photosynthesis Flashcards

1
Q

what does oxidation mean?

A

loss of electrons or hydrogen from a substance.

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2
Q

what is reduction?

A

gaining of electrons or hydrogen by a substance.

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3
Q

oxidation or reduction in photosynthesis?

A

in photosynthesis, carbon dioxide gains electrons to form glucose so it is reduced.

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4
Q

oxidation or reduction in cellular respiration?

A

in cellular respiration, glucose is broken down, it loses electrons and becomes oxidized.

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5
Q

autotrophs vs heterotrophs?

A

autotrophs are producers: they produce their own food from inorganic substances.
heterotrophs are consumers: they cannot produce their own food and rely on consuming organic compounds made by other organisms.

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6
Q

what organisms can perform photosynthesis?

A

plants, algae, cyanobacteria, some protists, and some photosynthetic bacteria can use sunlight, co2, and water to produce glucose and oxygen through the process of photosynthesis.

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7
Q

where does photosynthesis take place?

A

takes place in the chloroplasts

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8
Q

what is the structure of the chloroplast?

A

outer membrane, inner membrane, intermembrane space, stroma, thylakoids, granum,

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9
Q

do unicellular protists contain chloroplasts?

A

yes many unicellular protists contain chloroplasts and are capable of photosynthesis

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10
Q

do cyanobacteria and some photosynthetic bacteria have chloroplasts?

A

no they do not contain chloroplasts, they have thylakoid membranes and chlorophyll.

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11
Q

where are most of the chloroplasts found in plants?

A

most chloroplasts are found in leaves : 30-50 chloroplasts per plant cell.

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12
Q

what is the internal structure of a leaf?

A

there is the epidermis which is the outer layer that protects the leaf: covered by a waxy cuticle to reduce water loss.
the middle layer is the mesophyll: densely packed with chloroplasts and the air spaces facilitate the exchange of co2 and o2 necessary for photosythesis.
there are vascular bundle: xylem and phloem
and stomata: small openings in the epidermis that allow for gas exchange.
then there is the lower epidermis.

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13
Q

chloroplasts are found primarily in?

A

the cells of the mesophyll tissue.

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14
Q

how does co2 and h2o reach the structures?

A

co2 enters the leaf through small openings called stomata and eventually moves through the intercellular spaces of the mesophyll.
h2o: water is absorbed form the soil by the roots and travels up through the vascular bundle and eventually reach the mesophyll cells where photosynthesis occurs.

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15
Q

photosynthesis is a two stage process?

A
  1. light dependent reactions and light independent reactions: calvin cycle
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16
Q

light dependent reactions, role of light?

A

photosynthesis uses sunlight as its primary energy source. the visible light portion of the electromagnetic spectrum includes wavelengths that our eyes can see such as red, blue, green etc.

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17
Q

photosynthesis is driven by?

A

the visible light portion of the electromagnetic spectrum.

18
Q

the visible light(wavelengths we can see) is absorbed by?

A

pigments found in chloroplasts: chlorophyll a, chlorophyll b, and carotenoids

19
Q

different pigments absorb?

A

light of different wavelengths

20
Q

where are the pigments located?

A

in the thylakoid membrane

21
Q

why are leaves green?

A

the major pigment is chlorophyll a

22
Q

what is not absorbed by chlorophyll?

A

the green wavelength. chlorophyll gives plants their green color because it does not absorb the green wavelengths and it is reflected.

23
Q

what is absorbed by chlorophyll

A

absorbs in violent-blue and red light of the spectrum

24
Q

which wavelength of light can drive photosynthesis?

A

the wavelengths of visible light that effectively drive photosynthesis are blue light and red light.

25
Q

spectrophotometer?

A

measures the relative amounts of light at different wavelengths absorbed and transmitted by a pigment solution.
step1: white light is separated into wavelengths/colors by a prism
step 2: one by one, the different colors of lights are passed through the sample(chlorophyll).
step 3: the transmitted light strikes a photoelectric tube which converts light energy into electricity.
step 4: the electric current is measured by a galavantometer. the meter indicates the fraction of light transmitted through the sample from which we can determine the amount of light absorbed.

26
Q

high transmittance in a galvanometer means?

A

a large amount of light is passing through the sample without being absorbed. chlorophyll absorbs very little green light. low transmittance: high absorption: blue and red, but blue slightly better than red

27
Q

from the data, a graph plotting the pigments light absorption vs wavelength is called?

A

absorption spectrum: violet-blue and orange-red light work best

28
Q

chloroplasts contain different pigments. what does this help with?

A

helps to broaden the wavelengths that can drive photosynthesis.
chlorophyll a: primary pigment involved in photosynthesis: blue and red light.
chlorophyll b: acts as an accessory pigment, helps capture light energy and transfer it to chlorophyll a.
carotenoids: the color is yellow, orange or red. it is an accessory pigment. help to capture light energy and protect the plant from excess light and oxidative damage: absorbs blue and green light.

29
Q

why do the leaves turn color in the fall?

A

as autumn approaches, plants reduce the production of chlorophyll a and chlorophyll a starts to degrade due to shorter days and cooler temperature.
- the carotenoids become more prominent which are yellow and orange and red.

30
Q

what happens when a pigment absorbs light?

A

the energy from the absorbed light excites electrons in the pigment molecule and one of its electrons gets boosted to a higher energy level. the pigment molecule is in an EXCITED STATE.

31
Q

Light dependent reactions of photosynthesis occurs in?

A

thylakoid membrane

32
Q

the pigments are found?

A

as part of a photosystem in the thylakoid membrane of the chloroplast

33
Q

what does a photosystem consist of?

A

light harvesting complexes consisting of various pigment molecules bound to protein.
these complexes surround a reaction centre complex: consisting of a primary electron acceptor and a special pair of chlorophyll a molecules.

34
Q

there are two photosystems in the thylakoid membrane which are?

A

photosystem II: P680 and photosystem I: P700

35
Q

Both cellular respiration and photosynthesis involve?

A

the flow of electrons

36
Q

in the light dependent reactions of photosynthesis, electron flow can be?

A

linear and cyclic

37
Q

what does linear electron flow generate?

A

ATP and NADPH: which will then be used for the light independent reactions

38
Q

linear electron flow?

A

explained in doc

39
Q

cyclic electron flow?

A

explained in doc

40
Q

what does the cyclic electron flow generate?

A

atp