photosynthesis Flashcards

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1
Q

what is photosynthesis

A

Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms’ activities (energy transformation).

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2
Q

write brief notes on photosynthesis

A

Photosynthesis is essential to all life on earth; both plants and animals depend on it. It is the only biological process that can capture energy that originates in outer space (sunlight) and convert it into chemical compounds (carbohydrates) that every organism uses to power its metabolism.

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3
Q

how is sunlight energy used in photosynthesis

A

In brief, the energy of sunlight is captured and used to energize electrons, which are then stored in the covalent bonds of sugar molecules.

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4
Q

give examples of organisms that perform photosynthesis

A

Plants,
algae,
and a group of bacteriacalled cyanobacteria

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5
Q

what are chemotrophs

A

these are group of bacteria that synthesize sugars, not by using sunlight’s energy, but by extracting energy from inorganic chemical compounds

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6
Q

what is the importance of photosynthesis

A

it helps to store the energy in solar radiation (the “photo-” part) as high-energy electrons in the carbon-carbon bonds of carbohydrate molecules (the “-synthesis” part)

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7
Q

summarise briefly the process of photosynthesis

A

Photosynthesis is a multi-step process that requires sunlight, carbon dioxide (which is low in energy), and water as substrates

After the process is complete, it releases oxygen and produces glyceraldehyde-3-phosphate (GA3P), simple carbohydrate molecules (which are high in energy) that can subsequently be converted into glucose, sucrose, or any of dozens of other sugar molecules.
These sugar molecules contain energy and the energized carbon that all living things need to survive.

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8
Q

what are the products involved in photosynthesis

A

Photosynthesis uses solar energy, carbon dioxide, and water to produce energy-storing carbohydrates.
Oxygen is generated as a waste product of photosynthesis.

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9
Q

name the compound from which glucose is made during photosynthesis

A

Glucose, the primary energy source in cells, is made from two three-carbon GA3Ps.

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10
Q

which structure of the leaf does photosynthesis occur

A

photosynthesis generally takes place in leaves, which consist of several layers of cells. The process of photosynthesis occurs in a middle layer called the mesophyll. The gas exchange of carbon dioxide and oxygen occurs through small, regulated openings called stomata (singular: stoma

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11
Q

what is the function of the stomata(STOMA)

A

it play roles in the regulation of gas exchange and water balance.

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12
Q

what is the location of the stomata in a leaf

A

The stomata are typically located on the underside of the leaf, which helps to minimize water loss.

Each stoma is flanked by guard cells that regulate the opening and closing of the stomata by swelling or shrinking in response to osmotic changes.

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13
Q

where does photosynthesis take place in cells

A

photosynthesis takes place inside an organelle called a chloroplast

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14
Q

define thylakoids

A

these are disc-shaped structures found within the chloroplast

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15
Q

what is found embeded in the thylakoids

A

chlorophyl which is pigment (molecule that absorbs light) responsible for the initial interaction between light and plant material, and numerous proteins that make up the electron transport chain is found in the Thylakoids

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16
Q

what is a granum

A

it is a group or a stack of thylakoids

The thylakoid membrane encloses an internal space called the thylakoid lumen

17
Q

define the stroma(bed)

A

this is the the liquid-filled space surrounding the granum

Photosynthesis takes place in chloroplasts, which have an outer membrane and an inner membrane. Stacks of thylakoids called grana form a third membrane layer.

18
Q

whatare the stages involved in photosynthesis

A
  1. the light-dependent reactions
  2. the light independent-reactions
19
Q

what happens in the light dependent reaction

A

In the light-dependent reactions, energy from sunlight is absorbed by chlorophyll and that energy is converted into stored chemical energy.

20
Q

what happens in the light in-dependent reaction

A

In the light-independent reactions, the chemical energy harvested during the light-dependent reactions drive the assembly of sugar molecules from carbon dioxide.

although the light-independent reactions do not use light as a reactant, they require the products of the light-dependent reactions to function

21
Q

what does the sunlight do in the light independent reaction

A

it helps to activate several enzymes used in the light-independent reactions

22
Q

what does the light dependent reaction use to store energy

A

The light-dependent reactions utilize certain molecules referred to as energy carriers to temporarily store the energy

23
Q

what does the energy carriers do

A

they move energy from light-dependent reactions to light-independent

these energy carriers are rich in energy and after the energy is released, the “empty” energy carriers return to the light-dependent reaction to obtain more energy.

24
Q

where does the light dependent reaction take place

A

ight-dependent reactions, which take place in the thylakoid membrane, use light energy to make ATP and NADPH.

25
Q

where does the light-independent reaction takes place

A

The Calvin cycle or light-independent reaction takes place in the stroma, uses energy derived from these compounds to make GA3P from CO2.

26
Q

what is the overall function of the light dependent reaction

A

the function of light-dependent reactions is to convert solar energy into chemical energy in the form of NADPH and ATP. This chemical energy supports the light-independent reactions and fuels the assembly of sugar molecules.

Protein complexes and pigment molecules work together to produce NADPH and ATP.

27
Q

what is a photoystem

A

A photosystem consists of a light-harvesting complex and a reaction center.

28
Q

what happens in photosystem

A

Pigments in the light-harvesting complex pass light energy to two special chlorophyll a molecules in the reaction center. The light excites an electron from the chlorophyll a pair, which passes to the primary electron acceptor.
The excited electron must then be replaced.

29
Q

summary on phosynthesis

A

6CO2 + 6H2O + Light Energy → C6H12O6 + 6O2
Autotrophs store chemical energy in carbohydrate food molecules they build themselves. Most autotrophs make their “food” through photosynthesis using the energy of the sun.
Photosynthesis occurs in the chloroplast, an organelle specific to plant cells.
The light reactions of photosynthesis occur in the thylakoid membranes of the chloroplast.
Electron carrier molecules are arranged in electron transport chains that produce ATP and NADPH, which temporarily store chemical energy.
The light reactions capture energy from sunlight, which they change to chemical energy that is stored in molecules of NADPH and ATP.
The light reactions also release oxygen gas as a waste product.
The reactions of the Calvin cycle add carbon (from carbon dioxide in the atmosphere) to a simple five-carbon molecule called RuBP.
The Calvin cycle reactions use chemical energy from NADPH and ATP that were produced in the light reactions.
The final product of the Calvin cycle is glucose.