If you place a plant in a glass container with its roots in dirt, provide water

Question

If you place a plant in a glass container with its roots in dirt, provide water and sunlight, but seal the container so air cannot enter, the plant will survive and grow.   If you place a mouse in a glass container, provide shelter, water and sunlight, but seal the container to air, the mouse will not survive an hour. Answer the following questions relative to your discussion of energy metabolism this week and last week.

What are the two major metabolic pathways that allow the plant to survive and grow?

Explain how these pathways cycle the resources needed by the plant.

Assume that the plant (not a seed nor a seedling) when first placed in the container has a mass of about 20g. After 6 months, the mass of the plant is about 75g. When the plant grows, it increases in mass. Of the components in the container; dirt, water, CO2, and O2, which component can be directly attributed to the increase in mass in the plant? Provide a one-sentence explanation.

What is the metabolic pathway missing in the mouse that prevents if from surviving in the glass container. Explain why the lack of this pathway leads to death.

Explanation / Answer

The metabolic pathways which allow the plant to survive and grow are respiration ( Electron Transport Chain) and photosynthesis (Photophoshorylation and Calvin cycle).

During photosynthesis plant synthesize the energy source or food required for its survival and growth using carbon dioxide and water available in the surrounding in presence of sunlight and cholorophyll releasing oxygen to the surrounding container.

In absence of sunlight the rate of respiration would be higher in plants than photosynthesis. During respiration oxygen released by photosynthesis is used and release carbon dioxide to the surrounding container which can be used for photosynthesis in the presence of sunlight .Thus the resources needed by the plant are replenished or recycled alternatively by these pathways.

The glucose synthesised by the plants via photosynthesis is used for survival of the plant and for its growth. The excess of glucose produced is converted to starch and is stored in the plant so that it can be utilized during scarcity of energy resources. All these factors would contribute to increase in mass of plant.

Mouse is not an autotroph i.e they cannot prepare food required for its survival like plants by photosynthesis instead they are dependent on other sources for food.

Absence of photosynthesis would lead to accumulation of carbon dioxide released during respiration in the container. The mouse can survive until the oxygen present in the container is available for respiration. Since the carbon dioxide and oxygen is not recycled like in the container with plant (due to absence of oxygen released by photosynthesis) mouse cannot survive for a longer duration.

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