Lec. 18 - Cellular Respiration and Photosynthesis

Question 1

Describe oxidation-reduction reactions and their importance in cellular respiration and photosynthesis.

Answer 1

Redox reactions are chemical processes in which there is a transfer of electrons between reactants. In cellular respiration, they play a central role in extracting energy from organic molecules to produce ATP. In photosynthesis, they occur in chloroplasts and are responsible for converting light energy into chemical energy stored in glucose.

Question 2

Explain why photosynthesis is an endergonic process and cellular respiration is an exergonic process.

Answer 2

Photosynthesis is endergonic because it requires an input of energy in the form of light to drive the synthesis of glucose. Cellular resp. is exergonic because it releases energy by breaking down complex organic molecules to produce ATP.

Question 3

Compare and contrast the ETC and chemiosmosis in cellular respiration and photosynthesis.

Answer 3

Both involve electron transport, the generation of a proton gradient, and ATP synthesis. Differences are that in cellular resp., the ETC and chemiosmosis occur in the inner mitochondrial membrane but in photosynth. they happen in the thylakoid membrane of chloroplasts.

Question 4

Describe the process of generation oxygen in photosynthesis and water in cellular respiration.

Answer 4

In both, the generation of oxygen and water respectively is a result of specific chemical reactions involving the transfer of electrons and protons.

Question 5

Compare NAD+ and NADH; NADP+ and NADPH.

Answer 5

NADH is the reduced form of NAD+ and is a carrier of high-energy electrons. NAD+ is an electron acceptor. NADPH is the reduced form of NADP+ and serves as a carrier of high energy electrons and hydrogen ions.