Photosynthesis- Unit 2

Question 1

Autotrophs

Answer 1

Make their own food using energy form the environment and inorganic carbon sources such as CO2

Question 2

Photosynthesis

Answer 2

Plants and other autotrophs capture light energy and use it to build sugars from water and CO2 (metabolic pathway)

Converts light energy to chemical energy

Question 3

Heterotrophs

Answer 3

Get energy and carbon from molecules that other organisms have already assembled

Question 4

Biofuels

Answer 4

Increasing demand

Oils, gases, and alcohols made form organic mater that is no fossilized.

Materials currently used for biofuel production consists mainly of food crops, typically expensive, ecologically disruptive, and produced in competition with our food supply

Making biofuels from other plants require additional steps to break down cellulose

Question 5

Biofuel solution

Answer 5

Researchers work to find cost effective way to break down the cellulose in fast-growing weeds such as switchgrass

Question 6

Sunlight as an energy source

Answer 6

Visible light drives photosynthesis which begins when photons are absorbed by photosynthetic pigment molecules

Question 7

Properties of Light

Answer 7

Travels in waves and is organized as photons.

Visible light is a very small part of the spectrum of electromagnetic energy radiating from the sun

We see light of particular wavelengths as different colors

Wavelength- distance between two crests of 2 successive waves of light

Question 8

Light waves

Answer 8

Shortest waves are the highest energy (blues)
Longest waves are the lowest energy (reds)

Question 9

Pigments

Answer 9

Molecules that absorb light of a particular wavelength, photons that are not captured by a pigment are reflected as it’s characteristic color

Question 10

Chlorophyll A

Answer 10

The main photosynthetic pigment in plants

Absorbs violet and red light, so plant appears green

Question 11

Accessory pigments

Plants, protists, and bacteria share the majority. Protists and bacteria share the exact same

Answer 11

Color everything else

Question 12

Archaean photosynthetic pigment

Answer 12

Has one singular unique occurrence, retinal which emits the color violet.

Question 13

Pigment function

Answer 13

Absorbing a photon excites electrons in the pigment and boosts them to a higher energy level

Photosynthetic cells can capture energy emitted from electrons as they return to a lower energy level

When energy is passed to a special pair of chlorophylls the reaction of photosynthesis begins

Question 15

who discovered the rainbow

Answer 15

Theodor Engelmann identified the colors of light (red and violet) that drive photosynthesis in a photosynthetic alga

His results created an absorption spectrum which is a graph that shows how efficiently different wavelengths of light are absorbed by a substance

Directed light through a prism so that bands of color crossed a water droplet on a microscope slide. The water held strand of photosynthetic Cladophora and oxygen requiring bacteria. The bacteria clustered around algal cells that released most oxygen, reds and violets.

Question 16

Flow of energy in terms of pigment

Answer 16

Starts when chlorophylls and other photosynthetic pigments absorb the energy of visible light
In plants, some bacteria, and many protists, that energy ultimately drives the synthesis of glucose and other carbohydrates

Question 17

where does photosynthesis occur

Answer 17

Chloroplasts

Question 18

Photosynthesis as a reaction

Answer 18

6CO2+6h20=light energy= glucose and oxygen

series of reactions that occur in 2 stages, light-dependent and light-independent

Question 19

Light dependent reactions

Answer 19

First stage of photosynthesis, occurs at the thylakoid membrane, convert light energy to chemical energy (ATP)

Form ATP and NADPH, which donate their electrons and chemical bond energy

Question 20

Light independent reactions

Answer 20

Second stage of photosynthesis
Occurs in stroma
Use ATP to assemble sugars from water and CO2

Molecules that form in the first stage power the formation of sugar in the second stage

Synthesis part of photosynthesis

Sugars are assembled with carbon and oxygen atoms from CO2

Question 21

Light harvesting complexes

Answer 21

Light harvesting complexes in the thylakoid membrane absorb photons and pass the energy to photosystems which release electrons

Question 22

Photosystems

Answer 22

A cluster of hundreds of chlorophylls, accessory pigments and other molecules that convert light energy to chemical energy in photosynthesis

Question 23

Photolysis

Answer 23

Process in second stage by which light energy breaks down a molecule

Stage of photosynthesis replaces lost electrons by pulling them from water which then dissociates into H and O

Question 24

Energy flow in photosynthesis

Answer 24

Energy flow in light-dependent reactions is an example of how organisms use energy harvested from the environment to drive cellular processes

the simpler cyclic pathway evolved first and operates nearly all photosynthesizes

Some organismal populations evolved the additional photosystem II, beginning a sequence of reactions that removes electrons from water molecules, releasing hydrogen ions and oxygen

Question 25

Calvin-Benson Cycle

Answer 25

The cyclic light-independent reactions of the Calvin-Benson cycle are the synthesis part of photosynthesis.

Carbon fixation synthesizes sugar

Inside the stroma, the enzyme rubisco attaches a carbon from CO2 to RuBP to start the cycle

Question 26

Carbon fixation

Answer 26

The incorporation of carbon from an inorganic source such as CO2 into an organic molecule

Question 27

Rubisco

Answer 27

Most common enzyme on earth, plays an important part in the synthesis portion of photosynthesis

Question 28

Energy for Sugar Synthesis

Answer 28

Photo: ATP and NADPH are produced by the light-dependent reactions using light energy

Synthesis:
Light-independent reactions use energy from ATP and hydrogen and electrons from NADPH to synthesize sugars from CO2

Question 29

Carbon-Fixing and Alternate Pathways

Answer 29

When environment differs, so do details of light-independent reactions

Three pathways
C3, C4, CAM plants

Alternate: Details of light-independent reactions that vary among organisms are evolutionary adaptions to different environmental conditions

Question 30

Photorespiration

Answer 30

On dry days plants conserve water by closing their stomata
O2 from photosynthesis can’t escape and CO2 for it can’t enter

Question 31

Stomata

Answer 31

openings through plant surfaces that allow water vapor and gases to diffuse across the epidermis and through cuticle

Question 32

Green energy (process of carbon)

Answer 32

Photosynthesis removes carbon dioxide from the atmosphere, and locks it’s carbon atoms inside the organic compounds

When aerobic organisms break down the organ compounds for energy, carbon atoms are released in CO2

Since photosynthesis evolved, these two processes have constituted a balanced cycle of biosphere