Topic Objectives: Upon completion of this lesson, the student
will be able to:
Learning Outcome #:
(B-1) - Compare and contrast the processes of photosynthesis
and respiration.
(B-2) - Write the balanced formulas for both photosynthesis
and respiration and discuss how energy is acquired
and released through these reactions.
Special Materials and Equipment:
References: Hartmann, H. T., Flocker, W. J., & Kofranek,
A. M. (1981). PLANT SCIENCE: GROWTH,
DEVELOPMENT, AND UTILIZATION OF CULTIVATED
PLANTS. Englewood Cliffs, NJ: Prentice-Hall.
Evaluation: Unit Exam
TOPIC PRESENTATION: RESPIRATION IN PLANTS
A. The Importance of Respiration in Plants: Much is often made of the
unique ability of plants to photosynthesize, with the importance of
plant respiration proportionately overlooked. Those involved in
ornamental horticulture cannot afford to lack understanding of the
respiration process in plants. Some points to keep in mind:
1. While only green parts of a plant exposed to light photosynthesize,
RESPIRATION IS ESSENTIAL FOR SURVIVAL OF ALL LIVING PARTS OF THE
PLANT, INCLUDING THE ROOTS, THE STEMS, THE LEAVES, AND THE SEEDS!
2. Photosynthesis occurs during the time of day that light intensities
are high enough to drive the light reaction. RESPIRATION IS ONGOING
24 HOURS A DAY, AS LONG AS THE PLANT IS ALIVE!
3. Restricting a plant's photosynthesis will delay its growth.
RESTRICTING RESPIRATION WILL KILL PLANT TISSUE.
In essence, we can equate "respiration" with "life." The importance of
plant respiration in horticulture cannot be overstated.
B. Plant Requirements for Energy: All plants require energy
for growth, movement, and conducting essential metabolic processes.
In short, all plant life processes are energy consumptive.
1. Growth refers to an increase in size resulting from division and
expansion of cells. Energy is consumed during growth by the
complex reproductive processes of mitosis, by the enzymatic
activity associated with protein synthesis, and by the active
transport processes associated with cell expansion.
2. Cells also expend energy to accumulate and concentrate required
nutrients, and to move certain materials from one part of the plant
to another.
3. Plant movements, such as phototropic and geotropic responses,
consume energy, again because of the requirements of active
transport.
C. Respiration and Energy Release: To release and use the energy stored
as a result of photosynthesis, plant cells depend on the process of
respiration.
1. Respiration occurs in all cells where energy is required.
2. In respiration, foods are broken down in a long series of chemical
reactions that release energy a little at a time.
3. The overall process is called oxidation because carbon atoms from
the food molecules become bound to atoms of oxygen from the air.
4. Carbohydrates are the main foods used in respiration. Carbohydrates
can take many forms:
a. Carbohydrates include sugars and larger molecules made by
linking sugars into chains called polysaccharides.
b. There are many kinds of sugars. Examples are glucose, fructose,
and galactose.
c. Sucrose (table sugar) consists of glucose linked to fructose.
Sucrose circulates throughout most plants, serving
as a mobile energy source.
d. Starch consists of many glucose molecules linked together.
e. Other organic materials which plants consume in respiration
include malic acid, glycolic acid, proteins, fats, and lipids.
Building blocks of these materials include carbohydrates.
f. Before these substrates can be used in respiration, cells must
break these complex materials down to release the individual
sugar molecules.
5. The Respiration Process:
a. In respiration, cells convert sugars and oxygen (O2) into
carbon dioxide (CO2), water (H2O), and energy.
b. The actual process involves complex enzymatic activity,
requiring many steps to complete. While these are beyond the
scope of this lesson, the net result can by expressed in the
formula below:
C6 H12 O6 + (6) H2O + (6) O2 ----> (6) CO2 + (12) H2O + energy
One molecule of sugar combines with six molecules of water
and six molecules of oxygen to produce six molecules of carbon
dioxide, twelve molecules of water, and a release of energy.
Note that water appears on both sides of the equation. This
is to remind us that the oxygen does not interact directly
with the sugar, as it might in a high-temperature reaction.
There is, of course, a net production of six water molecules
produced for every molecule of glucose consumed.
c. This is the same overall process that occurs in combustion
(fire), except that cells conduct the process in small steps
that utilize energy in chemical reactions and the gradual
release of heat instead of releasing all the energy quickly
in the form of high temperatures and light.
d. Most energy released in respiration is used by the plant for
driving metabolic processes. Some energy is lost in the form
of heat.
D. Comparing Respiration in Plants and Animals: It is worth mentioning
here that the meaning of "respiration" as we apply it to plants, and
the same term as we usually apply it to animals and ourselves, have some
very important similarities AND differences. These similarities and
differences can be confusing for those learning about respiration
in plants, and deserve some attention.
1. Similarities:
a. The essential inputs (carbohydrate and oxygen) and products
(carbon dioxide, water, and energy) are the same in both cases.
b. All animal cells, like plant cells, need to respire at all times
to survive.
c. Both plants and animals require gaseous exchange for
respiration to occur.
2. Differences:
a. Plant respiration takes place more slowly. Demand for
substrates is not as high, and by-products, including heat,
do not accumulate as quickly.
b. Higher animals require much more extensive circulatory systems
to deliver the required food and oxygen to respiring cells in
the amounts needed. Because of this, we often equate the term
"respiration" with our process of breathing. This can lead to
confusion. While plants require gaseous exchange through
stomata and diffusion, they have no process equivalent to
animal "breathing." To say they respire is NOT to say they
breathe. However, this can help us remember the importance of
oxygen to all plant cells.
E. Environmental Factors Affecting Respiration: The rate of respiration
is influenced by environmental conditions such as moisture, temperature,
and oxygen concentration.
1. Too much moisture around the plant roots can inhibit oxygen
exchange and cut respiration.
2. Temperature increases result in dramatic respiration increases.
Respiration can as much as quadruple for each 10 degree Centigrade
increase in temperature.
3. Respiration decreases in direct proportion to decreases in atmospheric
oxygen concentration.
4. Respiration is also affected by the general health of the plant
with regard to such factors as macro- and micronutrient
availability. Another consideration is the stage of development of
the plant (growing plants use more energy than mature ones).
F. Photosynthesis and Respiration Compared: Photosynthesis and respiration
are often said to be the opposite of each other. Their main features are
contrasted in the following chart:
Photosynthesis Respiration
===========================================================================
Fixes chemical energy Releases chemical energy
Absorbs C02 Forms C02
Forms 02 Uses 02
Makes sugar Uses up sugar (and other substances)
Increases weight Decreases weight
Only in green cells In all living cells
Only in light At all times (in both light and
darkness)
===========================================================================
Wednesday, December 10, 2008
Science Vocabulary
1 stereotype placing a particular group into one pattern
2 botanist a scientist who studies plants
3 biologist a scientist who studies living things
4 chemist a scientist who studies chemicals
5 meteorologist a scientist who studies weather
6 graduated cylinder a cylinder with lines to measure capacity (liquid) (milliliters)
7 triple beam balance a tool with three moveable parts used to measure weight
8 meter stick a tool used to measure length (centimeters)
9 communication to convey a message or idea
10 measurement to determine the amount (length, weight, capacity)
11 data table a chart used to record information in an experiment
12 observation to gather information by using ones senses
13 qualitative observations observations obtained by looking, smelling, tasting, touching or listening
14 quantitative observations observations that require the use of numbers
15 classifying placing into groups
16 venn diagram a classifying tool that uses overlapping circles
17 dichotomus key classifying device that divides into groups of two until individual is reached
18 models a representation of something
19 variables a part of the experiment that changes
20 independent variable The manipulated variable
21 manipulated variable The independent variable.
The part of the experiment that is changed by the scientist.
22 dependent variable The responding variable.
The part of the experiment that usually changes because the independent
variable changes
23 responding variable The dependent variable.
The part of the experiment that usually changes because the independent
variable changes
24 control variable The part of the experiment that must remain the same. (Is not manipulated)
25 hypothesis guess made before conducting an experiment. If---- happens then — will happen
26 graph a picture using lines and symbols to show the results of an experiment
27 conclusion The results found after experimenting
28 inference Giving a reason WHY something may have happened in an experiment
29 prediction guess made after the experiment that uses the data collected from the results
30 matter anything that has mass and takes up space
31 weather daily conditions in the earths atmosphere
32 nitrogen 78% of the air is made of this gas
------------------------------------------------------------------------------------------------------------
33 oxygen 21% of the air is made of this gas. Animals breathe it to live.
34 carbon dioxide less than 1% of the air is made of this gas. We breathe it out.
35 troposphere lowest layer of the atmosphere, closest to the earth, where earth’s weather occurs
36 stratosphere atmosphere layer above the troposphere, contains ozone
37 ozone made of 3 oxygens, found in the stratosphere, absorbs and protects the earth from ultraviolet (UV) radiation
38 ozone depletion the break down of ozone molecules due to chlorofluorocarbons (CFC’s)
39 mesosphere atmosphere layer above stratosphere, burns meteoroids as they fall toward earth.
40 thermosphere top layer of the atmosphere, extends into outer space, transmits radio waves
-------------------------------------------------------------------------------------------------------------
41 conduction Heat transfer when molecules bump into each other (solid material)
42 convection Heat transfer when warm rises and cool sinks (liquids and gases)
43 radiation Heat transfer using rays or waves (gases)
44 infrared light energy that is HEAT
45 greenhouse effect gases in the atmosphere that hold heat on the earth
46 global warming when gases hold too much heat on the earth
47 climate zones Tropical (warm) , temperate (variable), polar (cold)
48 global winds Winds that blow high in the atmosphere
---------------------------------------------------------------------------------------------------
49 trade winds blow from east to west in the tropical region moving warm air
50 prevailing westerly blow from west to east in the temperate region (United States)
51 polar winds blow from northeast to west moving cold air
52 jet stream Fast moving ribbon of air that moves around the globe (blows west to east)
53 local winds Winds that blow low in the atmosphere (close to the ground)
54 land breeze Movement of air from the land toward the water (night)
55 sea breeze Movement of air from the water toward the land (day)
56 anemometer instrument used to measure wind speed
-------------------------------------------------------------------------------------------------------------
57 barometer instrument used to measure air pressure
58 thermometer instrument used to measure temperature
59 humidity moisture in the air
60 psychrometer instrument used to measure relative humidity
61 cumulus Puffy white clouds (picnic clouds) (Fair weather)
62 stratus layers of clouds (bring rain)
63 cirrus high, thin, white, feathery clouds, ice crystals (approaching storms)
64 cumulonimbus Big, dark clouds (Thunderstorms)
-------------------------------------------------------------------------------------------------------------
65 evaporation water enters the atmosphere as water vapor
66 transpiration water enters the atmosphere as water vapor from plants
67 condensation collection of water vapor and water droplets in the atmosphere forming clouds
68 precipitation water droplets fall from the sky in various forms
69 surface run-off groundwater flow, precipitation attempts to move back toward sea level
70 rain gauge Weather instrument that measures the amount of precipitation
71 hurricane storm that forms from a low pressure system over the ocean
72 tornado storm that forms in a cumulonimbus cloud, over land
-------------------------------------------------------------------------------------------------
73 isotherms lines on a weather map that connects areas with the same temperature
74 isobars lines on a weather map that connect areas with the same air pressure
2 botanist a scientist who studies plants
3 biologist a scientist who studies living things
4 chemist a scientist who studies chemicals
5 meteorologist a scientist who studies weather
6 graduated cylinder a cylinder with lines to measure capacity (liquid) (milliliters)
7 triple beam balance a tool with three moveable parts used to measure weight
8 meter stick a tool used to measure length (centimeters)
9 communication to convey a message or idea
10 measurement to determine the amount (length, weight, capacity)
11 data table a chart used to record information in an experiment
12 observation to gather information by using ones senses
13 qualitative observations observations obtained by looking, smelling, tasting, touching or listening
14 quantitative observations observations that require the use of numbers
15 classifying placing into groups
16 venn diagram a classifying tool that uses overlapping circles
17 dichotomus key classifying device that divides into groups of two until individual is reached
18 models a representation of something
19 variables a part of the experiment that changes
20 independent variable The manipulated variable
21 manipulated variable The independent variable.
The part of the experiment that is changed by the scientist.
22 dependent variable The responding variable.
The part of the experiment that usually changes because the independent
variable changes
23 responding variable The dependent variable.
The part of the experiment that usually changes because the independent
variable changes
24 control variable The part of the experiment that must remain the same. (Is not manipulated)
25 hypothesis guess made before conducting an experiment. If---- happens then — will happen
26 graph a picture using lines and symbols to show the results of an experiment
27 conclusion The results found after experimenting
28 inference Giving a reason WHY something may have happened in an experiment
29 prediction guess made after the experiment that uses the data collected from the results
30 matter anything that has mass and takes up space
31 weather daily conditions in the earths atmosphere
32 nitrogen 78% of the air is made of this gas
------------------------------------------------------------------------------------------------------------
33 oxygen 21% of the air is made of this gas. Animals breathe it to live.
34 carbon dioxide less than 1% of the air is made of this gas. We breathe it out.
35 troposphere lowest layer of the atmosphere, closest to the earth, where earth’s weather occurs
36 stratosphere atmosphere layer above the troposphere, contains ozone
37 ozone made of 3 oxygens, found in the stratosphere, absorbs and protects the earth from ultraviolet (UV) radiation
38 ozone depletion the break down of ozone molecules due to chlorofluorocarbons (CFC’s)
39 mesosphere atmosphere layer above stratosphere, burns meteoroids as they fall toward earth.
40 thermosphere top layer of the atmosphere, extends into outer space, transmits radio waves
-------------------------------------------------------------------------------------------------------------
41 conduction Heat transfer when molecules bump into each other (solid material)
42 convection Heat transfer when warm rises and cool sinks (liquids and gases)
43 radiation Heat transfer using rays or waves (gases)
44 infrared light energy that is HEAT
45 greenhouse effect gases in the atmosphere that hold heat on the earth
46 global warming when gases hold too much heat on the earth
47 climate zones Tropical (warm) , temperate (variable), polar (cold)
48 global winds Winds that blow high in the atmosphere
---------------------------------------------------------------------------------------------------
49 trade winds blow from east to west in the tropical region moving warm air
50 prevailing westerly blow from west to east in the temperate region (United States)
51 polar winds blow from northeast to west moving cold air
52 jet stream Fast moving ribbon of air that moves around the globe (blows west to east)
53 local winds Winds that blow low in the atmosphere (close to the ground)
54 land breeze Movement of air from the land toward the water (night)
55 sea breeze Movement of air from the water toward the land (day)
56 anemometer instrument used to measure wind speed
-------------------------------------------------------------------------------------------------------------
57 barometer instrument used to measure air pressure
58 thermometer instrument used to measure temperature
59 humidity moisture in the air
60 psychrometer instrument used to measure relative humidity
61 cumulus Puffy white clouds (picnic clouds) (Fair weather)
62 stratus layers of clouds (bring rain)
63 cirrus high, thin, white, feathery clouds, ice crystals (approaching storms)
64 cumulonimbus Big, dark clouds (Thunderstorms)
-------------------------------------------------------------------------------------------------------------
65 evaporation water enters the atmosphere as water vapor
66 transpiration water enters the atmosphere as water vapor from plants
67 condensation collection of water vapor and water droplets in the atmosphere forming clouds
68 precipitation water droplets fall from the sky in various forms
69 surface run-off groundwater flow, precipitation attempts to move back toward sea level
70 rain gauge Weather instrument that measures the amount of precipitation
71 hurricane storm that forms from a low pressure system over the ocean
72 tornado storm that forms in a cumulonimbus cloud, over land
-------------------------------------------------------------------------------------------------
73 isotherms lines on a weather map that connects areas with the same temperature
74 isobars lines on a weather map that connect areas with the same air pressure
How plants reproduce
1.The different ways where plants reproduce from plant part, 2.Recognize that plants can reproduce from various plants parts
-Spores
-Underground stem
-Leaves
-Suckers
Charcteristics of plants reproduce from undergrounf stems
1.It has buds and leaves
2.Leaves are not green
3.They can be scaly and fleshy
eg:
-A sealing wax palm
-A heliconia plant...
(Sucker grow beside of the old plant,it grows up right shoots.)
Reproduce from leaves
1.Some plant like byoplnyllum,reproduce from leaves.Such leaves are usually thick and fleshy.
Characteristics for plants which reproduce from leaves
-Leaves are usually thick and fleshy
-The bud will grow into new plant when mature leaves fall in the ground or the buds.
-Some buds may even start to grow roots while it is still on the leaves.
Advantages of reproduction from plant parts
-This process does not need wind or insects for pollination and dispersal
-No fertilisation is required.
-Desirable or beneficial qualities are passed in to young plants without any change.
Artificial methods of reproduction
-Stem cutting
-Leaves cutting
-Budding
Stem cutting
-Certain plant like the rose,hibiscus,bougainuillea,etc....do not produce seeds because of climatic condition (hight temperatures and heavy rainfall)
-They can be reproduce by aretificial methods like stem cutting
Leaf cutting
-Part leaf cutting
-Whole leaf cutting
Budding
-In budding,the bud from one plant is jioned to another plant called the stock.
The End
Posted by ailin at 7:57 PM 0 comments
BlogSkins.com Skin Screenshot - Enigma of a thousand flowers.
BlogSkins.com Skin Screenshot - Enigma of a thousand flowers.
Posted by AMIRA ~SUPERGIRL~ at 3:17 AM 0 comments
Thursday, March 20, 2008
Summary!!!
Seeds
-Flowering plants reproduce from seeds.
Spores
-Non-flowering plants such as Fern.
-Do not reproduce from spores unlike seeds.
*Some flowering plants can reproduce from plant parts such as stems,suckers and leaves.
*Under ground stems are usually swollen because they store food for the plant.
Suckers
-Plants like Banana and Pineapple reproduce by suckers.
-These shoots develop from a certain part of the stem.
Leaves
-Leaves plants like the Bryophyllum,Begonia and African violet can new plants.
-Such leaves are usually thick and fleshy.
Posted by chin_d-ylan at 11:37 PM 0 comments
On Thursday Miss Lim though us about plants that can reproduce from various plant parts such as:
-spores
-underground stems
-leaves
-suckers
First we learnt about spores.The spore bags will burst and the wind will carry the spores away.
Second we learnt about underground stems.Here are some examples of underground stems:
-ginger
-potato
-onion
Here are some characteristics of under ground stems:
-It has buds and leaves
-Leaves can be scaly and fleshy
Next we learnt about suckers.Examples of suckers are:
-wax plam
-Banana plant
-Pineapple plant
-Heliconia plant
Suckers are shoots that grows beside the parent plant.
Lastly,we learnt about plants that reproduce from leaves.Example of such plants are
-bryophyllum leaf
-african violet
-begonia plant
Characteristic of such leaves are:
-Leaves are thick and fleshy
-Buds will grow into new plant when mature leaves fall into the ground.
Faster method of reproduction are:
-stem cutting
-leaf cutting
-budding
Leave cutting:
-part leaf cutting
-whole leaf cutting
In budding the bud from one plant is joined to another plant called the stock
I also learnt that cetain plants like Rose,Hibiscus,bougainvillea do not reproduce seed because of climatic conditions.
Posted by jana at 4:55 PM 1 comments
Surmmary of Science unit 5
Today in school,we learn about Reproduction from plant parts.The are many kind of ways to reproduce from various plant parts.There are spores,underground stem,leaves and suckers.Non-flowering plants such as ferns reproduce from spores.Spores are kept in a bag called Spores bag and they are found on the underside of a fern leaf.Example of plants reproduce from spores:Bird nest ferns,Sword ferns and many more. Those plant reproduce by underground stem have buds and leaves,but leaves are not green and they can be scaly and flesly.Example of underground stem :potatoes,ginger ,onion and chestnut.Reproduce by leaves usually thick and flesly .Plants like banana and pineapples reproduce by producing upright shoot called suckers ,which develop from a certain part of a stem.Suckers grow into a new plant when the parent plant dies.Example of suckers:Sealing wax plam ,heliconia plant,banana tree and pineapple tree.There is a lot of ways to reproduce a plant:stem cutting,leaf cutting, budding and many more.Example of stem cutting:roses,hibiscus and bougainvillea.There are many ways for leaf cutting,you can cut the leaves into half or cut the stem of the plant which is called a full plant.In budding,the bud from one plant is joined to another plant called the stock.Plants have characteristics similar to the parent plants.
-Spores
-Underground stem
-Leaves
-Suckers
Charcteristics of plants reproduce from undergrounf stems
1.It has buds and leaves
2.Leaves are not green
3.They can be scaly and fleshy
eg:
-A sealing wax palm
-A heliconia plant...
(Sucker grow beside of the old plant,it grows up right shoots.)
Reproduce from leaves
1.Some plant like byoplnyllum,reproduce from leaves.Such leaves are usually thick and fleshy.
Characteristics for plants which reproduce from leaves
-Leaves are usually thick and fleshy
-The bud will grow into new plant when mature leaves fall in the ground or the buds.
-Some buds may even start to grow roots while it is still on the leaves.
Advantages of reproduction from plant parts
-This process does not need wind or insects for pollination and dispersal
-No fertilisation is required.
-Desirable or beneficial qualities are passed in to young plants without any change.
Artificial methods of reproduction
-Stem cutting
-Leaves cutting
-Budding
Stem cutting
-Certain plant like the rose,hibiscus,bougainuillea,etc....do not produce seeds because of climatic condition (hight temperatures and heavy rainfall)
-They can be reproduce by aretificial methods like stem cutting
Leaf cutting
-Part leaf cutting
-Whole leaf cutting
Budding
-In budding,the bud from one plant is jioned to another plant called the stock.
The End
Posted by ailin at 7:57 PM 0 comments
BlogSkins.com Skin Screenshot - Enigma of a thousand flowers.
BlogSkins.com Skin Screenshot - Enigma of a thousand flowers.
Posted by AMIRA ~SUPERGIRL~ at 3:17 AM 0 comments
Thursday, March 20, 2008
Summary!!!
Seeds
-Flowering plants reproduce from seeds.
Spores
-Non-flowering plants such as Fern.
-Do not reproduce from spores unlike seeds.
*Some flowering plants can reproduce from plant parts such as stems,suckers and leaves.
*Under ground stems are usually swollen because they store food for the plant.
Suckers
-Plants like Banana and Pineapple reproduce by suckers.
-These shoots develop from a certain part of the stem.
Leaves
-Leaves plants like the Bryophyllum,Begonia and African violet can new plants.
-Such leaves are usually thick and fleshy.
Posted by chin_d-ylan at 11:37 PM 0 comments
On Thursday Miss Lim though us about plants that can reproduce from various plant parts such as:
-spores
-underground stems
-leaves
-suckers
First we learnt about spores.The spore bags will burst and the wind will carry the spores away.
Second we learnt about underground stems.Here are some examples of underground stems:
-ginger
-potato
-onion
Here are some characteristics of under ground stems:
-It has buds and leaves
-Leaves can be scaly and fleshy
Next we learnt about suckers.Examples of suckers are:
-wax plam
-Banana plant
-Pineapple plant
-Heliconia plant
Suckers are shoots that grows beside the parent plant.
Lastly,we learnt about plants that reproduce from leaves.Example of such plants are
-bryophyllum leaf
-african violet
-begonia plant
Characteristic of such leaves are:
-Leaves are thick and fleshy
-Buds will grow into new plant when mature leaves fall into the ground.
Faster method of reproduction are:
-stem cutting
-leaf cutting
-budding
Leave cutting:
-part leaf cutting
-whole leaf cutting
In budding the bud from one plant is joined to another plant called the stock
I also learnt that cetain plants like Rose,Hibiscus,bougainvillea do not reproduce seed because of climatic conditions.
Posted by jana at 4:55 PM 1 comments
Surmmary of Science unit 5
Today in school,we learn about Reproduction from plant parts.The are many kind of ways to reproduce from various plant parts.There are spores,underground stem,leaves and suckers.Non-flowering plants such as ferns reproduce from spores.Spores are kept in a bag called Spores bag and they are found on the underside of a fern leaf.Example of plants reproduce from spores:Bird nest ferns,Sword ferns and many more. Those plant reproduce by underground stem have buds and leaves,but leaves are not green and they can be scaly and flesly.Example of underground stem :potatoes,ginger ,onion and chestnut.Reproduce by leaves usually thick and flesly .Plants like banana and pineapples reproduce by producing upright shoot called suckers ,which develop from a certain part of a stem.Suckers grow into a new plant when the parent plant dies.Example of suckers:Sealing wax plam ,heliconia plant,banana tree and pineapple tree.There is a lot of ways to reproduce a plant:stem cutting,leaf cutting, budding and many more.Example of stem cutting:roses,hibiscus and bougainvillea.There are many ways for leaf cutting,you can cut the leaves into half or cut the stem of the plant which is called a full plant.In budding,the bud from one plant is joined to another plant called the stock.Plants have characteristics similar to the parent plants.
Monday, December 1, 2008
Why Do Cut Apples Pears Bananas and Potatoes Turn Brown
Apples and other produce (e.g., pears, bananas, peaches, potatoes) contain an enzyme (called polyphenol oxidase or tyrosinase) that reacts with oxygen and iron-containing phenols that are also found in the apple. The oxidation reaction basically forms a sort of rust on the surface of the fruit. You see the browning when the fruit is cut or bruised because these actions damage the cells in the fruit, allowing oxygen in the air to react with the enzyme and other chemicals.
The reaction can be slowed or prevented by inactivating the enzyme with heat (cooking), reducing the pH on the surface of the fruit (by adding lemon juice or another acid), reducing the amount of available oxygen (by putting cut fruit under water or vacuum packing it), or by adding certain preservative chemicals (like sulfur dioxide). On the other hand, using cutlery that has some corrosion (as is seen with lower quality steel knives) can increase the rate and amount of the browning by making more iron salts available for the reaction.
The reaction can be slowed or prevented by inactivating the enzyme with heat (cooking), reducing the pH on the surface of the fruit (by adding lemon juice or another acid), reducing the amount of available oxygen (by putting cut fruit under water or vacuum packing it), or by adding certain preservative chemicals (like sulfur dioxide). On the other hand, using cutlery that has some corrosion (as is seen with lower quality steel knives) can increase the rate and amount of the browning by making more iron salts available for the reaction.
What Is a Chemical?
Short answer: Everything is a chemical. Longer answer: Chemistry is the study of matter and its interactions with other matter. Anything made of matter is therefore a chemical. Any liquid, solid, gas. Any pure substance; any mixture. Water is a chemical. Technically speaking, so is a chunk of your computer. A chemical can often be broken down into components, as is true with your computer. However, people generally use the term 'chemical' to refer to a substance that appears homogeneous or the same throughout its structure.
Which Elements Are Named After People?
There are 13 elements named after people, although only 12 of the names are formally accepted by the International Union of Pure and Applied Chemistry (IUPAC).
bohrium (Bh, 107) – Niels Bohr
curium (Cm, 96) – Pierre and Marie Curie
einsteinium (Es, 99) – Albert Einstein
fermium (Fm, 100) – Enrico Fermi
gallium (Ga, 31) – both named after Gallia (Latin for France) and its discoverer, Lecoq de Boisbaudran (le coq, the French word for 'rooster' translates to gallus in Latin)
hahnium (105) – Otto Hahn (Dubnium, named for Dubna in Russia, is the IUPAC-accepted name for element 105)
lawrencium (Lr, 103) – Ernest Lawrence
meitnerium (Mt, 109) – Lise Meitner
mendelevium (Md, 101) – Dmitri Mendeleev
nobelium (No, 102) – Alfred Nobel
roentgenium (Rg, 111) – Wilhelm Roentgen (formerly Ununumium)
rutherfordium (Rf, 104) – Ernest Rutherford
seaborgium (Sg, 106) – Glenn T. Seaborg
bohrium (Bh, 107) – Niels Bohr
curium (Cm, 96) – Pierre and Marie Curie
einsteinium (Es, 99) – Albert Einstein
fermium (Fm, 100) – Enrico Fermi
gallium (Ga, 31) – both named after Gallia (Latin for France) and its discoverer, Lecoq de Boisbaudran (le coq, the French word for 'rooster' translates to gallus in Latin)
hahnium (105) – Otto Hahn (Dubnium, named for Dubna in Russia, is the IUPAC-accepted name for element 105)
lawrencium (Lr, 103) – Ernest Lawrence
meitnerium (Mt, 109) – Lise Meitner
mendelevium (Md, 101) – Dmitri Mendeleev
nobelium (No, 102) – Alfred Nobel
roentgenium (Rg, 111) – Wilhelm Roentgen (formerly Ununumium)
rutherfordium (Rf, 104) – Ernest Rutherford
seaborgium (Sg, 106) – Glenn T. Seaborg
Can a Candle Burn in Zero Gravity?
Yes, can candle can burn in zero gravity. However, the flame is quite a bit different. Fire behaves differently in space and microgravity than on Earth.
A microgravity flame forms a sphere surrounding the wick. Diffusion feeds the flame with oxygen and allows carbon dioxide to move away from the point of combustion, so the rate of burning is slowed. The flame of a candle burned in microgravity is an almost invisible blue color (video cameras on Mir could not detect the blue color). Experiments on Skylab and Mir indicate the temperature of the flame is too low for the yellow color seen on Earth.
Smoke and soot production is different for candles and other forms of fire in space or zero gravity compared to candles on earth. Unless air flow is available, the slower gas exchange from diffusion can produce a soot-free flame. However, when burning stops at the tip of the flame, soot production begins. Soot and smoke production depends on the fuel flow rate.
It isn't true that candles burn for a shorter length of time in space. Dr. Shannon Lucid (Mir), found that candles that burn for 10 minutes or less on Earth produced a flame for up to 45 minutes. When the flame is extinguished, a white ball surrounding the candle tip remains, which may be a fog of flammable wax vapor.
A microgravity flame forms a sphere surrounding the wick. Diffusion feeds the flame with oxygen and allows carbon dioxide to move away from the point of combustion, so the rate of burning is slowed. The flame of a candle burned in microgravity is an almost invisible blue color (video cameras on Mir could not detect the blue color). Experiments on Skylab and Mir indicate the temperature of the flame is too low for the yellow color seen on Earth.
Smoke and soot production is different for candles and other forms of fire in space or zero gravity compared to candles on earth. Unless air flow is available, the slower gas exchange from diffusion can produce a soot-free flame. However, when burning stops at the tip of the flame, soot production begins. Soot and smoke production depends on the fuel flow rate.
It isn't true that candles burn for a shorter length of time in space. Dr. Shannon Lucid (Mir), found that candles that burn for 10 minutes or less on Earth produced a flame for up to 45 minutes. When the flame is extinguished, a white ball surrounding the candle tip remains, which may be a fog of flammable wax vapor.
What Is Absolute Zero?
Absolute zero is the point where no more heat can be removed from a system, according to the absolute or thermodynamic temperature scale. This corresponds to 0 K or -273.15°C. In classical kinetic theory, there should be no movement of individual molecules at absolute zero, but experimental evidences shows this isn't the case.
Temperature is used to describe how hot or cold an object it. The temperature of an object depends on how fast its atoms and molecules oscillate. At absolute zero, these oscillations are the slowest they can possibly be. Even at absolute zero, the motion doesn't completely stop.
It's not possible to reach absolute zero, though scientists have approached it. The NIST achieved a record cold temperature of 700 nK (billionths of a Kelvin) in 1994. MIT researchers set a new record of 0.45 nK in 2003.
Temperature is used to describe how hot or cold an object it. The temperature of an object depends on how fast its atoms and molecules oscillate. At absolute zero, these oscillations are the slowest they can possibly be. Even at absolute zero, the motion doesn't completely stop.
It's not possible to reach absolute zero, though scientists have approached it. The NIST achieved a record cold temperature of 700 nK (billionths of a Kelvin) in 1994. MIT researchers set a new record of 0.45 nK in 2003.
What Is a Chemical Element?
A chemical element, or an element, is a material which cannot be broken down or changed into another substance using chemical means. Elements may be thought of as the basic chemical building blocks of matter. Depending on how much evidence you require to prove a new element has been created, there are 117 or 118 known elements.
What Is the Greenhouse Effect?
The average temperature of the earth's surface is about 15°C (59°F). The temperature largely is determined by the amount of energy absorbed from the sun versus the amount of energy emitted into space by the earth. The energy absorbed by the sun mainly covers wavelengths from the ultraviolet (< 400 nm) through the visible (400 to 700 nm) though the ultraviolet (> 700 nm).
Any change in the balance between the quantity of energy absorbed compared to the amount emitted affects climate. The "greenhouse effect" is concerned with the infrared radiation given off by the earth. Part of this radiation is absorbed by the atmosphere, rather than being lost to space. The gases in the atmosphere that absorb infrared light primarily are water (H2), carbon dioxide (CO2), ozone (O3), nitrous oxide (NO2) and methane (CH4). The gases act as a sort of insulating blanket for the earth, in the same way they would act to lessen heat loss from a greenhouse, hence the name 'greenhouse effect'. It is estimated that the mean global surface temperature of the earth would be -25°C (-13°F) if not for the absorption of energy by carbon dioxide and water.
The concentration of water vapor in the atmosphere is higher than that of carbon dioxide. Consequently, most of this energy conservation is attributable to water. You can see this effect when you look at how temperature drops less on nights with heavy cloud cover as opposed to clear skies or when you consider how large the temperature difference between day and night is in places with lower relative humidity, like the desert.
Although the concentration of carbon dioxide in the atmosphere is low (~375 ppm in 2005), it has been increasing appreciably over time. A century ago, the carbon dioxide concentration was less than 300 ppm. Human activites are accountable for this increase, including consumption of fossil fuels and extensive clearing of land (less carbon dioxide can be consumed by photosynthesis). Changes in the levels of carbon dioxide in the atmosphere are associated with changes in the earth's climate.
Any change in the balance between the quantity of energy absorbed compared to the amount emitted affects climate. The "greenhouse effect" is concerned with the infrared radiation given off by the earth. Part of this radiation is absorbed by the atmosphere, rather than being lost to space. The gases in the atmosphere that absorb infrared light primarily are water (H2), carbon dioxide (CO2), ozone (O3), nitrous oxide (NO2) and methane (CH4). The gases act as a sort of insulating blanket for the earth, in the same way they would act to lessen heat loss from a greenhouse, hence the name 'greenhouse effect'. It is estimated that the mean global surface temperature of the earth would be -25°C (-13°F) if not for the absorption of energy by carbon dioxide and water.
The concentration of water vapor in the atmosphere is higher than that of carbon dioxide. Consequently, most of this energy conservation is attributable to water. You can see this effect when you look at how temperature drops less on nights with heavy cloud cover as opposed to clear skies or when you consider how large the temperature difference between day and night is in places with lower relative humidity, like the desert.
Although the concentration of carbon dioxide in the atmosphere is low (~375 ppm in 2005), it has been increasing appreciably over time. A century ago, the carbon dioxide concentration was less than 300 ppm. Human activites are accountable for this increase, including consumption of fossil fuels and extensive clearing of land (less carbon dioxide can be consumed by photosynthesis). Changes in the levels of carbon dioxide in the atmosphere are associated with changes in the earth's climate.
Why Do Onions Make You Cry?
Unless you've avoided cooking, you've probably cut up an onion and experienced the burning and tearing you get from the vapors. When you cut an onion, you break cells, releasing their contents. Amino acid sulfoxides form sulfenic acids. Enzymes that were kept separate now are free to mix with the sulfenic acids to produce propanethiol S-oxide, a volatile sulfur compound that wafts upward toward your eyes. This gas reacts with the water in your tears to form sulfuric acid. The sulfuric acid burns, stimulating your eyes to release more tears to wash the irritant away.
Cooking the onion inactivates the enzyme, so while the smell of cooked onions may be strong, it doesn't burn your eyes. Aside from wearing safety googles or running a fan, you can keep from crying by refrigerating your onion before cutting it (slows reactions and changes the chemistry inside the onion) or by cutting the onion under water.
The sulfur-containing compounds also leave a characteristic odor on your fingers. You may be able to remove or reduce some of the smell by wiping your fingers on a stainless steel odor eater.
Cooking the onion inactivates the enzyme, so while the smell of cooked onions may be strong, it doesn't burn your eyes. Aside from wearing safety googles or running a fan, you can keep from crying by refrigerating your onion before cutting it (slows reactions and changes the chemistry inside the onion) or by cutting the onion under water.
The sulfur-containing compounds also leave a characteristic odor on your fingers. You may be able to remove or reduce some of the smell by wiping your fingers on a stainless steel odor eater.
What Is the Chemical Composition of Air?
Nearly all of the Earth's atmosphere is made up of only five gases: nitrogen, oxygen, water vapor, argon, and carbon dioxide. Several other compounds also are present. Although this CRC table does not list water vapor, air can contain as much as 5% water vapor, more commonly ranging from 1-3%. The 1-5% range places water vapor as the third most common gas (which alters the other percentages accordingly).
This is composition of air in percent by volume, at sea level at 15°C and 101325 Pa.
Nitrogen -- N2 -- 78.084%
Oxygen -- O2 -- 20.9476%
Argon -- Ar -- 0.934%
Carbon Dioxide -- CO2 -- 0.0314%
Neon -- Ne -- 0.001818%
Methane -- CH4 -- 0.0002%
Helium -- He -- 0.000524%
Krypton -- Kr -- 0.000114%
Hydrogen -- H2 -- 0.00005%
Xenon -- Xe -- 0.0000087%
Ozone -- O3 -- 0.000007%
Nitrogen Dioxide -- NO2 -- 0.000002%
Iodine -- I2 -- 0.000001%
Carbon Monoxide -- CO -- trace
Ammonia -- NH3 -- trace
Reference: CRC Handbook of Chemistry and Physics, edited by David R. Lide, 1997.
This is composition of air in percent by volume, at sea level at 15°C and 101325 Pa.
Nitrogen -- N2 -- 78.084%
Oxygen -- O2 -- 20.9476%
Argon -- Ar -- 0.934%
Carbon Dioxide -- CO2 -- 0.0314%
Neon -- Ne -- 0.001818%
Methane -- CH4 -- 0.0002%
Helium -- He -- 0.000524%
Krypton -- Kr -- 0.000114%
Hydrogen -- H2 -- 0.00005%
Xenon -- Xe -- 0.0000087%
Ozone -- O3 -- 0.000007%
Nitrogen Dioxide -- NO2 -- 0.000002%
Iodine -- I2 -- 0.000001%
Carbon Monoxide -- CO -- trace
Ammonia -- NH3 -- trace
Reference: CRC Handbook of Chemistry and Physics, edited by David R. Lide, 1997.
What is the State of Matter of Fire or Flame?
The ancient Greeks and alchemists thought that fire was an element. They also considered earth, air, and water to be elements. However, the modern definition of an element defines it by the number of protons a pure substance possesses. Fire is made up of many different substances, so it is not an element.
For the most part, fire is a mixture of hot gases. Flames are the result of a chemical reaction, primarily between oxygen in air and a fuel, such as wood or propane. In addition to other products, the reaction produces carbon dioxide, steam, light, and heat. If the flame is hot enough, the gases are ionized and become yet another state of matter: plasma.
For the most part, fire is a mixture of hot gases. Flames are the result of a chemical reaction, primarily between oxygen in air and a fuel, such as wood or propane. In addition to other products, the reaction produces carbon dioxide, steam, light, and heat. If the flame is hot enough, the gases are ionized and become yet another state of matter: plasma.
Why Does Ice Float?
Water reaches its maximum density at 4°C (40°F). As it cools further and freezes into ice, it actually becomes less dense. On the other hand, most substances are most dense in their solid (frozen) state than in their liquid state. Water is different because of hydrogen bonding.
A water molecule is made from one oxygen atom and two hydrogen atoms, strongly joined to each other with covalent bonds. Water molecules are also attracted to each other by weaker chemical bonds (hydrogen bonds) between the positively-charged hydrogen atoms and the negatively-charged oxygen atoms of neighboring water molecules. As water cools below 4°C, the hydrogen bonds adjust to hold the negatively charged oxygen atoms apart. This produces a crystal lattice, which is commonly known as 'ice'.
Ice floats because it is about 9% less dense than liquid water. In other words, ice takes up about 9% more space than water, so a liter of ice weighs less than a liter water. The heavier water displaces the lighter ice, so ice floats to the top. One consequence of this is that lakes and rivers freeze from top to bottom, allowing fish to survive even when the surface of a lake has frozen over. If ice sank, the water would be displaced to the top and exposed to the colder temperature, forcing rivers and lakes to fill with ice and freeze solid.
A water molecule is made from one oxygen atom and two hydrogen atoms, strongly joined to each other with covalent bonds. Water molecules are also attracted to each other by weaker chemical bonds (hydrogen bonds) between the positively-charged hydrogen atoms and the negatively-charged oxygen atoms of neighboring water molecules. As water cools below 4°C, the hydrogen bonds adjust to hold the negatively charged oxygen atoms apart. This produces a crystal lattice, which is commonly known as 'ice'.
Ice floats because it is about 9% less dense than liquid water. In other words, ice takes up about 9% more space than water, so a liter of ice weighs less than a liter water. The heavier water displaces the lighter ice, so ice floats to the top. One consequence of this is that lakes and rivers freeze from top to bottom, allowing fish to survive even when the surface of a lake has frozen over. If ice sank, the water would be displaced to the top and exposed to the colder temperature, forcing rivers and lakes to fill with ice and freeze solid.
Why do things float?
A substance floats if it is less dense, or has less mass per unit volume, than other components in a mixture. For example, if you toss a handful of rocks into a bucket of water, the rocks, which are dense compared to the water, will sink. The water, which is less dense than the rocks, will float. Basically, the rocks push the water out of the way, or displace it. For an object to be able to float, it has to displace a weight of fluid equal to its own weight.
Subscribe to:
Posts (Atom)