Chapter 5 - Photosynthesis

Question 1

Autotroph

Answer 1

A plant, a “self-feeder” that uses inorganic substances such as water and carbon dioxide to produce organic compounds

Question 2

Heterotroph

Answer 2

An organism that obtains carbon by consuming preexisting organic molecules

Question 3

Photosynthesis

Answer 3

the process by which plans, algae, and some bacteria harness solar energy and convert it into chemical energy. Photosynthesis is an redox process. occurs in 2 stages, the light reactions and the carbon reactions.

Question 4

Photosynthesis chemical summary:

Answer 4

6CO2 + 6H2O (light energy) —> C6 H12 O6 + 6O2

Question 5

Plants using carbohydrates:

Answer 5

• Plants use glucose molecules as the building blocks of the cellulose walls that surround every plant
• Plants often combine carbohydrates with other substances to manufacture additional compounds, such as amino acids and other products forming rubber, medicines, and spices.
• Plants that produce more glucose than it immediately needs stores it as starch, evident in plants and fibers such as grains and tubors like potatoes, rice, wheat, and corn.
• Some plants store energy as glucose instead, such as sugarcane, sugar beets, etc.

Question 6

Electromagnetic spectrum

Answer 6

the range of possible frequencies of radiation.

Question 7

Photons

Answer 7

Discrete packets of kinetic energy that make up all electromagnetic radiation, including light.

Question 8

Photon’s WAVELENGTH

Answer 8

Wavelength of a photon is the distance it moves during a complete vibration. The shorter a photon’s wavelength, the more energy it contains.

Question 9

Sunlight

Answer 9

• consists of three main components:
• Ultraviolet radiation, has the shortest wavelengths. High energy photons can damage DNA, causes skin cancer and sunburn.
• Middle range, visible light provides the energy that powers photosynthesis, can be visible as a distinct array of colors.
• Infrared radiation, has the longest wavelengths. contain too little energy to be useful to organisms, and most of its energy is converted directly to heat.

Question 10

Chlorophyll a

Answer 10

The most abundant pigment in plant cells; is a green photosynthetic pigment in plants, algae, and bacteria. Absorbs red and blue wavelengths, and appear green because they reflect green light.

Question 11

Accessory pigments

Answer 11

energy capturing pigment molecules other than chlorophyll a. Chlorophyll b and carotenoids are accessory pigments in plants. Chlorophyll b absorbs red and blue wavelengths and appears green because it reflects green light. Carotenoids reflect longer wavelengths, and appear red, yellow, orange, and red.

Question 12

Stomata

Answer 12

(singular, stoma). Tiny openings in the epidermis of a leaf or stem. CO2 and O2 enter and exit a plant through these. allow for gas exchange, and water also evaporates through these openings. “guard cells” collapse around these openings when the cell loses too much water to close the pores.

Question 13

Mesophyll

Answer 13

A collective term for the cells filling a leaf’s interior (meso = middle). Where most photosynthesis occurs.

Question 14

Chloroplasts

Answer 14

The organelles of photosynthesis in plants and algae, contained in the mesophyll

Question 15

Stroma

Answer 15

The chloroplasts fluid inner region. Gelatinous fluid that contains ribosomes, DNA, and enzymes.

Question 16

Grana

Answer 16

Stacks of Granum suspended in the stroma, about 10-100 “stacks”.

Question 17

Thylakoid

Answer 17

Consists of a membrane that is studded with photosynthetic pigments. the thylakoid space is the inner compartment enclosed by a thylakoid membrane.

Question 18

Photosystems

Answer 18

Clusters of pigments and proteins that participate in photosynthesis, and are anchored in the thylakoid membrane.

Question 19

Reaction center

Answer 19

Includes a pair of chlorophyll a molecules that use the energy in photosynthetic reactions, in a photosystem. (If array of pigments in a photosystem is like a quiz show team, then the reaction center is analogous to the one member who announces the team’s answer to the show’s moderator).

Question 20

Antenna pigments

Answer 20

Additional pigments in the photosystem, because they capture photon energy and funnel it into the reaction center.

Question 21

Light reactions

Answer 21

Convert solar energy to chemical energy (thought of as the “photo” part of photosynthesis). In the chloroplasts thylakoid membranes, pigment molecules in two linked photosystems capture kinetic energy from photons and store it as potential energy in the chemical bonds of two molecules - ATP and NADPH.

Question 22

ATP

Answer 22

The nucleotide that stores potential energy in the covalent bonds between its phosphate groups. Is formed when a phosphate group is added to ADP.

Question 23

NADPH

Answer 23

An energy rich product of the light reactions, a coenzyme that carries pairs of energized electrons.

Question 24

Carbon reactions

Answer 24

the second part of photosynthesis - the chloroplast uses ATP, the high-energy electrons from NADPH, and CO2 to produce sugar molecules. (the “synthesis” part of photosynthesis”). ATP and NADPH comes from the light reactions, and the CO2 comes from the atmosphere…once inside the leaf, CO2 diffuses into a mesophyll cell and across the chloroplast membrane into the stroma, where the carbon reactions occur. Carbon reactions do not directly require sunlight, but do need the products of light reactions (ATP and NADPH)

Question 25

ATP synthesis

Answer 25

The enzyme complex that transforms the gradient’s potential energy into chemical energy in the form of ATP.

Question 26

Chemiosmotic phosphorylation

Answer 26

The coupling of ATP formation to the release of energy from a protein gradient, because it is the addition of a phosphate to ADP using energy from the movement of protons across a membrane.

Question 27

Calvin cycle

Answer 27

The metabolic pathway that uses NADPH and ATP to assemble CO2 molecules into 3-carbon carbohydrate molecules. This 3-carbon molecule (PGA) is the first stable compound in the pathway.

Question 28

Carbon fixation

Answer 28

the first step in the Calvin cycle, the initial incorporation of carbon from CO2 into an organic compound. Carbon combines with RuBP.

Question 29

RuBP (ribulose bisphosphate)

Answer 29

a 5-carbon sugar with two phosphate groups.

Question 30

Ribusco

Answer 30

an enzyme that catalyzes the first reaction in the Calvin cycle .

Question 31

C3 Pathway

Answer 31

Another name for the Calvin cycle, so named because the 3-carbon molecule created via the Calvin cycle (PGA) is the first stable compound in the pathway.

Question 32

Photorespiration

Answer 32

A series of reactions that begin when the rubisco enzyme adds O2 instead of CO2 to RuPB. The product of this reaction does NOT enter the Calvin cycle, and the plant therefore loses CO2 that it fixed in previous turns of the cycle, wasting both ATP and NADPH. This process is a contributing factor to the waste of solar energy that plants are involved in.

Question 33

C4 Pathway

Answer 33

A preliminary carbon fixation in mesophyll cells, when CO2 combines with a 3-carbon “ferry” molecule to form a four carbon compound, oxaloacetate (C4).

Question 34

Bundle-sheath cells

Answer 34

cells that surround the leaf veins

Question 35

CAM pathway

Answer 35

plants that use the CAM pathway fix carbon twice, but also open their stomata only at night, fix CO2, and then fix it again using the Calvin cycle during the day. Plants that use this method are mostly cacti and other plants who live in arid, hot, desert-like climates.