Ch.7.2 Flashcards
what is photosynthesis?
It is a plant’s process of producing their own food.
what does photosynthesis require?
—________ ______________: ______________________ and _____________
—an _____________ ______________: ___________________
raw materials: carbon dioxide, water
energy source: light
what is produced through photosynthesis?
_________________: _________________
______________________: _________________
food: glucose
by-product: oxygen.
how is carbon dioxide obtained by a plant?
it is obtained from the air.
how is water obtained by a plant?
it is absorbed from the soil.
what are the ‘raw materials’ also called in photosynthesis?
the ‘reactants’.
how is light energy obtained by a plant?
it is absorbed by chlorophyll.
how do plants use glucose?
for growth and respiration.
glucose that is not used immediately is ____________________________________________________.
converted into starch for temporary storage.
both glucose and starch are called ___________________________.
carbohydrates
what is chlorophyll?
it is a green pigment in the chloroplasts of green leaves or other green parts of plants.
what happens to the oxygen by the plant?
it is given out into the air as it is not needed by the plant.
name the process of energy conversion in photosynthesis.
light energy from the sun —photosynthesis—> chemical energy of the plant —human respiration—> energy for supporting life
word equation of photosynthesis:
carbon dioxide+water—light-energy-absorbed-by-chlorophyll—> glucose+oxygen
glucose is considered as the _________________ of photosynthesis; while oxygen, the _________________.
product, by-product
chemical equation of photosynthesis:
6CO₂+6H₂O—light-energy-absorbed-by-chlorophyll—>C₆H₁₂O₆+6O₂
from the chemical equation of photosynthesis, we can see that:
—carbon dioxide ________________ with water to ________________ glucose and oxygen
—the ________________ ________________ of ________________ ________________ (________________ atom, ________________ atom and ________________ atom) is the ________________ on both sides of the equation.
reacts, form, total number, each atom, oxygen, carbon, hydrogen, same
we can use ________________ _________________ to test for starch.
iodine solution
iodine solution changes __________________________________________________ in the presence of starch.
from brown to blue-black
steps of testing for starch in green leaves: 1. 2. 3. 4.
put the leaf in boiling water
put the leaf in hot alcohol
wash the leaf in hot water
add iodine solution to the leaf
what is the purpose of putting a leaf in boiling water before testing it for starch?
To kill the leaf cells and destroy the cell membrane so that iodine solution to be added later can enter the cells.
what is the purpose of putting the leaf in hot alcohol while testing it for starch?
To remove the chlorophyll of the leaf and make the leaf lighter in colour, so that a more obvious change can be detected later on.
what is the purpose of washing the leaf in hot water while testing it for starch?
To remove the alcohol and make the leaf soft.
what is the purpose of adding iodine solution to the leaf while testing it for starch?
To test the presence of starch in the leaf.
why do we use alcohol instead of water or remove chlorophyll from the leaf?
This is because chlorophyll dissolves better in alcohol than in water.
What safety precaution should we be aware of when we put the leaf in alcohol while testing for starch?
We should switch off the bunsen burner as the alcohol is flammable.
What happens when we put a glowing splint over a bottle containing a water plant that has been screwed tight inside the bottle with water and carbon dioxide for four hours? what does this indicate?
The splint relights. This indicates that the gas given out by the plant is oxygen, and that photosynthesis has taken place.
What role does sodium hydrogencarbonate play in testing for oxygen produced by photosynthesis?
It provides carbon dioxide for the plant to carry out photosynthesis.
How do we see oxygen that is given out by water plants in water?
They appear as bubbles in water.
How do we destarch a plant?
By placing it in the dark for at least 48 hours.
What happens when a plant is placed in the dark for 48 hours?
During this period, all the starch stored in the plant is converted into glucose which is then used by the plant.
Why do we have to destarch a plant before investigating whether different factors are necessary for photosynthesis?
This ensures that the plant does not contain any starch when the investigation begins, and that any starch we detect later is formed during the investigation, indicating that photosynthesis has taken place.
What kind of leaf should we use when we investigate if chlorophyll is necessary for photosynthesis?
A variegated leaf.
Briefly describe the experimental set-up of the investigation of whether chlorophyll is necessary for photosynthesis.
Put a destarched plant under a bright light for four hours after making sure that it has no starch, and conduct the iodine test on a variegated leaf.
What are the results of the investigation of whether is chlorophyll necessary for photosynthesis?
In the iodine test, the green parts of the variegated leaf become blue-black while the non-green parts are brown in colour. This shows that starch is produced in the green parts of the variegated leaf.
What special material do we need to investigate whether is carbon dioxide necessary for photosynthesis? What does it consist of? What does it do?
soda lime; sodium hydroxide and calcium oxide; it absorbs CO2.
Briefly describe the experimental set-up of the investigation of whether carbon dioxide is necessary for photosynthesis.
After confirming that a leaf of a destarched plant contains no starch, put one leaf of the plant into a plastic bag containing soda lime, and another leaf of the same plant into a plastic bag without soda lime, and place the plant under a bright light for four hours. Carry out the iodine test on both leaves.
What are the results of the investigation of whether is carbon dioxide necessary for photosynthesis?
The leaf with the soda lime in its plastic bag stays brown in colour, which means that no starch is produced, while the leaf without the soda lime in its plastic bag turns from brown to blue-black which means starch is produced and it has carried out photosynthesis.
What special material do we need to investigate whether is light necessary for photosynthesis?
black paper or aluminium foil, and paper clips.
Briefly describe the experimental set-up of the investigation of whether light is necessary for photosynthesis.
After confirming that a leaf of a destarched plant contains no starch, clip a strip of black paper or aluminium foil to a leaf of the plant, and place the plant under a bright light for four hours. Carry out the iodine test on the leaf.
What are the results of the investigation of whether is light necessary for photosynthesis?
The parts of the leaf that were covered with a strip of paper or foil stay brown, which means that no starch is produced; while the parts of the leaf that weren’t covered by the strip of paper of foil turn from brown to blue-black, which means that starch is produced, and photosynthesis was carried out.
There is no _________________ _________________ to show that water is a _________________ _________________ of photosynthesis. How do we know that water is necessary for photosynthesis?
simple experiment, necessary factor; This is because a plant will die if we remove all the water from it.
_________________, _________________ and _________________ _________________ are necessary for photosynthesis.
Chlorophyll, light, carbon dioxide
Photosynthesis is an _________________ _____________ _________________.
essential life process
State the TWO reasons why photosynthesis is significant to other living things.
—
—
providing food for living things
maintaining the balance of oxygen and carbon dioxide in Nature
Photosynthesis allows plants to ___________________________________________________.
make their own food.
As animals cannot _________________________________________________, some animals ____________________________________ and other animals _______________________________________.
make their own food, feed on plants, feed on animals
Photosynthesis is important in _________________ _________________ _________________ or _________________ for living things.
providing food directly, indirectly
Plants are called _________________, or _________________, as they can ____________________________________ by ____________________.
producers, autotrophs, make their own food, photosynthesis
Animals are called _________________ as they _____________________________________. They feed on _________________ or _____________________________.
consumers, cannot produce food on their own, plants, animals
The _________________ _________________ and the __________________________________ among living things can be shown by a _________________ _________________.
feeding relationship, flow of energy, food chain
Through a food chain, energy can ______________ through the _________________, and we can show it by using _________________.
flow, ecosystem, arrows
Since plants make use of the _________________________________________________ to carry out photosynthesis, _________________ is the __________________________________________ for all food chains.
light energy from the Sun, the Sun, ultimate source of energy
Humans are _________________. We consume both _________________ and _________________. Some animals are _________________/ _________________. They only consume _________________/ _________________.
omnivores, meat, vegetables
herbivores, carnivores, vegetables, meat
During ________________________ in a food chain, energy is lost to ___________________at each ____________ in the food chain; eg lost as ____________ through ________________.
energy conversions, environment, stage, heat, respiration
Why do we place the leaves on white tiles while performing experiments?
To see the change of colour more clearly.
