Answer :There was enough oxygen in the atmosphere to support a major burst of life on Earth
Explanation:
The Great Oxygen Event marks the time, approximately 2.5 billion years ago, when there was enough oxygen in the atmosphere to support a major burst of life on Earth
For the first half of the Earht's history, there was no oxygen in the atmosphere. It was inhabited only by single-celled organisms.Of those simple life forms, the cyanobacteria may have. evolved a way to take energy from sunlight, and used it to make sugars out of water and carbon dioxide. They used the same chemical process we know as photosynthesis. This released vast quantities of oxygen into the atmosphere and triggered the evolution of complex life.
Answer: d- because a model is never exactly the same as the thing it represents
Answer:
The correct answer is - temperature, pH, substrate concentration.
Explanation:
Various factors affect the rate of enzymatic reaction such as pH, temperature, substrate concentration, availability of activators or inhibitors in the reactions, and enzyme concentration.
Temperature: Temperature affects the rate of the enzyme-catalyzed reactions. Like most of the reactions with an increase in temperature rate of enzymatic reaction also rises up to a maximum level and then declines if the temperature continues to increase as enzyme denatures after a particular temperature.
pH: Similar to the temperature pH also increases the rate of reaction up to a maximum level and then declines the rate as every enzyme acts only at an optimum pH range.
Substrate concentration: If the substrate concentration is increased gradually while the concentration enzyme remains constant, the rate of reaction will increase until it reaches a maximum.
Answer: b. Acetyl Co-A
Explanation:
Acetyl CoA produced through pyruvate, amino acids, and fatty acids are oxidized in the Krebs cycle in CO2, obtaining as products NADH, FADH2 and GTP (ATP). Parallel to this oxidation, the Krebs cycle produces compounds used as precursors for biosynthesis. As it is a cycle, an oxaloacetate molecule could, in principle, oxidize an amount indefinite of acetyl CoA. Acetyl-CoA is formed from the oxidative decarboxylation of pyruvate, sequentially performed by pyruvate dehydrogenase -PDH (complex multi enzymatic of 3 enzymes), in the mitochondrial matrix.
