Unit 3 test

Cellular respiration involves three major groups of reactions: glycolysis, the Krebs cycle, and the electron transport chain. Explain the series of events that occurs in the cells of all organisms during the Krebs cycle.

During the Krebs cycle, pyruvic acid from glycolysis is used to make carbon dioxide, NADH, ATP, and FADH2 in presence of oxygen - pyruvate dehydrogenase complex (PDC) - Pyruvic acid from glycolysis enters mitochondria One carbon become CO2 and is released into the atmosphere Other two carbons join coenzyme A to form acetyl-CoA Acetyl-CoA enters Krebs cycle by joining a 4-carbon molecule to form citric acid - energy extraction via series of carbon compounds - · Citric acid is broken down into a 5-carbon, than a 4-carbon molecule · 4-carbon molecule is recycled to join more acetyl-CoA at start of cycle · In process of converting carbon compounds, 2 CO2 and 1 ATP are produced, and electrons are transferred to electron carriers NAD+ à NADH (same one as in glycolysis); FAD à FADH2

ADP is one of the principal chemical compounds that living things use to store energy.

False, ATP

The light-dependent reactions supply the Calvin cycle with CO2 and ATP

False, NADPH

Heterotrophs make their own food.

False, autotrophs

In prokaryotes, the electron transport chain is located in the inner membrane of the mitochondria.

False, cell membrane (Eukaryotes, inner membrane of mitochondria)

During the light-dependent reactions, plants use the energy in ATP and NADPH to build high-energy sugars.

False, light-independent reactions (Calvin cycle)

Cellular respiration releases energy by breaking down glucose in the presence of carbon dioxide.

False, oxygen

Either cellular respiration or fermentation can be used to release energy, depending on the presence of carbohydrates.

False, oxygen

If a plant and a burning candle are placed under a bell jar, the candle will burn because the plant gives off carbon dioxide

False, oxygen

The reactants of photosynthesis are the same as the reactants of cellular respiration.

False, products

Cellular respiration involves three major groups of reactions: glycolysis, the Krebs cycle, and the electron transport chain. Explain the series of events that occurs in the cells of all organisms during glycolysis.

Glycolysis (the first set of reactions in cellular respiration) is the process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid, a 3-carbon compound. 2 molecules of ATP are used to get glycolysis going. When glycolysis is complete, 4 ATP molecules have been produced. NADH holds the electrons until they can be transferred to other molecules (2 NADH are produced from 2 NAD+).

A student poured a solution of bromthymol blue into two test tubes. (Bromthymol blue turns from blue to yellow in the presence of carbon dioxide.) Then she placed an aquatic plant into test tubes #1 and #2. Test tube #1 was left in the light for 24 hours. Test tube #2 was put in the dark for 24 hours. After 24 hours, what color would you expect the solution in each test tube to be? Explain your answer.

Test tube 1 - blue does photosynthesis and cellular respiration in light (makes food and breaks it down as its making it) Produces CO2 (carbon dioxide) Can also do photosystem (absorb CO2 being made) Carbon dioxide can't accumulate, no indicators Can be used back by photosynthesis (cycles) Tube 2 - yellow Can't due photosynthesis Relies on cellular respiration (stored CO2) Indicator changes in presence of carbon dioxide (CO2 cannot be absorbed, keeps accumulating) Produces carbon dioxide but there is no photosystem to absorb it

Photosynthesis involves to major groups of reactions: the light-dependent reactions and the light-independent reactions (or Calvin cycle). Explain the series of events that occurs in the cells of plants during the light-independent reactions.

The Calvin cycle uses ATP and NADPH to produce high-energy sugars. The Calvin cycle takes place in the stroma of chloroplasts and does not require light. - CO2 (carbon dioxide) enters the cycle - Six CO2 molecules enter cycle from atmosphere Combine with other carbon molecules to create twelve 3-carbon molecules - Energy input - Twelve 3-carbon molecules are converted into higher energy forms using the energy from ATP and NADPH ATP à ADP; NADPH à NADP+ Lower energy forms (ADP & NADP+) are recycled back to light-dependent reaction - Glucose - Two 3-carbon molecules leave cycle to produce a glucose molecule (C6H12O6) - 5-carbon molecules regenerated - Remaining ten 3-carbon molecules are recycled back to the start of the cycle to combine with more CO2

Cellular respiration involves three major groups of reactions: glycolysis, the Krebs cycle, and the electron transport chain. Explain the series of events that occurs in the cells of all organisms during the electron transport chain.

The electron transport chain uses the high-energy electrons from the Krebs cycle to convert ADP to ATP. - electron transport using NADH & FADH2 - High-energy electrons from NADH and FADH2 are passed along the electron transport chain Oxygen is final electron acceptor-combines with H+ to form H2O - hydrogen ion movement - As electrons move down chain, their energy is used to move H+ across membrane H+ accumulate in inner membrane space forming gradient - ATP synthase - H+ go back across membrane through the enzyme ATP synthase Causes enzymes to spin and bind ADP to a phosphate molecule to make ATP

Photosynthesis involves to major groups of reactions: the light-dependent reactions and the light-independent reactions (or Calvin cycle). Explain the series of events that occurs in the cells of plants during the light-dependent reactions.

The light-dependent reactions use energy from sunlight to produce ATP, NADPH, and oxygen. Light-dependent reactions take place within thylakoid membranes of chloroplasts (ATP and ADPH the cell can actually use in Calvin Cycle). - Photosystem II - Light is absorbed by photosystem- light energy is absorbed by electrons in thylakoid membrane High-energy electrons are passed onto electron carriers (electron transport chain) Thylakoid membrane replaces lost electrons by splitting water molecules 2 H2O à 4e- (electrons) + 4 H (hydrogen) + + O2 (oxygen) (Water is split, this oxygen is released into the atmosphere) - electron transport chain - High-energy electrons move through electron transport chain (series of electron carriers) from Photosystem II to Photosystem I Energy from electrons is used to move hydrogen ions (H+) from stroma into thylakoid (across thylakoid membrane) Creates a concentration gradient of hydrogen - Photosystem I - Light is absorbed by photosystem to re-energize (lost when used to pump hydrogen) the electrons that have been transported there NADP+ picks up electrons and hydrogen in the thylakoid membrane to become NADPH (this will be used in Calvin cycle) - Hydrogen ion movement - Inside of thylakoid is filled with hydrogen ions as electrons are transferred Creates a gradient and charge difference across the thylakoid membrane (Positive inside, negative outside) - ATP (formation) synthase Hydrogen ions cannot cross (back across) the thylakoid membrane on their own to equalize the gradient Hydrogen ions pass through an enzyme called ATP synthase Causes ATP synthase to spin and bind ADP to a phosphate making ATP (this will be used in Calvin cycle) (puts hydrogen back in stroma to be put back into cycle [everything is recycled], hydrogen circle around)

NADH and FADH2 carry electrons from the Krebs cycle to the electron transport chain.

True

Plants gather the sun's energy with light-absorbing molecules called pigments.

True

The products of glycolysis are 2 ATP, 2 NADH, and 2 pyruvic acid molecules.

True

19. Starch molecules are synthesized from glucose within most cells of a leaf during the daylight hours. During the night, this starch may be changed back into glucose by the process of a. Hydrolysis b. photosynthesis c. dehydration synthesis d. cellular respiration e. polymerization

a. Hydrolysis (split) (tricky, first Unit memory)

24. During lactic acid fermentation, a. NAD+ is regenerated, allowing glycolysis to continue. b. glucose is split into three pyruvic acid molecules. c. oxygen is required. d. three ATP molecules are produced e. none of the above

a. NAD+ is regenerated, allowing glycolysis to continue.

14. Which equation best summarizes the process of photosynthesis? a. water + carbon dioxide + light → sugars + oxygen b. sugars + oxygen + light → water + carbon dioxide c. water + oxygen + light → sugars + carbon dioxide d. oxygen + carbon dioxide + light → sugars + oxygen e. sugars + carbon dioxide + light → water + oxygen

a. water + carbon dioxide + light → sugars + oxygen

17. During photosynthesis, molecules of oxygen are released from the splitting of water molecules. This is occurs during the a. light-independent reactions b. light-dependent reactions c. formation of carbon dioxide d. formation of ATP e. Calvin cycle

b. light-dependent reactions (photosystem 2)

25. Compared to a cell that is carrying on anaerobic respiration, a cell that is carrying on aerobic respiration a. uses less energy b. produces more ATP c. uses less carbon dioxide d. produces more alcohol e. is using glucose less efficiently

b. produces more ATP (aerobic, oxygen, more phases)

23. The high-energy electrons that move down the electron transport chain during cellular respiration provide energy to a. transport water molecules across the membrane. b. convert carbon dioxide into water molecules. c. convert ADP molecules into ATP. d. break glucose into pyruvic acid. e. synthesize glucose from carbon dioxide and water.

c. convert ADP molecules into ATP.

20. Which of the following is the correct sequence of events in cellular respiration? a. glycolysis → fermentation → Krebs cycle b. Krebs cycle → electron transport → glycolysis c. glycolysis → Krebs cycle → electron transport d. Krebs cycle → glycolysis → electron transport e. electron transport → Krebs cycle → glycolysis

c. glycolysis → Krebs cycle → electron transport

16. Which wavelength of light will be reflected most when a beam of white light is directed at a solution of chlorophyll? a. yellow b. blue c. green d. white e. black

c. green

18. NADP+ in photosynthesis a. provides energy to start the process b. serves as a building block for glucose c. provides energy to split water d. accepts electrons and carries them to the Calvin cycle e. activates the electrons in chlorophyll

d. accepts electrons and carries them to the Calvin cycle

21. Which of the following must be present for cellular respiration to begin? a. water and carbon dioxide b. water and oxygen c. pyruvic acid and ADP d. glucose and ATP e. glucose and carbon dioxide

d. glucose and ATP

15. The light-dependent reactions of photosynthesis occur in the _____; the light-independent reactions occur in the ______. a. cytosol; stroma b. stroma; cristae c. cristae; stroma d. thylakoids; stroma e. stroma; thylakoids

d. thylakoids; stroma

22. What happens during the Krebs cycle? a. Hydrogen ions and oxygen form water. b. The cell releases a small amount of energy through fermentation. c. Each glucose molecule is broken down into two molecules of pyruvic acid. d. Hydrogen ions build up on one side of the mitochondrial membrane. e. Pyruvic acid is broken down into carbon dioxide in a series of reactions

e. Pyruvic acid is broken down into carbon dioxide in a series of reactions

13. Autotrophic activity in green plant cells is most closely associated with organelles called a. mitochondria b. ribosomes c. vacuoles d. centrioles e. chloroplasts

e. chloroplasts