limewater?
A
turns from colourless to milky
8
Q
how to test for water and water vapour?
A
use dry cobalt chloride paper
9
Q
where is dry cobalt chloride paper stored in
A
desiccator
10
Q
what is desiccator used for?
A
preserving moisture-sensitive items
11
Q
what happens to the colour of cobalt chloride paper after dropping a drop of water onto it?
A
changes from blue to pink
12
Q
what is oxygen used for? (2)
A
- help patients with breathing difficulties (support life)
- used to produce a high temperature for cutting metals (support burning)
13
Q
what is carbon dioxide used for? (2)
A
- used in fire extinguishers to put out fires (doesn’t support burning and is denser than air)
- used on stages to produce a fog effect (dry ice changes directly to carbon dioxide at room temperature)
14
Q
what is nitrogen used for? (2)
A
- fill food packages to prevent the food from getting bad (unreactive -> bacteria cannot grow)
- liquid nitrogen is used for storing living cells and tissues
15
Q
what are noble gases?
A
a group of very unreactive gases (last group of periodic table)
16
Q
what is argon used for?
A
fill light bulbs
17
Q
what is helium used for?
A
fill balloons and airships (very light)
18
Q
what is neon used for?
A
fill advertising lights
19
Q
raw materials for photosynthesis?
A
carbon dioxide and water
20
Q
energy source for photosynthesis?
A
light energy, absorbed by chlorophyll
21
Q
what is chlorophyll?
A
a green pigment in the chloroplasts of green plants
22
Q
what is the energy conversion of photosynthesis?
A
light energy -> chemical energy
23
Q
what is the food produced?
A
glucose
24
Q
what is glucose used for?
A
growth and respiration
25
what can glucose convert to when it is not used immediately?
starch for temporary storage
26
what are glucose and starch?
carbohydrates
27
why are leaves green typically?
because of the chlorophyll in chloroplasts to carry out photosynthesis
28
why are leaves typically flat and broad?
easier to absorb sunlight to carry out photosynthesis
29
what is the by-product of photosynthesis?
oxygen
30
word equation of photosynthesis?
carbon dioxide + water -> glucose + oxygen
31
chemical formula of glucose?
C₆H₁₂O₆
32
chemical equation of photosynthesis?
6 CO2 + 6 H2O → C6H12O6 + 6 O2
33
what is the change and constancy in photosynthesis?
change: reactants react to give the products
constancy: the numbers of different atoms remain the same before and after the reaction
34
change and constancy of energy conversion in photosynthesis?
change: changes from one form to another (light energy to chemical energy in glucose)
constancy: energy is conserved
35
how to test for starch?
use iodine solution
36
how does the colour of iodine solution change when added to starch?
blue-black
37
how to test for starch in green leaves?
1. put the leaf in a beaker of boiling water for 2 minutes -> destroy cell membranes
2. put the leaf in a boiling tube containing alcohol in a beaker with hot water for 10 minutes -> removes the chlorophyll
3. wash the leaf for 30 seconds -> remove alcohol and makes the leaf soft
4. add iodine solution to the leaf
5. the leaf is blue-black in colour -> starch is present in the leaf
38
what is sodium hydrogencarbonate powder used for?
provides carbon dioxide for the plant to carry out photosynthesis
39
what is formed in the bottle with a green water plant after 4 hours providing sodium hydrogencarbonate powder?
gas bubbles (oxygen) are formed on the leaves and they rise to the water surface
40
4 necessary factors for photosynthesis
carbon dioxide, water, light, chlorophyll
41
how to test if chlorophyll is necessary for photosynthesis?
use variegated leaves with green and non-green parts
42
how to test if carbon dioxide is necessary for photosynthesis?
use soda lime wrapped in a plastic bag with a green leaf
43
what does soda lime do?
absorbs carbon dioxide
44
how to test if light is necessary for photosynthesis?
clip a piece of black paper on a green leaf
45
how to destarch a plant?
placing it in the dark for at least 48 hours
46
why do we need to place a plant in the dark for at least 48 hours to destarch it?
all starch in the plant is converted to glucose
47
2 significance of photosynthesis?
1. providing food directly or indirectly for all living things
2. maintaining the balance of oxygen and carbon dioxide in nature
48
what is the source of energy for living things?
food
49
what is respiration?
chemical process when the chemical energy in food is converted into other useful forms of energy
50
what is breathing?
physical process that involves inhaling and exhaling air
51
what is gas exchange?
biochemical process that oxygen is absorbed into the bloodstream and carbon dioxide is removed from the blood
52
word equation for respiration?
glucose + oxygen -> carbon dioxide + water
53
chemical equation for respiration?
C6H12O6 +6 O2 ——>6 CO2+ 6 H2O
54
when do plants carry out photosynthesis and respiration
plants carry out photosynthesis when there is a light source. And they carry out respiration all the time
55
describe the energy conversion in respiration
chemical energy is released from food for other useful forms of energy
56
where does respiration take place?
in both plants and animals
57
net gas exchange of plants in daytime
rate of photosynthesis > rate of respiration
-> net uptake of carbon dioxide and net release of oxygen
58
net gas exchange of plants at night
only respiration takes place
-> net uptake of oxygen and net release of carbon dioxide
59
when do plants give out carbon dioxide?
all the time
60
when do plants take in carbon dioxide?
under light conditions
61
colour change of hydrogencarbonate indicator?
<0.03%: purple
=0.03%: red
>0.03%: yellow
62
how is the amount of oxygen different in inhaled air and exhaled air
inhaled air: 21% (more)
exhaled air: 16% (less)
63
how is the amount of carbon dioxide different in inhaled air and exhaled air
inhaled air: 0.03% (less)
exhaled air: 4% (more)
64
how is the amount of water vapour different in inhaled air and exhaled air?
inhaled air: variable (less)
exhaled air: saturated (more)
65
how is the temperature different in inhaled air and exhaled air?
inhaled air: lower
exhaled air: higher
66
use of gas exchange?
allows our body cells to have a continuous supply of oxygen for respiration
67
what are the main parts of the human breathing system?
naval cavity, trachea, bronchus, bronchiole, air sac, intercostal muscle, rib, lung, diaphragm
68
what are air sacs surrounded by?
many small blood vessels called capillaries
69
how does gas exchange carry out?
-oxygen passes from the air sacs into the blood capillaries
-blood carries oxygen to the body cells for respiration
-carbon dioxide passes from the blood into the air sacs and breathed out
70
3 harmful substance that cigarette smoke contains
tar (brown sticky substance), nicotine (oily liquid), carbon monoxide (toxic gas)
71
2 harmful effects on health by tar
1. causes lung cancer
2. causes coughs and respiratory diseases
72
2 harmful effects on health by nicotine
1. causes addiction
2. increases heart rate and blood pressure -> heart diseases in the long term
73
2 harmful effects on health by carbon monoxide
1. reduces oxygen content in blood
2. heart needs to beat faster to provide enough oxygen to body cells -> heart diseases in the long term
74
2 other diseases that smoking increases the risk of
1. chronic bronchitis (narrow airway)
2. emphysema (walls of air sacs are damaged -> surface area for gas exchange is reduced)
75
how is the balance of carbon dioxide and oxygen maintained in nature?
respiration and photosynthesis
76
2 human activities that increases the amount of carbon dioxide in the atmosphere
1. burning fossil fuels
2. cutting down trees
77
what are greenhouse gases?
gases that can trap heat from the sun
78
3 examples of greenhouse gases
1. carbon dioxide
2. methane
3. nitrous oxides
79
what is the greenhouse effect?
greenhouse gases trap heat from the sun and keep the earth warm
80
how does the increasing amount of carbon dioxide affect the greenhouse effect?
it enhances the greenhouse effect
81
what is global warming?
increasing amount of carbon dioxide in the atmosphere enhances the greenhouse effect.
more heat is trapped in the atmosphere and the average temperature of the earth increases
82
2 harmful effects of global warming
1. melting of ice at polar regions
2. climate change
83
2 effects of melting of ice at polar regions
1. average sea levels rise -> flooding in low-lying coastal areas
2. living things in polar regions may lose their habitat
84
2 effects of climate change
1. more frequent heat waves, storms and droughts
2. weather becomes less favourable for growing crops -> food shortage
85
4 examples of air pollutants
1. carbon monoxide
2. sulphur dioxide
3. nitrogen oxides
4. suspending particulates
86
2 harmful effects on health by carbon monoxide (air pollution)
1. reduces oxygen content in blood
2. causes headaches, fainting and even death
87
harmful effects by sulphur dioxide and nitrogen oxides
causes irritation to our breathing system and eyes
88
harmful effects by suspended particulates
causes respiratory diseases (eg bronchitis and asthma) and lung diseases
89
what are fine suspended particulates?
particulate matter with a diameter less or equal to 2.5 μm (PM2.5)
90
what is AQHI used for?
a way to inform the public of health risks of air pollution
91
where are air quality monitoring stations set up
different districts by the environmental protection department (EPD)
92
purpose of control set up
-comparison between control and experimental set up -> can draw a valid conclusion
-only affected by the independent variable and not control variables
93
2 features of air sac and blood vessel that helps gas exchange
1. air sac is surrounded by blood capillaries -> rapid transport of gases to and from the lungs
2. wall of air sac is only one cell thick -> short distance for gas exchange
