Biology Related Topics: Cellular Metabolism Worksheet 1 ✓ Solved

Biology Related Topicscellular Metabolism Worksheet1 Is Cellular R

Identify whether cellular respiration and photosynthesis are endergonic or exergonic reactions. Explain the role of oxygen in cell respiration, including the final electron acceptor in aerobic respiration. Describe the three parts of the ATP molecule and compare ATP to RNA nucleotides. Discuss how enzymes function in cellular metabolism and define key terms including enzyme, substrate, active site, reactants, and products. Explain the nature of enzymes and the importance of selective permeability in cellular membranes, including which molecules pass easily and the conditions (isotonic, hypotonic, hypertonic) suitable for animal, plant, and bacterial cells. Compare active and passive transport, cofactor versus coenzymes with examples, and define concepts such as symbiosis, mutualism, commensalism, parasitism, autotrophs, and heterotrophs. Define oxidation and reduction, classify compounds like NAD+, NADH, FADH2, and FAD as oxidized or reduced, and associate key processes (glycolysis, citric acid cycle, electron transport chain, fermentation) with ATP production, pyruvate formation, CO2 generation, oxygen dependence, location within mitochondria, cytoplasm, and use of cytochromes. Explain under what conditions microbes and muscle cells produce lactic acid, whether the Pyruvate to lactate reaction produces ATP, and the function of this process. Determine the number of carbon atoms in glucose, pyruvate, acetyl groups, oxaloacetate, citrate, ethanol, and lactic acid. Define substrate-level phosphorylation and oxidative phosphorylation, and specify the locations of the Krebs cycle, oxidative phosphorylation, glycolysis, light cycle of photosynthesis, and Calvin cycle in eukaryotic and prokaryotic cells. Describe the origin of oxygen in photosynthesis.

Sample Paper For Above instruction

Cellular Metabolism and Photosynthesis

Cellular respiration and photosynthesis are fundamental biological processes that involve energy transfer within cells. These reactions are classified based on their energy dynamics: cellular respiration is an exergonic process, releasing energy by breaking down glucose molecules, whereas photosynthesis is endergonic, requiring energy input to synthesize glucose from carbon dioxide and water (Nelson & Cox, 2017).

The role of oxygen in cellular respiration is crucial; it acts as the final electron acceptor in aerobic respiration, forming water as a byproduct. Without oxygen, cells resort to anaerobic pathways such as fermentation (Voet & Voet, 2011). The ATP molecule comprises three parts: adenine base, a ribose sugar, and three phosphate groups. ATP is structurally similar to the nucleotides of RNA, with the key difference being the presence of three phosphate groups instead of one (Stryer, 1995).

Enzymes accelerate metabolic reactions by lowering activation energy. They bind specific substrates at their active sites, facilitating conversions into products. Enzymes are primarily proteins, characterized by their specificity and efficiency. Selective permeability of membranes allows cells to control internal environments, permitting some molecules to pass freely—such as oxygen and carbon dioxide—while restricting others. Molecules pass easily through membranes depending on polarity, size, and concentration gradients.

Cells maintain osmotic balance through isotonic, hypotonic, and hypertonic conditions. Animal cells thrive in isotonic environments, plant cells prefer hypotonic conditions where turgor pressure is maintained, and bacteria adapt to various osmotic conditions depending on their cell wall strength. Active transport consumes ATP to move substances against their concentration gradients, unlike passive transport which relies on diffusion or facilitated diffusion (Alberts et al., 2014). Cofactors are inorganic ions assisting enzyme activity (e.g., Mg²⁺), whereas coenzymes are organic molecules like NAD⁺, which assist enzymes in catalyzing reactions.

In biological interactions, symbiosis refers to close associations between different species; mutualism benefits both, while parasitism benefits one at the expense of the other. Autotrophs produce their own food using photosynthesis, whereas heterotrophs consume others’ organic matter.

Oxidation involves the loss of electrons, whereas reduction involves the gain of electrons. NAD⁺ is an oxidized coenzyme that becomes reduced to NADH during glycolysis and the citric acid cycle. FAD is similarly reduced to FADH₂ (Lehninger et al., 2017). In glycolysis, ATP is produced by substrate-level phosphorylation, while in the electron transport chain, ATP synthesis occurs via oxidative phosphorylation.

The Krebs cycle occurs in the mitochondrial matrix of eukaryotic cells and in the cytoplasm of prokaryotes, while oxidative phosphorylation takes place on the inner mitochondrial membrane in eukaryotes and the plasma membrane in prokaryotes. Glycolysis occurs in the cytoplasm in both cell types. The light-dependent reactions of photosynthesis occur in the thylakoid membranes of chloroplasts, whereas the Calvin cycle takes place in the stroma.

Oxygen generated from photosynthesis primarily originates from the splitting of water molecules (H₂O) during the light reactions (Nelson & Cox, 2017). Understanding these processes provides insight into cellular energy management and the vital interdependence of life forms.

References

• Alberts, B., Johnson, A., Lewis, J., Morgan, D., Raff, M., Roberts, K., & Walter, P. (2014). Molecular Biology of the Cell. Garland Science.
• Lehninger, A. L., Nelson, D. L., & Cox, M. M. (2017). Lehninger Principles of Biochemistry. W.H. Freeman.
• Nelson, D. L., & Cox, M. M. (2017). Lehninger Principles of Biochemistry. W.H. Freeman.
• Stryer, L. (1995). Biochemistry. W.H. Freeman.
• Voet, D., & Voet, J. G. (2011). Biochemistry. Wiley.