Question

EXAM 3: CHAPTER 7 1. Why are photosynthetic organisms also considered autotrophic? What are heterotrophic organisms? How are both autotrophs and heterophs the same when it comes to the use of organic molecules to produce energy? 2. What is the particular part that oxygen plays in photosynthesis and cellular respiration? 3. Describe the structural aspects of photosynthesis. For example, where does photosynthesis take place and what parts inside the cell are used to carry out photosynthesis? What chemicals are necessary for photosynthesis to occur? 4. What happens step by step in photosynthesis? 5. Write the chemical equation for photosynthesis. Which part of this reaction is the oxidation? Which part is the reduction? 6. How is NADP+ a critical player in photosynthesis? 7. Explain the light reaction and the Calvin Cycle. How are these two reactions working together to produce the sugar needed for the plant? 8. The light reactions are made up of two photosystems. Describe each of the photosystems. Where do these reactions occur? When do they occur? 9. How are pigments used in the photosystems? How is it possible for pigments to catch light or absorb light to fuel the reactions of the chloroplast? 10. What is carbon fixation? What is nitrogen fixation? The Calvin Cycle is also called the dark reactions. Why? 11. What are the steps in the dark reactions? What role do the stomata play in the dark reactions? What enzyme is primarily involved in capturing or fixing the carbon from CO2? 12. What serious risk does a plant take when it keeps its stomata open during the day? What alternative types of photosynthesis have evolved to compensate for this risk?

Answer 1

Answer 1: As we know that the photosynthetic organisms are the organisms which are able to produce their own food by the use of sunlight. The process of photosynthesis requires the chlorophyll molecule for this process.

The reaction for this process is as

CO2 + H2O + Sunlight------- Sugar + O2(byproduct)

By the definition of Autotrophs we know that the organism which do not depend on any other organis source as their food material but they are able to synthsize their own food by use of carbondioxide and water in presence of some energy source(sunlight).

As the plants do photosynthesis means they are self nourshing organisms so we can call them as autotrophs.

Hetreotrophs are the organism which depends on others for their food means they are unable to synthesize their own food by using sunlight so they are called as heterotrophs.For example all human beings as well as animals are heterotrophs.As heteros = different Trophs = nurishment so these organism get energy by eating other plants , animals or decomposers. They generally use

Sugar + Oxygen = Carbondioxide + water + energy (ATP)

As we know that life is based on carbon and life also needs energy source . In order to grow and develop so the source of carbon and energy are great to categorize organisms. Organisms that obtain their carbon source from various organic molecule in their environment are called as heterotrophs . While the other organis obtain their carbon source from carbon dioxide present in its environment are called as autotrophs.

Both (autotrophs and heterotrophs) are same when there is the process of production of energy because the mechanism of production ot energy that is ATP is same for both. The mechanism by which organism use their organic molecule(glucose) is same which is known as cellular respiration. The equation for this is as

Sugar + Oxygen = Carbondioxide + water + energy (ATP)